Hard Anodising
Hard Anodising is type of electrolytic metal finishing treatment that produces a translucent oxide coating. The process is very similar to sulphuric anodising but produces a thicker oxide layer providing increased corrosion and wear resistance. A thickness of 20µm to 70µm can usually be achieved, with thickness up to 100µm possible on some alloys.
Why choose Hard Anodising?
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Why choose MP Eastern?
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Our Hard Anodising specifications
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Our Turnaround Times
- Standard Turnaround is 7-10 working days
- Express Turnaround is available for additional charge
How to Order Hard Anodising
When specifying anodising we recommend referring to published standards wherever possible. Most standards will require you to provide at least the following information to us:
- The specification reference, film thickness and sealing requirements
- The grade and temper condition of the material
- The significant surfaces and areas where measurements of the coating thickness are to be made
- Any areas that must not be used as contact points for jigging (or areas that are to be used)
It is necessary to carry an electric current to the part during processing, these contact areas will remain uncoated, typically parts are located on jigs using holes, bores, tapped holes or along edges - Any special inspection and test requirements
The default inspection procedures for most specifications include for visual inspection and coating thickness measurement, if it is necessary to carry out other inspection procedures by batch or order then generally these have to be specified in the contract or order - Any special packing requirements
The grade and condition of the aluminium have a significant effect on the final product.
Feel free to get in touch with your requirements or for technical advice.
Our Specifications & Standards
We hard anodise to the following standards:
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Standard |
Notes |
Comment |
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BS EN 2536 |
Hard anodising |
Aerospace series |
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BS ISO 10074 |
Hard anodising; |
Supersedes |
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MIL-PRF-8625F |
Type III – Hard anodising; |
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We also hold a large library of customer-specific, superseded and legacy specifications. Please contact us with your requirements.
Information for Design Engineers
Thickness and Growth
Anodising is an electrolytic conversion coating which transforms aluminium on the surface of components into aluminium oxide. As a conversion rather than deposit process, there is both ingress and outgrowth of the material to form the coating thickness. Approximately 50% of the anodic film is below the original surface and 50% is above.
Anodising grows at right angles to the surface and where this growth meets at external sharp corners the coating can spall. Thicker hard anodised surfaces are susceptible to this spalling so corners should be radiused as much as possible.
The material has a significant effect on the final appearance and performance of the coating – different grades and temper conditions require different processing conditions. Different grades of alloy are not usually mixed during a process run.
Corrosion Resistance
Anodised aluminium shows high corrosion resistance in aggressive environments. Anodising will be vulnerable to alkalis and some acids, our technical specialists will be able to advise you on this and we are happy to provide compatibility testing.
Wear Resistance
Hard anodising is used for improved wear resistance. The best wear resistance is achieved at the higher thickness and by leaving the coating unsealed. Friction and release properties can be improved by sealing with PTFE.
Sealing
Anodic films are naturally porous, this allows them to be dyed. Most sulphuric anodising is sealed and this is our default process. For most applications, the most economic and most suitable sealing method is either cold sealing or hot water sealing. Good sealing is crucial to corrosion resistance.
Unsealed coatings are generally preferred when the hard anodising is for wear resistance. A suitable lubricant could be used to regain some of the corrosion resistance.
We provide the following sealing options:
- Hot Water seal (boiling seal)
- Nickel Acetate seal
- Nickel Fluoride seal (cold seal)
- PTFE seal
Colour Anodising
Hard anodising results in a coloured film depending on alloy type and film thickness. It is most suited for dyeing darker shades such as black.
Alloy Selection
Hard anodising gives best results on 6061 or 6082 alloys, but 6000 and 7000 series aluminium is generally suitable.
Our Tank Sizes
Length 2000mm x Width 400mm x Depth 800mm x Lifting 125kg
Safety & Environmental compliance
Our hard anodising service is compliant with RoHS (Restriction of Hazardous Substances) & REACH (Registration, Evaluation, Authorisation and restriction of Chemicals).
Environmental awareness is part and parcel of our business ethos. We have an active policy of using greener alternatives to the traditional processes. We have held a Environment Agency IPPC permit since 2005 and are regularly audited as part of our ISO 14001 certification.
Laboratory Analysis
Our laboratory routinely monitors process chemistry, we visually inspect parts before and after anodising and for specification work, eddy current gauges are used to measure the film thickness non-destructively. The accuracy and precision of measurements taken with these gauges are sensitive to material composition and surface finish.
We carry out periodic corrosion testing, coating weight and abrasion resistance testing on standard panels.
If you require batch or part specific tests these should be specified in the contract or on the drawing or order.
Applications & Industries
Hard anodised aluminium is used in industries such as:
- Military & Defence
- Firefighting
- Packaging
- Automotive & Motorsport
- Precision Engineering
- Subsea Engineering
And for purposes such as:
- Vehicles incl electric cars and batteries
- Engine components
- Busbars
- Household and industrial appliances
- Food equipment
- Furniture
- Electronics
- Pipework
- Pressure relief valves
Similar Processes
How We Can Help
We provide anodising services for the most challenging components and applications. We often take on the projects that other anodisers are unwilling or unable to do. We have extensive experience with dual-finishing, selective treatments, masking, creative jigging and multi-process finishing of complicated parts to achieve exceptional results. Get in touch with us for your next tricky project.
We provide a fast, high-quality anodising service that you can rely on. Customers from all over the UK and beyond choose us for our attention to detail and superior standards. Our quality system is designed to spot issues before they happen and save you time and money. We have an on-site laboratory for continual monitoring of tank chemicals, we do a full visual inspection of parts before and after processing, and we check thickness using eddy current gauges.
Choose a service that gets it right first time with fast turnaround and friendly service to match - get in touch with us today.