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Metal Finishing Services

Three Types of Anodising

 

silchrome plating chromatic anodisingsilchrome plating hard anodisingsilchrome plating sulphuric acid anodising

Anodising is one of the most widely used surface treatments for a variety of components. It is used to form a protective barrier against damage on metals such as Aluminium, Titanium and Magnesium as well as providing a base layer for a number of post treatments like painting. The process involves taking a metal part, submerging it in an acidic solution and applying a voltage. This promotes the absorption of oxygen to the surface forming a hard protective barrier. There are three different types of Anodising.

Sulphuric Acid Anodising: The most popular of the processes, Sulphuric Anodising provides components with increased hardness, wear and corrosion resistance. Sulphuric Anodising will be resistant to scratching and abrasion. When sealed it will improve corrosion resistance, but may be attacked in more chemically corrosive environments. Should wear and corrosion be prevalent, Hard Anodising should be considered. The thickness of the film can range from 5-25 microns and usually a deposit of between 10-15 microns will be required for adding coloured dye. Thickness of the coatings on titanium will however be significantly less. This process is sometimes referred to as ‘Natural Anodising’.

Chromic Acid Anodising: The key difference here is the makeup of the acidic solution in which the parts are submerged. Chromic Acid Anodising only produces a thin film between 1-10 microns, this makes it suitable for applications like Castings where a reduction of fatigue strength is not acceptable. Chromic Acid Anodising is the least popular of the process but is widely used in aerospace applications. It affords components with a good level of corrosion resistance, with will not act as an insulator to elctricity which also makes it suitable for electronic applications.

Hard Anodising: For applications with a higher level of wear and chemical corrosion, Hard Anodising should be considered. Hard Anodising is performed in a sulphuric acid solution that has a higher concentration of acid, the process is carried out at a lower temperature but uses a higher voltage of electricity. Hard Anodising can produce thicker coatings between 25-100 microns and where Sulphuric Acid is often largely considered a decorative process, Hard Anodising is certainly more functional, but can still be used as a base layer for dye.

What We Offer: Silchrome Plating offer all three Anodising options and are able to provide a wide range of post plating treatments including various coloured dyes. All of our processes are carried out in house in our production facility in Leeds and we are fully ISO 9001 and ISO 14001 certified.  

  • The official logo for the Surface Engineering Association.
  • The official logos for the ISOQAR and UKAS industry regulatory bodies.
  • The official logo for the Institute of Materials Finishing.
  • The official logos for the ISOQAR and UKAS industry regulatory bodies.