Page 49 - MetalForming January 2015
P. 49

 Lubrication
Press lubrication not only ensures press longevity but also contributes to process consistency. Process lubricants play a major role in the consistent qual- ity of the parts being produced. In- process lubrication provides consis- tent friction and cooling conditions, important to ensure consistent part production and to prolong tooling life.
Lubricant type and viscosity, the amount applied and its location, and its operating temperature range all are critical factors. Most lubricants are specifically formulated to work within specific process-temperature ranges.
Design
Product and tooling design repre- sent major contributors to stamped- part inconsistencies. Product designers often lack a thorough knowledge of what’s involved in producing the parts that they need and, consequently,
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length growing, so that the distance between the pilot holes exceeds design limits, or is it shrinking so that the dis- tance between pilots is less than designed? Is a stretch flange splitting due to a mismatched cut, or are extru- sions splitting due to a burr? Is the die hitting too hard or not hard enough? Are deep-drawn features splitting, due to restricted material flow or to an incorrectly specified radius? Is the car- rier design appropriate? Is the die hit- ting level in all the stations? Is die tim- ing correct with the die fully loaded? Do cutting clearances change with the die fully loaded due to tipping moments?
Achieving consistent part quality relates directly to how well pressroom personnel understand all of the stamp- ing-process inputs. Our challenge: Identify those variables that contribute most to part-to-part variation, and con- trol those variables to the best of our ability. MF
The power of Manufacturing.
introduce problems and inconsistency in the manufacture of those parts.
Tooling designs that cut corners to reduce tooling costs inevitably will pro- duce inconsistency. It may not happen at die buy-off, but such designs even- tually will be exposed. Examples include use of thin and weak sections that lack the rigidity needed to withstand long production runs; improper tooling materials that wear prematurely; improper cutting clearances; and inad- equate or ineffective piloting that results in inconsistent part location. “Form- ing in air” is the term used to describe forming operations where the part is not rigidly held by a spring-loaded pres- sure pad prior to forming; this practice almost always causes inconsistency.
Progressive-die processes can be challenging, especially when trying to solve quality-related problems. Did the material feed properly? Are the pilots positioning the strip accurately? Is pitch
Tooling by Design



































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