FIELD OF THE INVENTION
The present invention refers to developing of a sustainable, easy to produce, cost-effective and the durable machine tool structural material to improve structural damping, static, and dynamic characteristics.
BACKGROUND
Precision machining on metal cutting machine tools must produce close tolerance on dimensions, geometry, and surface finish of workpieces machined. The precision machining is one of the major criteria to be fulfilled. However, the micro or nano range surface quality cannot be achieved only through an optimum combination of machining parameters and cutting tool selection. Literature shows that cutting stability is one of the most notorious aspects associated with precision machining. Therefore, apart from the machining process parametric combination, alternate structural materials like cement concrete, polymer concrete, epoxy granite, etc.; have been used to enhance structural stability in machine tool structures. Also, filling a single material in hollow structures helps to obtain an improved stability.
The present invention relates to a simplified approach of filling the existing hollow metallic machine tool structure with a combination of the different set of two or more materials and designs as instead of a single filler material to improve structural damping, static, and dynamic characteristics to a greater degree.
DISCUSSION OF THE PRIOR ART
CN 101333098 A titled “High damping vibration attenuation cement concrete” discloses “a high-damping concrete, comprising ordinary Portland cement, sand, water, a polymer additive and additional water reducer and defoamer. By implementing the styrene-butadiene latex, acrylic copolymer emulsion or dispersible emulsion powder and other polymer additives as the modifier in the viscidity, the structural viscidity and inner friction performance of the concrete material, the high-damping cement concrete achieves the same vibration damping characteristics as the existing polymer concrete and does not change the other

properties of concrete. Existing polymer concrete has the components that of high cost thus by increasing the project cost.”(sic. Publication No. CN 101333098 A)
US 20120313307 A1 titled “Polymer composites possessing improved vibration damping” disclose “fiber-reinforced polymer composites which possess improved damping ability. In one aspect, the fibers provide a relatively high dynamic modulus composite for a given temperature over a broad range of frequencies. In another aspect, the polymer comprises a viscoelastic polymer possessing a relatively high loss factor for a given frequency and temperature. The polymer may be further tailored to control the center frequency at which the maximum loss factor of the polymer is achieved. The composite so formed a relatively small reduction in loss factor with a significant increase in dynamic modulus over a wide range of frequencies for a given temperature. The polymer possesses a high loss factor for a broad range of frequencies and related temperature.” (sic. US Publication No. 20120313307A1)
US6200204 B1 titled “Roll grinder with vibration dampening” discloses “a roll grinder system that has a roll grinder bed of high dynamic stiffness, with a roll support and a grinding wheel support fixedly mounted to the roll grinder bed. The roll grinder bed consists of a monolithic epoxy granite block with a steel plate embedded in the top surface and a steel plate embedded in the bottom surface. Both the beds for the support for the roll being ground and for the traversing carriage of the grinding wheel head a rigidly affixed to the top plate. Bed for the caliper is a fixed to a block’s lateral side. The caliper and grinding wheel traverse along the axis of the roll which is being ground. The bottom plate of the block contains the vibration isolators. Existing system in its structure consists of separate beds for each carriage hence equipment was large. Also, it generates greater vibration.” (sic. US Publication No. 6200204 B1)
This invention comprises of the elements with appropriate proportions that are less cost but with the same quality as in the prior systems. Fibre reinforced polymer composite improves the damping ability by detecting the frequency point

at which the maximum loss occurs; it results in small reduction. When considering the roll grinder for epoxy granite, several carriages are put into single bed. Thus the equipment is acquiring small size. The vibration is damped completely with an isolated system.
The objective of the invention is to develop a machine tool structure which is significantly cheaper, durable, easy to manufacture with minimum structural changes, and most importantly, sustainable when compared to the alternate materials presently in vogue stated above.
SUMMARY OF THE INVENTION
The present invention relates to vibration damping of structures. Instead of replacing the complete machine tool structure, which is conventionally made of gray cast iron or welded steel construction structures by those made with alternate materials like cement concrete, polymer concrete, epoxy granite, etc., or filling with a single material. A lightweight “composite” filler material set has been discovered which when filled into the existing hollow structure will improve the stiffness as well as damping compared to that of the metal structure without a significant increase in the total structural mass. This is advantageous regarding developing the machine tools structural damping (by about 10-20 times or higher), which leads to stable machining at higher production rate (i.e., even at a higher critical depth of cuts) and achieving better-machined surface quality. The total cost associated with the machine tool structure in this new filler approach is significantly less compared to the structures made entirely of non-traditional alternate machine tool structural damping materials. Also, the total weight of the newly filled structure element is less compared to structures of epoxy granite, polymer concrete, etc. with inbuilt steel reinforcements introduced to achieve the needed stiffness.

