We look at tolerances differently. Our standards both meet and exceed industry standards and are used as a guideline for designers worldwide. We believe that tolerances should be as tight as necessary, not as tight as possible.
We don’t believe the most important factors are how tight the tolerance can be or the process capability that can be achieved. Instead, we look at what’s needed to meet functional requirements and what dimensions and features are critical. Then we choose the process that will achieve them.
When we look at tolerances we carefully assess:
- The form of the part
- The proximity of the feature within the tool
- Its relation to other features on the part
We always take into consideration tool life and wear as this will affect short-term versus long-term process capabilities.
Moving Die Components
At what point do tolerances require machining instead of as cast die casting?
"With our zinc die casting, we can achieve the tightness tolerances without any secondary machining followed by magnesium and then followed by aluminum. With aluminum, we can cast an internal diameter to within +/- 100 microns. But with zinc, we could do that at half that tolerance +/- 50 or even +/- 25. We are controlling that internal diameter within +/- 25 microns with no machining, but aluminum is a much more aggressive process since it is a higher melting point alloy. Therefore it’s a higher injection pressure alloy, so it’s a more aggressive environment and that aggressiveness of the process causes the tooling to wear faster as well, so maintaining and controlling the tolerances as cast is more challenging in aluminum than it is in magnesium or zinc. We can achieve the tightest tolerance with zinc, then magnesium, then aluminum."