FIELD OF THE INVENTION
The present invetion relates to an instrument to measure the cm resistance of fabrics. The invention further relates to development of a simple model on the tuning forces and the distance slid to make a cut in the material. The invention also provides quantitative measures of factors that influence cut resistance of fabrics and which can be used to design a cut resistant fabric. BACKGROUND OF THE INVENTION
Cut resistance is the property demonstrated bv a material or combination of materials, when a sharp edged device initiates cut through. In general, there are two tvpes of cut hazards:
1. Clean, sharp edge cuts, such as knife blades and clean edge sheet glass.
2. Abrasive cut hazards: These include rough edge sheet metal; stamped or punched sheet metal; and rough edged sheet glass.
Clean Sharp Edge Cut Hazards
Cut resistance for clean sharp edges is measured with the Cut Protection Performance Test (CPPT) on ASTM Standaid Fl790-97. This test measuies the weight (in grams) required to cut through a glove on a 25 millimeter pass using a razor-sharp blade.
Factors influencing cut resistance to Clean Sharp EAge Flazards
1. Tensile strength: The strength of the fiber is so great that it cannot be broken. Stainless steel has this capability.
2. Abrasive action: The fiber is so hard that it will dull a passing metal blade. A glass fiber core can provide this feature.
3. Slippage: The blade actually slides across the yarn without catching to cut. Certain monofilament fibers have this advantage.
Fabrics that are designed to resist clean edge cuts are usually made with core yarns. Core yarns are manufactured bv wrapping different yarns around a center or solid fiber core. Each wrap provides a factor of cut resistance. When evaluating cut-resistant fabrics, a user should ask for the CPPT rating of the fabric, its fiber composition, and which factor of cut resistance each yarn provides. However, these fabrics cannot protect against moving or rotating blades or serrated edges. Moving blades will eventually cut through any fabric, and serrated edges can penetrate the finely knit cloth and cut the hand. Abrasive Cut Hazards
While there is no known test to measure abrasive cut resistance in gloves, the ASTM Fl790-97 standard is often used as a reference point. However, this standard tests with a razor-sharp blade. Abrasive cut hazards do not just cut, they tear and abrade and consequendy require a different type of fabric for protection. Fabrics used in these areas must provide cut resistance,

along with the additional requirements of abrasion resistance and tensile strength. Such fabrics also tend to be thicker in order to resist the rougher edges. There are several fatiors which influence resistance to abrasive cut ha/aids:
1. Stretch: This allows the fabric to move ahead of the cutting edge. This is win most cut resistant gloves are knit and not woven.
2. Rolling: The yarn fibers roll as the edge passes across.
3. Loft: A soft fabric resists the action of cutting edge. [Waco, Ocaijicitioiutl I cilth Sajelj 2004, 73, June, 86]
Simulation of the Cutting Process
The factors that need to be taken care while developing and testing a material for cut protection are:
(a) Transverse work of deformation.
(b) Longitudinal stretch.
In some cases, cut performance is related to the transverse mechanical properties of the fibers. To lelate the end use performance of a glove for example to the properties of the single fibers, a visualization of what happens during the cutting process has to be seen. The nature of fiber deformation as a result of initial contact with the blade lead to conclusion that the deformation appears to be a very much plastic lateral compressive deformation, with little-evidence of failure in transverse direction. In actual cutting process, the blade moves rapidly perpendicular to the fiber axis and a suggestion is that cutting is similar to a rapid wear process.
If there is any agreement on the general wear of solids, it is a complex process and not properly understood. There appear to be numerous ways to approach the subject depending upon the specifics of the process, the materials involved, and ones own personal inclination, For this case wear can be defined as
• The moving blade is large, essentially infinite source of energy.
• Energy transferred from the blade into the fibres by means of frictional forces.
• The energy transferred is then expanded through the permanent (non-recoverable deformation of the fibres).
• The non-recoverable deformation, that is moving of fiber material away from the fiber/blade contact point, is the cutting. The time (or cycles or cut distance), it takes to move all the material from under the blade is the measure of the cut performance.
Two major variables in the above definition will influence the cut performance, (i.) The amount of energy transferred from the blade to the fiber. This depends on the actual contact area between the blade and the fibres and the coefficient of friction.

In detail, it is very complex. In this treatment, the cncrgy transfer process is assumed constant, (ii.) The amount of energy necessary to move the fibres a\va\ from ihe fibrc/hlndc contact point. This is related to the mechanical properties ot the fibres in tin-direction transverse to the fiber axis. More specifically, it intolves the energy necessary to permanently deform the fiber. The transverse mechanical properties can be characterized by means of KES G X 1 fiber compression tester. The instrument is used to measure the compressive stress/strain curves of single fibres in the direction transverse to their longitudinal axis. Te data for each determination has to be analyzed to estimate the energy (work) necessary to attain 40% transverse compressive strain. By the curve of stress (gm/micron") and strain (displacement/diameter) we get the transverse work of deformation (TWO). Higher work of deformation means higher cut resistance. [Warren F Knoff, "Fiber resistance to cutting," Textile Asia, 2002, February, 33 . 36| Types of breakage during cutting
Breakage can be of the fiagile type of the ductile type. Breakages of fibres like carbon oi glass are of the fragile type whereas for organic fibres especially high performance ones are of the ductile type. Organic fibres are anisotropic (they have outstanding performance in the longitudinal sense but poor in the lateral one), so organic fibres arc to be avoided for cut resistant applications. Carbon and glass have good resistance to lateral compression. The cut performance also depends on the longitudinal stretch. When fibres arc exposed to a longitudinal stress or lateral impact it doesn't generally deform by pure lateral compression, but breaks and deforms by longitudinal traction. Tearing occurs when elongation at Lear is reached. Mechanism of energy transfer during cutting
In case of fast shocks, the energy of impact is also propagating at a longitudinal speed v. Fabric tearing also depends on the dissipation of the energy in the fiber at a speed of v and longitudinal traction. The transmission speed v is measured using a device using two -piezoelectric transducers, tie taken T by the signal to reach the receiving end of the transducer from the emitting end is calculated; the knowledge of this speed v, enables us to calculate the sonic modulus E„ as: E, = pv"
The speed of propagation of waves through the material is V= (E/d) where E is the tensile modulus and d is the density of the material.
The transmission of waves over the fabric surface also depends on the construction parameters; in case of woven structures, the main decision has to be the weave type. It is found that increasing the number of crossover points in the fabric has a positive effect in the transmission of energy. The energy is spread over a larger area. This is because of the contact

points that the wave is transmitted to the other varus. It has been found (hat when a lamination is provided on the surface of the individual fibres this transmission is reduced. Bul an increase in the number of cross over points also has a negative impact. The increase in the number of these crossover points results in deflection of the wefts from these points. These points act as li\ed points in the transmission of the weft and as a result, the reflection of these waxes from the cross over points increases the amplitude of the waves and can reach the maximum value and lead to failure. In case of non-wovens, the energy transfer and tear have a different mechanism. The mechanism of resistance to puncture docs not rely on tearing; instead, fiber deformation plays a major role. There is a reflection of shock waves at the end of non wovens 'I'he amplitudes of incident and reflected waves arc of opposite signs and waves tend to cancel each other. Elongation at break is not reached. With felts, a flock of fibrous material which stops tin-initial penetration of the cutting material is formed at the top.
Also coating prevents from fiber spacing and has a positive effect on the puncture resistance. Flexibility and thickness may be adjusted for more comfort. High performance fibres can be divided into two types, fust is the stiff chain l\pe and the second being the flevible drain type. Stiff chain type includes aramids, which have a fibrillar morphology and the ordinary fibres which have a spherulitic morphology. ["Effect of friction on cut resistance of polymers," Jot/mi/ of Thermoplastic Composite Ma/eiials, 2005, 18(1), 23-25] Cut Resistant Fibres and Properties
Fibre technology has improved substantially in the last decade to provide textile engineers design opportunities to increase performance levels and reduce weight in different technical textiles. New lightweight, high-strength fibres and innovations in engineered yarns have created recent advancements in cut protection by offering products that are soft and flexible.
Inhercndy cut-resistant materials are those materials that roll with the cut threat, that have a lubricious surface causing the cut threat to "glide" over the fabric, or that have a molecular structure whose bonds are great enough to resist or prevent separation thereby slowing the cutting edges' ability to pass through the material. Exemplary inherently cut-resistant materials include aramids, ultra high molecular weight extended chain polyethylene, liquid crystal polyester, polyolefins, polyesters, polyamides, PBO, polybenzothiazoles PBZT, bicomponents, coated materials, and blends thereof. Those materials can also be combined with an elastomer. Exemplary high tensile strength materials include those materials having a tensile strength of at least 9.0 grams per denier. Cutting of fibers
Fibers can be served in other ways than by the application of tensile, torsional, flexural or shear stresses. Cutting is a method which may be deliberate or accidental, and the appearance of

