Aluminum repair and contamination control

Modern cars combine multiple materials to save weight and aluminium is increasingly used in engine hoods, screens and entire body structures on certain models. Aluminium behaves fundamentally differently than steel — both mechanically and chemically — and therefore requires a different work routine if the repair is to last.

§Why aluminium and steel must not be mixed

When aluminium comes into contact with a more noble metal such as steel or copper in the presence of an electrolyte – for example moisture or saltwater from road salt – the aluminium is broken down by galvanic corrosion. Even a few steel particles from a shared grinding disc can embed themselves in the aluminium surface and start a local corrosion that only becomes visible as blisters in the paint months later. Eurocode 9 (EN 1999-1-1) therefore recommends stainless A4 fittings for joints where aluminium and other metals meet precisely to avoid this type of breakdown.

§Separate tools and work areas

Many workshops working seriously with aluminium have invested in dedicated grinding discs brushes clamps and in some cases an entire separate room or shielded zone exclusively for aluminium work. The purpose is simple: to prevent steel dust from the ordinary sheet metal workshop from ending up on an aluminium surface where it can trigger corrosion that cannot be seen or fixed once it starts.

§Fire hazard from aluminum dust

Sanding dust from light metals such as aluminium and magnesium can under the right conditions be flammable or even explosive — a situation covered by ATEX regulations on explosive atmosphere. Workshops sanding in aluminium must therefore have extraction and collection equipment suitable for flammable metal dust, empty dust containers regularly and avoid open fire or sparks from simultaneous steel work nearby. A risk assessment of explosion hazard is part of the workplace risk assessment (APV) in a workshop working with aluminium.

§Welding in aluminium

Aluminum conducts heat far better than steel and is covered with a thin but tough oxide layer that must be removed mechanically immediately before welding, otherwise it prevents a proper fusion. Welding requires its own wire and gas type as well as a technique that accounts for rapid heat dissipation – an approach that is markedly different from MIG/MAG welding in steel.

• 01Use tools and abrasives marked exclusively for aluminium.
• 02Physically separate aluminum work from steel work where possible.
• 03Clean for oxide layer immediately before welding or gluing.
• 04Provide extraction suitable for combustible metal dust.
• 05Use stainless steel A4 fasteners at joints between aluminium and other metals.