3M 55378, Flap Disc 566A, 40, T27 Quick Change, 4-1/2 in 5/8″-11, Giant, 7010361786, 10 per case

We use self-fracturing alumina zirconia abrasive with a superior cut-rate to aluminum oxide, and versatile performance on many metal types. The 566A flap disc is made with strong yet flexible YF-weight polyester-cotton backing that is well-suited for handling sharp edges and medium to high pressure applications, making this disc a great choice for the majority of grinding and finishing jobs. It is resin-coated for heat resistance. Under normal conditions, flap discs will generate a finish that is one grade finer than the finish of a fiber disc of the same grade.

Flap discs are three-dimensional grinding discs with overlapping layers or flaps that fan out from a central hub. These abrasive-coated, polyester-cotton flaps continually wear away with use to expose fresh mineral for a fast, consistent cut. And, because their overlapping construction allows more abrasive material to be loaded onto the cutting surface, they far outlast typical discs. Flap discs are ideal for a wide range of applications, including grinding of small welds (with grades less than 80), deburring, rust removal, edge grinding, and weld seam blending.

We chose alumina zirconia (sometimes called AZ or zirconia alumina) because it fractures frequently to continually produce fresh sharp points and deliver a faster cut-rate than aluminum oxide. A man-made mineral, it was developed for heavy stock removal and high pressure grinding.