Steinbeis team advises injection molding firm on 3D printing in manufacturing
Injection molding is regarded as one of the most important processes in modern mass manufacturing. Not only does it enable large manufacturing volumes of both identical and different parts, the production times are also much faster compared to other methods. Manufacturers use injection molding processes when making the move to series production. Currently, one of the major challenges here is the high cost of producing tools. Tools used in injection-molding require cost-intensive expertise in terms of design, production, testing, and validation. This process can sometimes be extremely protracted, requiring several months until the tool is finished. Introducing new production methods, such as additive manufacturing or 3D printing technology, makes it possible to quickly manufacture parts regardless of their design complexity. The IMAPS Institute for Material Applications & 3D Printing Solutions is a Steinbeis Consulting Center based in Karlsruhe, and conducts research into future solutions in this field.
Despite the relative lack of research into the potential uses of 3D printing, the Steinbeis team is confident that in future, the technology will help engineers to easily overcome challenges in production. The ongoing research is encouraging. A series of promising experiments was recently conducted in which 3D printing technology was used to produce injection mold inserts from polymers. These materials are both affordable and facilitate a relatively simple manufacturing process. This makes producing the mold inserts more cost effective. It also means different design variants of a product can be tested, with the number of repetitions in the development cycle falling significantly.
As most 3D printed mold inserts are made from polymers, the number of potential loading cycles is much lower than in metal inserts due to the polymers’ low mechanical strength and structural stability. One problem that also affects short cycles is that molding processes involving polymer mold materials take longer than those using metal materials. This is primarily due to the polymers’ poor thermal conductivity. Good thermal conductivity ensures that the thermal load that accompanies the melt when it flows into the empty space in the mold dissipates as quickly as possible. This safeguards the solidification and part-forming process, guaranteeing the quality of the parts during the short injection procedure. In order to confront this challenge of handling materials, the IMAPS Steinbeis Consulting Center is cooperating with partners from the 3D printing industry to develop and test new materials. These materials include polymers with high thermal conductivity, such as graphene, carbon nanotubes, graphite and aluminum. Provided they can be 3D printed, these polymer-based compounds will open up new possibilities for other branches of industry beyond injection molding.
The experts at Steinbeis offer their expertise in 3D printing to customers of all sizes and from all sectors. Merkel-Czeschner GmbH, an injection molding firm from the Rhine region near Karlsruhe, is currently battling with the problem of high manufacturing costs for the low-volume parts it produces for one of its customers. The mold inserts are currently processed from aluminum blocks, before being delivered to the injection molding firm by an external workshop. The average delivery time for the inserts is 90 days. These low-volume parts are sometimes elements within a product development cycle in which the design is changed gradually. Operations at the firm are currently constrained due to the delivery times, tool costs, and design variations. To improve this, the project partners designed a mold insert for a certain part (a functional component used as a button in a control system), before manufacturing it from PEEK in a 3D printing process using machinery from Apium Additive Technologies GmbH. PEEK retains its mechanical strength up to 260°C, making it one of the most thermally resistant polymer materials in engineering.
The injection-molded button parts made from various other materials (polyethylene, polystyrene, and polypropylene) all had melting points well below 260°C. One of the greatest challenges in this 3D printing solution is the time it takes to discharge the finished part from the mold. A metal mold insert usually requires 30 seconds from filling to discharge. By contrast, the 3D-printed PEEK insert takes four minutes to discharge the button parts for Merkel-Czeschner’s customers. Although this delay is acceptable for the button parts in this case, the consultants from Steinbeis are aiming to improve the speed of the 3D printing mold insert. One solution currently being researched is to construct channels, hollow spaces, and heat transfer ribs in the mold insert to increase the cooling rate of the melt. This makes it possible to reduce the discharge time for each loading cycle.
The role of the team from the IMAPS Steinbeis Consulting Center is to advise injection molding firm Merkel-Czeschner with help from Apium Additive Technologies. Their current project aims to reduce material input costs, improve process speed, and save on tool production using 3D printing. One approach would be for the injection molding firm to use the 3D printing solution and operate the printer on site to develop and produce its own mold inserts. Since the mold insert contract would not be outsourced to an external service provider, this would help safeguard the confidentiality of their designs. Another promising development is the use of high-temperature polymers like PEEK to produce the mold inserts used in the injection molding procedures involving polyurethane and ABS. The properties of PEEK enable a longer thermal cycle, as well as a much greater mechanical strength than polymeric materials currently in use.
Brando Okolo, Tony Tran-Mai, Anastasia Oranskaja
IMAPS Institute for Material Applications & 3D Printing Solutions (Karlsruhe)