TH38803A - A thin, hard-bonded abrasive wheel. - Google Patents

Abstract

DC 60 (05/08/42) Thin, straight, single-piece abrasive wheels are made from heavy, strong abrasive grains and sintered metal bonds. These, incorporating hardening metal elements, exhibit superior hardness. The metal can be selected from a wide range of sintered metal alloys; nickel and tin alloys are suitable. Hardening metals are those capable of providing measured increases in bond strength without significantly increasing bond hardness. Molybdenum, rhenium, tungsten, and alloys of these metals are suitable. Generally, sintered bonds are formed from various powders. Diamond abrasive wheels and sintered nickel/tin/molybdenum bonded abrasive wheels are suitable. Such wheels are beneficial for abrasive operations in the electronics industry, such as cutting thin sheets of silicon and alumina-titanium carbide. The hardness of these new abrasive wheels is higher than commonly used single-piece straight wheels, thus improving cutting accuracy and generating fewer chips without increasing wheel thickness and associated with increased saw kerf loss. Thin, straight, single-piece abrasive wheels. Straight abrasive wheels are made from heavy, strong abrasive grains and sintered metal bonds. These wheels, incorporating hardening metal elements, exhibit superior hardness. The metal can be selected from a wide variety of sintered metal alloys; nickel and tin alloys are suitable. Hardening metals are those capable of providing measurable increased bond strength without significantly increasing bond hardness. Molybdenum, rhenium, tungsten, and alloys of these metals are suitable. Generally, sintered bonds are formed from various powders. Diamond abrasive wheels and sintered nickel/tin/molybdenum bonded abrasive wheels are suitable. Such wheels are beneficial for abrasive operations in the electronics industry, such as cutting thin sheets of silicon and alumina-titanium carbide. The hardness of these new abrasive wheels is higher than that of commonly used single-piece straight abrasive wheels, resulting in improved cutting accuracy and less chipping without increasing wheel thickness and associated with increased saw kerf loss.

Claims (46)

