Patent ID: 11867205
Assignee: INDUSTRIES MAILHOT INC.
Field: Surface technology, coating (Chemistry)
Classification: CPC F  C | IPC C  F

Claim 0:
1. A method for making a piston rod for a hydraulic cylinder comprising a cylindrical barrel in which a piston connected to the piston rod moves back and forth, the barrel being closed on a first side thereof by a cap and at a second side thereof by a cylinder head where the piston rod comes out of the barrel, the head comprising a fluid seal to prevent pressurized oil from leaking past an interface between the piston rod and the head, the piston rod being in friction contact with the fluid seal , in operating conditions, the method comprising selecting a substrate for the piston rod in one of: steel, stainless steel, aluminum and plastic, selecting a fluid seal in one of: a plastic material, urethane, and Polytetrafluoroethylene, depositing a diamond-like carbon layer, on the piston rod, of a thickness in a range between 1 and 5 μm, the piston rod having a hardness in a range between 1000 and 4000 HV and a coefficient of friction in a range between 0.1 and 0.05, and modifying a resulting surface finish by at least one of polishing, microbead blasting and texturization, yielding a surface roughness profile comprising peaks and valleys with a peak-to-valley height in a range between 0.5 and 2 μm providing hydraulic oil retention between the fluid seal and the piston rod, the piston rod and the fluid seal thus being in contact with a surface comprising peaks and valleys under the operating conditions.