the break depends not only on the fiber type but also on the instrument. With a bluna knife-, cutting may be little more than a means of applying tension, so that break is a distorted form of tensile failure. But with sharper instruments distinct forms occur.
A sharp razor gives a clean cut across a fiber with the only features being some grooves in the direction of cutting and a small lip at the edge of the fiber. In contrast to this, cutting with a knife shows more spreading of the break. There is some similarity to the high speed breaks and a common feature may be heating of the fiber which could occur as the knife is drawn across it.
The grooves in the end of a nylon fiber cut with a razor blades is quite deep. In poh ester, perhaps because there is a higher resistance to cutting, there is more distortion of the fiber and in a razor cut. The effects of different forms of cutting on most of the fibers are broadly similar in form. A razor cut of cotton is clean, with a few grooves on the surface and perhaps some tearing. Tearing and squashing are much more apparent in a knife cut. The scissor cut of cotton is somewhat sharper, the razor cut of viscose rayon shows much less distortion of the fiber end than the knife cut.
Differences between the clean cuts with a razor and the greater distortion of the knife and scissor cuts arc shown by acetate fibers, acrylic fibers and wool. [Hearle ] W S, Lomas B, Fiberfailure and Wear of Materials, Ellis Horwood Ltd] Organic fibres Kevlar
KEVLAR is a remarkable fibre invented by DuPont more than 25 years ago. It is five times stronger than an equal weight of steel, has exceptional stretch resistance and is inherently flame resistant. It is a natural choice for soft body armor fabrics. The chemical structure of aramids distinguishes them from other commercial man-made and natural fibers and gives KEVLAR® its unique properties. It has high strength, high modulus (stiffness), toughness and thermal stability.
Kevlar is an aramid fiber whose strength comes from its chemical composition and how those various chemical elements bond. Its strength also comes from how it is spun (or turned into thread/fiber). Kevlar has the feel of cotton but offers a higher level of cut protection "without loss of dexterity. Kevlar's weakness is low tolerance to chlorine bleach. One drawback of para-aramid fibers is that they tend to suffer from a relatively low abrasion resistance due to their fibrillation tendency. The risk associated with this modest abrasion resistance is the reduction of die cut performance of the protective clothing with time under service. There is still a need to provide a material having both a high and durable cut performance and a very high abrasion resistance. Now, it has been found that by combining specific fiber ingredients in a specific construction style, it was possible to realize rapidly, direcdy and easily very high cut resistant and

high abrasion resistant fibrous material. In particular, it is possible to reach the same cut resistance level with higher level of abrasion resistance than if same liber ingredients are either taken separately or combined in a different construction style. |http://www.vnscll Procoin] Spectra
Spectra is a high modulus, high tenacity blend of Polyethylene and Pnlypropylcne (plastics) and are often referred to as a continuous filament fiber. This gives Spectra its amazing strength especially when it comes to cut resistance. Spectra® is the strongest, lightest man made biber. It is referred to as ultra high molecular weight extended chain polyethylene. Spectra.RTM. 1000 has a molecular weight (Mn) of 1,500,000; a breaking strength (e.g. tenacity) of 3.0 GPa; and a modulus of 170 GPa. Tablet: Properties of Spectra Fibers [http://www.spectrafiber.com/cut/indcx.html]

(Table Removed)
Spectra arc 10 times stronger than steel, 40 percent stronger than aramids and stronger and lighter than virtually every other commercial high modulus panel. It has excellent vibration dampening, flex fatigue and internal fiber-friction characteristics. [http://www.Lasco Intl Group.com]
Gloves made of Spectra are often much cooler than gloves made of Kevlar but they tend to offer less dexterity. Spectra are also much "slicker" due to its construction, and it has a low tolerance to heat. These differences are the reason why Kevlar is better suited for most industrial/automotive applications and Spectra is better suited for food sen-ice and meat processing. [http://www.Ansell Pro.com] Other organic fibres
Liquid crystal polyester, polyolefins, polyesters, polyamides, polybenzoxazoles PBO, polybenzothiazoles PBZT, cotton, wool, rayon, TEFLON, PBD and blends thereof. These fibres though do not possess inherent cut resistant property, are used in the development of cut resistant yarns along with other fibres. Filled cut resistant fibres
Cut-resistant rnulticomponent fiber, usually a sheath/core bicomponent fiber, comprises a core component of filled aromatic polyamide polymer and a sheath component of unfilled

aromatic polvamidc polvmcr. The fibre forming polunci preferably is melr processable, in which case, the cut-resistant fiber is tvpicallv made by melt spinning. For polymers that cannot be spun into fibers in the melt, wet spinning and drv spinning niav also IK- used lo produce fibers ha\ ing improved cut resistance. Amorphous polymers, semi crystalline polymers and liquid crystalline polymers can also be used. Of these, semi-crystalline and liquid crystalline polymers arc preferred. The core component formed from a fiber-forming aromatic polvamidc polymer and a hard filler, having a Mohs Hardness Value greater than 3, being present in an amount of about 0.05% to about 20% bv weight based on the total weight of the fiber. Filler has an average diameter up to 20 microns and an average length up to 20 microns, liller is selected from the "group consisting of metal oxides, metal carbides, metal nitrides, metal sulfides, metal silicates, metal silicides, metal sulfates, metal phosphates, metal borides, and mixtures thereof. The hard filler can also be a metal or metal allov selected from the group consisting of iron, nickel, stainless steel, tungsten, and mixtures thereof.
The hard filler is present in an amount ranging from about 0.06% to about 50% by weight based on the weight of the core component.
The sheath component consists of an unfilled fiber-forming aromatic polvamidc polymer, having a denier in the range of about 1 to about 50 dpf. It is found that the cut resistance of the filled fibre improved by at least 20% compared with a fiber comprising said polymer without said filler. The sheath comprises about 5% to about 75% by volume of the sheath/core fiber. It is found that the cut resistance is higher when fewer sheaths is used, with 10% by volume of sheath polymer giving good CPP values and a smooth fiber. It is contemplated that the sheath could be as low as about 5% by volume up to as much as 50% by volume, with the overall increase in cut resistance being proportional to the amount of filled fiber in the sheath/core fiber. However a loss of up to 40% tensile strength can result when filling mono-component Kevlar fiber to improve its cut resistance.
In contrast, the filled bi-component fibers can have improved cut resistance without sacrificing tensile strength, even for fibers formed of para-aramid polymers. It is believed that the unfilled aramid component of the fibers allows the fibers to maintain desired tensile properties (particularly for para-aramid polymers) while the filled component imparts desired cut resistance. Indeed, the unfilled component can comprise up to about 75% by volume of the fiber as a whole without exhibiting significant loss in cut resistance.
The filled fiber resists flexural fatigue. Thus a flexible, flcxural fatigue-resistant and cut-resistant fiber may be made from a suitable polymer filled with a hard material that imparts cut resistance. The fiber will generally have a denier in the range of about 1 to about 50 dpf, preferably in the range of about 2 to about 20 dpf, and most preferably about 3 to about 15 dpf.

lor isotropic polymers and particularly for filled Pl'.'l I lie mosi p'refcrred range of fiber sixe is
about 1.5 to about 15 dpf, and most preferably about -1 dpf. One difficult in making and using
cut resistant fibers and yarns described above is abrasn encss of filled fibers, which causes faster
wear of the equipment used to process the fiber. [IS 6,162,538, I S 6,210,798, L'S 6,127,028]
Inorganic Fibres
Glass, carbon and ceramic fibres are used in cut resistant textiles.
Metal Fibres
By metal fibers is meant fibers or wire made from a ductile metal such as stainless steel, copper, aluminum, bronze, and the like. Stainless steel is the preferred metal. The metal fibers are generally continuous wires. The metal fibers are 10 to 150 micrometers in diameter, and arc .preferably 25 to 75 micrometers in diameter. |LTS 6,21(),798| Essential Properties for Fibres to Be Cut Resistant
1. Low coefficient of friction.
2. High resistance to flex fatigue.
3. Good resistance to abrasion.
4. High tensile strength.
Methods of Manufacturing Cut Resistant Yarns Spectra Guard Engineered Yarn
This patented system combines Spectra® fiber (big 1) with glass fiber in the core, wrapped with Spectra fiber. The result: products with two to five times the cut resistance of spun aramids without sacrificing comfort, dexterity or tactile sensitivity. It provides premium cut ~ resistance in protective gloves and sleeves for high-risk applications, such as meat processing, glass and metal handling. [http://wn.vw.spectrafiber.com/pdfs/hon-pf-ps25-SG.pdf] Properties
Flexible design options allow for products with exceptional dexterity, comfort, cut and abrasion resistance, and tactile sensitivity. Excellent tear and slash resistance create performance for vandal-resistant and safety fabrics. Other fibers, such as nylon and polyester, can be used in the Spectra Guard™ engineered yarn system to create value-priced options for specific applications that do not require the highest level of cut protection.
Provides premium cut resistance in protective gloves and sleeves for high-risk applications, such as meat processing, glass and metal handling, easy to launder, resists bleach and other chemicals. [http://www.spectrafiber.com/pdfs/hon-pf-ps26-SGcx.pdf] Friction-Textured Cut-Resistant Yarn (Fig 2)
A cut-resistant yarn formed of a multifilament yarn, each filament of a polyester material having ceramic platelets embedded to provide a yarn having cut resistance, and the yarn having a

