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Autokinetics is a Rochester Hills MI design firm working with Armco, a supplier of stainless steel. Together, they have developed an architecture that replaces the traditional stamped and spot welded steel unibody with a novel stainless steel spaceframe architecture. Fabrication Rollformings Thin wall castings Progressive die stampings Plastic support and exterior panels Assembly - Spot, laser, and MIG welding Relative to conventional steel unibodies, the Autokinetics spaceframe architecture offers a number of projected advantages. Substantial mass reduction Increased safety Improved ride and NVH More flexible packaging Lower lifecycle impact Potential for paint shop elimination The obvious question that arises, and the one that this paper will answer, is: How does the Autokinetics spaceframe architecture compete on cost?

Aluminum and polymer composites have long been considered the materials of choice for achieving mass reduction in automotive structures. As consumer and government demand for mass reduction grows, the use of these materials, which have traditionally been more expensive than the incumbent steel, becomes more likely. In response to this growing challenge, the international steel community has joined forces to develop the Ultra Light Steel Auto Body (ULSAB). The resulting design saves mass and increases performance relative to current steel unibodies. Although mass savings are not as dramatic as those achieved by alternative materials, this design offers the potential to be accompanied by a manufacturing cost reduction. The projected manufacturing piece and investment cost for the ULSAB are investigated using technical cost modeling. The results presented here examine the elements that contribute to the cost, including treatments for stamping, hydroforming, assembly and purchased parts.

In the past decade, the demand for and development of tailor-welded blanks (TWBs) has increased dramatically. TWBs help reduce body mass, piece count and assembly costs, while potentially reducing overall cost. IBIS Associates, Inc. has performed a cost analysis of tailor welded blank manufacturing through the use of Technical Cost Modeling (TCM), a methodology used to simulate fabrication and assembly processes. IBIS has chosen the automobile door inner panel for comparison of TWBs and conventionally stamped door inners with added reinforcements. Manufacturing costs are broken down by operation for variable costs (material, direct labor, utility), and fixed costs (equipment, tooling, building, overhead labor, maintenance, and cost of capital). Analyses yield information valuable to process selection by comparing cost as a function of manufacturing method, process yield, production volume, and process rate.

Hyrdroformed tubes have seen use in the aerospace industry for many years and are seeing increased use in the automotive body-in-white (BIW). The automotive industry has chosen to use hydroformings for a number of reasons including reduced part weight, piece count reduction, and the flexibility to form complex shapes of varying wall thickness. With all of these potential advantages, still one more provides the greatest incentive to switch from a stamped assembly to a hydroformed tube: the ability to reduce cost. It is generally accepted that hydroformings can indeed be cost effective to produce, yet the question remains: when should a stamped assembly be replaced by a hydroformed component? This paper will attempt to answer the question above by laying out several case studies and comparing their direct manufacturing costs.

Despite repeated challenges from alternative materials and processes, the stamped and spot welded steel unibody remains the near-unanimous choice of automakers for vehicle body-in-white (BIW) structures and exterior panels in volume production. Conventional steel's only weakness is mass; aluminum and polymer composites offer the potential for considerable mass savings, but generally at a higher cost. Efforts within the automakers as well as by outside organizations such as the international steel industry's Ultra Light Steel Auto Body (ULSAB) program are underway to improve the steel uni-body's mass and cost position. To reduce cost, it is first necessary to identify cost. The measurement of cost for a complex system such as an automobile BIW is far from a trivial task. This paper presents an analytical approach to understanding the manufacturing cost for a conventional steel unibody. The results of this cost analysis are then used to outline a strategy for future cost reduction.

Automotive exterior body panels are a critical component of today's vehicle. They provide a surface for painting, offer the first line of defense against damage from accidents and the elements, and in most cases add to the overall stiffness of the vehicle. Despite small inroads from aluminum and polymer systems, steel remains the predominant body panel material. Of the alternatives, sheet molding compound (SMC) has been the most successful challenger. This paper examines the cost and market conditions affecting SMC today and in the near future. The impact on cost of SMC compression molding process improvements is assessed over a ten year period for a full body panel set. These results are compared to stamped steel as a function of annual production volume and other key factors. The result is a cost “crossover” point below which SMC has the lower cost.

The Partnership for a New Generation of Vehicles (PNGV), a collaborative government-industry R&D program, has laid out and initiated a plan for a “Supercar” with the following specifications: a fuel economy of 80 miles per gallon (2.9 liters/100 km), size comparable to a midsize, four door sedan, equivalent function in other performance areas, and cost commensurate with that of today's automobile. Together, the performance and cost goals are formidable to say the least. The PNGV projects that a 50% mass savings in the “body-in-white” (BIW) is a necessary contribution to meet the 80 mpg goal. The two most likely materials systems to meet the mass reduction goal are aluminum and carbon fiber reinforced polymer composites, neither of which are inexpensive relative to today's steel unibody.

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.

In order to determine the best way to evaluate materials selection from an economic standpoint, a discussion of conventional cost estimation is given versus a more precise technique, Technical Cost Modeling. Automotive body panels are used as an application for the costing techniques; conclusions about fabrication costs and parts consolidation are drawn with regard to these parts.