Marketing Makes a Difference for Manufacturers — Part 1: Joe Brown
Breaking Speed Limits, Part 2: Peter Ulintz
Can Robotics Help a Tool and Die Shop?: Bob Quinn
The Sensor that Cries Wolf—or, Eliminating Nuisance Faults: Drew Stevens
and from Danny Schaeffler of Engineering Quality Solutions (EQS)...
The 20-Percent Maximum Thinning Rule (or, How Much is Too Much?)
Everyone likes to have a “Rule of Thumb” to use as a quick and easy guide. To make the best use of these maxims, it helps to understand where they come from, and what the limitations are in their use.
When it comes to taking the right steps to ensure a robust stamping process, a surface-strain analysis using a forming-limit diagram (FLD) is recommended. The forming limit curve (FLC) should be generated from the minimum allowable thickness and the lower mill production limit (or the -3σ value) for the strain-hardening exponent (n-value). To bypass some of the work involved in generating this information, some companies have chosen to use a rule of thumb that calls for a maximum 20-percent thickness reduction on a formed part compared with the initial flat-blank thickness. In some cases, this is an acceptable substitution, but in many cases, using this 20-percent threshold only confuses the proper course of action.
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