Metal Finishing Guide Book

2011-2012 Surface Finishing Guidebook

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Page 28 of 707

For flexible polishing of thermosetting plastic articles, greaseless compound pro- vides a dry and resilient abrading face for removal of light or residual flash, imper- fections in the surface, and cutting tool marks, or for smoothing out irregularities on the contours left by the belting operation. Thermoplastic articles readily distort with frictional overheating. To avoid this problem minimum work pressure against the coat- ed buff wheel and low peripheral speeds are needed. To assure low frictional heat devel- opment, grease sticks also can be applied to the coated buffing wheel. This gives added lubrication and lowers the amount of drag, which produces the heat buildup. BUFFING OF PLASTIC Buffing is usually divided into cutdown and luster or color buffing. Cutdown buffing produces a semigloss finish from the dull, sanded surface resulting from belt sanding or greaseless compound operations. This semigloss finish is ade- quate as a final finish in some cases. Where a higher luster is required, this cutdown buffing is the intermediate operation prior to the final high luster buffing. The most popular buffs used are full disk sewn 80/92 count cloth for cutdown and full disk loose, bias type, or ventilated 64/68 count for luster. Buffing pressure should be at a minimum and the buff speed slow to prevent "burning" the plastic. Keeping the buff well lubricated with buffing compound in the cutdown operation helps minimize the burning. MILL AND ARCHITECTURAL FINISHES (STAINLESS STEEL) The main concern of most fabricators of stainless steel is to remove welds and machining marks, and blend and sim- ulate the final finish with the original mill finish or the sheet or coil stock. To refine the area of welds and machin- ing marks, standard rough polishing procedures used are as those previous- ly discussed. Note that the final sur- face finish must closely approximate the original mill finish. There are eight basic stainless steel mill finishes used in the industry by product designers and architects. Mill finish Nos. 3, 4, 6, 7, and 8 are produced mechanically using some type of abrasive media and buff- ing wheels. Finish Nos. 3 and 4 have proven to be the most popular among fabricators of dairy, kitchen, cafeteria, chemical equipment, and architectural and decorative structures. The simplest way to produce these blended finishes is with string wheels coated with grease- less abrasive compositions containing 80, 120, or 180 grit abrasive, operating at relatively low speeds. Narrow, flat, or curved areas can eas- ily be blended with a portable power tool and a string wheel up to 8 inches in face width. Medium or very wide areas are finished with a string wheel log held ISO 9001: 200 Certified Manufacturers of fine polishing compounds for over 8 years. ● BARS ● LIQUID ● ● BUFFS ● PASTE BELTS For Metal, Fiberglass, Marble and Paint All compounds are crystalline silica free. Private labeling available. ● CUSTOM KITS ● LUBRICANTS SPECIALTY DEGREASERS 4800 South St. Louis Avenue ● Chicago, Illinois 60632, U.S.A. Phone: 773-847-1111 Fax: 773-847-3399 email: 27

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