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™ 17323, Versaflo™ Respiratory Helmet Assembly M-407, with Premium Visor and Flame Resistant Shroud, 7000002395, 1 EA/Case
Dynabrade 78423 4-1/2" Dia. x 3/8" Very Fine DynaBrite Surface Conditioning Disc, 25/pack
Dynabrade 98272 1/2" NPT Female Plug
Dynabrade 95544 Gear Grease, 2.5oz. Tube
3M 24306, Double Coated Polyethylene Foam Tape 4496W, White, 1 in x 36 yd, 62 mil, 9 rolls per case, 7000123606
Dynabrade 61420 Raptor Vac Electric Portable Vacuum System
Norton 66254497067 - 2" X 1/4" 100 - 150 Grit Medium Grade Aluminum Oxide Vortex Rapid Blend Blue TR Non-Woven Abrasive Disc, 25 Each
Insize 4808, WIRE GAGE, 0-36(.3249~.0050"), 6928640330155
3M 29611, 641WY 1/4" X 24", 100 Mesh Diamond Cloth Belt, 7010534832
3M 22396, Roloc Disc 361F, 36 YF-weight, TR, 1-1/2 in, Die R150S, 7000045091 
