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Ask the Stamping Expert: How to start using tool coatings

Best approaches when applying coating to extend the life of a tool

Tool and die for metal stamping

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Q: I would like to experiment with applying coatings to extend my tool life. What is the best approach?

A: Good question! As with any improvement, when adding coatings, you have to be careful. You might think nothing will change, but the addition can cause unintended consequences.

The purpose for adding coatings and using tooling materials that exhibit greater resistance to wear is to improve the cycle time between consumables (cutting, forming, and camming components) changeout. This extends their life.

New projects developed using tool coatings should be straightforward. Once development is complete, as long as all the tooling material and coatings remain the same moving forward, everything should proceed without problems. If you are trying coatings in an existing, ongoing production process, it’s a different story. You must exercise due diligence.

New tooling may be built with standard, uncoated tool steel for two reasons:

  1. Development of forms and trims will need to be changed as the tool is groomed for part to print. Special tool steels and carbide coatings can be three times costlier than standard tool steel, and so coatings at this stage could be very wasteful when making changes on-the-fly in development.
  2. Development may result in grinding off the coatings or require new components to be made the same day. Coating costs and lead times make this infeasible.

When development is completed, the tool moves as is to the repair and maintenance tooling group, which in any best-in-class manufacturing operation is part of its long-term continuous improvement process. This should include upgrading tool steels and trying coatings to improve tooling life. And this process should never end. Its purpose is not to “put out fires” by fixing, sharpening, and repairing in reaction to unplanned tooling downtime.

Before moving to coated tooling, you need to establish a baseline of the current production process. This is done by setting up process control limits on data taken off key part parameters before making changes. Then you monitor the part data (in real time) to these predetermined control limits. This serves three purposes:

  1. Ensures the process is stable. You can’t improve a process that you can’t control!
  2. Identifies when uncoated tooling wear components must be replaced to ensure quality requirements are met continuously.
  3. Establishes a baseline expected lifespan of the uncoated tooling.

Changes in the tooling materials and coatings are subject to the same controls as all replacement tooling, including verification that components meet all dimensional requirements on the component print.

After tooling wear components are replaced, either with or without upgrades in materials and coatings, standard good manufacturing practice applies. The part inspection data verifies that there have been no unassignable shifts. The maintenance cycle then repeats during production through the entire life of the program.

While pursuing continuous improvement, remember Tooling Law No. 10: “Grow and improve in steps,” and Tooling Law No. 4: “If nothing changes, then nothing will change.” Continuous improvement requires changes, so seek them out! If you don’t innovate, the competition will pass you by. Every employee can be a leader in this process by being a proponent of change. Remember, one second saved in a minute of production yields almost a full workweek (35 hours).

About the Author
Micro Co.

Thomas Vacca

Micro Co.

Has a shop floor stamping or tool and die question stumped you? If so, send your questions to kateb@thefabricator.com to be answered by Thomas Vacca, director of engineering at Micro Co.