Description:FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION: “A SAND COMPOSITION FOR FOUNDRY PROCESS FOR CASTING”
2. APPLICANT:
(a) Name : DEV INDUSTRIES
(b) Nationality : INDIAN
(c) Address : 98-100, 102-103, GIDC –Ranasan
Near Dev Circle, Vijapur 382 870,
Dist: Mehsana, Gujarat, India.
PROVISIONAL
The following specification describes the invention.  COMPLETE
The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF INVENTION
The present invention relates to a sand composition for foundry process for casting. More specifically, the present invention relates to the sand composition in order to provide better quality and to overcome the defects observed while moulding and casting.

BACKGROUND OF THE INVENTION
In the foundry industry, the production of castings with smooth surfaces has always been the goal pursued by foundry workers. The foundry sand have been widely used for years, but such sand have many objectionable characteristics which are reflected disadvantageously in the appearance, surface texture and average cost of the satisfactory castings produced.

It has been found that the sand will stick to the patterns unless moistened with great uniformity, and will pack too hard to allow the gases to escape if too much moisture is used. Furthermore, the sand will fuse in contact with the molten metal, irrespective of the skill with which the sand is prepared, and such fusing or burning of the sand will form gases and slag, which can render the surface of the casting irregular, and will lower the bonding and refractory qualities of the sand at such an extent as it can make a substantial portion of the same unfit for subsequent use.

Further, there are various foundry process such as sand casting, die casting, shell mould casting, investment (lost wax casting), continuous casting, centrifugal casting, plaster mould casting, green sand casting, vacuum casting and expendable pattern casting, no bake sand casting from which the foundry process that employs the usage of the sand are sand casting, green sand casting, shell moulding and no bake sand casting.

The shell mould casting employed by the foundry industry has been widely used since some years. The shell process (also known as the croning or C process) is used to produce hollow light weight molds and cores for pipe hubs, cores, crank shafts, intake manifolds for engines, etc. In fact, more foundries utilize the shell process, to produce resin sand cores and molds, than any other process. The process is extensively applied worldwide.

The resin coated sand (RCS) is commonly used in shell mould casting for sand core production. Sand cores are used to provide cavities in parts produced by a casting process. Thus, it is crucial that sand mould casting should have proper mechanical properties to provide the cores made from it to have enough strength to prevent core crack during the casting process and thus some researchers have studied relevant factors affecting to quality and improve properties of the foundry process.

Further, as the requirements for the quality of castings become more sophisticated, such as thin wall, light weighting and improved dimensional accuracy, the industry has put forward higher requirements for casting molding materials.

Moreover, it is observed that the above mentioned foundry process can be expensive; the process is complex and requires specialized equipments, refractory materials and time consuming. Further, the said foundry process leaves defects such as caved surfaces, open shrinkage defects [also known as shrinkage porosity] that form across the surface of the casting.

CN104139153A discloses the environment-friendly foundry sand and relates to the field of foundry materials. It comprises of 60-70 parts of silica sand, 5-10 parts of chromite sand, 30-40 parts of household refuse ash, 6-8 parts of coal ash, 6-8 parts of lime powder, 3-5 parts of furan resin and 4-10 parts of coal dust.

JPS61169128A discloses phenolic resin binder for shell mold and resin coated sand for shell mold. In particular, the said prior art compounds carbon powder with a phenolic resin to form a phenolic resin binder for a shell mold without using a mold coating material.

CA631535A discloses foundry sand composition for use in casting molten metal and to a method of preparing these compositions. In particular, it relates to sand compositions containing a carbonaceous material comprised of a high melting point asphaltic pitch and lignite.

As per the above it can be concluded that there is a requirement to improve/modify the previous known process for foundry. The present invention provides better particle size distribution, increases the workability, strength and durability of the sand.

Therefore there is an urgent need to develop new formulations to achieve a sand composition for foundry process for casting which provides effective result and better quality hence achieving better casting surface which can overcome gas issue, crack issue, bubbling issue, formation of pin and blow holes and to overcome the existing problems and can be prepared easily without much complex manufacturing process.

The present inventors have surprisingly developed an effective sand composition which ameliorates the aforesaid shortcomings of the prior arts and makes the present invention effective, innovative and cost effective.

OBJECT OF THE INVENTION

The principal object of the present invention is to provide a sand composition for foundry process for casting utilized in foundry.

Yet another object of the present invention is to provide better quality of sand to prepare casting parts.

Another object of the present invention is to provide a sand composition to achieve proper grain size, shape, structure, distribution, strength and stability of the sand.