friction textured false twist inserted therein to pro\ ide :i surface exhibiting lomlort characteristics rendering the yarn suitable for use in apparel, the vain before being friction textured has a denier of between 20-500 denier and after being friction textured a denier of ISO, and is comprised of 68 filaments. The yarn includes a strand of spandex vain attached to the multifilament yarn for providing stretch to the yarn; the strand of spandex vain is attached to the multifilament yarn by air tacking. Air tacking is a process b\ which the filaments of the textured yarn are separated by a jet of air, providing space in the fiber bundle for the elastomeric yarn to be entangled and thus held in place by those filaments.
The tacking process may be carried out during the friction texturing process, or may be carried out as a separate step after the yarn has been removed from the friction texturing machine. The elastomeric yarn 25 is preferably in the range of 10-240 denier, and the cut resistant yarn is in the range of 20-1000 denier. [US 6,766,635] Cut Resistant Para-Aramid Yarn
A yarn having increased cut resistance is made from para-aramid fibers, wherein the \arn has low twist and the staple fibers in the yarn have high linear density. The yarn has a linear density of 150 to 5900 dtex and a twist factor of less than 26 wherein it includes para aramid staple fibers having a linear density of 3 to 6 dtex and a length of 2.5 to 15.2 centimeters. It has been discovered that protective garments made from spun yarns of para-aramid fibers are softer if made from yarns which have a low degree of twist. Moreover, it has been discovered that the cut resistance of the fabric of such garments is independent of the degree of twist imparted to the varns in the fabric and that the cut resistance ot the fabric is improved by increasing the linear density of the individual fibers used in the yarns.
In the past, it has been the usual practice to use yarns with a high degree of twist for cut resistant fabrics in protective garments. It was generally believed that the high twist was necessary for providing a yarn of high strength; and that the high strength was necessary for good cut resistance. That high degree of twist causes the fibers to be rather tighdy bundled in the yarn form and creates a rather hard yarn.
It has now been discovered that yarns of high twist are not necessary for effective protection; and, in fact, it has been learned that cut resistance is substantially independent of the degree of twist in yarns. It has been discovered that fabrics made using yarns of low twist are much softer with a finer "hand" than fabrics made using highly twisted yarns. Moreover, it is believed that decreased twist results in increased fabric softness, irrespective of the kind of yarn or the material from which it is made.
While it is necessar}7 to have some degree of twist in the yarns in order for the yarns to stay together, tests indicate that cut resistance is not affected by changes in yarn twist. That is,

the additional strength provided to the varn b\ the use of increased twist does not translate lo improved cut resistance. As to the linear density of indi\ idual staple libers, it has been discovered that increased linear density in the staple results in increased cut resistance for the \arn. In (In-past, cut resistant protective garments have utilized yarns having individual staple fibers ol about 2.5 dtex or less. But later it was found that fibers of less than about 3 dtex may not yield the improved cut resistance. Fibers of more than 6 dtex exhibit very good cut resistance; but are not aesthetically acceptable and may not yield fabrics with adequate comfort. The Cut Resistance is a definite function of staple linear density and is relatively independent of twist. The cut resistance improves dramatically with increase in staple linear density and the increase is most dramatic at staple linear densities of greater than 2.5 dtex.
The yarns can be made by any appropriate spinning process among which can be mentioned, cotton/worsted/woolen ring and open end spinning. The cut resistance is a function of the linear density of filaments in the yarn and not of the manner that the yarn is presented in a fabric. Composite Cut Resistant Yarn
US 4,384,449 provides cut resistant/protective fabric is made from a composite yarn having a core of a flexible wire alongside an aramid fiber strand and a wrap of an aramid fiber.
US 4,470,251 teaches cut resistant/protective fabric is made from a composite yarn having a core of two annealed stainless steel wires and a high strength aramid fiber, and a multi-layered wrap having a bottom layer of an aramid fiber and a top layer of a nylon fiber.
US 5,119,512 teaches cut resistant/protective fabrics is made from a composite yarn.
This composite yarn is made from at least two non-metallic fibers; one fiber has a high level of
hardness, and the other is an inherently cut resistant fiber like a polyethylene fiber such as
_ Spectra. This patent also discloses that man-made synthetic fibers may be used in both the core
and the wrap.
US 5,442,815 discloses cut resistant/protective fabric is made from a composite yarn having a core of an elastomeric (Spandex) fiber, and a wrap of a cut resistant fiber. This cut resistant fiber has a tenacity of at least 15 grams/denier.
Another cut resistant composite yarn made from low tenacity high performance fibres. The yarn includes a polyethylene fiber having a tenacity of less than 10 grams/denier and a molecular weight of about 100,000. The polyethylene fiber is in the wrap. The core may comprise one or more fibers of similar or dissirnilar materials. The core fibers may be selected from the group consisting of metal wire, fiberglass, man-made synthetic fibers, and combinations thereof. The wrap may comprise one or more fibers of similar or dissirnilar materials. The wrap

may have one or more layers of fibers. The wrap fibers ma\ be selected 1mm the group consisting of metal wire, fiberglass, man-made synthetic fibers, and combinations thereof.
Man-made synthetic fibers include, but are not limited to, the following fibers identified
~by their generic names: acrylic, modacryhc, polyester, rayon, acetate, sarnn, a/lon, nytril, nylon,
rubber, spandex, vinal, olefin, vinyon, metallic, glass, anidcx, noyoloid, aramid, and I'BI. Also
included in the foregoing are man-made synthetic polymers that are doped or loaded with
materials that enhance the cut-resistant properties of the fibers.
The cut resistant fiber referred to herein is preferably a high performance fiber, having a tenacity of less than about 10 grams/denier. The preferred cut resistant, high pcrformanci. fiber is a polyolefin fiber, e.g. polyethylene fiber. The polyethylene fiber has a molecular weight of about 100,000 and a tenacity of less than about 10 grams/denier. This polyethylene fiber specifically excludes SPECTRA.RTM fiber and conventional high density polyethylene (HDPE) fibers. Conventional high density polyethylene fibers are characterized as having tenacities of less than 6 grams/denier. Polyethylene fibers with molecular weights greater than 150,000, or with tenacities greater than 15 grams/denier, are also excluded from the material claimed herein. The preferred polyethylene fiber is CERTRAN.RTM.
The core consists of a twistless 500 denier polyester yarn and a monofilament stainless steel wire (0.003 inch diameter). The bottom wrap, surrounding the core, consists of CERTRAN.RTM. M high performance fibers wrapped in the "Z" direction with 11 turns per inch (TPI)- The top wrap, surrounding the bottom wrap, consists of 500 denier polyester yarn wrapped in the "S" direction with 11 turns per inch (TPI). [Hearle J W S, Lomas B, Fiberfailure and Wear of Materials, Ellis Horwood Ltd]
Cut resistance of the foregoing yarns demonstrated that their cut resistance was the same as that of yarns made with "high strength" polyethylene yarns or fibers (e.g. polyethylene yarns made with Spectra.RTM. or CERTRAN.RTM. HMPE). This is contrary to the conventionally held wisdom that cut resistance is a function of fiber strength. Additionally, it would appear that cut resistance is not a function of molecular weight. As an example of the foregoing comparison of the cut-resistance between the three yarns discussed, the following test results are set forth. [Hearle J W S, Lomas B, Fiber failure and Wear of Materials, Ellis Horwood Ltd]
Table 2: Comparison of cut resistance of yarns

(Table Removed)

Ply-twisted yarn for cut resistant fabrics
A ply-twisted yarn useful in cut resistant fabrics is made by pn>\ iding a first multifilament yarn of continuous organic filaments having a tensile strength of at least -I grams per denier and having a twist in a first direction of from 0.5 to 10 turns per inch; providing a second vain -comprising 1 to 5 continuous inorganic filament(s); and ply twisting each other 2 to IS turns per inch in a second direction opposite to that of the twist in the first vain to form a plv twisted varn having an overall effective twist of +/-5 turns per inch. By "effective twist level" it is meant the algebraic sum of the turns per inch, taking the multifilament twist direction as being negative and the ply twist direction as being positive. It is desirable that the effective (wi*l lex cl IK- beluL-en -2 and 2 and it is preferred that the effective twist level be positive. The multifilament continuous filament vam has preferably a denier in the range of 200 - 1000 denier, and after plv twisting with the inorganic filaments the cut resistant ply-twisted varn has a denier preferably in the range of 320 - 1400 denier. Inorganic filaments include glass filaments or filaments made from metal or metal alloys. The preferred continuous inorganic filament yarn is a single metal filament made from siaiuless steel. The fabrics made with these ply-twisted yarns have in combination improved cut resistance and improved tear resistance over prior art fabrics and preferably have improved abrasion resistance. These fabrics typically weigh in the range of 4 to 12 ounces per square yard and can be any orthogonal weave, however plain and 2/1 twill are the preferred weaves. The cut resistant yarn component can also have, incorporated in the multifilament continuous filament yarn, or in the plied varn as a separate entity, up to 10 weight percent and as much as 20 percent by weight nylon fiber for improved abrasion resistance. [US 20040065072) Methods of Manufacturing Cut Resistant Fabrics
The cut resistance of textiles depends on the arrangement of the cut resistant fibres in the fabric. The relation between fibre arrangement and cut resistance are almost unknown though. Weaving, weft knitting and warp knitting provide different possibilities concerning the additional incorporation of high performance fibres. Layered composite high performance fabric
A composite layered protective fabric having an outer primary layer composed of an abrasive material and an inner primary layer composed of an inherendy cut-resistant material positioned below the outer primary layer and when assembled into a garment is positioned proximate to the wearer's skin.
As shown in Figure 3, the fabric includes an outer primary layer 11 and an inner primary layer 13. The outer primary layer 11 is formed with yarn made from an abrasive material. Exemplary abrasive materials include fiberglass, wire, fiberglass and wire, grit based fibers, bicomponents (extruded filaments surrounding a core of dissimilar material), coated materials,

