This assembly allows 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 foot (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).

3M 24049, Wetordry Cloth Disc 281W, P1000 YF-weight, 8 in x NH, Die 800JM, 7000045052
3M 60178, Scotch-Brite High Strength Satin Pleated Buff Wheel, HS-SB, 4A Fine, 14 in x 2 in x 1-1/4 in, 7010329306, 180 per case
Insize 3332-1B, INDICATING MICROMETER, 0-1", without support, 6928640355677
3M 08360, Urethane Seam Sealer, White, 310 mL Foil Pack, 7000036353, 6 per case
Dynabrade 15420 Dynafile III Abrasive Belt Tool
Dynabrade 95821 Dynabrade Air Lube 10W/NR, 4oz Bottle
3M 20365, Scotch-Weld Epoxy Adhesive 2216, Gray, Part A, 5 Gallon Drum (Pail), 7000046361
3M 22409, Roloc Disc 361F, P120 XF-weight, TR, 1-1/2 in, Die R150S, 7000045103 