The claimed filler design for improved damping is planned to be applied in the following fields, and should not be construed to limit the scope of the present invention:
1. Mechanical Engineering: Machine structures like bed and elements especially machine tools structure, bed and elements.
2. Civil Engineering: Engineering structures in ocean engineering as well as in several civil engineering applications like a roof deck, window frame, railway track construction, construction of playgrounds, etc.
3. Chemical Engineering: Pipes, pumps, valves, storage tanks, etc.
4. Miscellaneous Applications: Biomedical engineering, artistic work, etc.
The further efforts will be directed towards the achievement of best possible damping characteristics for a filled metal structure with all the possible design combinations of foam concrete and ethylene propylene diene monomer (EPDM) or foam concrete and epoxy granite. The optimum design is applied for designing and building of full-scale machine tool structures.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1a shows a typical metallic hollow machine tool structure in a top and front view with foam concrete filling.
Figure 1b shows the top and front view of the machine tool structure with ethylene propylene diene monomer (EPDM) sheets pasted on the inside walls and the rest of the cavity filled by foam concrete.
Figure 2a shows the top and front view of the machine tool structure that has EPDM sheets pasted on the inside walls and two squares of EPDM surrounded by foam concrete.
Figure 2b shows the top and front view of the machine tool structure that has EPDM sheets pasted on the inside walls and a solid EPDM bar fixed at the center of the filled column.

Figure 3a shows the machine tool structure having crossed EPDM sheet arrangement in the top view and EPDM sheets pasted on the inside walls.
Figure 3b shows the top and front view of the machine tool structure with EPDM pellets distributed randomly within the foam concrete filling.
Figure 4a, 4b, 4c, 4d shows the top and front view of the machine tool structure with a combination of EPDM sheets adhered to the walls and EPDM pellets distributed in the concrete filling.
Figure 5a and 5b shows the top and front view of the machine tool structure filler design with systematically arranged EPDM pellets.
Figure 6 shows the top and front view of the machine tool structure filler design with a combination of foam concrete bricks and epoxy granite.
Figure 7 shows the rectangular hollow column made of gray cast iron.
Figure 8 shows the experimental setup to analyze dynamic characteristics of hollow cast iron (CI) column structure.
Figure 9 shows the Time decay plot for an unfilled cast iron column-1.
Figure 10 shows the Frequency domain plot for the unfilled cast iron column-1.
Figure 11 shows the Time decay and frequency domain plots for hollow unfilled column-2.
Figure 12 shows the Development steps for 3D filled column models.
Figure 13 shows the Time decay plot for Ordinary concrete (C01).
Figure 14 shows the Frequency Response Function (FRF) plot in particular Y-Y direction for Ordinary concrete (C01).
Figure 15 shows the Time decay plot for Ordinary concrete with EPDM rubber (CR01).
Figure 16 shows the FRF plot in particular Y-Y direction for Ordinary concrete with EPDM rubber (CR01).
Figure 17 shows the Time decay plot for Foam concrete (FC01).

