A single-flute milling cutter is used as the milling tool. This has a large clamping groove, which ensures good chip removal and thus good heat dissipation. A milling tool with a diameter of 3 mm is used to achieve the largest possible milling depths. In contrast to the baseline, this has a cutting edge length of 22 mm instead of 10 mm. No cooling medium is used. This could cause the component or the printing plate to cool down excessively and thus inhibit the adhesion of the component to the printing bed.

The printing bed of the AddProKMU printer has been completely redesigned and made more efficient. In a final step, a new BuildTak coating was applied today to improve the adhesion of the components.

As part of his studies on “Technical Journalism/Technical PR”, Mr Robert Conrad wrote an article about our AddProKMU project:

Modular 3D printing concept

3D printing has emerged as a manufacturing method for industry and science. Professor Michael Koch from Nuremberg Tech has been conducting intensive research into this technology for the last three years, and private individuals are also relishing the novel opportunity to manufacture objects. While domestic applications are mostly frivolous in nature, such as printing figurines or small replacement parts for broken household appliances, the motivation for this manufacturing process in industry lies elsewhere, namely small-series production.

Although 3D printers for use at home are entirely up to the task, they are generally a bit shaky, inaccurate and slow, especially in direct comparison with their expensive industry counterparts. The price tag of both printer categories gives you some idea of the difference in quality. Whereas 3D printers for use at home cost up to around three thousand euros, the starting price for the professional version is rarely less than fifty thousand euros. There are only a few options in between.

This poses a huge investment problem for small and medium-sized enterprises. On the one hand, they can make good use of the new technology to produce prototypes or small series more quickly, for example. On the other hand, the professional devices represent a financial challenge that often does not pay off due to the small quantities involved. The entry-level models, in turn, are not up to industrial requirements, as they can only print with a few materials that are mostly not industrial grade. Hundreds of businesses find themselves in this predicament.

An industrial device at a low price

In order to solve this problem, Professor Koch has been working on a new 3D printing concept for the last three years. Funded by the European Regional Development Fund, he and a team of three others are developing a modular 3D printer as part of a transfer project. He and the team are also being supported by several small and medium-sized industry partners from the metropolitan region. The underlying idea is quickly explained. “We want to get as much as possible out of as little as possible,” says Professor Koch.

Although no expensive control units are used, his concept still relies on particularly high-quality mechanics and electronics. One example of this is the use of precise stepper motors, instead of the customary servomotors. The basic structure, also referred to as the basic version, consists of drive units for all three axes, an operating unit, and a printing head. This arrangement can be used for precise printing at a cost of three thousand euros.

The special feature of this concept is its modular nature. If required, the user can extend the system by adding additional operating units. Automatic gripper tongs, a tool change unit, and additional printing heads can be retrofitted, for example. “Fully equipped, our 3D printer costs around ten thousand euros,” says project contributor Frank Prechtel. The open source approach for hardware and software is of particular interest for industry partners.

Tailored to individual needs

This allows users to better integrate the printer into their working processes, and adapt it to their needs. “The aim is to empower small and medium-sized enterprises to enter the world of 3D printing without having to invest hundreds of thousands of euros in a machine that is ultimately not worth it,” says Professor Koch. Only a small amount of existing infrastructure and know-how is required to successfully integrate the new printer into your company.

After all, this printer is not an out-of-the-box solution. The individual modules must be assembled by experts. Once the printer is ready, users can enjoy the latest 3D printing technology. If, for example, the module with the automatic grippers is installed, the printer will then be able to insert metal inserts into the component during the printing process. The printer can also be operated independently by any service network, as on-site experts can carry out the necessary repairs and maintenance work themselves.

Three industry partners have already decided to build the modular 3D printer themselves. However, there are still two major goals on Koch’s agenda, which should be welcome news to those customers who have already invested and those who will in the future – namely combining 3D printing with milling machining technology in three and five axes, and enabling printing of materials in five axes. In these cases, the printing table would also be able to move in addition to the printing head. Previously, you had to choose between “either printing or milling, but now it will be possible to alternate between the two," says Professor Koch.

Applied science

However, this will not be the only unique selling point that distinguishes the printer from the labs of Nuremberg Tech from expensive industrial printers. Professor Koch is also planning to make progress in the field of materials engineering, saying: “Ceramics have been somewhat neglected in 3D printing technology to date.” This is due to the fact that materials printed from ceramics often have to be re-treated with acetone in order to release a filler. “However, the component shrinks by up to 30 percent during the subsequent sintering process,” says Professor Koch.

Despite this, he does not want to abandon the material and will instead adapt the printers to the expected loss of volume. But even aside from materials engineering, the 3D printer is full of science across a wide range of disciplines. Project contributor Frank Prechtel describes the mechanical engineering aspect as follows: “The tip of the printing head must be able to move in any direction. There are several concepts for how this can be implemented in mechanical terms. We opted for Cartesian.”

The electro-technical control system drives the guides and spindles. In turn, it receives its information from the software. Their contribution is important. Finally, the printer must also be able to print the object that the designer has planned on the computer. Here, the software acts as intermediary. It breaks the complex 3D model down into machine language and transmits the information. Mathematics is also very important here.

Dentists and hearing aid technicians are already using 3D printing. For example, rows of teeth or auricles can be 3D scanned to produce perfectly fitting tracks or hearing aids. In prosthesis building, on the other hand, it will be some time still until the scan-print method can be used. This is because a huge amount of know-how is required to build a prosthesis. “This is not just to do with ensuring a precise fit, but rather finding the correct contact points between the prosthesis and the stump,” says Professor Koch, adding: “Until that works, there are perhaps still things that have to happen in the field of artificial intelligence.” The simple 3D printing of the correctly planned prosthesis is, on the other hand, quite possible and already being practised.

Robert Conrad
in January 2021

https://leonardo-zentrum.de/visualizing-monsters-workshop/

On 22 January 2020, 12 students from the Helene-Lange-Gymnasium in Fürth visited the AddProKMU project. They were given printing demonstrations and chatted about 3D printers.

On 17 January 2020, 15 students from the Wolfgang Borchert Gymnasium in Langenzenn visited the AddProKMU project to learn about 3D printing in general and the AddProKMU printer specifically.

On 11 December 2019, 20 students from the Geschwister-Scholl-Gymnasium in Röthenbach visited the AddProKMU project to learn about 3D printing in general and the AddProKMU printer specifically.