HYDROFORMED TUBE Tooling, welding concerns are driving caution in Detroit

Apr 01, 2008 | 01:36 PM |

Suppliers might be bullish on the prospects for hydroformed tubes in car and truck bodies, but many consumers are more cautious. Hydroformed tubes can help reduce weight and boost safety, they acknowledge, but in most cases they take longer to make and are more expensive than traditional stamped parts.

In general, there aren't many hydroformed tubular structures in Chrysler LLC vehicles, said David Reed, the Auburn Hills, Mich.-based automaker's body-in-white core lead. Part of the problem is that hydroformed tooling is expensive—roughly double the cost of stamped construction. "Your business case has to be really solid as far as piece-cost savings to pay for the tooling," he said.

Tubes also are limited by the vehicle manufacturing process, which typically involves resistance spot welding, Reed said. That involves two electrodes coming together and sending an electric current through two metal panels in order to join them. However, because a tube is hollow the current won't move between the two sides. Instead, single-sided welding or laser welding is required—and those technologies aren't as easy to integrate into the traditional vehicle manufacturing processes.....