Page 45 - MetalForming June 2013
P. 45
The Science of Forming
when the output data are averaged, summarized or otherwise modified for ease of reporting. For example, the average rejects of fenders stamped over an entire shift hides critical information that all rejects occurred in the first 15 min. of the shift. Likewise, an average shift-reject rate of five percent does not help solve a reject rate of 10 percent for the right fender and 0 percent for the left fender.
Stampers often fail to appreciate the complex interactions within the forming system, the system variations, the distribution curves and the lack of system controls. Instead we tend to view the forming system as a black box that directly links input to output on a one-to-one basis. When the black box begins to respond unpredictably, we blame the black box for deviating from how we think it should behave.
To accelerate this critical matching of material properties to the needs of the press/die, leading-edge material suppliers and press shops have begun to implement virtual forming—also referred to as computerized die tryout or computerized forming-process development. The first run through such a system will confirm if the base- material properties match the die design required to meet part print. Need different material properties? Rather than wait 4 to 12 weeks for a new coil, a simple keyboard change of material properties can determine whether the new grade is a successful buyoff or failure. This virtual-evaluation process proves more critical for higher- strength materials, including the new types of advanced high-strength steels.
Here I have presented reasons why our industry has been slow to match material properties to the needs of the press/die. Unfortunately, adoption of virtual forming has been even slower. The concept of a computer being more accurate than 30 years of on-the-floor experience is a hard sell—this explains why OEM/Tier 1 stampers and major mills comprise the bulk of virtual-form- ing users. MF
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