Press forming is used at many manufacturing sites as a means of producing large quantities of products having the same shape in a short time. Press drawing,which can create a seamless three-dimensional shape, has the advantage that procedures such as welding can be skipped and less material is wasted, but friction becomes a major problem in this process. As friction generates blemishes,cracks, and heat in the product, it is commonly believed that a lubricant must be used during the pressing process, but then the lubricating oil must be washed off before the press-formed products are shipped. To establish a lubricant-free pressing (dry pressing) technology, which would greatly contribute to improvements in two major problem areas, environment and cost, a fundamental study directed toward optimization of dry pressing conditions was carried out using quality engineering techniques. As a result, a method was developed in which distortion generated in a pressing machine is used to evaluate pressing stability, and a start was made on the optimization of the dry pressing conditions.
