Electroless Nickel vs Hard Chrome: Which Coating Fits a Machined Part?

It is often considered for components with multiple faces, holes, grooves or complex geometry where relatively consistent thickness matters. Corrosion and wear performance depend on coating chemistry, thickness, substrate preparation and post-treatment. Blocks, housings, plates, mould parts and components requiring multi-face coverage are typical candidates. Deep blind holes and trapped-air regions still need specific review.

Hard chrome is commonly used on rods, pistons, guides, journals and sliding or wear surfaces. A thicker deposit may provide allowance for cylindrical grinding or polishing to final size and roughness. Thickness distribution around edges, grooves and section changes may vary, so racking, auxiliary anodes, masking and allowance must be reviewed by the coating specialist.

Start with service conditions and the finishing route.

• Complex geometry and multi-face coverage: consider electroless nickel
• A journal or sliding diameter to be ground after coating: consider hard chrome
• Corrosion is primary: specify the nickel system, thickness and relevant test
• Wear or diameter restoration: hard chrome may be an option
• Food, chemical or regulated use: verify the applicable standard rather than relying on the coating name

A coating adds material to every treated surface. An outside diameter generally increases by approximately twice the coating thickness when opposite sides receive similar deposits; a bore reduces on the same principle. Actual distribution depends on geometry and process. Drawings should state whether tolerances apply before or after plating, which areas are masked and where thickness is measured.

Tool marks, pits and sharp edges in the substrate can affect the coating. Machining, edge preparation and cleaning must be suitable before treatment. Tight roughness or dimensional requirements may require grinding, honing or polishing after plating. Grinding hard chrome needs suitable wheels, parameters and coolant to avoid overheating, cracking or delamination.

Final inspection may include dimensions, coating thickness, adhesion, appearance, hardness, roughness and corrosion testing as specified. Thickness measurement must suit the substrate and coating. Masked areas, threads, fits and measurement datums should be identified before processing.

Complete input prevents quotations based on assumptions.

• Controlled 2D drawing and 3D model if available
• Substrate, heat treatment and pre-plate hardness
• Coating type, standard and thickness range
• Coated, masked, threaded and bored areas
• Final tolerances, roughness and acceptance state
• Surfaces to be ground and planned allowance
• Certificate, adhesion or corrosion-test requirements
• Quantity and requested delivery

VietTech performs CNC machining, grinding and inspection to drawing. Electroless nickel and hard chrome are coordinated through suitable specialist partners. VietTech reviews pre-plate dimensions, masking, finish allowance and post-treatment inspection before confirming feasibility.