MAN Truck & Bus
The laser relentlessly draws its line of fire. Sparks are flying in all directions like from a sparkler at the point where the shimmering beam of light hits the fine metal powder on the 3D printer’s base plate. As they die away, a rectangular metal outline becomes apparent on the base. But only for a moment. Seconds later, a scraper coming from the left spreads the next wafer-thin layer of the grey metal powder over the base and the shape disappears. The laser starts firing down again from the top of the chamber. The dancing sparks reveal where the workpiece is slowly emerging in the flat bed of metal powder. A whole six hours later, the part is ready. It is embedded in a 15 centimetre high plateau of metal powder and is now being exposed using a suction pipe. Gradually revealing an aluminium thermostat housing.
This brand new part is in fact a replica: it’s needed as a replacement part in a MAN truck that is over 30 years old. The housing is still firmly fused to the printing plate and now has to be released from it using a copper wire. Dr Peter Scharf and Marcel Flügel are observing this process from a safe distance. Scharf is a recognised MAN expert in new material concepts and surface functionality and is based in Nuremberg. Flügel is a project manager in Central Truck Production Planning in Munich. A few minutes later, the two of them are bending over the thermostat housing for an initial inspection.
Marcel Flügel picks up the replacement part. He looks at it from all sides and explains what he believes is the great potential of 3D printing: “This process offers us a degree of design freedom that didn’t exist before. 3D printing enables us to produce unusual shapes and surfaces, for instance – even in small quantities – without their production becoming too complex. That simply isn’t possible with traditional manufacturing techniques like forging or milling.”
Visiting friends MAN's 3D printing experts Marcel Flügel (left) and Peter Scharf have come to Audi's 3D printing center in Ingolstadt to print spare parts. Before printing begins, they confer once again with Martin Bock, project manager at the Metal 3D Printing Center, at the entrance to the 3D printing production hall.
Starting signal New metal powder has just been filled into the printer, which is now evenly distributed by the plant operator. One of the heart pieces of the printing plant: the sieving station for powder preparation (right).
The preparations are complete The system operator starts the print job on a monitor and the first sparks fly immediately. It takes several hours until the workpiece is ready.
Close together When printing is complete, the support structures that fix the workpiece in the correct position on the printing plate are removed. This is how the workpieces, efficiently positioned in the printing chamber, come out of the printer. Here, too, the support structures are removed afterwards.
Under the microscope For each 3D build job, samples printed from the same material are subjected to metallographic examination. Typical microstructure of a 3D-printed aluminum-silicon alloy (right). The so-called micro-welds must look flawless in the magnified assessment.
Peter Scharf also takes a close look at the thermostat housing. He was the one who introduced 3D printing at MAN. As an engineer also acting as a technology scout, his first live experience of the process was in 2013. It was immediately clear to him that it would play a major part in an increasingly digitised commercial vehicle sector, where fast response times are crucial. “So we didn’t waste any time and quickly started printing test specimens”, he says.
These first trials were conducted a few years ago. MAN has since acquired in-depth know-how when it comes to 3D printing. Taking part in research projects has enabled the company to continuously develop its expertise in this field. “We know exactly for which applications 3D printing is suitable and when it doesn’t make sense – because the costs are too high, for example”, says Marcel Flügel. “Such printing is however highly promising for the after sales sector – as in the case of this thermostat housing. Seldom needed replacement parts for older trucks, buses or even old tractor units can be produced on demand. This eliminates the need for costly storage of the parts and their associated tools.”
MAN can also benefit from using 3D printing in the vehicle customisation segment. Here customised parts can be made quickly according to customer requirements, also in small quantities. Another advantage: 3D printing can help shorten the development cycles for parts and prototypes.
3D printing plays a major part in the increasingly digitised commercial vehicle sector, where fast response times are crucial.
“3D printing enables us to produce unusual shapes and surfaces, for instance – even in small quantities – without their production becoming too complex.”
MAN currently has four 3D printers for plastic components. For printing metal parts, the company works closely with Audi. Peter Scharf and Marcel Flügel are in regular contact with Audi's metal 3D printing center and plastics 3D printing center, both located at the Ingolstadt site, to realize prototypes and spare parts, for example. A precise commissioning workflow has been established to ensure smooth operations.
Today, Scharf and Flügel are on site in Ingolstadt for the production of the thermostat housing and prototypes. "The coordination with Audi works very well," says Peter Scharf, while in the background everything is being prepared for the next printing. "Both the human contact and the technical exchange are an enrichment for us." The cooperation is also the best example of MAN's Smart Innovators strategy, he adds. "It's about not wanting to do everything ourselves or investing in equipment right away, but rather jointly exploiting synergies, potential and know-how," Marcel Flügel elaborates and then looks in the direction of the printing system, where a colleague is currently filling the storage container with the very fine metal powder. To prevent him from inhaling any metal dust, he wears protective equipment with a mouth guard, filter and visor. The 3D data for the next object, the so-called STL files, have already been fed into the system. The colleague closes the door to the storage container and starts the printing process via a display on the outside of the housing.
If everything runs optimally, a component can be realized in three to four days from the creation of the STL files, according to the experts Scharf and Flügel. "In parallel, we print samples to test the material properties," explains Peter Scharf. A part is only released after a precise quality check for cracks, flaws or other defects. The thermostat housing also awaits strict inspection at the Central Materials Technology Department in Nuremberg. Peter Scharf places the part and still-finished prototypes in a sturdy box for transport.
Despite the numerous new possibilities, the MAN experts would not yet describe 3D printing as creating a revolution in commercial vehicle construction. “Care is required in the case of safety-related parts, for example, because their long-term behaviour has not yet been sufficiently tested”, Peter Scharf points out. “Parts like thermostat housings, coolant manifolds, money trays or cup holders, on the other hand, present no problems at all.”
Marcel Flügel adds that 3D printing may not be cost-effective in every situation: “The printers aren’t yet quick enough for large parts and high volumes. Albeit we do expect significant progress in the so-called build-up rates in the next two to three years.”
Peter Scharf and Marcel Flügel prepare to leave with the finished part packed away. “We want to use 3D printing in series production as soon as possible, for instance to produce parts for the interior and exterior of the cab”, Flügel defines the objective for the near future. “We’re keen to exploit the full potential offered by this technology.”
MAN is using the resources available in the VW Group to accelerate this process. Marcel Flügel and Peter Scharf belong to the 500 or so members of the Volkswagen 3D printing community and regularly exchange experiences and innovations in the group’s 3D printing technology circle. A brand-focused working group within MAN itself, with around 30 members and working across all divisions, is ensuring that knowledge about the possibilities of 3D printing is spread within the company. “Soon there’ll also be web-based training on the topic”, Marcel Flügel announces. “This will enable all MAN employees to acquire initial basic knowledge of 3D printing in 30 to 45 minutes.”
Peter Scharf, however, believes that the best way to fan the flames for the technology is to observe 3D printing – especially the final stage: “I always find it exciting to watch as the excess dust is extracted. It reminds me of archaeological excavations, where the sand and dust is removed and the artefact is finally revealed.”
„We’re keen to exploit the full potential offered by this technology.“