A cylindrical metal part that guides the piston to move in a straight line in a cylinder. Air in the engine cylinder through expansion of heat energy into mechanical energy, gas in the compressor cylinder by the piston compression and increase the pressure. The shell of a turbine, rotary piston engine, etc. is often called a "cylinder". Application fields of cylinder: printing (tension control), semiconductor (spot welding machine, chip grinding), automatic control, robot, etc. HCVAC coating machine is used for cylinder parts. Coating and heat treatment for engineering parts in automotive industry can reduce fuel consumption, improve wear resistance and achieve compact design. Improve the wear resistance and service life of components, so as to extend the maintenance interval and reduce the demand for spare parts. Allows a more compact design and the use of lighter materials to reduce overall weight and reduce friction losses in the engine, thereby improving the efficiency of the overall drive system.