Figure 18 shows the FRF plot in particular Y-Y direction for Foam concrete (FC01).
Figure 19 shows the Time decay plot for EPDM rubber sheets of twelve-millimetre thickness, pasted at cast iron inside walls and filled with Foam concrete (FCRP01).
Figure 20 shows the FRF plot in particular Y-Y direction for EPDM rubber sheets of twelve-millimetre thickness pasted at cast iron inside walls and filled with Foam concrete (FCRP01).
Figure 21 shows the Time decay plot for EPDM rubber sheets of twelve-millimetre thickness pasted at cast iron inside walls and crossed EPDM sheets arranged inside, and filled with Foam concrete (FCRPC01).
Figure 22 shows the FRF plot in particular Y-Y direction for EPDM rubber sheets of 12 mm thickness pasted at cast iron inside walls and crossed EPDM sheets arranged inside, and filled with Foam concrete (FCRPC01).
Figure 23 shows the Time decay plot for EPDM rubber sheets of 12 mm thickness pasted at cast iron inside walls and EPDM pellets distributed in the Foam concrete filling (FCRPB01).
Figure 24 shows the FRF plot in particular Y-Y direction for EPDM rubber sheets of twelve-millimetre thickness pasted at cast iron inside walls and EPDM pellets distributed in the Foam concrete filling (FCRPB01).
Figure 25 shows the Time decay plot for EPDM rubber sheets of twelve-millimetre thickness pasted with a gap from the cast iron walls and filled with Foam concrete (FCRPG02).
Figure 26 shows the Time decay plot for EPDM rubber sheets of 12 mm thickness pasted with the gap from the cast iron walls and EPDM blocks and filled with Foam concrete (FCRPGB02).

Figure 27 shows the Time decay plot for EPDM rubber sheets of twelve-millimetre thickness pasted with the gap from the cast iron walls and central EPDM sheet and filled with Foam concrete (FCRPGP02).
Figure 28 shows the Time decay plot for EPDM rubber sheets of twelve-millimetre thickness pasted with the gap from the cast iron walls and filled with Foam concrete in a manner of kebab design (FCRBK03).
Figure 29 shows the FRF plot in particular Y-Y direction for EPDM rubber sheets of twelve-millimetre thickness pasted with the gap from the cast iron walls and filled with Foam concrete in a manner of kebab design (FCRBK03).
Figure 30 shows the Time decay plot for Liquid EPDM rubber layer of eight to ten-millimetre thickness pasted onto cast iron walls and filled with Foam concrete (FCRL03).
Figure 31 shows the FRF plot in all directions for Liquid EPDM rubber layer of eight to ten-millimetre thickness pasted onto cast iron walls and filled with Foam concrete (FCRL03).
Figure 32 shows the Time decay plot for Liquid EPDM rubber layer of eight to ten-millimetre thickness pasted onto cast iron walls and EPDM are distributed in a Kebab manner in the Foam concrete filling (FCRPLK03).
Figure 33 shows the FRF plot in all directions for Liquid EPDM rubber layer of eight to ten-millimetre thickness pasted onto cast iron walls and EPDM are distributed in a Kebab manner in the Foam concrete filling (FCRPLK03).
Figure 34 shows the Time decay plot for the sixteen millimetre thick EPDM sheets pasted to cast iron walls and filled with foam concrete (T04).
Figure 35 shows the FRF plot in all directions for sixteen millimetre thick EPDM sheets pasted to cast iron walls and filled with foam concrete (T04).
Figure 36 shows the Time decay plot for the filler with a combination of foam concrete bricks and epoxy granite.

Figure 37 shows the FRF plot for the filler with a combination of foam concrete bricks and epoxy granite.
Figure 38 shows the Comparison of Average Damping factors for various filler designs for metal columns.
Figure 39 shows the Comparison of Time decay for various filler designs for metal columns.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention consists of advanced composite filler material which can be packed inside hollow metallic machine tool structural parts such as bed, column, milling head, and other structural parts of CNC and NC milling, turning, drilling, boring, and other machining tools to achieve better damping, static, and dynamic characteristics of the machine tool in terms of its overall damping factor, dynamic mass, mechanical impedance and dynamic stiffness. The present filler design comprises of a combination of foamed cementitious material (foam concrete) with ethylene propylene diene monomer (EPDM) placed in a typical arrangement of various types as illustrated in the diagrams inside a hollow machine tool metallic structural part. Along with the above designs, a specific filler design consisting of rectangular foam concrete bricks, pasted one over the other in a vertical direction with an epoxy granite material has been discussed in the later part of the application.
The foam concrete 3 is a mixture of Portland cement, fly ash and water. The percentage of the components in the foam concrete is 40% of Portland cement, 29% of fly ash and 31% water. The foam which is a blend of protein based foaming chemical with water is mixed with a combination of the Portland cement and fly ash so that the final density of the foam concrete achieved is 1000Kg/m3. While filling the hollow machine tool structure, a 30% of the total hollow volume is filled with EPDM, and the rest 70% is filled with foam concrete 3 with described composition. This can be achieved by varying the proportions and compositions indicated above.

