INFORMATION
FINISH DESIGNATIONS

Due to the different alloys, variations in final finish may occur.  Variations may also occur by the type of buffing equipment used, type and size of the buff wheels, peripheral 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.
Guidlines for Comparing
Stainless Steel Finishes

Roughness average (Ra) is the most accurate and is measured in micro inches.  Grit and polish numbers are dependent on methods and materials used, and are a subjective assessment.

Ra                    Grit                  No.
43-48                 120                     3
30-35                 150                     4
23-28                 180                     4
15-20                 240                     7
9-17                  320                     8
4-16                  400                     8
Polished Finish No. 3:  An intermediate polished finish generally used where a semi-polished surface is required for subsequent finishing operations following fabrication, or as a final finish with a 50- or 80- grit abrasisve compound.
Polished Finish No. 4:   A general purpose bright polished finish obtained with a 100-180 mesh abrasive, following initial grinding with coarser abrasives.
Buffed Finish No. 6:  A soft satin finish having a lower reflectivity than No. 4 finish.  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 been refined to approximaly a No. 6 finish, then buffed lighlty with a white rouge without removing satin finish lines. 
Buffed Finish No. 8:  The most relfective finish commonly produced. It is obtatined by flexible polishing with successively finer abrasive compounds, then buffing extensively with a very fine chromium green rouge bar compound.
Mechanical Polishing Process

Mechanical polishing is a process where material surfaces are improved through pressurized contact with rotating abrasive material. Varied combinations of abrasive material are utilized to achieve desired outcome. Outer circumferences and interior diameters can be effectively polished mechanically with only very minute changes in component dimensions. Typical components requiring mechanical finishing are forgings, castings, fabricated tubular/pipe products, extrusions and plate/sheet fabrications. Finishes range from “rough” through mirror and can be industry specific, such as stainless steel components used in pharmaceutical, medical, or food/beverage applications. Since mechanical polishing is performed in steps, raw material selection is critical. Too many, or major surface anomalies can easily add considerable cost to a mechanically polished component due to extra steps required to complete. Many components are electropolished after mechanical polishing to ensure a completely clean surface with added durability. In many instances, finishes must achieve a certain roughness value (Ra) to be considered acceptable.  Mechanical polishing is an effective process to meet specific surface roughness requirements.  When Ra requirements are met, electropolishing may be included as a final step. It is important to note that in many cases, electropolishing cannot be substituted for mechanical polishing. Although electropolishing enhances component corrosion resistance and adds brightness, it will not remove weld seams, orange peel, machine tool inclusions, or pitting in base material.
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