Sand 3D Printing Benefits Lightweighting and EV Production

Brooks Crownhill Limited (BCP) uses Voxeljet’s 3D sand printing systems for prototyping a variety of automotive parts. This strategy enables the company to rapidly design and test highly-complex parts before manufacturing production tools, saving time and money.

Sand molds are relatively cost-effective and sufficiently refractory for application in steel and aluminum foundries. For this reason, casting with sand molds continues to enjoy great popularity, especially in the automotive industry. Voxeljet says industrial 3D printing technologies like its own binder jetting system have expanded foundaries’ range of design possibilities to include highly complex molds and cores.

Light, Enhanced Designs

"We have been using 3D printing and casting, or printed casting, for quite some time now,” says Lee Henderson, sales director at BCP. “The process is fast, cost-effective and gives designers enormous creative freedom. This is important for rethinking established components and saving as much material as possible, for example by optimizing the topology of the components."

“Today, engineers can use finite element analysis (FEM) to optimize functionality and then directly 3D print the designs,” Henderson continues. “This makes the design of engine parts a lot faster and, more importantly, the components are stronger, which in turn allows drastic weight reductions. This is extremely attractive, especially in the wake of current environmental regulations such as lightweight construction, and the associated energy savings."

Voxeljet says “lightweight” design is one of the most important design trends of recent years. Customer designs move closer and closer to the limits of manufacturability with thinner wall sections of the entire casting and higher tolerance bands for positional accuracy. As BCP largely manufactures engine components and, more recently, electric motor housing components for its customers in the automotive sector, it is on the forefront of this design trend.

"3D sand printing is irreplaceable,” Henderson says. “Not only because it allows us to realize geometries that would not be possible using conventional processes such as milling or core shooting, but, especially when we want to test brand new designs, we need the optimized prototypes quickly. We then take a close look at these with specific integrity tests (NDT, non-destructive testing) before we give the go-ahead for series production."

New Metal Casting Possibilities

"In modern engineering, 3D printing means above all that we can print complex inner cores as one part,” Henderson says. “This saves us a lot of work in casting preparation. And we can be confident that all tolerances on wall thickness and the associated stability of the cores will be maintained during the enormous stresses of metal casting. Further economic opportunities are opened up by time-saving printed castings when you reduce potential costs and conventional assembly time on complex core-stack assemblies line-side. This has a direct impact on the business model, ongoing costs and delivery times to the customer."

However, Henderson also notes that the benefits of additive manufacturing of molds and cores are not yet one hundred percent clear in the minds of engineers. "3D printing, unfortunately, still has a niche existence,” he says. “It is increasingly recognized within the foundry industry as a fully-fledged manufacturing process for casting molds, but I'm not sure to what extent the advantages are even known by both engineers and also the key buyers. There are still unimagined design and cost opportunities that could be leveraged here."

Process Optimization through AM Design

Other advantages go beyond the product, into the production process itself.

"With 3D printing, we can plan gas channels into the sand cores and molds during the design stage,” Henderson explains. “These are used for venting and outgassing during the casting process, making our job much easier, and have a great effect on the quality of the cast parts in terms of density and surface quality. Adding structural tie rods for better transportability of the parts is also possible and simplifies the handling of the printed parts."

BCP also relies on the use of different sand systems for specific applications. For example, it uses high-strength and high-temperature cores to ensure stability and concentricity of the inner cores during the casting process of high-temperature alloys.