The epoxy granite is a composite made of granite particles and epoxy resin. In the present application, the granite particles of 0.6 mm to 2.8 mm size have been used. The Huntsman resin (LY 556) with a Hardener (HY 951) in the ratio of 100:10 has been used. The mixture of above two has been filled in a cavity inside metal structure along with the foam concrete bricks. In this application, three bricks were placed one above the other inside the metal structure.
The filler designs in a typical metallic hollow metal structure with a combination of foam concrete and EPDM filler material or foam concrete and epoxy granite with front and top view are shown in the diagrams, schematics are not per scale but are the typical representation of filler design. Figures show some combination of arrangements of the composite materials and are only illustrative.
The possible filler designs with above material combination have been presented in Figures. Figure 1a illustrates the front view 1 and top view 2 of a typical metallic hollow machine tool structure filled with the foam concrete 3. In Figure 1b the filling in the metallic hollow machine tool structure is a combination of the EPDM sheets 4 and foam concrete 3. On the inner walls of the metallic structure, the EPDM sheets 4 of 12 mm thickness are pasted, and the rest of the cavity is filled with the foam concrete 3.
Figure 2a and Figure 2b represents different design combinations between the foam concrete 3 and EPDM sheets 4. Two squares of EPDM sheet are surrounded by the foam concrete 4 in Figure 2a and a solid 20×20 mm2 EPDM bar 7 is fixed at the centre of the filled column in Figure 2b.
A crossed EPDM sheet arrangement 8 can be seen in the top view of the Figure 3a. In Figure 3b, 20×20×12 mm3 EPDM pellets 5 are randomly distributed inside the foam concrete filler.
Figures 4a, 4b, 4c, 4d represents a combination of sheets of EPDM 4 adhered to the walls of the metal structure and also inside the foam concrete filling along with the random distribution of EPDM pellets 5.

Figures 5a, 5b represents the filler design which consists of systematically arranged (zigzag/ kebab type) EPDM pellets 5. The EPDM pellets are arranged in a typical design. The EPDM pellets 5 with a dimension of 20×20×12 mm3 are attached to a thin EPDM cord 10 with a diameter of 2mm and a length similar to the height of the machine tool structure. These EPDM cords 10 along with EPDM pellets 5 attached to it in a zigzag manner along its length have been placed inside the hollow metallic machine tool structure and successively filled with the foam concrete 3.
Figure 6 illustrates a specific filler design consisting of the rectangular foam concrete bricks 11 three in number were placed one above the other inside the metal structure in a vertical direction and the surrounding cavity is filled with epoxy granite composite 12.
The metallic machine tool structure filled with the above-explained filler designs that include foam concrete are then cured in water and air.
All these designs and other possible material combination designs are developed either by sticking EPDM sheets at the inside walls of the metal structure, or EPDM liquefied paste applied to the inner walls of the metal structure or the combination of both or the foam concrete bricks placed inside the metal structure surrounding with epoxy granite composite.
In the case of application of EPDM paste, an EPDM green material (raw EPDM rubber without mixing with hardener) is mixed with CnH2n+2 (petrol) to achieve a constant viscosity in the range of 1500 – 2500 poise. Further, this EPDM-CnH2n+2 paste is mixed with a hardener ‘Desmodur RE’ in the proportion of 80 ml per 1 litre of EPDM paste.
The composition, sizes, and specifications mentioned are representative and indicative, but it is recommended to apply this composite material filling idea in all possible variations.

Experimental validation of Filler Technology 1. Unfilled column
Specimen: Rectangular Hollow Column is used as a specimen as shown in Figure 7. The rectangular hollow column is made of cast iron of 350mm height, 130mm in width and 13mm in thickness.
Experimental Modal testing to determine dynamic performance
The typical metal column used as a test specimen is shown in Figure 8, which was hung at a corner near flange using an eye bolt and tension spring 101 to imitate free-free condition. An accelerometer 105 is put at various positions on column structure 103 while hammering by an impact hammer 104 at a constant position. The effort was made to suspend the specimen with minimum constraints and to excite as many modes as possible. The acceleration data acquired 106 from a sensor is then analyzed 102 using an application. Results obtained from various models and series of experiments are analyzed.
The dynamic characteristics of hollow cast iron metal column in terms of time decay, which determines the decay time taken for the structural vibrations generated due to hammering 104. The accelerometer 105 acquires the amplitude of the vibrations as a function of time through the data acquisition system 106. The time decay plot is drawn by considering amplitude A verses time T (g/N v/s sec.), and the frequency domain plot is drawn by considering amplitude A verses frequencies F (g/N v/s Hz). Further, this time domain plot is converted into frequency domain plot by Fast Fourier Transform (FFT). Figures 9 and 10 depicts the time decay and the frequency domain plots for an unfilled cast iron column, respectively. Similarly, plots in Figure 11 show repeatability of the experimental data both in time decay and frequency domain.
The result of the above experiment is summarised as follows, the decay time taken for the structural vibrations generated due to hammering is 0.2 to 0.3 seconds,