Yet another object of the present invention is to overcome the defects of moulding breakage, poor flowability, slow invest rate, lamination, peel back, sticking and warpage.
Yet another object of the present invention is to overcome the defects of casting such as cracking, gas defects, metal penetration, nitrogen defects, bubbling issue, poor shakeout, veining, pin and blow holes.

Still another object of the present invention is to provide a sand composition for foundry process with best quality and also cost effective.

SUMMARY OF THE INVENTION

The present invention relates to a sand composition for foundry process for casting. Particularly, the present invention provides sand composition to provide proper grain size, shape, structure, distribution, strength and stability of the sand. In addition to that, the sand composition comprises 30 ASTM sieve size 0.01 to 3% of sand; 40 ASTM sieve size 5 to 10% of sand; 50 ASTM sieve size 10 to 20% of sand; 70 ASTM sieve size 30 to 35% of sand; 100 ASTM sieve size 30 to 35% of sand; 140 ASTM sieve size 8 to 13% of sand; 200 ASTM sieve size 0.01 to 4% of sand; and 270 ASTM sieve size 0.01 to 1% of sand. Further, the sand composition prevents from cracking and increases the flowability which in turn improves the performance of foundry process. The sand composition of present invention overcomes/controls errors such as formation of cracks, bubbling, pin holes, gas issue, blow holes, poor shakeout, metal penetration, veining, poor flowability, breakage, slow invest rate, lamination, peel back, sticking, warpage. In addition to that the present invention employs the best quality of the mould and casting surface finish in a cost effective manner.

BRIEF DESCRIPTION OF DRAWINGS

It should be noted that the figures are only intended to facilitate the description of the preferred embodiments. The figures do not illustrate every aspect of the described embodiments and do not limit the scope of the present disclosure.

Other features and advantages of the present invention will become apparent to those of ordinary skill in the art through consideration of the ensuing description, the accompanying drawings, and the appended claims.

Fig 1 illustrates the images of mix flow impeller using comparative example 1 (A) and present invention’s sand composition (B).
Fig 2 illustrates the images of radial flow impeller using comparative example 1 (A) and present invention’s sand composition (B).

DETAILED DESCRIPTION OF THE INVENTION
Before explaining the present invention in detail, it is to be understood that the invention is not limited in its application to the details of the parts illustrated. The invention is capable of other embodiments, as described above and of being practiced or carried out in a variety of ways. It is to be understood that the phraseology and terminology employed herein is for the purpose of description and not to limitation. The invention may have various embodiments and they may be performed as described in the following pages of the complete specification.

The terms and words used in the following description are not limited to the bibliographical meanings, but, are merely used by the inventors to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the scope of the invention.

It is to be understood that the singular forms "a," "an," and "the" include plural reference unless the context clearly dictates otherwise.

Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.

It should be emphasized that the term "comprises/comprising" when used in this specification is taken to specify the presence of stated features, steps or components but does not preclude the presence or addition of one or more other features, steps, components or groups thereof.

The term “HTS” refers to hot tearing susceptibility. HTS is a casting defect responsible for external and internal cracks on casting products. This irregular undesired formation is often observed during solidification and freezing.

The term “GAS” refers to a gas hole as a defect in the casting that occurs due to trapped gases and dirty metal.

The term “CH” refers to core hardness. In particular, core hardness indicated that the material was in hardened and tempered condition.

The term “AFS” refers to Average Fineness Number which is the standard for reporting the grain size and distribution of sand to assess the particles.

The term “ASTM” refers to American Society for Testing and Materials/ American Standard Test Sieve Series to distinguish small particles from bigger particles.

It is to be noted that the measurement considered by the present invention is of ASTM sieve size however the present invention is also applicable on the measurements of BSS [British Standard Sieve] and ISS [Indian Standard Sieve].

The present invention relates to the sand composition for foundry process for casting.. However, in order to achieve the best quality of the casting surface, the composition of the sand is equally important and plays a vital role to overcome the defects of the moulding and casting.

Further, there are various foundry process such as sand casting, die casting, shell mould casting, investment (lost wax casting), continuous casting, centrifugal casting, plaster mould casting, green sand casting, vacuum casting and expendable pattern casting, no bake sand casting from which the foundry process that employs the usage of the sand are sand casting, green sand casting, shell moulding and no bake sand casting.

Table 1: The present invention provides the composition of sand as follows:

AFS value 55-65
ASTM sieve In percentage (%)
30 0.01 to 3
40 5 to 10
50 10 to 20
70 30 to 35
100 30 to 35
140 8 to 13
200 0.01 to 4
270 0.01 to 1

The “sand” is selected from silica sand, quartz sand, white sand, burned thermal sand, raw sand, industrial sand and combination thereof. The present invention has been worked on white sand.

