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Aluminium Alloy

Aluminium alloys are lightweight and can carry useful loads relative to their weight (specific strength). They can be die cast, extruded, stamped, forged or machined. Alloy grade and temper (the soft or heat-treated condition) affect strength, corrosion response, machinability and colour. Common uses include housings, brackets and lightweight fittings.

Structure and manufacture

Section titled “Structure and manufacture”

Low density reduces weight, but does not mean that every aluminium part will be stronger at the same thickness. Wall sections, ribs, radii and joints still need to reflect the load, span and impact conditions. CNC-machined aluminium can provide accurate geometry and a refined surface. Die casting supports complex parts in volume, although tooling, trials and finishing make the development programme more involved.

Why direct plating is difficult

Section titled “Why direct plating is difficult”

Aluminium rapidly forms a stable oxide film, so conventional plating does not bond reliably without specialist preparation. A plated route may require controlled cleaning, zincating or another transition system, with adhesion and corrosion performance validated for the actual alloy. Decorative parts more often use anodising, wet paint, powder coating or electrophoretic coating, described in surface finishing.

Anodising converts the aluminium surface into an oxide layer that can retain a metallic texture and accept colour. Paint and powder provide a wider palette and greater hiding power. The silicon content, porosity and microstructure of die-cast aluminium can affect decorative anodising, so the colour of a CNC sample should not automatically become the standard for a die-cast production part.

Development checks

Section titled “Development checks”

Define the alloy, forming route, visible faces, electrical contacts or masking areas, gloss and physical colour sample. An anodised or painted layer can affect close fits, so threads, earth contacts and moving surfaces may need masking. Colour approval should also control lighting and texture direction and link to the colour-difference plan.

Section titled “Related terms”

Die casting · Surface finishing · Colour difference · Stainless steel