A parts washer is a piece of equipment used to remove contaminants or debris, such as dirt, grime, carbon, oil, grease, metal chips, cutting fluids, mold release agents, ink, paint, and corrosion from workpieces.[1] Parts washers are used in new manufacturing and remanufacturing processes; they are designed to clean, degrease and dry bulk loads of small or large parts in preparation for assembly, inspection, surface treatment, packaging and distribution.

Parts washers may be as simple as the manual "sink-on-a-drum" common to many auto repair shops, or they may be very complex, multi-stage units with pass-through parts handling systems. Parts washers are essential in maintenance, repair and remanufacturing operations as well, from cleaning fasteners, nuts, bolts and screws to diesel engine blocks and related parts, rail bearings, wind turbine gears boxes and automotive assemblies.

A parts washer is distinctly different from a pressure washer in that parts washers typically clean parts automatically in an enclosed cabinet, while pressure washers typically have a single spray jet mounted at the end of a manually operated wand. Modern industrial technology makes it possible to combine many parts of the finishing process into one.

As an integrated part of the manufacturing process, automatic parts washers are able to load, wash, rinse, dry and unload parts based on a preset computer-controlled program and the help of a conveyor belt to save time, money and man-power and ensure a quality product; innovations are being made to ensure parts washers are water and energy saving.