Further, it should be noted that the burned thermal sand and raw sand can be taken into consideration in an amount of 90-95% and 5-10% respectively.
The manufacturing process of the sand composition for foundry process comprises mixing of the sand size as mentioned in Table 1:

It is to be noted that the below shown manufacturing process is applicable to the foundry process as mentioned above however, in order to provide definite result, the present invention has considered the shell mould casting as one of the foundry process which involves the usage of sand.

Step 1: The sand is sieved through ASTM sieves to remove unwanted particles.

Step 2: Upon completion of step 1; the quality of the obtained sand is checked through AFS.

Step 3: After receiving the confirmation from the quality; the weight of the obtained sand is calculated and loaded into sand coating hopper.

Step 4: On completion of step 3; the phenolic resin and hardener are added into the sand coating hopper as per the above provided range and the requirement of foundry.

Step 5: The obtained mixture is provided with 5 to 10 minutes for coating time heated at 125° to 250° C temperature.

Step 6: Upon completion of step 5; the above mixture is tested through AFS, HTS, GAS and other parameters such as hardness.
Step 7: At last, after receiving confirmation of all the parameters as mentioned in step 6; packaging and dispatch of the final product is done.

In addition, it should be noted that in step 1; burned thermal sand can also be taken into consideration. Particularly, the burned thermal sand is converted into fresh raw sand at 600° to 700° C temperature in thermal reclaim furnace. Further, after the completion of steps 1 and 2, raw sand upto 5% to 10% if required is added in the sand mixer machine as per the requirement. The remaining steps 3 to 7 as mentioned above are followed.

Table 2: The below shown table shows the ingredients and its amount if required in percentage to prepare foundry process, in particular shell mould casting:

Sr. no. Name of the ingredient Range [in percentage]
1. Sand 100%
2. Phenolic resin 2.10 to 3.10% of sand
3. Hardener 15 to 20% of resin

The phenolic resins also known as phenol formaldehyde resins or phenoplast are thermosetting polymers. Further, they are known for their excellent heat resistance, flame retardency and dimensional stability. The resins are defined by their high cross linking density, which contributes to their exceptional mechanical and thermal properties, particularly in combination with carbon fibre reinforcement.

The phenolic resins are selected from but not limited to bakelite, novolac, catalin, fiberloid, marblette, agatine, durite, durez, prystal, fiberlon, resole resin, liquid resin, opalon, carvacraft, solid resin.

The most preferred phenolic resins for the present invention are selected from liquid resin and/or solid resin.

It is to be noted that the heater temperature for liquid resin is 230°C to 240°C temperature whereas the chamber temperature is 50°C to 60°C temperature. Further, the heater temperature is 120°C to 150°C for solid resin.

The hardener as mentioned in the present invention increases the resilience of the mixture once it sets. Further, it can also be considered as a curing component. These hardener additives serve as catalysts that speed up the curing process.

The hardeners are selected from but not limited to amines, aliphatic amines, aromatic amine, acid anhydrides, mercaptans, carboxylic acids, hexamethylenetetramine, calcium stearate, phenols, methanamine.

Further, it is to be noted that Fig. no.1 shows the images of mix flow impeller using comparative example 1 (A) and present invention’s sand composition (B). In particular, (A) shows the comparative example and defects in the casting which is not intact whereas (B) shows the casting without any defects and is intact with the help of sand composition of present invention.

Moreover, Fig no. 2 shows the images of radial flow impeller using comparative example 1 (A) and present invention’s sand composition (B). In particular, (A) shows the comparative example and defects in the casting which is not intact whereas (B) shows the casting without any defects and is intact with the help of sand composition of present invention.

The present invention showcases one of the foundry process’s working example i.e. shell mould casting. It is to be noted that the sand composition is fruitful for the foundry processes as mentioned above, in particular foundry process which employs the usage of sand however, in order to prove the sand composition, the present invention has employed the said composition on shell mould casting.

EXAMPLES

The present invention has been described with the below shown working examples which do not limit the scope of the present invention and merely illustrates the sand composition of the present invention fruitful for the foundry process:

COMPARATIVE EXAMPLE:

Table 3:
Type of sand White sand
Sr. no. Sieve series in micron ASTM sieve Weight (gm) % Retained Difference Multiplying factor Product
1 1700 12 0.000 0.00% 0.00% 5 0
2 850 20 0.000 0.00% 0.00% 10 0
3 600 30 0.000 0.00% 0.00% 20 0
4 425 40 0.300 0.60% 0.60% 30 0.180046812
5 300 50 4.328 8.66% 8.66% 40 3.463300458
6 212 70 20.937 41.88% 41.88% 50 20.94244504
7 150 100 20.065 40.14% 40.14% 70 28.09830556
8 106 140 3.715 7.43% 7.43% 100 7.431932302
9 75 200 0.606 1.21% 1.21% 140 1.697241283
10 53 270 0.036 0.07% 0.07% 200 0.14403745
Pan - 0.000 0.00% 0.00% 300 00
Total gram = 49.987 Total = 100% 100.00% AFS = 61.9573089

The above Table 3 showcases the ASTM sieve size and the amount of the sand considered for the same.

