Abrasive machining media containing thermoplastic polymer
The present invention incorporates at least one thermoplastic or elastomeric polymer in abrasive flow machining media either as the sole or as one of the polymeric constituents. The presence of thermoplastic polymer imparts a greater elastomer characteristic (elasticity, compression resistance, increased relaxation times) as contrasted with traditional media. Enhanced elastomeric characteristics enable more uniform abrasive machining. In a particularly preferred embodiment, silicone- or polyorganosiloxane-based medium contains elastic silicone rubber particles dispersed therethrough to achieve increased relaxation times comparable to those attainable with the inclusion of a thermoplastic polymer.
1. An abrasive machining medium comprising: a quantity of abrasive particles dispersed in a viscoelastic base medium containing at least one thermoplastic polymer therein.
2. The machining medium according to claim 1 wherein said thermoplastic polymer is a styrene polymer.
3. The machining medium according to claim 2 wherein said styrene polymer is admixed with a silicone polymer.
4. The machining medium according to claim 1 wherein a diluent is present selected from the group consisting of mineral oil and paraffin oil.
5. The machining medium according to claim 1 wherein said thermoplastic polymer is present in the amount of about 0.001-100% by weight of said base medium.
6. The machining medium according to claim 1 wherein said thermoplastic polymer is present in the amount of about 0.25-100% by weight of said base medium.
7. The machining medium according to claim 1 wherein said thermoplastic polymer is present in the amount of about 0.5-100% by weight of said base medium.
8. The machining medium according to claim 2 wherein said styrene polymer is present in the amount of about 5% by weight of said base medium.
9. The machining medium according to claim 2 wherein said styrene polymer is present in the amount of about 20% by weight of said base medium.
10. The machining medium according to claim 2 wherein said styrene polymer is present in the amount of about 25% by weight of said base medium.
11. The machining medium according to claim 2 wherein said styrene polymer is present in the amount of about 40% by weight of said base medium.
12. The machining medium according to claim 2 wherein said styrene polymer softens within the temperature range of about 180°-375° F.
13. The machining medium according to claim 3 wherein said silicone polymer and said styrene polymer are admixed in about equal parts by weight.
14. The machining medium according to claim 3 wherein said silicone polymer is present in the amount of about 60-80% by weight and said styrene polymer is present in the amount of about 20-40% by weight in said base medium.
15. The machining medium according to claim 3 wherein said silicone polymer is present in the amount of about 65-75% by weight and said styrene polymer is present in the amount of about 25-35% by weight in said base medium.
16. The machining medium according to claim 3 wherein said silicone polymer is present in the amount of about 70% by weight and said styrene polymer is present in the amount of about 30% by weight in said base medium.
17. A method of making the machining medium according to claim 1 by softening a thermoplastic polymer constituent and incorporating it into the base medium recited in claim 1 in an amount sufficient to increase the relaxation time of the base medium to at least about 1.
18. A method of making the machining medium according to claim 17 by admixing the softened thermoplastic polymer constituent and melt-blending it with the base medium at the time of initial polymer manufacture of the base medium.
19. A method of making the machining medium according to claim 1 by shredding a thermoplastic polymer constituent and incorporating the discrete thermoplastic particulates thus produced into the base medium recited in claim 1 in an amount sufficient to increase the relaxation time of the base medium to at least about 1.
20. A method of making the machining medium according to claim 19 wherein the volumetric concentration of said thermoplastic particulates is half or more of the volumetric concentration of one or more abrasive particles also included in said medium.
21. The method according to claim 19 wherein said thermoplastic polymer is selected from the group consisting of styrene, ethylene, polyurethane, polyvinyl, polyamide, polycaprolactone, and polypropylene containing polymers.
22. A method of using the machining medium of claim 1 by applying it under pressure over a fabricated surface to be honed.
23. A machining medium comprising a viscoelastic base medium selected from the group consisting of a silicone polymer and a polyorganosiloxane polymer, a quantity of abrasive particles admixed therewith, and a quantity of elastic silicone rubber particles admixed with said viscoelastic base medium and said abrasive particles.
24. The machining medium according to claim 23 wherein said abrasive particles have a size of up to about 4/6 sieve and said elastic silicone rubber particles have a size of up to about 4/6 sieve.