and blends thereof. The inner priman liner 13 is formed with \arn made l"r< mi an inhereiul\ cm resistant material or a high tensile strength material. . Inherently cut resistant materials are those materials that roll with the cut threat, that have a lubricious surface causing the cut threat l<> "glide" over the fabric, or that ha\ e a molecular structure whose bonds are great enough to resist or prevent separation thereby slowing the cutting edges' abilin lo pass through the material. Exemplary inherently cut-resistant materials include aramids, ultra high molecular weight extended chain polyethylene, liquid ciystal polyester, polyolcfins, polyesters, polyamides, polybenzoxarolcs PBO, polybcnzothiazoles PBZT, bicomponcnts, coated materials, and blends thereof. Those materials can also be combined with an elastomer. Exemplary high tensile strength materials include those materials having a tensile strength of at least 9.0 grams per denier.
The inner priman- layer 13 and outer primary layer 11 are simultaneously combined in a continuous one-step knitting process that plates the layers together. The resulting protective fabric provides significantly greater cut protection than a single layer fabric of the same weight.
As shown in Figure 3, cae.li vain has alternating bottom stitches and top stitcher. The top stitches 15 of the outer priman- layer 11 are aligned with the top stitches 16 of the inner primary -layer 13 and the bottom stitches 17 of the outer priman- layer 11 are aligned with the bottom stitches 18 of the inner priman- layer 13.
The continuous one-step manufacturing process plates the outer primary layer 11 to the inner priman- layer 13. The top stitches 15 of the outer primary layer 11 are intertwined with adjacent bottom stitches 17 of the inner primary layer 13 and the bottom stitches 17 of the inner primary layer 13 are intertwined with adjacent top stitches 15 of the outer primary layer 15 thereby plating the layers together.
The outer primary layer 11 is the layer first contacted by the cutting edge of a sharp object. Because the outer primary layer 11 is made from an abrasive material, the abrasive material in the outer layer acts to dull the sharp edge of the cutting surface. As a result, once the sharp edge penetrates through the abrasive outer primary layer 11 to the inner primary layer 13, the material in the inner primary layer 13 can more effectively repel the sharp object.
As shown in Figure 4, an alternative design of the fabric which includes a secondary- layer 25 in addition to the outer primary layer 21 and the inner primary layer 23. Each of the three yarn layers has alternating top and bottom stitches. The top stitches 27 of the outer priman- layer 21 are aligned with the top stitches 29 of the inner primary layer 23 and the top stitches 31 of the secondary layer 25. Also, the bottom stitches 33 of the outer primary layer 21 are aligned with the bottom stitches 35 of the inner primary- layer 23 and the bottom stitches (not shown) of the secondary layer 25. The upper stitches 31 of the secondary layer 25 are intertwined with the

bottom stitches 33 of the "outer primarv layer 21 therein" plating i lie sec oiul:n\ la\ei 25 m i IK-outer primary layer 21. The upper stitches 27 of the outer pnman lau'r 21 an- intertwined with the bottom stitches 35 of the inner primary layer 23 thereby plating ihe inner pnman l:i\er 23 lo the outer primary layer 21.
Moreover different materials can be used which can create garments that can address almost a limitless range of potential threats experienced by a given wearer. Some of these materials include antimicrobial materials, static dissipativc materials, high visibtlin fibers, impact absorbing materials of synthetic or manmade components such as foam ncoprcne extruded thread, as well as the full range of conventional and unconventional textile materials. These materials may be combined in many fashions including but not limited to twisting, wrapping, spinning, commingling, coating, co extruding, braiding, entangling, plying, and others. The shared commonality between the materials is limited only to their ability to be knitted or woven into a protective fabric having an abrasive layer and an inherently cut-resistant layer interior to the abrasive layer. Finally, a secondary layer can be added to serve a large variety of functions. [US 5,965,223] Aramid fabrics to offer stab-resistance
To meet the requirements of a cut resistant fabric it has to be made of fibres with high _ tensile and shear strength. These properties are met best by para-aramid fibres.
WO 97/49849 discloses a tightly woven fabric for protection against sharp instruments
such as awls or ice picks. The construction is based on yarns of less than 500 dtex which have a
toughness of at least 30 J/g. In the yarns, individual filaments are less than 1.67 dtex. The fabrics
are joined around their edges, but otherwise are free to move relative to each other. The patent
says that for sometime it was believed that ballistic resistance could do to a large extent be
equated with stab resistance., but that this has proved to be fallacious-thc requirements for stab
resistance are quite different. For example, making a fabric with yarns that have filaments of
1.67dtex or less, dramatically improves its stab resistance. The implication is that these fine
filaments produce articles having reduced interfilament spaces and so create a structure that is
more difficult to penetrate with sharp articles. Further in anti-ballistic vests the multiple layers of
-fabric need to be joined, whereas in this latest development stab resistance is increased if they are
not. Another important requirement for stab resistance is the tightness of the fabric, defined by
the ratio of the actual cover factor to the maximum cover factor. The patent says this should be
at least 0.75. For instance, the maximum cover factor for a plain weave is 0.75 so a plain weave
with an actual cover factor of 0.68 has a fabric tightness of 0.91. The specification that the yarn
should be less than 500dtex is based on the reasoning that in larger materials there is a tendency
for the yarns and the filaments to yield, so easing penetration by the sharp instrument. However,

at less than lOOdicx it is hard to weave yarns wiihoui damage. |liil'p:, . w \\ A .technical
textiles.net]
Cut-resistant warp-knitted textiles
The fabrics have a warp-knitted face structure and an aramkl vain struciiiiv as the cut resistant side. The warp knitting technology has the best conditions to anah/c ihc relation between the arrangement of the cut resistant yarns and its cut resistance. The basic fabnc provides only the general properties for use and has poor cut resistance. The implementation of the cut resistance is done bv weft insertion of high performance fibres on the back side and it's -binding with stitch threads. The use of high performance fibres as stitch threads makes no sense because of the insufficient protection against UY radiation and rapidlv increasing material costs. The warp knitting technology provides a certain number of variations to bind the weft insertions. The straight arrangement of the reinforcement thread system is analyzed in group 1. The variation in the warp density of the reinforcement threads can determine the relation between reinforcement thread distance and achievable cut resistance. In this group, an increase of cm resistance is achieved ordiogonal to the reinforcement direction. Additional well insertions can provide reinforcement in warp direction.
In group 2 (Fig 5) the reinforcement structures are arranged in the most common way of weft insertion used in warp knitted fabrics. The variation of the set-up and the use make cut resistant fabric for protective apparel; and the fabric is comfortable and non abrasive as well as cut resistant. It has been found that a very small amount of metal fiber can increase cut resistance of the fabric to a surprising degree. The bundles 1 may be the same or different. If the fabric is knitted, any appropriate knit pattern is acceptable. Cut resistance and comfort are affected 1>\ tightness of the knit and that tightness can be adjusted to meet any specific need. A veineffective combination of cut resistance and comfort has been found in for example, single jcrscv and terry knit patterns. The strands whether including a metal fiber core or not, may have some twist. The yarns, also, will have some twist lcore fabric layer of a high tenacity fiber material and a >1 surface fabric layer of aramid fibers, the high tenacity fiber material preferably having a tenacity of > 1 N/tex. Core fabric layers in the form of woven scrim fabric are particularly preferred. The cut-resistant composite fabric comprises a first layer of a fabric of a high tenacity fibrous material and a second layer of a non-woven fabric comprising aramid fibres. "High tenacity" in this present context means a tenacity of at least lN/tcx, more preferably in excess of 2N/tex. Preferably the two layers are bonded by needling them together, although stitching and gluing techniques may also be used.
Particularly preferred high tenacity fibrous materials include polymeric materials such as ultra-high molecular weight polyethylene or aromatic polyesters. The first fabric layer may be a relatively open woven or knitted fabric; it could also b a non-woven fabric incorporating ultrahigh molecular weight fibres in the form of laid-in yarns. Processes and compositions for treating fabric
A composition and method for treating fabric to increase abrasion resistance and cut
-resistance of the fabric was sugessetd. The composition includes from 1 to 20% of a softener by
weight, from 0.1 to 20% of a surfactant by weight and from 60 to 98.9% water by weight. In the

method, a fabric is saturated with the fabric treatment mixture. Excess fabric ireatnien mixture is removed from the fabric. The fabric is dried to cure the fabric treat men: mixture.
An approach to making cut resistant fabrics is disclosed in IS 4,555, S13 to Johnson. The patent discloses coating a surface of a fabric to create an abrasion resistant or cut resisiane gripping surface of a glove. A fabric web comprised of a woven or non-woven web is coated with a foam surface that increases cut resistance of the article. Methods of application include, but are not limited to, application by dipping, spraying, or roller coating.
In general, the composition comprises:
A. Softener in an amount ranging from 1 to 20 parts by weight; a preferred silicone softener
being ULTRATEX. Other silicones softeners that may be used in accordance with the present
invention include cationic reactive silicone softeners, anionic and non-ionic silicone softeners
and the like. Moreover, the silicone softener may include additional chemical softeners such as
polyethylene and fatty acid type softeners
B. Surfactant or surface active agents in an amount ranging from 0.1 to 20 parts by weight;
picferied first surfactants include fluoiopolymers especialh those sold under the trademark
ZONYL.
C. A second surfactant in an amount ranging from about 0.01 to about 2 parts bv weight based
upon the total weight of the composition, preferred second surfactant being selected from the
group consisting of anionic, cationic, or non-ionic surfactant such as those sold by Fisher
Scientific under the trade name ALKANOL.
D. water in an amount ranging from about 78 to about 98 parts by weight based upon the total
weight of the composition.
The solution is then dried in a dryer that raises the temperature of the fabric to -approximately 300° F. Fabrics can be coated using conventional means such as immersion, spraying, dipping, and the like. The surface leveling agents that are preferably used are long chain fluorinated compounds and salts. Role of silicon softeners
Silicone softeners provide the following advantages when applied to fabric:
• Improves wetting resistance;
• Increases abrasion resistance; and
• Increases cut resistance.
The surfactants or surface active agents offer the following advantages when applied to fabric:
• Reducing the surface tension;

