1995-02-01

High Precision in Car Body Manufacturing 950573

Flexible car body production, including prototyping, is one answer to the market targets where customers ask for an increasing number of models / variants and shorter lead time. The in-house interests of car builders are, besides investment and manpower flexibility, also improved product quality. Quality in body in white is mainly related to geometry (= high precision), to make sure that the final assembly shops will have the right conditions to keep customers satisfied (flush in doors, hood, fenders etc.).
The consequences are that both the product and the process equipment have to be in a stable condition to guarantee low spread in the complete car-body. CAD technology is one of the keys to reach this goal, where:
  • Off-line tooling
  • Off-line programming
  • Flow simulation
  • Measurement strategy, off-line / in-line
are the main powerful tools to reduce lead time as well as costs.
In the realisation phase of the new flexible body shop, in VTK / Gothenburg Sweden, new methods were used for the interaction with all process-suppliers. The co-operation at early stages was highlighted under the aspect of simultaneous engineering.
The bottleneck was to find an overall measurement strategy that could be used in all phases of the project, including maintenance during later production. Geometry-wise the targets, for the complete car body, were focused on completely new demands in body-in-white history, with dimensions defined as:
  • ≤ 0.2 mm spread in stamped parts,
  • ≤ 0.5 mm spread in pre assembled parts,
  • ≤ 0.7 mm spread in complete car bodies,
for functional values.
To reach these values, a metrological concept was developed with a Norwegian company, before the start of the project, and later implemented in our work routines as a standard tool.
Process equipment from the main suppliers for the new flexible body shop was controlled geometrically by Volvo-teams with transportable Metronor systems during the three phases:
  • Equipment assembly at suppliers site,
  • Installation on site,
  • Maintenance in production,
using the same method of measurement.
The result out of this project was that car no. 1 already showed customer quality, even if control-fixtures were not used in the flexible body shop.

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