1. The abrasive wheel must consist of an abrasive disc containing approximately 2.5-50% by volume of abrasive grains and a total filler volume of 100% by volume of sintered bonds of the necessary components, consisting of nickel and tin, and a hardening metal selected from a group containing molybdenum, rhenium, tungsten, and at least two alloys of such hardening metals. 2. The abrasive wheel of claim 1, where the dissimilar elastic modulus is at least approximately 130 GPa. 3. The abrasive wheel of claim 1, which requires that the necessary components consist of a majority fraction of nickel and a minority fraction of tin. 4. The abrasive wheel of claim 3 in which the sintered bonds consist of (a) nickel approximately 38–86 n%, (b) tin approximately 10–25 n%, and (c) a hardening metal approximately 4–40 n%, and in which all of (a), (b), and (c) are 100 n%. 5. The abrasive wheel of claim 4, where the hardening metal is molybdenum. 6. The abrasive wheel of claim 4, where the hardening metal is rhenium. 7. The abrasive wheel of claim 4, where the hardening metal is tungsten. 8. The abrasive wheel of claim 4, where the hardening metal is an alloy of at least two of the following: molybdenum, rhenium, and tungsten. 9. The abrasive wheel of claim 8, in which molybdenum comprises the majority fraction of the mixture. 10. The abrasive wheel of claim 1, where the required sintered bonds consist of nickel powder, tin powder, and sintered hardening metal powder. 11. The abrasive wheel of Patent 1, where the abrasive media is a hard abrasive media selected from a group consisting of diamond, cubic boron nitride, silicon carbide, fused aluminum oxide, microcrystalline alumina, silicon nitride, boron carbide, tungsten carbide and a mixture of at least two of the abrasive media mentioned above. 12. The abrasive wheel of claim 11, where the abrasive grain is diamond. 13. Abrasive wheels of claim 4 with uniform width in the range of 20-2,500 micrometers. 14. The abrasive wheel of claim 13, where the proposed abrasive grains contain 20-50% volume of the disc and the disc has a maximum of approximately 10% volume of burned bonds and abrasive material. 15. The abrasive wheel of Patent 13 must consist of an abrasive disc with a circumferential diameter of 40-120 mm, with a spindle bore limited to 12-90 mm, with a uniform center thickness in the range of 175-200 micrometers, and must contain diamond particles and a sintered bond that must consist of 18% tin, 24% molybdenum, and 58% nickel. 16. The abrasive wheel of Patent 13 must consist of an abrasive disc with a circumferential diameter of 40-120 mm, which limits the spindle bore to 12-90 mm, which has a uniform width of 175-200 micrometers, and which must consist of diamond particles and a sintered bond that must contain 18% tin, 24% tungsten, and 58% nickel. 17. The abrasive wheel of Patent 13 must consist of an abrasive disc with a circumferential diameter of 40-120 mm, with a spindle bore limited to 12-90 mm, with a uniform width in the range of 175-200 micrometers, and must consist of diamond particles and a sintered bond that must contain 18% tin, 24% rhenium, and 58% nickel. 18. Cutting method consisting of a step in contact with the workpiece with at least one abrasive wheel consisting of an abrasive disc that must contain 2.5-50% volume of abrasive grit and a total of 100% volume of sintered bonds of the necessary components consisting of nickel and tin, and a hardening metal selected from a group consisting of molybdenum, rhenium, tungsten and an alloy of at least two of such hardening metals. 19. The method of claim 18, whereby abrasive wheels are required to consist of an abrasive disc with a circumferential diameter of 40-120 mm, which limits the spindle bore to 12-90 mm, and which has a uniform width in the range of 175-200 µm, whereby the abrasive disc is required to consist of diamond grains and sintered bonds of a necessary alloy containing 38-86 n% nickel, 10-25 n% tin, and 4-40 n% molybdenum, with the total of nickel, tin, and molybdenum being 100 n%. 20. Method of claim 18 where the specimen is selected from a group consisting of alumina-titanium carbide and silicon. 21. Method of claim 18 where abrasive wheels must consist of an abrasive disc with a circumferential diameter of 40-120 mm, which limits the spindle bore to 12-90 mm, and has a uniform width in the range of 175-200 µm, which abrasive disc must consist of diamond particles and a sintered bond that must contain 38-86 nW% nickel, 10-25 nW% tin, and 4-40 nW% tungsten, with the total of nickel, tin, and tungsten being 100 nW%. 22. Method of claim 21 in which the workpiece is selected from a group consisting of alumina-titanium carbide and silicon. 23. Method of claim 18 where abrasive wheels must consist of an abrasive disc with a circumferential diameter of 40-120 mm, which limits the spindle bore to 12-90 mm, and which has a uniform width in the range of 175-200 µm, which abrasive disc must consist of diamond particles and a sintered bond that must contain 38-86 nW% nickel, 10-25 nW% tin, and 4-40 rhenium, with the total of nickel, tin, and rhenium being 100 nW%. 24. Method of claim 23 in which the workpiece is selected from a group composed of alumina-titanium carbide and silicon. 25. The method for making abrasive tools consists of the following steps: (a) preparation of the particulate components, which include (1) abrasive grains; and (2) a binding compound, which must contain nickel powder, tin powder, and a hardening metal powder selected from a group containing molybdenum, rhenium, tungsten, and at least two of such hardening metal alloys; (b) mixing the particulate components to obtain a uniform compound; (c) placing this uniform compound into a mold; (d) pressing the mold to a pressure in the range of 345-690 MPa for the effective time to form the molded object; (e) heating the molded object to a temperature in the range of 1050-1200 °C for the effective time to sinter the binding compound; and (f) cooling the molded object to form the abrasive tool. 26. The method of claim 25, which is further comprising a depressurization procedure on the compressed material to a low pressure of less than 100 MPa after the compression step and the maintenance of that low pressure during the heating step. 27. Method of claim 26 in which the pressure on the compressed object is maintained in the range of 25-75 MPa during the heating process. 28. Method of claim 26 which comprises a particulate that must contain (a) nickel 38-86 n%; (b) tin 10-25 n%; and (c) molybdenum 4-40 n%, the total of (a), (b) and (c) is 100 n%. 29. Method of claim 26 where the particulate components required to contain (a) nickel 38-86 n%; (b) tin 10-25 n%; and (c) tungsten 4-40 n%, the total of (a), (b) and (c) is 100 n%. 30. Method of claim 26 where the necessary particulate components must consist of (a) nickel 38-86 n%; (b) tin 10-25 n%; and (c) rhenium 4-40 n%, the total of (a), (b) and (c) is 100 n%. 31. Method of claim 26 where the abrasive tool is a disc of uniform width in the range of 175-200 mm, circumferential edge with a diameter of 40-120 mm, and where the disc limits the hole of the spindle to 12-90 mm. 32. Method of claim 26 where the particulate compound consists of 20-50% volume of abrasive grains of a hard abrasive selected from a group consisting of diamond, cubic boron nitride, silicon carbide, fused aluminum oxide, microcrystalline alumina, silicon nitride, boron carbide, tungsten carbide and a mixture of at least two such abrasives. 33. The method of claim 32 where the abrasive is a diamond. 34. Method of claim 25 in which the heating step occurs while the compressed material is maintained at the pressure of the compression step. 35. Method of claim 34 where the tarticulate components required to contain (a) nickel 38-86; (b) tin 10-25 n%; and (c) molybdenum 4-40 n%, all of (a), (b) and (c) are 100 n%. 36. Method of claim 34 where the required particulate components must consist of (a) nickel 38-86 n%; (b) tin 10-25 n%; and (c) tungsten 4-40 n%, all of (a), (b) and (c) are 100 n%. 37. Method of claim 34 where the necessary particulate components must consist of (a) nickel 38-86 n%, (b) tin 10-25 n%; and (c) rhenium 4-40 n%, the total of (a), (b) and (c) is 100 n%. 38. Method of claim 34 where the particulate compound consists of 20-50% volume of abrasive grains of a hard abrasive selected from a group consisting of diamond, cubic boron nitride, silicon carbide, fused aluminum oxide, microcrystalline alumina, silicon nitride, boron carbide, tungsten carbide and a mixture of at least two such abrasives. 39. The method of claim 38, where the abrasive is a diamond. 40. A sintered bonding compound for a monolithic abrasive wheel that must consist of nickel and tin, and a hardening metal selected from a group consisting of molybdenum, rhenium, tungsten and at least two of these metals, where the sintered bond has an elastic modulus of at least 130 GPa and a Rockwell B hardness less than approximately 105. 41. The mixture of claim 40 must contain 38-86% (non-weight) of nickel, 10-25% (non-weight), and 4-40% (non-weight) of hardening metals; the total of nickel, tin, and hardening metals must be 100% (non-weight). 42. A mixture of claim 40 in which the hardening metal is molybdenum. 43. A mixture of claims 40 in which the hardening metal is tungsten. 44. A mixture of claims 40 in which the hardening metal is rhenium. 45. A mixture of claim 40 in which the hardening metal is a mixture of at least two of the following: molybdenum, rhenium, and tungsten. 46. A mixture of claims 45 in which molybdenum comprises the majority fraction of the mixture.