number of the major resonance peak in FRF is 12, and the highest amplitude in FRF is seen to be 17.6 g/N at a frequency of 2500 Hz.
Development of Filler Technology
The specimen used for the testing is a rectangular filled column of 350mm height, 130mm in width, and 13mm in thickness made of cast iron and is filled with filler material. The filler material is Foam concrete with an outer layer either of EPDM Rubber or polymer concrete as shown in Figure 12 with the development steps for 3D filled column models. Step I consists of the unfilled cast iron column 1 which is filled with a layer of EPDM or polymer concrete 4 in Step II. The final step shows the foam concrete material 3 in the cast iron cast iron column 1 as the inner layer.
Experimental Modal testing to determine dynamic performance
The same test setup and procedure as for the unfilled column is applied.
Experimental data: The time decay plots with Amplitude A verses Time T, and frequency domain (FFT) plots with Amplitude A verses Frequencies F are shown in each case of filler design for a comparison of the effectiveness of filler technology over the unfilled metal columns for their dynamic characteristics.
1) Filler Material: Ordinary concrete (C01)
The decay time taken for the structural vibrations generated due to hammering is 0.2 seconds (highest g/N is 540). The time decay of this set-up is improved 0.5 times compared to the unfilled filler material. The major resonance peaks in Frequency Response Function (FRF) is 7. The highest amplitude in FRF is seen to be 4 g/N at a frequency of 2560 Hz, indicating a frequency shift towards higher value as shown in Figures 13 and 14.

2) Filler Material: Ordinary concrete with EPDM rubber (CR01)
The decay time taken for the structural vibrations generated is 0.1 seconds (highest g/N is 4800). The time decay of this set-up is improved three times compared to the unfilled. The major resonance peaks in FRF is 4. The highest amplitude in FRF is seen to be 16.6 at 2550 Hz as shown in Figures 15 and 16.
3) Filler Material: Foam concrete (FC01)
The decay time taken for the structural vibrations generated is 0.13 seconds (highest g/N is 3500). The time decay of this set-up is improved twice as compared to unfilled. The major resonance peaks in FRF is 4. The highest amplitude in FRF is seen to be 36.4 at 2490 Hz as shown in Figures 17 and 18.
4) Filler Material: EPDM rubber sheets of 12 mm thickness pasted at
Cast iron inside walls and filled with Foam concrete (FCRP01)
The decay time taken for the structural vibrations generated is 0.03 seconds (highest g/N is 2700). The time decay of this set-up is improved ten times compared to the unfilled. The major resonance peaks in FRF is 1. The highest amplitude in FRF is seen to be 5.4 at 2540 Hz as shown in Figures 19 and 20.
5) Filler Material: EPDM rubber sheets of 12 mm thickness pasted at
cast iron inside walls and crossed EPDM sheets arranged inside, and filled
with Foam concrete (FCRPC01)
The decay time taken for the structural vibrations generated is 0.02 seconds (highest g/N is 2700). The time decay of this set-up is improved fifteen times compared to the unfilled. The major resonance peaks in FRF is 2 to 3. The highest amplitude in FRF is seen to be 5.5 at 2550 Hz as shown in Figures 21 and 22.
6) Filler Material: EPDM rubber sheets of 12 mm thickness pasted at
cast iron inside walls and EPDM pellets distributed in the Foam concrete
filling (FCRPB01)
The decay time taken for the structural vibrations generated is 0.025 seconds (highest g/N is 3500). The time decay of this set-up is improved twelve times

