Anodising is not only an inexpensive and durable finish but is often used to decorate and improve the aesthetics of aluminium parts with a variety of colours, making it an incredibly popular finish. This article will answer your questions on how to anodise colour parts, what colours you can anodise in, and the difficulties of colour matching.
Anodised aluminium offers a wide range of colour and gloss options for aesthetic appeal, while still maintaining its metallic appearance. The main achievable colours include:
Examples of colour anodised parts made at HLH Rapid
With anodising, achieving the colour ‘white’ is not possible. You can however produce a uniform ‘clear’ film by forming a transparent oxide layer on the surface of the aluminium part, which will allow the metal’s natural metallic colour show through.
Example of colour anodised part made at HLH Rapid
While anodised aluminium can be dyed virtually any colour, precise colour-matching is typically not feasible. Even if you were to provide an RAL colour code or tightly control the process, achieving an exact match is still incredibly challenging. This is because there are numerous factors involved in the anodising process such as voltage, current density, temperature, and material conditions, which can make it highly unpredictable.
Getting colours to match from order to order is also extremely difficult, a near impossible job. When ordering anodised parts, expect some deviation from your specifications.
There are three ways in which colour can be added to the anodised parts:
1. Dip Colouring: This method is relatively straight forward. The anodised metal is immersed in a dye solution and the colour fills the pores. Dip colouring may require maintenance or reapplication of colour over time, as the dye tends to fade over time when overexposed to UV rays.
2. Altering the Thickness of the Oxide Layer: This method involves growing an oxide layer on the metal surface by controlling the parameters of the anodising process, such as voltage and time. Thicker oxide layers tend to produce different colours compared to thinner layers.
3. Electrolytic Colouring: This method involves immersing anodised metal in an electrolyte solution and subjecting it to an electric current. metal ions to migrate through the oxide layer, causing metal ions to migrate through the oxide layer, resulting in the formation of coloured metal compounds within the oxide layer.
While you can change the colour of anodised aluminium, it is challenging. To do so, you typically have to remove the existing anodised coating and start over, adding a new colour when you create a whole new anodised oxide layer.
Looking to produce custom CNC parts with a colour anodised finish? Contact the HLH team to leverage decades of quality machining expertise. Simply submit your STEP files and project details via our site contact form, and our team will get back to you with a quote within 24 hours.
Discover all CNC surface finishing options here: HLH Rapid’s Full CNC Finishes List
