Additive manufacturing (AM) is a compelling complementary manufacturing technology to conventional plastic part production along the entire lifecycle of a product, according to Fabian Krauss, who is now leading the EOS polymer business in North America. EOS (Krailling, Germany) will feature its technology and AM production equipment at K 2019 in booth C 25 in hall 4, when the international plastics and rubber trade show comes to Düsseldorf, Germany, from Oct. 16 to 23.
While polymer additive manufacturing began as a quick way to create part models and prototypes, Krauss noted that it has expanded into low-volume production parts and is now coming into mid- and high-volume production. One example that Krauss provided to PlasticsToday is the mass production of mascara brushes that have reached the “pretty significant volume” of 1.2 million units per month for one customer.
“As part volume increases, the amortization of tooling costs becomes more interesting,” said Krauss. “When you go from hundreds of thousands to millions of components you can amortize your tooling costs over these larger volumes.”
Both AM and injection molding can be used to develop a component and to improve the mold before hard tooling is built. “That’s where we see a change in plastic direct part printing to metal mold making,” explained Krauss. “The sweet spot is to print the mold in plastic and get a few thousand shots using the specified polymer material before going into a metal mold.”
Krauss said that using AM and conventional injection molds and molding allows manufacturers to cover the entire life cycle of a component. Starting with AM for a model or prototype to low-volume production, the evolution reaches mid-volumes and then to high-volume steel production tooling. Finally, the end-of-life component requirements revert back to low volumes for spare parts that are printed directly to meet demand.
While there is a fundamental difference in the processes between AM and injection molding pressure, the quality of the parts are nearly equal. “With AM, you don’t have a heated mold or pressure, and compared to injection molding the part has a short cool-down process,” Krauss explained. “If your part is designed for injection molding in a certain material, you can direct print the part in the same material, but you can re-engineer any part to fit the process and get the same part characteristic with a different solution.”
Krauss confirmed that 3D-printing today is more accurate and results in improved surface features compared with earlier technologies. “If you look at the surface and detail accuracy, we’re getting very close to injection molding accuracy,” he said. “You can still add secondary processes to make improvements to the surface—you will feel a certain haptic in the parts—but for many applications, such as functional components, no post processing is needed. However, for consumer goods that have visually demanding applications, such as eyewear, customers use secondary processes for surface cleaning and polishing. You can tune your printing process for productivity and sacrifice quality, improving the part surface in a second step. It’s really all about engineering the right solution for the right application.”
There are several reasons to use AM instead of injection molding, one of which is to save on tooling costs. If production volumes are too low to amortize the cost of the tooling, direct 3D printing makes economic sense.
Second, you can actually make your part better, as happened with the mascara brush. The application was very demanding, said Krauss, requiring a process with internal channels to hold the mascara and very fine hairs for the brush. 3D printing enabled combining components to reduce the number of parts. “The product might become a bit more expensive, but the process adds value,” said Krauss. “It might cost 20% more to print the part than to mold it, but [the customer] can sell [the product] at twice the price.”
Third, AM is used to keep the product the same but change the supply chain. For example, spare parts are printed on demand, which is ideal for companies in the mobility sector. “The RV industry makes spare parts for 15 to 20 years—beyond the life of the mold or because the mold has been lost,” said Krauss.
“The golden nugget is that you improve the product and the supply chain,” he concluded. “You can give individual consumers the chance to customize their product, such as the interior of the Mini Cooper, and bypass the entire retail chain while providing a superior connection with the customer.”