General Motors adopts a new welding system for aluminium

General Motors is also joining the aluminium bandwagon but quietly unlike Ford Motor Co., who has spent millions of dollars for the complete restructuring of its assembly plants.

Ford has come up with rivets and industrial adhesive to join its aluminium parts but General Motors is adopting a new welding system for the joining task.

General Motors will keep the existing production lines and simply spot weld the aluminium sheets for the doors, hoods and tailgates using the same robots and welding guns that are used for steel. The special technique of aluminium welding adopted by GM is being called a breakthrough in manufacturing technology by Richard Schultz, MD of a consulting firm in suburban Detroit named Ducker Worldwide.

Mark Reuss, the global product chief of GM says that they have no plans till now to make a fully aluminium-bodied car but there is a definite need to reduce the weight of the vehicles to stay in the competition.

Welding aluminium had always been challenging since the oxide that forms on the surface makes it difficult to create a strong bond, moreover, since the oxide traps hydrogen gases it makes the structure porous and weak.

The simple solution to the problem was to add copper welding caps as the scribed circles on the caps will constantly disrupt the oxide thus enabling a strong weld.

The new GM welding system is also easy to implement as only minor changes are needed un the production equipment. These include liquid cooling line for keeping the copper tips at a proper temperature, a machine that resurfaces the copper welding tips and additional transformers to enable the higher voltage required to weld aluminium sheets.

"Our view is we want to be able to reuse our existing infrastructure. We don't want to have to retool," said Blair Carlson, GM's manufacturing systems research lab group manager.