• Improving wettability; and
• Controlling viscosity and consistency.
The composition may also contain chemical additives. Examples of surfactant and wetting agents are modified polyethers, modified alkvlpcroxy ethanols and ethoxylaird acelylcnie compounds. The chemical additives have the following functions:
• Adjusting pH;
• Improving shelf life stability;
• Improving wetting of the fabric;
• Maintaining solubility; and
• Improving coatability of the composition.
The curing of the fabric includes solidifying of the composition as a result of a chemical reaction as well as solidifying of the composition as a result of evaporation and that does not involve a chemical reaction. It has been found that once the fabric is cured and dried that the treated fabric displays increased abrasion and cut resistance for up to twenty to twenty-five launderings. [US 20040026652] Test Methods to Measure Cut Resistance Testing Principles
The basis to test the cut resistance of fabrics is the modeling of the cutting process. This is done under the assumption that the tearing occurs by piercing of the fabric and pulling of the fabric outwards. Using this assumption a basic model is proposed [Finkelmeyer S, Sontag P, Hoffmann G, Offermann P, Asian Textile journal, 1997, July, 63-68], the model (Fig 10) shows the basic parameters and the effective load components which occur during the cutting process. Cut resistance can be measured in various directions i.e. in the weft direction, in the warp "direction and also in various other directions as 45° to the warp and the weft. The basic assumption behind this is that the exact motion of the tearing instrument at the time of tear is not known, so to get a more realistic picture of the cut resistance is to be measured in various directions. [S. Finkeimever, P. Sonntag, G. Hoffman & P. Offermann, "Cut resistant warp knitted Textiles," Asian Textile journal, 1997, July, 62 -68] CPP Test: ASTMF1790-97
The American Society for Testing and Materials has collaborated with the industry to develop the Cut Protection Performance (CPP) Test, ASTM F-1790-97 using a razor blade to cut through a fabric while sliding a distance of one inch. The average force it takes to sever the material is its CPP.

This test uses a load-versus distance "evaluation to determine the cm through poini of a material. A cutting blade (surgical-grade razor) with a specified load (weight) is moved across a material. The distance at which the blade traveled from the original contact point to the cut through point is measured for several loads (weights). After several tests, a load versus distance curve is plotted and this is used to determine the load required lo cut through the material at 25MM (reference load).
The CPPT is used to compare the relative cut resistance of fabrics in a laboratory simulation of exposure to a sharp object. The results of these tests are only a prediction of cut resistance under these conditions Because the dynamics of real exposures to sharp cutting or snagging objects may vary greatly, these results do not duplicate or represent glove or fabric performance under actual exposure conditions. [ASTM P1790-97, "Standard Test Method for Measuring Cut Resistance of Materials used in Protective Clothing," American Sockl\ foy'Veslin^and Materials, 11.03, 1048-1053 and http://www.spcctrafiber.com/pdfs/hon-pfps25 S(l.pdf| Classifications: 5 levels. TDM tester: ISO 13977
In the ISO test method a constant force is applied perpendicularly between a straight blade and the sample material, with a constant blade speed and independent of force. In both the ASTM and the ISO test methods the distance to cut through is measured. Values are recorded after repeated measurements at different loads. A best-fit curve is calculated and the load at a particular distance is the reference load used to compare materials; currently for ISO it is 20 mm. rhttp://www.spectrafiber.com/pdfs/hon-pf-ps25-SCj.pdf| ITF tester: CEN 388
With the CEN test method, a circular blade slides while rotating simultaneously on a sample. A weight corresponding to a force of 5N is applied directly on the blade. Cut resistance is evaluated by the number of cycles to cut through sample compared to the number needed to cut through the cotton reference material. fhttp://www.spectrafiber.com/pdfs/hon-pf-ps25-~SG.pdf] Measurement of Cut Resistance on Instron Tensile Strength Tester
The fabric is stretched in a circular sample holder 4 inches in diameter and pre-tensioned by applying a two pound force to the center of the circle. The test is performed in an Instron tensile tester. The circular sample holder is clamped into the tensile tester at a 450 angle with respect to the floor. The sample holder is raised in a direction perpendicular to the floor at a speed of 5" per minute so that the fabric meets a stationary (non-rotating) carbide blade at an angle, thereby simulating a slicing action. The fabric is mounted so that the knit of the fabric is

perpendicular to the direction of tin- simulated slicing action. I he fmcc required for cuinni;
through the fabric (in pounds) is measured bv the tensile tester. |l"S 6,210,~9(S|
Test Method to Measure Cut Resistance of Yarns
Examination of the mechanical cutting characteristics of the yarns
Tests have been carried out by the 'IV Dresden and W.I.. (iore to evaluate (he cut resistance of spring wire, netting wire, polyester monofilament yarns and aramid imillifilameiii -yarns. The course of the cutting force over the cutting path is determined exclusive^ by the stress/strain behavior of the yarn. The moment (if yarn breakage is determined by the resistance of the yarn to the tensile, compression and bending loads occurring in the cutting /one. The \va\ in which the yarns are incorporated into the fabric also has a decisive effect on the cutting resistance. [Offermann-P; Pietsch-K; Finkelmeyer-S; Ulbricht-Y; Schirmacher-I', Mclliuml Textilberichte, 2003; 84(5), 395-398] Testing of cut resistant yarns
A test procedure for evaluating the cut resistance of yarns under tension-shear loading conditions is described and demonstrated. A knife blade is pressed transversely at a constant rate against a yarn gripped at its ends, the load-deflection relation is measured, and the energy required to cut through the yarn is computed. Results for Zylon (polybenzobisoxazolc or PBO) are presented. The cut energy and strain to initiate cutting depend on the sharpness of the blade, the slicing angle, and the pre-tension in the yarn. The dependencies arc explained by changes in failure mode of fibers within the yarn. [Hyung Seop Shin, D C Krlich, D A Shockey, Journal of Materials Science, 2003, 38 (17), 3603-3610]
Vandalism is the major cause of mechanical damage to public transportation seating. In view of the increasing incidence of vandalism, there is an increasing demand for cut-resistant fabrics, especially in the public sector. In the case of clothing for use in industrial environment, resistance to mechanical damage is often important in order to protect the wearer from injury, or at the least, from damage to normal clothing worn beneath a protective suit. The demand for cut resistant textiles has developed because it is now possible to replace materials such as metals and plastics with lighter, more flexible textile structures and consequenth' protect items from being vandalized. There is a continuing need for fabrics that resist cuts and abrasions that occur when a sharp edge of a knife, a tool having a sharp edge or items having sharp edges are encountered. Such fabrics are particularly useful for making protective clothing, such as gloves, for use in activities such as meat cutting, handling of metal and glass articles that have rough edges and automotive applications. The metallic wires used for making cut resistant fabrics until now is not adequate, since it has a high bending stiffness and poor comfort, and broken wire can frequently cause injury. This emphasizes the need for the development of cut resistant fabrics using cut

resistant hbcrs of high tensile and shears strength. The level of cm resistance provided vy the reinforcing yarns depends on the way in which they are incorporated in the textile substrate. With regard to many different fabric- manufacturing techniques available, a large number of alternatives for developing cut resistant textiles are feasible.
In the present invnetion, an instrument to measure the oil resistance of the labne will be-designed and the developed instrument will be used for testing some selected woven fabrics for cut resistance. An attempt will also be made to develop a simple model on the cutting forces and the distance slid to make a cut in the material. OBJECTS OF THE INVENTION
The main object of this project is to quantify the cut resistance of the fabrics so as lo design a cut resistant fabric suitable for protection against all kinds of cut hazards, say n a clean sharp edge cut hazard or an abrasive cut hazard.
Another object of the present invention is design and development of an instrument to measure the cut resistance of fabrics.
Another object of the present invention is calibration of the instrument, identification of the problems and their rectification.
Another object is to stud}- on effect of fabric constructions and fabric parameters on cut resistance of the fabric and hence optimizing the type of constructions suitable for a fabric to be _cut resistant.
Another object is to development of a simple model on cutting forces and the distance slid to make a cut.
Still another object is the determination of the factors influencing the cut resistance of fabrics in terms of process and material parameters. EMBODIMENTS OF THE INVENTION
The present invetion provides a method and an instrument to quantify the cut resistance of the fabric so as to design a cut resistant fabric suitable for protection against all kinds of cut hazards, say it a claean sharp edge cut hazard or an abrasive cut hazard
In one embodiment an instrument to cut resistance of fabrics is designed, developed and calibrated.
In another embodiment effect of fabric construction and fabric parameters on cut resistance of the fabric is studied and type of construction suitable for a fabric to be cut resistant is optimized.
In another embodiment a simple model on cutting forces and the distance slid to make a cut is developed.

