Why Tool Design and Maintenance are Critical in Deep Draw Metal Stamping
By Anthony Romero – Sales and Application Engineering Manager
The design of deep draw tooling is based on engineering data, simulation, and external software modified with internal concepts. Some of the items that are considered are work piece material properties, draw reduction ratios, clearances, press speeds, blank holder pressure, and others.
However, there is metal-forming expertise that is involved as well. This is where our toolmakers interact with the assigned engineer to optimize the tooling based on historical data and expert knowledge. As mentioned in our blog on the “importance of mentorship” in our industry, it is crucial for the experienced toolmaker (i.e., the metal-forming expert) to pass their insights on to apprentices in the team. (Check out “The Experts Among Us” by Peter Ulintz in MetalForming magazine, March 2017.)
The Many Tooling Considerations in Deep Draw Manufacturing
We take many considerations into account regarding the tooling for our projects. For example, the number of stations is based on the draw and complexity of the part. The photo above shows a process that requires 10 stations and the respective punch and die, as well as the fingers that are required to transport the work piece from one station to the other.
Another variable to be considered is the estimated production volume. The material chosen for some of the punches and dies will depend on this volume and the actual load calculated during the deep draw operation. Special coatings or tool steels might also come into play (carbide coatings, A2, or M2 material), depending on the potential volume and high loading.
Taking Responsibility for Tooling
It is important to keep in mind that a reputable deep draw metal stamper like Prospect Machine Products (PMP) assumes all liability for the tooling for the service life of the work piece – potentially several years. This is a critical concept, since tooling costs can be significant. But with PMP, it is a one-time investment.
Offshore competitors understand this barrier to entry, so they amortize the tooling cost on the piece price to soften the initial financial impact. PMP doesn’t use this somewhat deceptive tactic, since the customer might end up paying several times the initial tooling cost when the project or the production part lasts several years.
Tooling Forensics Extends Tool Life
Another place where the toolmaker’s skill and experience are valuable to the customer is in what is referred to as “tooling forensics.” PMP’s toolmakers inspect all tooling for irregular wear, chipping, or other early degradation after the initial runs and setups.
Then, light design modifications and lubrication changes are made to increase the life of the tooling. This important step has a positive impact in keeping lead times short and helping to ensure on-time delivery (OTD).