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 correctly. Many factors contribute to a successful design for high-volume manufacturing, and our team of engineers helps thousands of customers successfully launch new projects each year.

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

When designing a part for die casting, many of our customers seek to reduce not only component cost but also overall weight. To achieve this, our die casting engineering team assesses the component as a whole and uses 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 also as a high-quality component that will not fail in service.

Questions related to die casting design

At the end of each of our metal solutions webinars, we allow time for attendees to ask questions of our presenter. Here are just a few of the questions raised during the design webinar that we believe may be helpful to others.

What is the ideal wall thickness for die castings?

Wall thickness for aluminium die casting is typically 2mm. Customers are seeking lighter-weight castings, and it often depends on the thickness-to-length ratio. If you have a very long part, it is more difficult to achieve 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. For a larger part, we typically design it to be trimmed using a trim die; in this case, it is ideal to apply draft to the gate or overflow edge. The draft minimises the potential for the trim die blade to skive the side of the part.

Is venting required in die casting?

Venting is always required in die castings. Dynacast uses mould flow analysis to determine the best locations for overflows and vents to create higher-quality parts.

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

There are two forms of porosity: gas porosity and shrinkage porosity. Gas porosity is caused by air entrapment within the casting. Using mould flow analysis, our designers can identify where air is likely to be trapped and design the tooling with strategically placed vents that can eliminate much of the air. During design, slight modifications to the part may also allow the material to flow in an optimal pattern, avoiding pockets and features that can cause turbulence and trap air.

For shrinkage porosity, our mould flow software can again be used to perform a thermal analysis and 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. Uniform wall thickness is also always preferred. Thin and thick cross-sections result in longer solidification times that can create shrinkage porosity.

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

These features do not significantly affect tool life. With zinc die castings, you can achieve more than a million shots from the die blocks. Core pins may wear, but Dynacast designs interchangeable inserts for features that wear faster than the tool.

Aluminium die castings can produce 150,000 shots depending on the requirements, but adding certain features will not have a major impact.

Compared with plastic parts, are castings more tolerant of irregular wall thickness?
Yes, in that you will not see sink marks. In plastic parts, you are more likely to see a sink mark in cross-sectional areas. Metal alloys have surface tension that maintains integrity. Our engineers always aim to achieve uniform wall thickness, but compared with plastic, die castings are more tolerant of irregularities.

Die casting 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!