In still another embodiment factors influencing the cm rcsMiincc <>l l-ibrics in lenns o|
process and material parameters arc determined.
BRIEF DESCRIPTION OF DRAWINGS
Fig 1: Spectra guard engineered yarn
Fig 2: Friction textured cut resistant varn
Fig 3: Construction having each varn with alternating bottom stitches and lop stitches
Fig 4: Construction including secondary layer
Fig 5: Normally inserted weft
Fig 6: Weft insertion in more voluminous way - Fig 7: Public made from bundled yarn
Fig 8: Representation of bundled yarn
Fig 9: Bundled yarn with core-shcath structure
Fig 10: Basic parameters and effective load components occurring during the cutting process
Fig 11: Front view of the instrument
Fig 12: Side view of the instrument
Fig 13: Control Panel
Fig 14: Schematic representation of cutting force
Fig 15: Relationship between forces
Fig 16: Representation of applied forces
Fig 17: CRI of different weaves in warp direction
Fig 18: CRI of fabrics of different weaves
Fig 19: Effect of decreasing PPI on cut resistance in warp direction
Fig 20: Effect of decreasing PPI on cut resistance in weft direction
Fig 21: CRI of the fabrics in warp direction
Fig 22: CRI of the fabrics in the weft direction
DESCRIPTION OF THE INVENTION
A.DESIGN AND DEVELOPMENT OF THE INSTRUMENT
The present invention provides an instrument (Fig 11 and Fig 12) to measure cut resistance of a material. The instrument measures the cut resistence in the following parameters:
1. The load required to make a cut in the fabric in a single stroke of the specimen
2. The distance traveled (in mm) by the mandrel assembly to cut the fabric for any applied load on the fabric.
STRUCTURE OF THE INSTRUMENT
The equipment is fabricated on an 1820 cm2 carbon steel base and is horizontally aligned with respect to the ground by means of leveling screws. The main parts of the instrument are the

top arm, the two side shafts along which the top arm ran be lifted up or lowered, the mandrel
assembly, blade holder fitted to the top arm, a motor and the control panel. There are two
proximity sensors which are involved in the reversal of the direction of the mo\ ement of the
mandrel assembly. The instrument has a rotary encoder for measuring the distance traveled bthe mandrel.
Dimensions of the instrument
The instrument is designed with following dimensions:
Length: 52 cm.
Width- ^5 cm
Height: 70 cm.
Working height: 40 cm.
The top arm
The top arm is a rectangular plate made of carbon steel which is 50cm long, 10cm wide and 5mm thick.
It is held in a horizontal position by means of two side shafts, one on each side, along which the top arm can slide up and down with the help of bearings provided with the side shaft. The top arm which weighs about 6 kilos is counterbalanced by means of two dead weights each weighing about 3kgs placed one on both sides of the instrument. The top arm serves for two functions such as a support for the blade holder at its bottom and a provision on its top part for the normal load to be applied on the fabric. It is manually moved up and down along the side shaft. -Blade holder
The blade holder is made of two rectangular bars positioned by a steel plate which is screwed to the bottom part of the top arm. The blade holder which is 125 mm long is made of fiber glass. The blade is clamped to the blade holder by means of screws provided each at the ends of the blade holder. Mandrel assembly
The mandrel also referred to as the specimen holder is made of an electro conductive material so as to have an electrical contact (closed circuit) between the blade and the mandrel after the fabric is being cut. The mandrel which is 150mm long has its top surface in a rounded form which has an arc of 32mm in a circle of radius 38mm. The fabric whose cut resistance is to be measured is mounted on the mandrel with the help of two rectangular clamps placed one on "both sides of the mandrel. The clamps are knurled and are provided with screws at their edges.
The mandrel is mounted on an assembly which gets drive from the lead screw, which in turn is driven by a 3-phase induction motor and thus the movement of the mandrel in the

forward and the reverse direction along the length of the- equipment is attained. In addition to ~this motion, the mandrel can also be manualh moved forward and hackwarti across (he width of the instrument. This is achieved by adjusting the screws which are used lo position the mandrel in its assembly. This motion is provided with an objective to expose different parts of the fabric to the cutting edge, thereby performing a number of tests with a single sample and thus saving time.
Blade specifications
The blade selected is made of stainless steel with the following specifications: Blade thickness- 0.34 mm Width of the blade: 18 mm Angle at cutting edge: 18" Length of the blade: 100 mm. Control panel The control panel (Fig 13) consists of the following:
1. A knob for regulating the speed of the mandrel assembh
2. Three types of switches such as a "manual switch", a "reset switch", and an "auto cycle ON switch". The functions of these switches are:

• The manual switch is pressed when the mandrel is required to move for a single traverse.
• The reset switch is used to bring the mandrel to the starting point of its traverse at the end of each test.
• The auto cycle ON switch is pressed to move the mandrel for a number of traverses, so as to measure the distance traveled by the mandrel to make a cut in the material whose cut resistance has to be measured.

3. A display for indicating the distance traveled in mm by the mandrel to make a cut.
4. A display to indicate the speed of the mandrel assembly in cm/min.
5. A knob for emergency stoppage of the instrument. MEASUREMENTS AND CONTROLS Speed control of the mandrel assembly
The mandrel is driven by a 3-phase induction motor, whose speed is adjusted by a power controller.
Motor specifications: Motor type: 3 phase A/C Supply voltage: 220 V Current rating: 0.45 A.

Motor Speed: 2800 RPM.
Power: 1/8 HP.
Control of the displacement of the mandrel
The reversal of the movement of the mandrel asscmbly during its traverse is attained b\ the two proximity sensors which arc fitted just behind the mandrel. The mandrel is given a displacement of 70mm during each traverse and the traverse length cm be varied bv adjusting the distance between the proximity sensors. The mandrel can also be reset to its initial opposition at the end of each test bv pressing the reset button provided on the electronic panel. Measurement of the speed of the mandrel
The average linear speed is displavcd on the panel. The time between two end points is divided from the distance (70mm) to get the average linear speed. However, since the speed range is vast, the speed can be varied in steps up to 70cm/min, but thereafter the motor pulley is to be changed for varying speed in steps from 70cm/mn to 500 cm/mir.. _ Measurement of the distance traveled
The distance traveled bv the mandrel asscmblv is converted into the rotarv movement of the encoder pulley which is fixed to the mandrel assembly. The total distance moved by the mandrel to make a cut on the fabric is displayed on a digital indicator. Output of the instrument
The instrument is designed to determine the cut resistance of the material in terms of two parameters such as follows
• The distance (in mm) traveled by the mandrel to make a cut on the fabric for any particular normal load applied on the fabric.
• The load required to be applied on the fabric to make a cut in a single traverse of 70mm of the mandrel.
"Digital Displays The following digital displays are provided:
• Distance traveled by the mandrel in mm.
• Speed of the mandrel assembly in cm/min.
• Direction of movement of the mandrel assembly.
WORKING PROCEDURE
The instrument is first leveled with the help of a spirit level an'd by adjusting the four leveling screws that are provided. Then it is plugged in without blades or weights in operating position. The test specimen is cut according to the size of the mandrel and is mounted on the mandrel in such a way that it is clamped at one end and a small weight is hung at the other end

to give the required tension. The clamp at the other end is lightened so that there is no slippage
between the fabric and the top surface of the mandrel. The fabric to be tested should be free
from wrinkles and creases.
The blade is fixed to the blade holder by means of the screws. Care should be taken that
the blade is straight and fully seated in the slot of the blade holder before tightening the screws.
Care should also be taken that the electric wire which is in contact with the blade is not
disconnected. Then the mandrel is positioned in its support column with respect to the blade by
manually moving it forward and backward in the support column. The screws are then tightened
to fix the mandrel in a particular position.
The reset switch is pressed to bring the mandrel assembly to the initial position. Then the
top arm with the blade fixed to the bladed holder is manually brought down very slowly so that
the blade just touches the fabric. The loads which are in the form of rectangular bars are placed
on the top arm as per the requirement and the speed of the mandrel assembly is set at the
desired level by adjusting the knob provided on the panel, when the output required is the cut
-resistance in terms of displacement or bv pressing the manual switch which gives a single stroke
for the mandrel, when the output required is the cut resistance in terms of the normal load
applied. Continue testing different parts of the same fabric sample by manually moving the
mandrel along the width of the machine.
In the latter case, if no cut through occurs within a single traverse of the mandrel, reset
the machine, remove the loads, move the mandrel to expose a new part of the sample to culling,
increase the load on the top arm and repeat the testing procedure as discussed earlier. If a cut
through occurs within one traverse of the mandrel, the machine will stop automatically. The
distance is noted from the distance meter and a graph is plotted between the distance traveled
and the applied load. The load corresponding to a distance of 25mm is used as a measure of the
cut resistance of the material.
CALIBRATION
Calibration of the blade
For this, a reference material such as Teflon is clamped on the mandrel along with the
fabric in one side and the test is done alternatively for the reference sheet and the fabric. Finally,
the cut resistance of the fabric is expressed in terms of an index which is the ratio of the distance
required to make a cut on the fabric to the distance traveled by the mandrel to make a cut in
Teflon.
(Table Removed)

The blades used must lie new and the reference material chosen should have the oil resistance in more or less the same ramie as that of the fabric. Thus bv expressing the cut resistance of the fabric as an index which is relative rather than in terms of the absolute value, the variability due to the blade is minimized. Calibration of the top arm
With no weights on the top arm and a used blade mounted in the blade holder, adjust the position of the counter weights until the edge of the blade just touches the top surface of the mandrel without exerting anv visible force on the mandrel. PROBLEMS ENCOUNTERED IN THE SYSTEM
Owing to the acceleration and deceleration of the motor, the sensitivity of the instrument is 13mm. This implies that even after the fabric is cut, the mandrel moves further to a distance of 13mm before it stops bv electrical contact between the mandrel and the blade. This leads to development of cuts on the mandrel, which will nor onlv reduces the life of the mandrel but will also give inaccurate and faults results. Rectification of the problem
The above problem encountered in the instrument is overcome bv placing anv flexible conductive plate such as a copper plate on the top surface of the mandrel and the fabric is mounted over this plate on the mandrel. This facilitates in exposing different portions of the plate by moving it along with the fabric, thus avoiding the formation of grooves on the mandrel. B. DEVELOPMENT OF A MODEL FOR CUTTING FORCES AND CUT RESISTANCE
In another embodiment of the invention a model for cutting forces and cut resistance was developed as explained below: Forces involved in cutting
To relate the cut resistance of a material to the properties of the material, it is essential to visualize the actual cutting process and the forces involved during cutting a material. In order to - analyze the type of deformation and hence to derive an equation for the cutting force, the cutting process is related to the general wear of solids. Energy transfer process in cutting
In the present context, the wear is defined as an energy transfer process as follows:
• Blade that is supplied with a normal and a tangential force is a large reservoir of energy.
• Energy is transferred from the blade to the fabric by means of frictional forces.
• The energy transferred is then converted to the permanent deformation of the fabric after overcoming the compressive and shear stresses of the fabric.

