Hiomakiekkoja

Hiomakiekkoja are abrasive discs used with grinders to remove material and finish surfaces. They are circular discs mounted on angle grinders or bench grinders and consist of abrasive grains bonded to a backing with a binder. The most common abrasive materials are aluminum oxide for ferrous metals and silicon carbide for harder stones and non-ferrous metals. Some discs use newer grains such as zirconia alumina or ceramic for higher wear resistance and longer life.

Construction and sizes vary. Typical diameters include 115 mm and 125 mm, with larger discs like 180 mm used on some machines. Thickness usually ranges from about 1 to 6 mm. Many hiomakiekkoja have depressed centers (for example type 27) or flat designs, and mounting holes are commonly 22.23 mm in diameter to fit standard power tools. Backing can be fiber, resin, or thin flexible substrates, and discs may attach by screw-on hubs or quick-change systems, including hook-and-loop (Velcro) styles.

Applications and selection depend on the material and finish required. They are used for removing rust and old coatings, deburring weld seams, shaping edges, and smoothing surfaces. Grit size indicates roughness: coarse grits around 40–60 remove material quickly, medium grits around 80–120 smooth surfaces, and finer grits around 180–320 produce a finishing touch. The maximum operating speed (RPM) printed on the disc must be matched to the tool’s speed and the guard in use.

Safety and usage considerations include wearing eye and face protection, gloves, and hearing protection; inspecting discs for cracks or damage before use; ensuring proper mounting and guards; and never using damaged discs or exceeding rated speed.