Die Casting Design FAQ

High pressure die casting is a fast, repeatable process that delivers quality metal components, every time—but only if your component is designed properly. There are many factors that go into a successful design for high-volume manufacturing and our team of engineers helps thousands of customers each year successfully launch new projects.

Keep reading to learn the answers to some of our most frequently asked questions about die cast design.

When designing a part for die casting, many of our customers are looking to reduce not only the cost of their component but overall weight as well. To do this, our die cast engineering team looks at the component as a whole and utilizes our DFM (design for manufacturing) methods to design out inefficiencies. What does this mean for you? Your final part will be designed not only to your specific requirements but it will be a high-quality component that won't fail you down the road.

Die Casting Design Related Questions

At the end of each of our metal solutions webinars, we leave time for attendees to ask questions to our presenter. Here are just a few of the questions that were asked during the design webinar that we feel would be helpful to others.

What is the ideal wall thickness for die castings?

Wall thickness, typically is 2mm for aluminum die casting. Customers are looking for lighter weight castings and a lot of times it depends on the thickness to length ratio. If you have a very long part, it is more difficult to have a very thin wall.

Should parting line flats have draft?

They can, but they can also be straight. With smaller die castings, we can use vibratory tumbling. With a larger part, we typically design it to be to be trimmed via a trim die and then it is ideal to draft the gate or overflow edge. The draft minimizes the potential for the trim die blade to skive the side of the part.

Is a venting required in die casting?

Venting is always required in die castings. Dynacast uses mold flow analysis to determine the best areas for overflows and vents to create better quality parts.

Beyond looking at wall thickness, what can be done to mitigate or eliminate porosity?

There are two forms of porosity; gas and shrink porosity. Gas porosity is due to air entrapment within the casting. With mold flow, our designers can see where the air is likely to be trapped and can design the tool with strategically placed vents that can eliminate much of the air. Also during design, slight modifications to the part may allow the material to flow in an optimal flow pattern avoiding pockets and features that can cause turbulence entrapping air.

With shrink porosity, again using our mold flow software we can run a thermal analysis to isolate hot spots within a part during solidification. These hot spots can then be addressed with cooling channels in the die to help extract heat. Also, uniform wall thickness is always preferred. Having thin and thick cross-sections adds to longer solidification times that can create shrink porosity.

How do surface finishes such as knurling and embossed letters impact tool life?

The features don't really impact the life of the tool. With zinc die castings you can get a million plus shots off the die blocks. A lot of times it's the core pins that may wear, but Dynacast designs interchangeable inserts for features that wear faster than the tool.

Aluminum die castings can produce 150,000 shots depending on the requirements, but adding certain features won't have a major impact.

Relative to plastic parts, are castings more tolerant of irregular wall thickness?
Yes, to the point that you will not see the sink marks. In plastic parts you are more likely to see a sink mark in cross-sectional areas. Metal alloys have surface tension that hold the integrity. Our engineers strive to always achieve uniform wall thickness, but in comparison to plastic, yes die castings are more tolerant of irregularities.

Die Cast Design Expertise

During our Die Cast Design webinar, we cover a variety of design techniques including:

• Parting lines 1
• Core pins 2
• Section lines 3
• Flats
• Parting lines on threads
• Gating
• Assist flow
• Ribs
• Wall thickness 2
• Fillets and radii
• Draft
• Holes and slots
• Knurling, lettering, and logos
• And more!