A model to determine the cutting force
The cutting process, which is referred to as the moving of the liber material away from the fiber/blade contact point, involves the application of mechanical forces in the direction transverse to the fiber axis. An attempt has been made to develop a model to determine the actual force that is involved in cutting. The model is based on the following assumptions:
• The real area of contact increases proportionately to the load.
• The material undergoes plastic deformation on the application of load.
• Ihe energy- dissipated is proportional to the volume of wear.
• The frictional force is directly proportional to the load applied. Equation for the cutting force
Fig 14 shows a schematic representation of cutting force, wherein
FN : Normal load
Ft : Pretension
V : Velocity of blade
Ff : Frictional force
Fs : Separation force
tf : Thickness of material
y : Current separation between the cutting edge and the base of the material.
Relationship between the various forces involved in cutting
The free body diagram (Fig 15 and Fig 16) shows the forces involved in cutting in three mutually perpendicular directions, say along i, j and kth directions. If Fl and F2 are Uvo forces in ith and jth directions respectively, separated bv an angle 0, then

(Equation Removed)
Which implies thai (lie resultani force is in (k'h) direction.
But we have in (+k) direction, the following two forces.
(i) Fs (+k)
(ii) F1(+k)
These two forces will balance the other two forces acting along i and j direction.

(Equation Removed)

Equation for the distance slid "S".
Consider a uniform Teflon sheet of thickness tf which is presented to a cutting edge of thickness tb placed perpendicular to the sheet. Let a normal load FN be applied to the cutting edge and then allowed to slide over the material with a sliding velocity V. .Assuming plastic deformation of the material on the application of the normal load, as the smooth surface of the cutting edge which is hard approaches the smooth surface of the Teflon sheet which is soft in nature, it compresses the material to a certain height. Hence the normal approach will be given by (Vy), where y is the current separation between the cutting edge and the base of the material. When a hard surface is slide over a soft surface, it tends to dig into the softer surface during sliding and produces a groove. The energy of deformation represented by the cut must be -supplied by the friction force, which will therefore be larger than if no such groove is formed. Hence an additional component to the frictional force is involved rRabinowicz F, Friction and Wear of materials, John Willy & Sons Inc, 7, 191-200]. Let the area over which the shear force is applied to initiate sliding be AH. Horizontal area of contact: AH = Length of contact (cut) X Thickness of the blade edge. Let the initial vertical area of contact after the normal load is applied be Av. Initial vertical area of contact: Av = length of contact X (tf-y) During sliding, the penetrated area swept out is given by AN Av = length of contact X thickness of the material (tf).
Let the additional resistance of sliding, consisting of the need to displace an area Av during sliding be Av. P and is referred to as the ploughing term.
Let Ff be the frictional force, which is the tangential resistance to sliding and Ff involves two terms, a shear term and a ploughing term. Ff = AH. S + Av. P
Where S is the shear stress required to initiate sliding P is the yield stress of the material.

(Equation Removed)
Volume of wear, Q = AH X Depth of cut
Amount of energy dissipated for a sliding distance D is
E = FfXD
Assume, energy dissipated ©(volume of wear

(Equation Removed)
Fr D is the sliding distance, which is a measure of the cut resistance of the material. C is a constant, which is related to the transverse work of rupture of the material. -Factors influencing cut resistance of fabrics
Resistance to cutting
Intrinsic strength of material Frictional contribution
Cutting which involves a normal and a sliding movement is strongly controlled by friction between the blade and the cut material. That is the total energy required to propagate a cut strongly depends on the co-efficient of friction between the cutting edge and the material. However, this co-efficient of friction depends on both the nature of the blade and the nature of the cut material, especially its surface roughness. It has been reported that an increase in the coefficient of friction increases or decreases the cut resistance of the material depending on the thickness and the microstructure structure of the material to be cut. ["Effect of friction on cut resistance ofpolymers," Journal of Thermoplastic Composite Materials, 2005, 18(1), 23-25] Process parameters 1. Normal load

As the load applied increases, the cut resistance of the fabric decreases. This is because of the increase in the factional force, which in turn augments the cutting action.
2. Sliding velocity
As the sliding velocity increases, the time required to cut decreases, which implies that the cut resistance of the material decreases.
3. Sliding distance
Higher the distance slid, higher is the cut resistance of the material as the energy dissipated in cutting the material is more.
4. Co-efficient of friction between the blade and the fabric
Higher the co-efficient of friction between the blade and the fabrics, better is the grip between them, resulting in a little or no slippage, thus decreasing the cut resistance of the material. However, the increase in the co-efficient of friction may increase or decreases the cut resistance based on the thickness and structure of the material to be cut.
5. Co-efficient of friction between the fabric and the support on which it is mounted
This depends on both the surface roughness of the fabric and the surface of die support. However when the human skin is considered, the co-efficient of friction mainly depends on the nature of the fabric and its surface roughness. For a smooth fabric, the co-efficient of friction between the fabric and the human skin is lower than that for a rough fabric. This results in slippage between fabric and skin which in turn doesn't facilitate good cutting action of the blade. Hence the cut resistance of the fabric increases with decrease in the co-efficient of friction between the fabric and its support (skin). Material parameters
The material parameters that influence the cut resistance include that of the type of fabric and its construction parameters, yarn related factors and also the fiber related factors. Fabric related parameters 1. Surface roughness of the fabric
With very smooth surfaces, the friction tends to be high, because the real area of contact grows excessively, whereas with very rough surfaces, the friction is high owing to the need to lift one surface over the asperities on the other. Hence the cutting action is augmented in case of both very smooth and very rough fabrics. Higher the surface roughness of the fabric, better the grip between the blade and the fabric, which augments the cutting action of the blade. -2. Fabric thickness
The energy required for the blade to penetrate the fabric and make a cut is higher for a thicker fabric than that for a thinner fabric. Hence higher the fabric thickness better is its cut resistance.

3. The type of fabric construction
The type of construction which offers a good elasticity for the fabric is usually the one chosen for making a cut resistant fabric. A fabric of higher stretch shows a batter cut resistance compared to that of a stiff and low stretchability fabric.
4. Fabric tightness
Higher the fabric tightness better is the cut resistance, as more number of threads pet-unit space can take up the cutting force resulting in better cut resistance. Yarn related parameters
1. Yarn twist
The cut resistance decreases as the twist in the yarn increases beyond a certain level, which is due to the increase in the yarn tension. Higher the twist, rougher the yarn becomes, and _this facilitates a better grip between the blade and the material resulting in poor cut resistance.
2. Yarn fineness
The cut resistance of the fabric made of large diameter (lower fineness) yarns is higher than that of fabrics made of yarns of higher fineness. This is because fabrics made of coarser yarns have greater thickness and hence the cutting energy required is higher.
3. Yarn to yarn friction
Higher is the yarn to yarn friction, lower is the yarn mobility, which facilitates better gripping action between the blade and the fabric resulting in poor cut resistance.
4. Yarn structure
A loose yarn construction gives a better cut resistance than that of a yarn of a tighter construction. -5. Yarn packing co-efficient and inter fiber friction in the yarn. Fiber related factors
1. Transverse mechanical properties of the fibers
It has been reported that the type of deformation undergone by the fiber during the cutting process appears to be a very much plastic lateral compressive deformation, with the evidence of actual failure in either transverse tension or shear. [29]. Hence greater is the work required to deform the material in the transverse compression, higher is the energy dissipated which implies better cut resistance of the material.
2. Fiber to fiber friction
Higher the fiber to fiber friction, lower is their mobility during cutting as they offer a good grip for the cutting edge, thus resulting in poor cut resistance.
3. Fiber fineness

Higher the fiber fineness, lower is the cm resistance of the individual fibers/filaments as the distance that the blade has to penetrate to make a cut is lower.
The present invention provides an instrument to measure cut resistance of fabrics with good repeatability and reproducibility. The instrument measures cut resistance of fabrics in terms of both the load required to make a cut in a single traverse and the distance slid to make a cut for any specific load.
The instrument designed and developed in the present invention can be further modified to develop a mechanical means of lowering the top arm so as to make the blade touch the fabric without any impact. A load cell can be attached to the mandrel assembh so as to very precisely quantify the actual load that is being applied on the fabric to make a cut. The instrument and the model described in the present invention can be used bv a cut. The instrument and the model described in the present invention can be used bv a skilled artisan to design a cut resistance fabric.
The working of the present invention is described with reference to the following examples, which are given b\ way of illustration and should not be construed to limit the scope of the present invention. EXAMPLE Selection of materials
Fabrics of different constructions and set made from 100% cotton yarn were selected for determining the cut resistance, so as to find the effect of weave pattern and fabric tightness on cut resistance. The types of weaves selected were plain, 3/1 twill, 2/2 matt and 8end honey comb weaves. Out of this, the 3/1 twill weave was selected and fabrics of different pick per inch were constructed so as to find the effect of the fabric cover factor on cut resistance. To study the .effect of fiber material on cut resistance, fabrics woven from Kevlar, HDPE, Nylon monofilament and nylon multifilament yarns were chosen. Measurement of fabric parameters
Counting glass was used to count the end and pick density. An average of ten readings was taken. Count of the yarns
The fineness of the warp and weft yarns was determined using the Beesley balance which gives the fineness in terms of cotton count. An average of 5 readings was taken. Fabric weight (g/m2)
A sample of 10 X 10 cms was taken and weighed on an electronic balance which gives the weight of the fabric in grams.
Fabric weight (g/m2) = weight in grams X 100.

