Metal Finishing Guide Book

2011-2012 Surface Finishing Guidebook

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with two hands or by two operators. Such a polishing log is made up of string wheel sections on a desired width shaft of a sufficiently powered portable tool. The greaseless compound is applied to the rotating string wheel log and allowed to dry a few minutes. String wheel blending is then quickly accomplished in the direction of the lines of the original mill finish. Mill finishes Nos. 6, 7, and 8 are most generally used on consumer products, although on some architectural sections they are produced for contrasting patterns. BASIC STAINLESS STEEL SHEET FINISH DESIGNATION The following list of stainless steel sheet finish designations includes a brief description of how each finish is obtained. Unpolished Finish No. 1: A dull finish produced by hot rolling to specified thickness, followed by annealing and descaling. Unpolished Finish No. 2D: A dull finish produced by cold rolling to specified thickness, followed by annealing and descaling. May also be accomplished by a final, light roll pass on dull rolls. Unpolished Finish No. 2B: A bright finish commonly produced in the same way as No. 2D, except that the annealed and descaled sheet receives a final, light cold-roll pass on polished rolls. This is a general purpose, cold-rolled finish, and is more readily polished than the No. 1 or No. 2D finishes. Polished Finish No. 3: An intermediate polished finish generally used where a semipolished surface is required for subsequent finishing operations following fab- rication, or as a final finish with a 50- or 80-grit abrasive compound. Polished Finish No. 4: A general purpose bright polished finish obtained with a 100 to 180 mesh abrasive, following initial grinding with coarser abrasives. Buffed Finish No. 6: A soft satin finish having lower reflectivity than No. 4 fin- ish. It is produced with a greaseless compound, #200 grit, top dressed with white rouge or chromium green rouge. Buffed Finish No. 7: A highly reflective finish produced by buffing a surface that has first been refined to approximate a No. 6 finish, then buffed lightly with a white rouge without removing satin finish lines. Buffed Finish No. 8: The most reflective finish commonly produced. It is obtained by flexible polishing with successively finer abrasive compounds, then buffing extensively with a very fine chromium green rouge bar compound. FINISHES FOR ARCHITECTURAL ALUMINUM Due to the different aluminum alloys, variations in final surface finish may occur. Variations may also occur by the type of buffing equipment used, type and size of the buff wheels, peripheral speed of the buff, the type of abrasive composition used and operator's technique. When using automatic equipment, the operator technique is replaced by a mechanical system controlling such variables as pressure, time cycle, conveyor speed, and contact time against the buffing wheel, resulting in a more con- sistent finish. Aluminum and its alloys are soft metals with a high frictional coefficient. As pre- viously discussed, tripoli or silica is used for a cutdown or cut-and-shine operation on aluminum. Calcined alumina compounds are used for shine on the aluminum surface. DESCRIPTION OF ARCHITECTURAL FINISH DESIGNATIONS Series (a) As fabricated. No buffing or polishing required. Series (b) Medium bright soft textured satin finish. Series (c) Bright buffed finish over soft texture satin. 28

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