Angle Grinder Accessories: Cutting, Grinding, Flap, and Wire Wheel Guide

Cutting Wheels

Cutting wheels (also called cut-off discs) are thin, flat discs designed for slicing through metal, concrete, and tile. Metal cutting wheels are typically 1/16-inch thick or less. The thin profile concentrates force into a narrow kerf, making clean cuts with minimal material removal. They cut steel, stainless, aluminum, and cast iron depending on the abrasive composition.

Never use a cutting wheel for grinding (pressing the flat face against a surface). Cutting wheels are reinforced for radial loads (edge-first cutting) but not for lateral loads (face grinding). Side pressure on a cutting wheel can shatter it, sending fragments at high speed. Use a grinding disc or flap disc for surface work.

Metal cutting wheels are rated by material: aluminum oxide for mild steel, zirconia alumina for stainless steel, and silicon carbide for non-ferrous metals and stone. Using the wrong wheel for the material causes premature wear, overheating, and poor cuts. Check the label — it specifies compatible materials.

Diamond cutting wheels handle concrete, brick, tile, and stone. They cost more than abrasive wheels but last dramatically longer. Segmented diamond blades are for rough cuts in concrete and brick. Continuous-rim diamond blades produce smooth cuts in tile and natural stone. Turbo-rim blades split the difference.

Grinding Discs

Grinding discs (depressed-center wheels) are thick, rigid discs for removing material from surfaces — smoothing welds, beveling edges, deburring cuts, and shaping metal. They are 1/4-inch thick and designed to handle face grinding pressure that would destroy a cutting wheel.

The depressed center keeps the mounting nut recessed so you can grind flat against a surface without the nut hitting the workpiece. Type 27 (depressed center) is the standard grinding disc shape for angle grinders. Type 28 (saucer shape) gives a more aggressive cutting angle for heavy stock removal.

Grit determines how aggressively the disc removes material. 24-grit is extremely coarse — it removes metal fast but leaves deep scratches. 36 to 40-grit is the standard for weld grinding and general stock removal. 60 to 80-grit smooths surfaces after initial grinding. For finish work, switch to a flap disc rather than going to finer grinding discs.

Grinding discs have a maximum RPM rating printed on the label. Never exceed it. A 4-1/2-inch disc on a grinder running at the correct speed (10,000 to 11,000 RPM) is within safe limits. Mounting a larger disc on a smaller grinder (to gain reach) exceeds the rim speed rating and risks disc failure.

Flap Discs

Flap discs are layered, overlapping abrasive flaps bonded to a fiberglass backing. They combine grinding and finishing in one disc. A coarse flap disc (40-grit) removes material nearly as fast as a grinding wheel but leaves a smoother surface. A fine flap disc (80 or 120-grit) blends surfaces and prepares metal for paint.

Flap discs are more forgiving than grinding discs for beginners. The flexible flaps conform to curved surfaces, feather edges smoothly, and are less likely to gouge the workpiece if you change the angle during use. For weld blending on visible work, flap discs produce a better finish than grinding discs with less effort.

Two flap angles exist: Type 27 (flat) and Type 29 (angled at about 15 degrees). Type 29 is more aggressive because the angled flaps present more abrasive to the workpiece. Use Type 29 for heavy stock removal and Type 27 for lighter blending and finishing work.

Zirconia alumina flap discs outlast aluminum oxide on steel and stainless. Ceramic flap discs cost the most but last the longest and cut the fastest on hard metals. For occasional use, aluminum oxide is adequate. For frequent welding and fabrication, ceramic or zirconia pays for itself in disc changes saved.

Wire Wheels and Specialty Discs

Wire wheels and wire cups strip paint, rust, scale, and corrosion from metal surfaces without removing base metal. Twisted wire (knotted) wheels are aggressive — they remove heavy coatings and rust quickly. Crimped wire wheels are gentler — they clean surfaces and remove light rust without gouging.

Wire cup brushes fit angle grinders and cover flat surfaces efficiently. Wire wheel brushes (round profile) get into grooves, inside corners, and contoured surfaces. Both throw wire fragments, so face shields (not just safety glasses) and leather gloves are mandatory. Stand to the side of the wheel rotation, not in line with it.

Sanding discs turn an angle grinder into a power sander. Hook-and-loop backing pads accept sandpaper discs from 40 to 400-grit. This works for wood and metal finishing but is aggressive — an angle grinder spins much faster than a random-orbit sander, so use light pressure and keep the disc moving to avoid burning or gouging.

Polishing pads with compounds like rouge, tripoli, or diamond paste bring metal to a mirror finish. Start with a cutting compound on a stiff pad to remove fine scratches, then switch to a polishing compound on a soft pad for shine. This multi-step process works on stainless, aluminum, brass, and copper.

Frequently Asked Questions