Die casting design FAQ

High-pressure die casting is a fast, repeatable process that consistently delivers quality metal components—but only when your component is designed correctly. Many factors contribute to successful high-volume manufacturing design, and our engineering team helps thousands of customers successfully launch new projects every year.

Read on 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 both component cost and overall weight. To achieve this, our die casting engineering team assesses the component as a whole and applies DFM (design for manufacturing) methods to eliminate inefficiencies from the design. What does this mean for you? Your final part will be designed to your specific requirements and will be a high-quality component that provides reliable performance over time.

Questions related to die casting design

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

What is the ideal wall thickness for die castings?

Wall thickness for aluminium die casting is typically 2mm. Customers are looking for lighter-weight castings, and this 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. For smaller die castings, we can use vibratory tumbling. For larger parts, we typically design them 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 shave 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 produce 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 results from air entrapment within the casting. Using mould flow analysis, our designers can identify where air is likely to be trapped and design the tool with strategically placed vents that can eliminate much of the air. During design, minor modifications to the part may also enable 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 identify 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, which 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. Often, it is the core pins that 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, to the extent that sink marks will not be visible. 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 strive 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 range of design techniques, including:

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