Additive manufacturing (AM) has a lot to offer the world of production, specifically design freedom and quick fabrication times, among other benefits. However, the technology is not necessarily here to replace traditional technologies, which bring their own advantages to the table.
One startup that has found this to be true is AddiFab, which has developed a method for 3D printing sacrificial molds for use in injection molding (IM). The end result is the potential to combine the benefits of both technologies, possibly changing the way manufacturing is performed overall. Engineering.com spoke to AddiFab US CEO, Carsten Jarfelt, to learn more.
Freeform Injection Molding
IM has become the ideal manufacturing process for producing huge numbers of plastic or metal components, with molten material shot into a metal mold, filling the cavity, cooling and hardening into the final part. AddiFab’s Freeform Injection Molding (FIM) technology disrupts and augments this legacy technique by 3D printing of sacrificial molds for standard IM machines.
FIM uses a digital light processing (DLP) printer system designed in-house to 3D print objects from photoreactive resin. Similar to other DLP technologies, UV light is projected onto the resin, hardening the material layer by layer. And while Jarfelt suggests that the system itself has been designed to deliver highly precise parts in a highly repeatable fashion, the resin formulas are where much of the magic lies.
The material is formulated such that a completed print can be placed into a standard IM machine to produce an instant IM part. 3D-printed parts are designed in a hollow manner so that they can then be filled with the molding material. According to AddiFab, this molding material is limited only to the over 40,000 varieties available with IM—not just plastics, but metals, ceramics and fiber-reinforced materials as well.
When it comes to photopolymers, most 3D printer and resin manufacturers attempt to replicate industrial thermoplastics and silicones. Even when thermoplastics are used, such as in fused deposition modeling, the feedstocks are limited to plastics that have been specially formulated as filaments. This selection is further limited by the capabilities of the printers themselves, with many machines unable to 3D printing with a wide array of high quality aerospace plastics, like polyether ether ketone (PEEK) or similar materials.
“With legacy 3D printing, we’re used to having rubber-like or ABS-like [materials],” Jarfelt said. “We have to trade off the flexibility of 3D printing with the materials available.With FIM, we can do ceramics, metal—any silicone you can think of, with any shore you can think of. We did some light-weighting of a part, redesigning it as a lattice structure.We made it with carbon-filled PEEK that was super strong—actually so strong that we could park a 3.5 ton tractor on it—which we did just for the fun of it.”
Building on the Legacy of Injection Molding
The benefits of using injection molding materials with 3D-printed designs extend beyond the fact that material possibilities are opened far beyond those typically associated with AM. That IM has been in existence for nearly 150 years means that materials made for and parts made with the technology have been subject to significant regulation and standardization. This means that parts made with FIM can be held up to the same standards as those made with IM.
In other words, a medical part made with FIM can bypass some of the hurdles set up by the U.S. Food and Drug Administration for 3D-printed implants and an aerospace part made with FIM won’t need to undergo the same amount of quality testing associated with the major aerospace manufacturers. These advantages translate over to time to market for bureaus that might use a technology like FIM because less time will be required to obtain the proper certifications.
This only adds to the already quick nature of 3D printing itself. Whereas it might take weeks to receive an injection molded part from a service provider, due to the need to first CNC a metal mold based on a CAD design, FIM makes it possible to quickly 3D print a mold and subsequently use IM to create a final part in just a day or two.
In one case study, a client found that FIM was 80 percent faster and 90 percent less expensive than conventional IM. The lead time for FIM totaled 20 days and cost €2,500, compared to a lead time for tooling that totaled 100 days and cost €25,000.
The historical legacy of IM also ensures that users know what their end parts will look like, meaning that it is actually possible to prototype designs using IM and in the same material that will ultimately be used for mass production.
“We literally had a hearing aid company drop by our office and, in two days,we had nine [hearing aid shell] variations in four materials,” Jarfelt said. “That might cost a few thousand dollars to do that, but now they know which they like best because in front of them they had those designs in the actual materials they would use for mass manufacturing.”
Jarfelt also explained that 3D-printed molds can actually be added to existing metal molds to modify products. He used the example of a window frame manufacturer whose product is relatively ordinary except for intricate designs featured in the lower corners of the window. A miniature, 3D-printed mold could be dropped inside of the larger mold for the window frame to handle those complicated features.
For readers already thinking ahead, yes this does mean that it’s possible to perform IM with customization, including spinal implants. “We can literally IM a spine replacement from ceramics at a cost-efficient level without scrapping anything. That wasn’t possible before because you had to use six- or seven-axis CNC,” Jarfelt said.
FIM in the Market
“Our supply chain is very traditional. We don’t want to be the SAP of hardware implementation, where we clear the whole production floor, and install things you’ve never heard of,” Jarfelt said. “These are molds that you print and can send to any IM service in the whole world and get the injection molded part.”
In other words, he sees FIM as a method for fitting into and augmenting the existing IM manufacturing chain, not something to disrupt it. In this way, IM users can begin offering short-run contract manufacturing jobs.
AddiFab—which has offices both in the Copenhagen area of Denmark and in Palo Alto, California—has also just announced an investment from Mitsubishi Chemical Holdings Corporation’s (MCHC’s) U.S. venture arm Diamond Edge Ventures (DEV).
“Our investment in AddiFab reflects MCHC’s dedication to the 3D printing community,” said DEV President Patrick Suel, who has joined the AddiFab Board of Directors. “FIM gives customers the flexibility and speed of 3D printing with the consistency and reliability of injection molding. The industry can now rely on an existing and independent supply chain of existing and proven materials. We have already brought the tried and trusted materials from the DIAKON, KyronMAX, Ketron, Tefabloc and Trexprene into the additive world created by FIM and more will follow as a result of this collaboration.”
FIM is currently available using AddiFab’s ADDLINE AFU5 3D and AFU5-SU1 3D printers, with a subscription to the firm’s resins. While both printers have the same build envelope of 96mm x 54mm x 150 mm, the AFU5-SU1 is automated, featuring up to 72 build planes, automatic build recovery and resin supply. The company claims that it can operate continuously, with errors corrected automatically and without operator intervention. According to the company, the AFU5-SU1 can produce 1,440 hearing aid shells or 10,000 dental crowns.
However, before one might commit to purchasing a machine, AddiFab also offers contract manufacturing services, as well. This has given AddiFab further insight into its own technology and process, allowing them to optimize it further during development.
To learn more about the company, visit the AddiFab website.