Table 4:

sr.no. Specification I II III Avg kg Resin (%) Hardener (%) Resin gm/kg Hardener gm/kg
1 HTS 19.5 18.5 18.4 18.8 AFS time 5 mins 2.75 18.00 1.375 0.248
2 GAS 11.2 9.9 10.1 10.4
3. CH 78.0 79.0 80.0 79.0

The above Table 4 showcases the specifications such as hot tearing susceptibility, gas and core hardness of the shell mould when the resin and hardener is used.

EXAMPLE 1:
Table 5:
Sr. no. Type of sand White sand
Sieve series in micron ASTM sieve Weight (gm) Retained (%) Difference Multiplying factor Product
1 1700 12 0.000 0.00% 0.00% 5 0
2 850 20 0.212 0.42% 0.42% 10 0.04241 1875
3 600 30 0.972 1.94% 1.94% 20 0.388908 894
4 425 40 2.617 5.24% 5.24% 30 1.57063977 9
5 300 50 6.855 13.71% 13.71% 40 5.48553595
6 212 70 17.572 35.15% 35.15% 50 17.5769 2154
7 150 100 15.842 31.69% 31.69% 70 22.1850118
8 106 140 4.879 9.76% 9.76% 100 9.760733005
9 75 200 1.023 2.05% 2.05% 140 2.865202257
10 53 270 0.014 0.03% 0.03% 200 0.056015684
11 Pan - 0.00% 0 00% 300 0
Total gram = 49.986 Total =100.00% 100.00% AFS = 59.93138079

The above shown Table 5 showcases the ASTM sieve size and the amount of the sand considered for the same.

Table 6:
Sr no. Specification I II III Avg Kg Resin (%) Hardener (%) Resin gm/kg Hardener gm/kg
1. HTS 29 .7 31.4 30.8 30.6333333 AFS time: 5 mins 2.65% 16.00% 7.950 1.272
2. GAS 12.2 11.6 11.8 11.8666667
3. CH 89 91 90 90

The above shown Table 6 showcases the specifications such as hot tearing susceptibility, gas and core hardness when resin and hardener is used.

Table 7:
Sr no. specification MIN MAX AVG One time accepted value:
1 AFS 55 65 59.93 56 64
2 HTS 28 32 30.63 25 33
3 GAS 9 13 11.86 8 14
4 CH 88 92 90 80 95

The above shown Table 7 showcases the specifications such as hot tearing susceptibility, gas and core hardness whilst maintaining the AFS value.

Conclusion: It can be clearly understood from the above shown working example that the sand composition of present invention requires less usage of resin and hardener thus achieving better quality of sand grain having proper size, shape, structure, distribution, strength and stability of the sand.

Further, the sand composition of present invention controls/overcomes the defects when compared with the comparative example. The present invention provides better quality by overcoming/controlling the defects of hot tearing susceptibility, core hardness, moulding breakage, poor flowability, gas defects, cracking, bubbling issue, pin and blow holes, metal penetration, nitrogen defects, poor shakeout, veining slow invest rate, peel back, sticking and warpage which in turn provides best quality and cost effective result.

Further, the method to prepare the sand composition can be modified accordingly by any person skilled in the art based on the knowledge of manufacturing the composition. However, all such variation and modification is still covered by the scope of present invention.

The present invention has been described with reference to specific embodiment which is merely illustrative and not intended to limit the scope of the invention as defined in the present complete specification. , Claims:We claim:

1. A sand composition for foundry process for casting comprises:
30 ASTM sieve size sand 0.01 to 3%;
40 ASTM sieve size sand 5 to 10%;
50 ASTM sieve size sand 10 to 20%;
70 ASTM sieve size sand 30 to 35%;
100 ASTM sieve size sand 30 to 35%;
140 ASTM sieve size sand 8 to 13%;
200 ASTM sieve size sand 0.01 to 4%; and
270 ASTM sieve size sand 0.01 to 1%.

2. The sand composition as claimed in claim 1, wherein sand is selected from silica sand, quartz sand, white sand, industrial sand, raw sand, burned thermal sand and combination thereof.

3. The sand composition as claimed in claim 2, wherein the burned thermal sand is 90-95% and raw sand is 5-10%.

Dated this on 03rd December, 2024