Complex Impeller

Cost-effective investment casting with 3D printing

Until now, the production of small batches of complex parts using the investment casting method has been associated with considerable time and cost requirements. 

The Schmolz + Bickenbach Guss Gruppe shows that there is another way: It favors voxeljet's 3D print technology for the production of lost wax models, and is setting a new standard for cost efficiency and production time.

Whether in the automotive industry or machine building, the production of complex parts such as wheels, gearboxes and similar products in batches of one or small series should be quick and efficient. Conventional investment casting features has several weaknesses in this respect. Thomas Peipp, Investment Casting Manager at Schmolz+Bickenbach Guss GmbH in Ennepetal says: "The problem is the cumbersome production of the necessary wax models. This requires expensive injection molding tools and wax presses. Tool costs can become prohibitively expensive when used for small series production, as they result in very high unit prices." 

voxeljet's 3D print technology can help with these types of situations. The state of the art 3D printers of the Augsburg-based provider can produce plastic models quickly, precisely and cost-effectively. These PMMA models can completely replace traditional wax models. And the most important part: The production of the plastic models using 3D printing is very simple. No tools are required, as the digital printing process is based on the CAD data for the part. The 3D printer builds the model layer by layer using the digital data.

The downstream process for digitally printed parts is the same as for those parts produced conventionally by injecting wax into a metal tool. The first ceramic coatings are applied after the receiving inspection and mounting of the deadhead system. Afterwards, the models are put into the kiln. Since the plastic models soften and shrink at 73°C, as a result there are no cracks or tears in the ceramic shell. Once the temperature reaches 700°C or more, the molds will burn out completely without any residue.

The casting dies must be cleaned out with air pressure before the molten steel or aluminum alloys are poured into the dies. There is no requirement to wash out the molds. After the cooling period, the dies must be removed along with the casting and feeding systems, sharp corners must be deburred and any unwanted surface defects must be removed. This process is followed by non-destructive inspections and dimension controls in accordance with the customers' specifications. "Whether prototype, individual part or small series–3D printing technology makes it possible to produce highly complex design and investment casting models quickly, easily and cost-effectively. That's an enormous advantage for investment casting specialists, and especially our customers," concludes Thomas Peipp.