compared to the unfilled. The major resonance peaks in FRF is 4. The highest amplitude in FRF is seen to be 6.5 at 2540 Hz as shown in Figures 23 and 24.
7) Filler Material: EPDM rubber sheets of 12 mm thickness pasted with
gap from the cast iron walls and filled with Foam concrete (FCRPG02)
The decay time taken for the structural vibrations generated is 0.09 sec. The time decay of this set-up is improved three times compared to the unfilled column as shown in Figure 25.
8) Filler Material: EPDM rubber sheets of 12 mm thickness pasted with
gap from the cast iron walls and EPDM blocks, and filled with Foam
concrete (FCRPGB02)
The decay time taken for the structural vibrations generated is 0.093 sec. The time decay of this set-up is improved three times compared to the unfilled column as shown in Figure 26.
9) Filler Material: EPDM rubber sheets of 12 mm thickness pasted with
gap from the cast iron walls and central EPDM sheet, and filled with Foam
concrete (FCRPGP02)
The decay time taken for the structural vibrations generated is 0.09 sec. The time decay of this set-up is improved three times compared to the unfilled column as shown in Figure 27.
The filler designs 7, 8 and 9 (FCRPG02, FCRPGB02, and FCRPGP02) as shown in Figures 25, 26 and 27 are being summarized. Due to manufacturing difficulties, EPDM sheets cannot be pasted inside ribbed walls of actual CNC machine columns and beds, in spite of best results achieved. To avoid difficulties, the said three designs 7, 8 and 9 (Figure 25, 26 and 27) were proposed which are FCRPG02, FCRPGB02, and FCRPGP02. However, it was found that the time decay has improved only three times compared to that of fifteen times wherein EPDM sheets were in direct contact with cast iron walls. As a result, these three designs were abandoned and were not analyzed further. It was estimated that the

EPDM pellets could be distributed in a better way to improve damping and the “Kebab design” is an outcome.
10) Filler Material: Kebab design: EPDM rubber sheets of 12 mm
thickness pasted with gap from the cast iron walls and filled with Foam
concrete (FCRBK03)
The decay time taken for the structural vibrations generated is 0.05-0.09 seconds (highest g/N is 2200). The time decay of this set-up is improved three times to six times compared to unfilled though slightly improved as compared to gap designs. The major resonance peaks in FRF is 4. The highest amplitude in FRF is seen to be 7.8 at 2480 Hz as shown in Figures 28 and 29. Due to less improvement (three to six times), the Kebab design has been abandoned.
11) Filler Material: Liquid EPDM rubber layer of 8-10 mm thickness
pasted onto cast iron walls and filled with Foam concrete (FCRL03)
The decay time taken for the structural vibrations generated is 0.05 seconds (highest g/N is 650). The time decay of this set-up is improved six times compared to unfilled. The major resonance peaks in FRF is 2. The highest amplitude in FRF is seen to be 2.2 at 5840 Hz as shown in Figures 30 and 31.
12) Filler Material: Liquid EPDM rubber layer of 8-10 mm thickness
pasted onto cast iron walls and EPDM are distributed in a Kebab manner in
the Foam concrete filling (FCRPLK03)
The decay time taken for the structural vibrations generated is 0.049 seconds (highest g/N is 146). The time decay of this set-up is improved six times compared to unfilled. The major resonance peaks in FRF is 2. The highest amplitude in FRF is seen to be 1.5 at 5840 Hz as shown in Figures 32 and 33.
13) 16mm thick EPDM sheets pasted to cast iron walls and filled with
foam concrete (T04)
The decay time taken for the structural vibrations generated is 0.029 seconds (highest g/N is 3040). The time decay of this set-up is improved ten times

