Key Features

Wear & Corrosion Resistance: The hard chrome plating, with a minimum thickness of 20 microns and a surface hardness of 850-1150 HV, provides a shield against abrasion and corrosion, significantly extending the service life of your components.

Precision: With a mirror-smooth surface finish of Ra ≤ 0.2μm and tight diameter tolerances of ISO f7.

Superior Strength: Made from CK45 medium-carbon steel (equivalent to SAE1045), our hard chrome plated piston rods offer an optimal balance of strength and toughness, with a tensile strength of ≥610 N/mm² and yield strength of ≥355 N/mm².

Rigorous Quality Assurance: Every hard chrome plated piston rod is backed by ISO 9001 certified processes and undergoes strict testing, including salt spray tests per ASTM B117 for up to 72 hours.

Materials Selection and Pretreatment

Material selection: CK45 is a common medium carbon steel material; good mechanical and processing properties make it suitable for the manufacture of hard chrome bars. The chemical composition and subsequent mechanical properties of the 74gD powder are strictly controlled to maintain a consistent quality of the final product.

(Pop-up) Surface Pretreatment: The hard chrome plated piston rod must go through a series of pretreatment processes - degreasing, alkaline washing, pickling, water washing, etc. Oil, rust and various other surface impurities need to be removed; deciding the adhesion and near perfect coverage of the future coating is a primary concern of these procedures.

Hard Chrome Plating Process

Hard chrome plating itself is an electroplating process. A hard chrome bar is submerged in an electrolyte (chromic acid based, with some form of sulfuric acid), chromium adhering to the hard chrome plated piston rod surface via electrolysis. Fine control of multiple parameters - current density, temperature, time being the main ones - is required to achieve both the desired thickness and all round quality of coating.

Theoretical coating thickness determination: Thin hard chrome is typically 10-500 microns, application specific. Thicker coatings offer greater (though not always practical) wear and/or corrosion resistance. Electroplating the thicker options is time and money intensive.

Control of microcracks: Microcracks are and will always be a potential problem within the hard chrome coating; starting at least partially from this line of thought, optimizing the electroplating process (and all that follows) to at least reduce or eliminate microcracks and all associated corrosion, is a near constant aim of the post processing work.

Post processing

Ground and/or polished hard chrome plated piston rods are the end result of all of the above. Surface roughness is a critical, and to a large extent sealed, dynamic system.

Heat Treatment: After electroplating, quenching and tempering are generally used to improve the surface hardness and subsequently the wear resistance specific to hard chrome plated piston rods. This process pushes further the various mechanical properties that the hard chrome bar itself possesses.

Quality control and testing

Salt spray test: A very common test for hard chrome bars; salted atmospheric conditions are placed upon them to check a form of corrosion resistance. Test results show a relatively good corrosion resistance for the chrome piston rod, red rust being the more severe test - over 240h is a accepted standard, white rust being less time intensive but still well within expected parameters.

Hardness test: Evaluating the coating via a hardness test is both simple and effective. Hard chrome plating (as previously mentioned) sits well above HV800, near constant wear resistance being one of the more desired end results of hard chrome; all round protection is sought after.