Collection: Flap Discs

A Type 27 disc is flat and is meant to be worked at a shallow angle — roughly 0–15° — on flat surfaces, blending and light stock removal. A Type 29 is conical, which presents the abrasive at a steeper angle of about 15–35° and puts more of the flap in contact. Use a Type 29 for edge work and faster stock removal, and a Type 27 when you need to finish flat without gouging.

36 and 40 grit are for heavy stock removal, weld knock-down and edge bevelling. 60 and 80 are the general blending grits. 120 and finer leave a finish rather than removing material. The lower the number the more it cuts, the higher the finer the surface it leaves.

Aluminium oxide is the general-purpose grain for everyday work on steel where cost per disc matters most. Zirconia alumina is tougher and cuts faster and longer on steel and stainless. Ceramic grain fractures as it works so it keeps exposing fresh cutting edges, which gives the fastest cut and the longest life on stainless and hard alloys.

Phenolic backing is the rigid standard and wears back with the flaps. Aluminium backing is lighter, runs cooler and can be recycled once the flaps are spent. Trimmable backing lets you cut the worn backing away so the remaining flaps keep working.

Yes, and zirconia or ceramic grain is the better choice because it cuts without loading up. Keep abrasives used on stainless separate from those used on carbon steel — carbon particles carried across will embed in the stainless and rust.