Anodising cost is determined by a number of factors and it is helpful to understand these factors before you request a quote. This will allow you to specify your work more accurately.
Alloy Choice
Not all aluminium alloys are suitable for anodizing. Some more difficult materials to anodize include High-Silicon Casting Alloys, and certain 2000-series alloys. These materials typically require different process parameters to achieve a satisfactory finish. Other materials, such as the standard 6000-series aluminium alloys, are generally easily anodized and are the most cost effective.
Part Size and Geometry
Larger parts require bigger tanks and complex parts with many contours require more time to accurately rack. Also parts with deep recesses or internal bores can suffer from uneven coating build up. Additional processing is then required to rectify this problem.
Layer Thickness
A coating thickness is expressed in microns and is produced by the anodising process to form an oxide layer on the surface of the aluminium. The standard sulphuric acid anodising process produces a 25 micron thick coating but this can be increased to 50 microns or more by the hard anodising process.
Batch Size
Smaller numbers of parts are generally less cost effective than larger quantities. This is because fixed costs (such as tank filling and preparation, racking, inspection) are spread over fewer parts. It makes sense to try and combine orders where possible.
Colour and Sealing
The cost of anodizing a surface can also be influenced by the type of coating finish that is applied to the surface. The cheapest anodized finish is clear or natural anodizing. However, anodized surfaces can also be coloured using dyes. The cost of colouring an anodized surface is influenced by the type of dye used and some colours are more expensive than others. Sealing an anodized surface also has a higher cost than hot deionised water sealing and typically uses a nickel acetate or PTFE-impregnated seal. For more information on aluminium finishing standards refer to the UK aluminium industry body.
Masking Requirements
If areas of the part are to remain uncoated, these must be masked prior to processing. Parts that have very close tolerance features such as threaded holes, mating surfaces and electrical contacts all require considerable time to set up for processing. For Anodising, see poeton.co.uk/surface-treatments/anodising.
Get your spec right. This is the easiest way to ensure you are charged for your order in the most cost-effective way.