compared to unfilled. The major resonance peaks in FRF is 0-1. The highest amplitude in FRF is seen to be 0.56 at 1570 Hz as shown in Figures 34 and 35.
14) Filler Material: A combination of foam concrete bricks and epoxy granite (EG03 and SEGBRICKS)
The decay time taken for the structural vibrations generated is 0.043 seconds (highest g/N is 4200). The time decay of this set-up is improved seven times compared to the unfilled metallic structural column. The major resonance peaks in FRF is 0-1. The highest amplitude in FRF is seen to be ~2.70 at ~2500 Hz as shown in Figures 36 and 37.
Figure 38 shows the comparison of average Damping factors D for various filler designs C of metal columns in which the filler design with the highest peak is efficient, and Figure 39 shows the comparison of Time decay B for various filler designs C for metal columns in which the filler design with the lower peak is efficient. The filler designs which are considered for the comparison are Unfilled column 20, columns filled with Concrete 21, Concrete and rubber 22, Foam concrete 23, EPDM sheet and foam concrete 24, EPDM sheet and foam concrete and cross EPDM sheets 25, EPDM sheet and foam concrete and pellets 26, EPDM Kebab and foam concrete 27, EPDM paste and foam concrete 28, EPDM paste and Kebab and foam concrete 29, 16 mm thickness EPDM sheets pasted to cast iron walls and filled with foam concrete 30, epoxy granite 31 and SEGBRICKS 32.
The advantage achieved by filler technology over the unfilled column for damping factor is up to five times and for time decay is up to fifteen times. The weight added by the filler is only 15-30% of the total weight of the metal column.

A light-weight, durable and advanced composite filler material that can be filled inside a hollow metallic machine tool structural parts for better damping, static, and dynamic characteristics of the machine tool.
The light-weight, durable and advanced composite filler material of Claim 1, wherein filler designs comprises of a combination of foam concrete 3 with ethylene propylene diene monomer (EPDM) placed in a typical arrangement of various types inside a hollow machine tool metallic structural part.
The light-weight, durable and advanced composite filler material of Claim 1, wherein possible arrangement of the filler material in the hollow machine tool structure are:
(a) Filling with the foam concrete 3; and
(b) The combination of the foam concrete 3 and EPDM, further:
(i) Pasting EPDM sheets on inner walls of the hollow machine tool
structure, and rest of the cavity is filled with the foam concrete
3; (ii) Two squares of the EPDM sheets are surrounded by the foam
concrete 4; (iii) A solid EPDM bar 7 is fixed at the center of a filled column; (iv) A crossed EPDM sheet arrangement 8 with the foam concrete
filling in between; (v) A combination of the EPDM 4 adhered to walls of a metal
structure and also inside the foam concrete filling along with
random distribution of EPDM pellets 5;

(vi) The EPDM pellets 5 are randomly distributed inside the foam
concrete 3 filler; and (vii) Systematically arranging the EPDM pellets 5 alongside a thin
EPDM cord 10 and successively filled with the foam concrete
3.
The light-weight, durable and advanced composite filler material of Claim 3, wherein the filled metallic machine tool structure are then cured in water and air.
The light-weight, durable and advanced composite filler material of Claim 3, wherein other possible combinations are developed either by sticking EPDM sheets at the inside walls of the metal structure or EPDM liquefied paste applied to the inner walls of the metal structure or the combination of both.
The light-weight, durable and advanced composite filler material of Claim 5, wherein during application of the EPDM paste, an EPDM green material which is raw EPDM rubber without mixing with hardener, is mixed with CnH2n+2 (petrol) to achieve constant viscosity in the range of 1500 – 2500 poise, further, this EPDM-CnH2n+2 paste is mixed with a hardener ‘Desmodur RE’ in the proportion of 80 ml per one litre of the EPDM paste.
The light-weight, durable and advanced composite filler material of Claim 1, wherein advantage of filler technology over unfilled column for average damping factor is up to five times and for average time decay is up to fifteen times, with an added weight of only 15 to 30% of the total weight of the metal column in case of foam concrete-EPDM filler, and of 30% of the total weight of the metal column in case of foam concrete bricks-epoxy granite filler.

A method of the light-weight, durable and advanced composite filler material that can be filled inside a hollow metallic machine tool structural parts for better damping, static, and dynamic characteristics of the machine tool, comprising the steps of:
(a) Mixing the foam which is a blend of protein based foaming chemical with water in a combination of the Portland cement and fly ash such that the final density of a foam concrete 3 achieved is 1000Kg/m3;
(b) Filling the hollow machine tool structure such that 30% of the total hollow volume is filled with EPDM and the rest 70% is filled with the foam concrete 3 with described composition that can be achieved by varying the proportions and compositions indicated above; and
(c) Filling the hollow machine tool metal structure with the foam concrete bricks and filling the surrounding cavity with epoxy granite composite.