US Patent 7347136 Airless sprayer with hardened cylinder

An airless sprayer for paint or the like consists of an electric drive unit connected to a piston. Driven by the electric drive unit, the piston reciprocates within the cylinder, thus spraying the paint or the like. Because of the close tolerance between the piston and cylinder (typically about 0.0002 to about 0.0003 inches), the sprayed liquid provides a seal between the piston and cylinder. To prevent this tolerance from increasing to the point of failure, the cylinder is manufactured from nitride hardened steel. A process for manufacturing the airless sprayer is also disclosed.