This assembly allows the 3M Disc Pad Face Plate to be easily changed without removing the disc pad hub, allowing the operator to use a single tool for multiple applications from heavy grinding to finishing a workpiece.
Some face plates have ribbing on the bottom face. Ribbed face plates provide additional force when needed for optimal fracturing of the abrasive mineral. By reducing the area of contact, or pressure per square inch (PSI), ribbed face plates increase the grinding pressure of the abrasive with the same amount of operator effort, and extend disc life when dulling is a problem.
Choose a plate with the level of firmness needed for the application?a lighter density face plate for lighter weight grinding applications, and a harder density face plate for more heavyweight grinding applications. Using the correct face plate for the application ensures that the abrasive mineral will fracture as it should, maximizing the life of the abrasive. The plate comes in one of four different colors that indicate the density so the correct plate can be easily identified in the workroom: red = extra hard (for heavy grinding with the coarsest grades), black = hard (for heavy metal removal, large welds, etc.), gray = medium (for general purpose grinding and finishing), and white = soft (for finishing operations on flat or contoured surfaces).

Dynabrade 14360 Pneumatic Pipe Belt Finisher
Dynabrade X61V 6" (152 mm) Dia. Central-Vacuum Dynorbital Extreme Random Orbital Sander, .3 HP, 12,000 RPM, 3/16" Orbit, Hook-Face
Dynabrade 53282 9" (180 mm) Dia. Right-Angle Grinder, 2.8 HP, 6,500 RPM, 5/8"-11 Spindle
3M 54370, Particulate Respirator 8576, P95, with Nuisance Level, Acid Gas Relief, 7000002061, 80 EA/Case
3M 14593, Scotch-Brite Cut and Polish Disc, 3" x 1-1/4" x 1/4" A Medium, D5, 7000045941, Box of 10
3M 22392, Roloc Disc 361F, 24 YF-weight, TR, 3 in, Die R300V, 7000045090
3M 77558, Cubitron II Hookit Cloth Disc 947A, 77558, 40+ to 120+, 6 in x NH, Die 600Z, 7100232737 
