Method of manufacturing piston rod

A method of manufacturing a piston rod for a shock absorber including:

• a cylinder in which a working fluid is sealed;
• an oil seal provided in an opening of the cylinder;
• and
• the piston rod that is provided to protrude from the opening of the cylinder, slides along an axial direction thereof while contacting with the oil seal, and includes a slide surface which repeatedly movable between an inside and an outside of the cylinder,
• the method comprising:
• a plating step of forming a chrome-plated layer on a surface of the piston rod where the sliding surface is to be formed;
• a first polishing step of, after the plating step, forming a plurality of oil reservoir grooves in which the working fluid is to be held on the chrome-plated layer, using a first polishing film with rotating the piston rod around an axis thereof;
• and
• a second polishing step of, after the first polishing step, forming the oil reservoir grooves to have a plateau shape using a second polishing film with rotating the piston rod around the axis, wherein
• in the first polishing step,
• the chrome-plated layer is polished by feeding the first polishing film and contacting the first polishing film with the chrome-plated layer while rotating the piston rod, and
• a pressing force of pressing the first polishing film against the chrome-plated layer is 0.15 MPa to 0.3 MPa.