General Motors is developing new hard-facing approaches using titanium and titanium carbide as it bids to expand the use of low-cost tooling made from aluminum or plastic composites for automotive parts.
The new technology is designed to expand the life of molds made from softer materials than tool steel. A benchmark of one million parts’ lifetime is often cited although GM makes no claims in a new patent on the lifetime of tools made with its hard-cladding system.
In the new GM approach, a part-forming cavity is first machined in an aluminum-nickel alloy substrate. After oxidation is removed, the substrate is hard-faced with a laser working on metallic material. The coating is machined and polished deposited in powder or wire form. The coating is machined and polished.
The purpose of the cladding is to improve corrosion resistance, wear resistance, and thermal conductivity. The range of hardness achieved is 400 kg/mm2 to about 600 kg/mm2. Hardened tool steel readings are around 550 kg/mm2.
Efforts to expand use of aluminum tooling for automotive parts have been expanding since breakthrough work by Honda about a dozen years ago. GM launched a part for its Volt electric car made in an aluminum tool in 2011.
The work on advanced aluminum tooling fits hand in glove with GM’s efforts to dramatically expand its fleet of electric vehicles, which generally have shorter production runs than current models and require innovative methods to reduce costs.
The lead inventor on the GM patent issued yesterday is Julien Mourou, who is lead engineer – Advanced Vehicle Development at General Motors. His specialty is upper exterior trim.