An introduction to die casting: frequently asked questions

The die casting process can offer significant advantages over other manufacturing processes—such as machining and stamping—resulting in major savings in piece price and overall production costs. With die casting, you can create complex net-shapes, including intricate internal and external features with minimal draft angles—minimising secondary operations. However, as with any production process, there is much to consider before deciding which process is best suited to your component.

In January 2021, Form Technologies hosted the first instalment of the Metal Solutions Webinar Series – EU. This webinar, An Introduction to Precision Die Casting, presented by the European Dynacast team, aims to guide customers in taking advantage of the benefits of die casting. Our webinars give attendees the opportunity to ask our experts questions about the die casting process during the live question-and-answer session. Review some of the most frequently asked questions below.

What is the minimum wall thickness for die cast components?

The minimum wall thickness we can achieve depends on the part geometry and part design, but under ideal conditions, Dynacast can cast aluminium walls as thin as 0.3mm. Generally, a minimum wall thickness of 0.5mm – 1.0mm is advisable to maintain high strength.

What is the ideal wall thickness for die casting?

There is no single ideal wall thickness for a die cast component. Instead, it is extremely important to maintain consistent wall thickness and reduce weight where possible to achieve a strong, cost-effective component. The best way to achieve this is to incorporate optimised gate and overflow locations into your part design to avoid unnecessary porosity and maintain strength.

What is the tightest tolerance Dynacast can maintain?

Dynacast takes pride in maintaining the tightest tolerances in the industry, but as with wall thickness, tolerance largely depends on part geometry. For the most exact tolerances, zinc can generally achieve between ±0.001" and ±0.002", whereas aluminium can achieve between ±0.002" and ±0.004".

However, although a tolerance of ±0.001" is possible with Dynacast, manufacturers must take care to avoid engineering unnecessary cost into the design. Too often, companies specify exacting tolerances and minimal draft angles when such features are not required to maximise part performance. As a result, their castings fail.

Instead, take a more holistic approach to your design. With the help of our die casting engineers, identify the non-critical dimensions of your component to allow more generous tolerance zones. In addition to extending the life of your tool, as there are fewer exact geometries subject to wear, allowing for tolerance zones also makes it easier to plan the tolerance stack-up of your entire component. This will help you avoid machining and secondary operations wherever possible, enabling your design to make the most of the die casting process.

Which die cast metals are environmentally friendly to use and produce?

All of the die cast materials we use, aluminium, zinc, and magnesium, are environmentally friendly because they are recycled. At Dynacast, our plants operate in a closed-loop cycle, using advanced remelting capabilities to reuse excess metal recovered from runner systems in the dies. After reclaiming the excess metal, Dynacast verifies its chemical composition with spectrometers to ensure that it retains the physical and mechanical properties of newly sourced metal.

In production terms, aluminium is the most environmentally friendly of all die casting metals. Aluminium is 100% recyclable, and 75% of all aluminium ever produced is still in use today. As aluminium can be recycled repeatedly without deterioration in its mechanical or physical properties, it can serve the same applications with the same performance level as primary aluminium extracted directly from bauxite ore—all while positively affecting the environment and your bottom line.

The physical and mechanical properties of aluminium make it the ideal choice for parts used in almost any industry, including aerospace, defence, consumer electronics, healthcare, automotive, and more. 

What are the benefits of die casting over screw machining?

The benefits of die casting are largely associated with production speed and savings in total piece price. Dynacast's Multi-Slide machines can be designed with multiple cavities, enabling our engineers to cast extremely complex parts quickly. Our Multi-Slide die casting machines operate at speeds of up to 75 cycles per minute, delivering 4,500 shots per hour. In a two-cavity tool, this equates to 9,000 parts per hour.

A faster cycle time contributes to a lower overall cost per piece. Additionally, die casting tools provide unmatched complexity in internal and external geometries, resulting in fewer secondary operations. With Multi-Slide die casting, you can cast complex geometries that would otherwise need to be manufactured from two or more pieces and assembled using other processes.

While screw machining offers a lower upfront tooling cost, die casting more than compensates for this through overall piece price savings. For an ideal part (one that is small, high volume, and can be cast in zinc), the tool is fully paid back somewhere between 10-14 months of production. Every part produced after that contributes to your bottom line.

Do you have materials that are corrosion resistant without surface treatment?

The level of environmental resistance provided depends on the material and your project requirements. Zinc, for example, is relatively self-resistant compared with aluminium alloys, although zinc oxide, or white rust, may occur. However, if your die cast component requires a high level of environmental resistance, we recommend using one of our surface treatments—from treatments and coatings that provide corrosion resistance, high-gloss finishing, painting, and more.

How can you determine whether die casting is cost-effective compared with other fabrication processes?

The cost-effectiveness of the die casting process must be evaluated on a case-by-case basis. In many cases, converting from screw machining, machining from solid, stamping, or welding to die casting results in improved part performance and lower cost at full-scale production. However, we invite you to contact an engineer to determine whether converting to die casting is the best solution for you.

With over 80 years of experience, Dynacast consistently delivers value through engineering expertise, efficient operations, and Advanced Quality Planning systems.