A Manufacturing Cost Analysis of Tube and Node Steel Spaceframes

The design and manufacture of today's automobile structure is dominated by a single approach: the stamping and spot welding of sheet steel. There are, however, a number of potential challengers to this steel unibody approach. These include a steel spaceframe, an aluminum unibody, an aluminum spaceframe, a composite monocoque, and hybrids of these types. The primary barriers to adopting these alternatives have been technical practicality and cost.

This paper considers one of the alternative approaches -the steel spaceframe- and examines its cost for two potential design and manufacturing scenarios using a computer spreadsheet based technique called Technical Cost Modeling. Selected default assumptions -including annual production volume, piece count, and assembly rates- are then varied to assess their impact on overall cost. The manufacturing costs for a conventional steel unibody as well as several of the other alternatives are used as a baseline for comparison. The results of this paper shed light on the economics of the steel spaceframe and thus its potential for market acceptance.