Changing of Stamping Process Design and Practice Due to Integrated Design Approach to Car Body Quality Enhancement 970983

Customer preference for the “eye catching” and aesthetically good looking product has made the car quality a key competitive issue. Manufacturers have no choice but to design and manufacture products to exceptional levels of quality while remaining cost competitive. If excessive costs of “quality” are to be avoided, product and process design standards must be harmonised to ensure that product quality can be designed in from the start of a new product development cycle. However, the subjective nature of the car body aesthetic quality makes it difficult to ensure effective communication across different functions of the organization.

Traditionally, product engineers are more used to designing for product performance targets such as stiffness, dentability and weight, while process engineers are primarily concerned with ensuring manufacturing feasibility within an agreed cost target. For these reasons and without part specific aesthetic quality target, delivery of product quality has largely remained the responsibility of manufacturing operations who end up carrying the burden of rework cost for the product lifetime.

Computer simulation analysis tools are in wide use for product and stamping process design validation. For example, they allow quite a good prediction of problems like splitting and wrinkling. In the main, computer simulation analysis tools can only check and validate designs as opposed to helping engineers create optimum product designs. Also considerable efforts are required to create design geometry and computer simulation aesthetic quality of the car. The process appears to be reliable and provides a good basis for assessing and comparing aesthetic quality of different car models. This process also helps to improve future product quality by setting challenging targets. The downside of this process is that continual demand imposed by ever increasing quality standards can lead to excessive manufacturing costs unless quality is achieved through proven pro-active design measures.

It is well known in the industry that the quality of any product is largely decided by upfront design/analysis activities. Downstream activities cannot make the quality any better. However, cost of quality rises rapidly if up-front activities had poor influence on the design, see Figure 1.

It is not an easy task since it requires a detailed understanding of product aesthetic quality requirements, and development of part specific quantitative quality targets to guide design and manufacturing processes. Above all it requires no compromising culture when it comes to product performance and quality.

Continual improvement in car body paint quality can now highlight skin panel cosmetic defects that are only a few microns. The challenge facing stamping process simulation technologies is to provide understanding and capabilities to solve very small skin panel cosmetic defects known as “highs and lows”, “teddy bear ears” or “crows feet”.