Printing instead of casting How additive manufacturing revolutionises foundry technology

Editor: MA Alexander Stark

Germany — 3D printing of metals is currently changing many production processes in the industry. As a supplement and alternative to foundry technology, the 3DMP process offers an opportunity to manufacture even large workpieces economically in small numbers. This does not necessarily have to be seen as a competition — an additive manufacturing machine could be an ideal expansion of the manufacturing processes offered by foundries.

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In the Application Center, Gefertec can carry out feasibility studies for individual components on arc machines.
In the Application Center, Gefertec can carry out feasibility studies for individual components on arc machines.
(Source: Gefertec)

Speed, low cost and high quality — these are the essential criteria when evaluating the processes for the production of metal parts. Depending on the number, size and complexity of the components as well as the selected metal, different manufacturing processes are suitable. Additive processes have captured new areas of application in recent years. Powder-based 3D printing processes are most widely used. The process enables production of very fine structures but is often limited in speed and size. Another disadvantage: Powder as a material is very expensive and its handling is a comparatively complex process.

3DMP as an alternative and supplement for foundries

Gefertec has further developed the WAAM process and brought it to market maturity with its 3DMP WAAM technology solution (see text box). The arc welding process uses wire as the starting material, which makes it possible to print even large and heavy components at high speed. For the material 316L, the technology achieves a build rate of up to 3.6 kg/h. Wire from all common metals - including expensive materials such as corrosion-resistant, heat-resistant steels or nickel-based alloys - is available at comparatively low prices. This makes the process significantly more cost-effective than powder-based 3D printing methods. With these advantages, 3DMP lends itself as a complement to conventional casting methods. As there is no need for the elaborate production of models or molds, Gefertec machines can be used to produce near-net-shape blanks from metal quickly and cost-effectively. The final processing then takes place using conventional processing methods such as turning and milling — a step that is also necessary after casting, depending on the required surface quality of the component. Another positive aspect of manufacturing components using 3DMP is the smaller CO2 footprint. The considerable amount of energy required for casting can be reduced by up to two thirds using 3DMP.

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The innovative additive manufacturing process enables the production of high-quality components. The material properties correspond to those of casting components or even exceed them (see table above). By using qualified process parameters and integrated monitoring during the process, formation of cavities or porosity in the components can be excluded. 3DMP shows its superiority especially in small quantities and by making usage of materials that are difficult to process or are expensive. Typical examples include nickel-based alloys, stainless steel or hot-work steel.

Feasibility studies as a service

Adopting new technologies is a big step for most companies. Especially when experience is lacking, those responsible often shy away from the related investments. Gefertec has therefore set up an Application Center at the company's headquarters in Berlin, Germany to manufacture components on their arc machines and offer a wide range of services.

The Application Center carries out feasibility studies on the use of 3DMP manufacturing technology, focusing on component development based on customer requirements. This may for example include customer-specific requirements for material testing. Following those studies, the customer can decide whether to invest in an arc machine or outsource the 3D printing of components. The Application Center makes the results obtained during the study available to enable a seamless transfer of knowledge, which makes feasibility studies an excellent opportunity for a foundry to first evaluate the new manufacturing process in detail.

If the customer decides to outsource the printing process, Gefertec, together with its contract manufacturing customers, offers contract manufacturing of blanks or finished components according to the design drawings provided. Optional heat treatment of the manufactured parts is also possible. The delivery time is only a few days and depending on the material production costs can be reduced by up to 30 %.

Successful applications

Gefertec has already conducted the presented feasibility studies successfully in several customer projects. A project ran for Deutsche Bahn focused on using the 3DMP process to manufacture mobility-relevant spare parts that are no longer available from stock and sometimes had extremely long delivery times. A typical component is the secondary roll stop required in the bogies of ICE trains. This component limits the transverse play of the railroad car body and thus ensures the safe cornering of the trains in tight track curves. The Application Center showed in the feasibility study that this component could be manufactured in high quality on the arc machines. The actual production took place at Rolf Lenk, a specialist in additive manufacturing. The company manufactured the component in a very short time and made it available to Deutsche Bahn. The very short production times have a positive effect on the availability of the vehicles at Deutsche Bahn.

For another customer, Gefertec's specialists investigated the production of large rotationally symmetrical plant components made of corrosion-resistant steels that are used, for example in food production or the chemical industry. The process also impressed this manufacturer with excellent component quality as well as faster and more cost-effective production. The difficulties that are common with corrosion-resistant steel in other manufacturing processes do not arise with 3D metal printing on the arc machines.

Portfolio expansion in a foundry

The 3DMP process for additive manufacturing of metal components is an ideal option for foundries to expand their portfolio. This process is particularly suitable for metallic materials that are difficult to process using other methods and for the production of smaller quantities. Another decisive advantage is the high production speed: If short delivery times are required, the 3DM process is an excellent alternative. Companies can test the new technology risk-free by using the services of the Application Center at Gefertec. With the associated knowledge transfer, foundries can integrate the process step by step.