Hard Chrome Plating

We offer a hard chrome plating service using Chromic Acid - Chromium Trioxide Flake from Elementis. Our solution is made up of 250g/l CrO3 and Sulphuric Acid at a 100-1 ratio.

Background: Hard chrome plating, sometimes referred to as functional chrome plating, can be applied in thick layers for heavy industrial applications. It increases wear and corrosion resistance whilst creating a low co-efficient of friction. With abrasion being the most common and destructive wear process found in industry, hard chrome has the potential to solve many problems in pumps, valves, bearings, etc. throughout a wide range of industries; including pharmaceutical, chemical, oil and gas, textiles, printing, food, mining, and countless others.

One application for hard chrome is the refurbishment of worn components where the metal has been lost through wear or been manufactured under size, or, even where there has been an excessive distortion during the hardening process. This application usually requires a thicker deposit and components are pre-chrome ground then a suitable deposit of hard chrome is applied before they are ground back to original sizes and tolerances.

Process: Hard Chrome plating is an electrolytic process utilising a chromic acid-based electrolyte. The component requiring plating becomes the cathode and, with the passage of a DC current via anodes, chromium metal builds on the component surface.

Applications: Hard Chrome plating has many typical applications, some of which are detailed below:

• Machine spindles and housings
• Motorcycle forks
• Pump shafts or rotors
• Hydraulic rods and cylinders
• Any sliding or rotating shafts

Tanks: We offer tank sizes up to 3.6m long.

Thickness: Coatings can be applied to customer specification and requirements. For heavier deposits i.e. approx. 0.5mm, it is advisable, if possible, to capture the ends of the component being plated to reduce the chance of “chipping” of edge build up.

Coating thickness is directly proportional to the parameters dictated by amount of time a component is required to be in the tank and the calculated running current (normally 2amps per square inch).

Hardness: Hardness is 950 - 1150HV.

Materials: Most materials can be Hard Chrome plated, including:

• Steel
• Stainless Steel
• Cast Iron
• Copper
• Brass
• Bronze Alloys
• Nickel Alloys

Plating Vats: We have the capacity to chrome up to 3.6metres in length and if you think you may have a possible application for a component not listed, please contact us to discuss this further.

Stopping Off: Selective Hard Chrome plating can be achieved through masking with clamca wax or stopping-off lacquer.

Etching: Etching is carried in accordance with the guidance relevant to the base material being plated. All components are etched before Hard Chrome plating to provide a good key for the hard chrome deposit to be applied.

Jigging: Careful jigging is required for hard chrome plating, taking into consideration current carrying capacity and weight of component. Special attention is necessary for the plating of internal surfaces. One of the characteristics of hard chrome is its poor throwing power, therefore auxiliary anodes maybe required at strategic locations.

Jigging: For high tensile steels (above 1000N/mm2), there can be a need for a post-plating heat treatment to eliminate the effect of hydrogen embrittlement which may occur during the plating process.