Page 40 - MetalForming August 2016

Tooling by Design
By Peter Ulintz
Die-Design Validation
It makes little difference how much individual experience we acquire or the number of experienced tool- makers and engineers that we collec- tively involve in our die-design process- es; sooner or later we find ourselves uttering these dreaded words:
“If we only knew then what we know now, we would have designed this die differently.”
To a great extent, metal-stamping processes succeed or fail based on the suitability of the die design. If the tool- ing is not designed properly, there’s not much that can be done in the press shop to develop a process that runs reliably and profitably.
Unfortunately, many dies are thought to be designed properly if they can repeatedly produce parts within part-print specification at a predeter- mined production rate during die try- out. However, two problems arise with this approach. First, validating a design after the product already has been pro- duced does not represent sound engi- neering or business practice. Shouldn’t a metalformer test and validate the design before investing time and money in die construction? Secondly, after production begins the stamper often finds that small and seemingly
Peter Ulintz has worked in the metal stamping and tool and die industry since 1978. His back- ground includes tool and die making, tool engi- neering, process design, engineering manage- ment and advanced product development. As an educator and technical
presenter, Peter speaks at PMA national seminars, regional roundtables, international conferences, and college and university programs. He also pro- vides onsite training and consultations to the met- alforming industry.
Peter Ulintz
Technical Director, PMA pulintz@pma.org
insignificant changes in process inputs —material properties, die lubrication, die temperature or tool geometry, for example—can send the process out of control.
During most die-design and engi- neering evaluations, engineers have
substantial freedom early in the design phase. This design freedom degrades quickly as build and tryout phases approach. When design freedom is at its highest, the engineer often has very little part-specific manufacturing knowledge (Fig. 1). Without knowledge
High
Manufacturing Knowledge
Design Freedom
Low
Process Concept
Design Build Tryout
Fig. 1
High
Process Modeling
Design Freedom
Reduced Lead Time
Tryout
Manufacturing Knowledge
Low
Process Concept
Design
Build
38 MetalForming/August 2016
www.metalformingmagazine.com
Fig. 2