An average of 5 readings was taken for each sample. Measurement of fabric thickness
The thickness of a textile material as defined bv the AS'I M is the distance between the -upper and lower surface of the material, measured under specified pressure of 20 g/cm".
Following procedure was followed for the measurement of thickness on I'.ssdiel thickness tester.
1. Level the apparatus.
2. Without any fabric under the pressure foot, rotate the black knob in anti-clockwise direction till the red light is on.
3. check for the position of the needle whether it is pointing at zero. If not, then rotate the dial as required to set the needle pointing towards zero.
4. I nscrew the black knob to enable the sample to be placed between the pressure foot and the anvil table.
5. rotate the black knob in the clockwise direction till the red light is visible after allowing the pressure foot (area 325 mm2) to rest on the fabric for 30 seconds. The reading which the needle corresponds to on the dial is noted as the thickness of the fabric.
6. Repeat the procedure at different places in the fabric.
7. An average of the 10 readings is taken. Measurement of cut resistance of fabrics
The measurement of cut resistance of various fabrics was carried out on the developed instrument. A strip of Teflon and a strip of the fabric of dimensions 6*2 cms are mounted adjacent to each other on the mandrel.
The distance taken bv the mandrel to make a cut in the reference material and in the fabric was determined alternatively. Finally the cut resistance of the fabric is expressed in terms of an index which is the ratio of the distance traveled by the mandrel to make a cut in the fabric to the distance traveled to make a cut in the reference material and is referred to as the cut resistance index (CRI). Test method
1. The cutting edge with a specified load is placed on the mandrel over which a strip of fabric and Teflon sheet of 6x3 cms are mounted adjacent to each other.
2. The mandrel is moved to and fro at a particular speed as indicated by the digital speed meter and is reset to its initial position at the end of each test.
3. The cut through is electronically recorded as the cutting edge makes contact with the sample holder. The distance traveled is recorded on a distance meter capable of recording to 1mm.

4. A scries of tesrs is performed altcrnatiyely for different portions of the reference material and the fabric along the length of the mandrel. This is accomplished by moving the mandrel forward or backward at the end of each test.
5. The cut resistance of ihe fabric is expressed in terms of an index referred to as the cut resistance index (CRI).
Determination of the cut resistance index of the selected woven fabrics
The specifications of the fabrics are as shown in table 1. Four different types of the basic-weaves were selected to study the effect of weave structure on cut resistance. Among these weaves, the 3/1 twill weave was chosen and is constructed with different picks/inch with an objective to studv the effect of fabric tightness on cut resistance. Testing conditions:
Reference material: Teflon (0.25 mm thickness) Speed: 70 cm/min Load: 250 g Tabic 3: Specifications of the woven fabrics

(Table Removed)

Determination of the cut resistance index of some selected high performance fabrics
Certain high performance fabrics, whose specifications are given in table 2 were selected with an objective to study the effect of fiber material on cut resistance. Testing conditions:
Reference material: Teflon (0.5mm thickness) Speed: 70 cm/min Load: 750 g

Table 4: Specifications of the selected high performance fabrics

(Table Removed)

Cut resistance of the woven fabrics of different construction parameters Table 5: CRI of woven fabrics of different weaves and tightness

(Table Removed)

Effect of weave pattern on cut resistance
The cut resistance index (CRI) of the woven fabrics constructed from different weave pattern was calculated.
Fig 17 shows CRI of different weaves in warp direction. The results reveal that the plain weave has the maximum cut resistance followed by the 2X2 matt weave and the 3/1 twill, while the honey comb weave exhibits the least cut resistance. This can be attributed to the greater number of intersections per unit area of the plain weave which enables the cutting force to be shared by a greater number of threads and hence higher cut resistance. In a simpler way, this is

because of the better stress propagation as more number of threads takes up and shares the
cutting force.
As shown in Fig 18, the honey comb weave has very poor cut resistance as compared to
the other weaves because of its rough surface (special diamond and raised effect) which
ultimately increases the friction between the cutting edge and the fabric, thus providing a better
grip resulting in poor cut resistance.
The cut resistance index of the weaves in the warp direction (Fig 19) is slightly higher
than in the weft direction (Fig 20). This can be attributed to the higher number of ends per inch
as compared to the number of picks per inch.
Effect of pick density on cut resistance
The cut resistance of the fabrics decreases as the pick density decreases. This can be attributed to the decreased number of threads which has to take up the same cutting force as that compared to the other fabrics.
CUT RESISTANCE OF THE FABRICS MADE OF DIFFERENT HIGH PERFORMANCE FIBERS Table 6: CRI of the selected high performance fabrics

(Table Removed)

The results on the CRI of the different high performance fabrics (Table 6) show the highest cut resistance for the nylon monofilament fabric in both the warp ( Fig 21) and weft Fig 22)directions, while the lowest cut resistance is exhibited by Kevlar fabric in warp direction and

the HDPK fabric along the weff direction. The high cut resistance of the monofilament fabric is mainly due to its very low compressibility, and hence when llu- normal load was applieil there was no plastic deformation of the fabric and thus greater energ\ was dissipated in sliding to make a cur. The poor cut resistance of the MDPE fabric in the weft direction may be attributed to the very low pick density compared to the end density.

We claim:
1. An instrument tor measurement of cut resistance in fabrics comprising a lop arm, a vertical frame formed from two side shafts along which the top arm is moveable in a vertical direction, a mandrel assembly provided on a base frame, a blade holder provided fitted to the top arm, a motor operativelv connected to said instrument and a control panel to operate said instrument, wherein at least two proximity sensors are provided operativelv associated with said control panel and along the mandrel assembly to monitor reversal of the direction of the movement of the mandrel assembly, and a rotary encoder for measuring the distance traveled bv the mandrel.
2. An instrument as claimed in claim 1 wherein said top arm comprises a rectangular place
made of carbon steel.
3. An instrument as claimed in claim 1 or 2 wherein each of said side shafts are provided
with bearings to move said top arm in slideable manner.
4. An instrument as claimed m anv of claims 1 to 3 wherein said top arm is provided with
dead weights at each end thereof located on either side of the instrument tor counter
balancing said top arm.
5. An instrument as claimed in any of claims 1 to 4 wherein said blade holder comprises two
rectangular bars positioned with a plate fixed to the lower part of said top arm.
6. An instrument as claimed in claim 5 wherein said blade holder is made of fiber glass and wherein a blade is fixed to said blade holder by means of screws at each end of said holder.
7. An instrument as clamied in any of claims 1 to 5 wherein said mandrel is made of an electroconductive material to provide an electrical contact between said blade and said mandrel when the fabric is cut.
8. An instrument as claimed in claim 7 wherein said mandrel has a rounded top surface and is provided with mounting means to mount the fabric to be cut.
9. An instrument as claimed in claim 8 wherein said mounting means comprise clamps located on either side of said mandrel, said clamps being knurled and provided with screws at their edges.
10. An instrument as claimed in any preceding claim wherein said mandrel is mounted on an assembly driven by a lead screw, which in turn is driven by a 3-phase induction motor to enable movement of the mandrel in a forward and reverse direction along the length of the instrument.
11. An instrument as claimed in any preceding claim wherein said control panel is provided with means for regulating speed of the mandrel assembly and operation of the instrument,

a display for indicating the distance traveled by the mandrel to make a cut, a display to indicate the speed of the mandrel assembly and a stop means to enable emergency stop.
12. A method for the measurement of cut resistance of fabrics comprising mounting a fabric on an instrument as claimed in any preceding claim and applying a mechanical force in a direction transverse to the fabric axis.
13. A method as claimed in claim 12 wherein the cut resistance of the fabric is measured as a ratio of the distance traveled by the mandrel to make a cut in the fabric to the distance traveled to make a cut in a reference material.
14. A method as claimed in claim 12 wherein the cutting edge with a specified load is placed on the mandrel over which a strip of fabric and a Teflon sheet are mounted adjacent to each other; the mandrel is moved to and fro at a particular speed as indicated by the digital speed meter and is reset to its initial position at the end of each test; the cut through is electronically recorded as the cutting edge makes contact with the sample holder and the distance traveled is recorded on a distance meter.
15. An instrument to measure the cut resistance of a fabric substantially as described hereinbefore and with reference to the accompanying drawings.
16. A method for the measurement of cut resistance of fabrics substantially as described hereinbefore and with reference to the accompanying drawings.