Rapid Tooling Two examples of additive toolmaking projects

From Stefan Guggenberger

Additive manufacturing is becoming increasingly relevant for serial production. While many think of printing prototypes, there is another possibility: tools made with 3D printers. We show the advantages of this method with two exciting use cases.

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Does additive manufacturing have what it takes to revolutionise industrial toolmaking? We have carried out a hands-on assessment on the basis of two cases.
Does additive manufacturing have what it takes to revolutionise industrial toolmaking? We have carried out a hands-on assessment on the basis of two cases.
(Source: unsplash)

Toolmaking is often complex, time-consuming and expensive. Due to the enormous freedom in design and the fast development and production processes, additive manufacturing can improve toolmaking in a number of ways. Faster production times, shorter process chains and lower material consumption usually noticeably reduce costs. But even 3D printing cannot work magic; the production of precise tools remains a demanding task.

1. Cooling tools for serial production

For car manufacturers, cycle time (i.e. the average time it takes for a unit of quantity to leave a production system) equals money. Therefore, manufacturers are constantly looking for ways to make their production lines more efficient and thus faster. Cooling times, during which metal or plastic parts have to rest, are a time-eater in every automotive production. Additively manufactured tools can help to shorten these cooling times.

Mould and moulded part: The near-contour tempering reduced the cycle time by 17% and improved the quality of the armrest part.
Mould and moulded part: The near-contour tempering reduced the cycle time by 17% and improved the quality of the armrest part.
(Source Innomia, Magna)

The supplier Magna traditionally produces armrests using injection moulding. Considering the large quantities and the lack of customisation of the component, 3D printing would not be suitable for this. However, Innomia has developed a cooling tool from the 3D printer that can reduce the cycle time of an armrest by 17%.

To achieve this, the designers began by developing an efficient cooling system for the mould insert. This near-contour cooling system is designed so that the cooling channels extend over almost the entire 3D-printed tool surface. The DMLS (direct metal laser sintering) process was the most effective way of implementing the fine channels. The tools were produced from the 3D printer on machines from EOS. According to the designers, the process used also helps to improve the durability as well as the quality of the tool.

In the end, the heat dissipation could be made much more homogeneous and thus more efficient. The cooling channels of the 3D printed tool resulted in a 17% reduction in the time required for a production cycle compared to the conventional tool. In addition, the components deform significantly less due to the uniform heat dissipation. The results are based on values measured by Magna after approximately 370,000 armrests had been produced. During this period, the complete savings of around 20,000 euros.

2. 3D printed precision drills

3D printers are now capable of processing tool steel that is suitable for machining extremely resistant materials. Tool manufacturer Mapal relies on additive manufacturing to produce insert drills. To do this, they use Selective Laser Melting (SLM) technology from Concept Laser. Stainless steel 1.2709 is used.

Additive manufacturing allows for smaller diameters and up to 100 % more coolant throughput
Additive manufacturing allows for smaller diameters and up to 100 % more coolant throughput
(Bild: Mapal)

For a long time, additive manufacturing for cutting tools was only used for prototypes as the required quality or cost-effectiveness could not be achieved with additive processes. However, as Mapal's drill proves, it is now possible to produce high-precision tools on a 3D printer that even outshine their conventionally manufactured competitors in terms of functionality.

Mapal states that the drill offers good chip deformation and reliable chip transport. In addition, it is now possible to manufacture drills in the diameter range from 8 to 12 mm. Previously, 13 mm was the smallest diameter possible. The reduction in size is possible thanks to the coiled cooling system. This cooling system is based on a completely new geometry and allows for a 100 % increase in coolant flow. According to the manufacturer, the design would not have been possible with conventional methods.

How long before all tools will be 3D printed?

Although the possibilities are seemingly unlimited and despite the production-ready technology (as described in this article) - additive tool manufacturing also has its limits. Many companies shy away from the additional investments or simply do not (yet) have the right know-how to implement the new technology. Although the examples mentioned above lead to measurable improvements, there are a number of other factors to consider when implementing the technology.

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With complex and precisely coordinated production lines, it is not enough to replace a single tool. To truly work more effectively, upstream and downstream production steps would also have to be adapted. Often, however, this is not possible because, for example, material-related cooling times must not be undercut. If cooling is too fast, the workpiece becomes brittle or deformed.

Even the above-mentioned drill cannot do without conventional processes. Every drill has to be re-machined after printing in order to achieve accuracies in the thousandths range.

No revolution in toolmaking after all?

On the one hand, additive processes can lead to significant improvements in the functionality of 3D printed tools, and on the other hand, many manufacturers are not yet prepared to place their trust in 3D printing. This is understandable, as conventional processes are usually more mature and deliver expectable results. Compared to milling processes, for example, additive manufacturing is still in its infancy. Those who want to use the new technology must cultivate an open error culture in their companies. The principle of trial and error is an important part of the additive manufacturing process.

The human factor and its qualification should also not be underestimated. Since the training of designers today is still geared towards conventional manufacturing, some companies lack the right know-how. But beware: those who remain asleep for too long will soon no longer be able to catch up. As our examples show, it is absolutely possible to use additive manufacturing in industrial toolmaking and the full potential is far from being tapped.

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