The process of anodising aluminium involves submerging the metal in an acid electrolyte bath and passing an electrical current through the solution. The bath has a cathode attached to it and the aluminium acts as the anode. When the electrical current is passed through, oxygen forms on the surface of the aluminium creating an aluminium oxide or anodic layer. The quality of this anodic layer depends on many things including the temperature and concentration of the solution as well as the current passed through.
The thicker the anodic layer created, the greater the corrosion resistance and typically this layer is between 5 to 25 microns thick. The thickness of the layer is determined by the length of time the current is passed through the solution and the longer the metal spends in this state, the thicker the anodising layer.
Anodising is most commonly used for improved corrosion resistance on certain types of aluminium alloys. Aluminium alloys that are subject to marine environments typically benefit from anodising. Ship hulls, dock components, and oil rig structures are common examples of these.
BS 1615 / BS EN 12373-1 2001
DEF Stan 03-25
MIL-A-8625 Type III
Hard Anodising is a high-tech, extreme engineering finish. It is extensively used in the aerospace and marine industry on components which are subject to extreme heat, abrasion and corrosive conditions.
The finish is ultimately is the thickest form of anodising, creating an oxide layer which is between 20 to 100 Microns thick, depending on the base alloy being treated. It offers the highest increases in hardness, wear resistance and electrical resistance and is primarily a functional coating. It is also performed in a sulfuric acid solution, but with higher acid concentration, low temperature and a higher voltage applied.
DEF STAN 151-3 25-50µm
DEF 03-26 25-50µm
BS 5599 25-50µm
Up to 75 microns
We are able to offer a range of anodising colours. Anodising colour can be affected by a number of variables: alloy type and temper, load time, etch time, tank temperature and coating thickness.
Similar to Natural Anodising, Architectural Anodising is primarily used for protecting aluminium window frames, handrails, roofing and other external building components from the elements.
The process is defined within its own specification to ensure a consistant finish is applied across large prjects. Colours for this type of finish usually include Silver, Gold, Black and Bronze
Mechanical Polishing is the smoothing of a surface using mechanical tools. Mechanical polishing is performed in steps with progressively finer abrasives until a smoothness is achieved.
The component is usually presented onto a linishing belt. it can then be brightened by mopping or buffing after linishing. The linishing belt and mop rotates on the end of a spindle that is attached to a lathe.The belt has various grades of grit from fine to coarse dependant on how much metal needs to be removed.