3D printing inches closer to Holy Grail—series production of plastic parts without injection molds
Ever since 3D printing or additive manufacturing came on the scene about 30 years ago, the Holy Grail for that industry has been series production of plastic parts fast enough and cheap enough to eliminate injection molds and even the molding process. With the announcement at the RAPID 2017 trade show by Stratasys (Eden Prairie, MN) of its Continuous Build 3D Demonstrator process, that goal appears to be on the horizon.
While 3D printing is an ideal process for prototypes—in fact, the technology was known as rapid prototyping for decades—the industry was eager for a way to make mass production, end-use parts a reality. The rapid prototyping name stuck for a long time, which tended to define the process in the minds of those in the engineering and manufacturing communities. Because of the lack of polymers that would allow end-use applications and some other obstacles, prototypes were all the manufacturing community expected from the technology for many years.
Over the past couple of decades, the additive manufacturing appellation more accurately defined the goal of the 3D printing industry—actual manufacturing of end-use parts—and things began to change. As build chambers got larger, the process became more accurate and repeatable and low-cost desktop 3D printers became almost as ubiquitous as fax machines, large manufacturing corporations like GE Aviation took a real interest in what was possible with the technology, driving it to new heights.
Mold manufacturers were—and many still are—slow to pay attention to the possibilities of 3D printing to add value to their activities by printing part iterations and making design changes early in the process to save time and dollars down the road. There were even opportunities to 3D print a core and cavity set and injection mold a few parts to provide mold design information prior to cutting steel. However, with 3D mold design and material flow software such as Moldflow and Moldex 3D, moldmakers never warmed up much to the idea of bringing 3D printing in house.
It was primarily large manufacturers that latched onto the possibilities that 3D printing offered in engineering new components, and before long many corporate engineering departments were filled with desktop 3D printers.
Molders weren’t too hot on the idea of 3D printing, either, and barely took notice of the fact that the 3D printing industry was eager to eliminate tooling and maybe even some injection molding through advances in printer speed, size and cost. That meant that producing pilot molds for part configuration validation and molding a hundred or so test parts wouldn’t be needed anymore. It wouldn’t be long before both moldmakers and molders would be sitting on the outside looking in and perhaps wondering what happened.
Now that Stratasys has demonstrated the capabilities of storing prints in the cloud and having banks of 3D printers spitting out parts—not as fast as an injection molding process, but fast enough and without tooling—disruption is on the horizon.
German RepRap put out a case study at RAPID 2017 that explained how one of its customers in Germany made 40,000 parts in a series production using nine German RepRap machines. Thomas Pazulla, owner of technical services firm TP Technische Dienstleistungen (near Munich, Germany), has purchased three machines per year after buying his first two and seeing the benefits. Today, TP has nine printers in the shop.
Increased demand for series production led TP Technische to accept an order for series manufacturing of 40,000 parts for an automotive client. To achieve this level of manufacturing on time meant that 500 parts had to be manufactured daily. Eight of the 3D printers were essentially running 24/7 to fulfill this order; 16 parts took about 8 hours to print. Each machine printed 16 of these parts simultaneously.
Thus, after eight hours, eight 3D printers finished the job and together delivered 128 parts; that meant 384 parts after a 24-hour shift. Sometimes, the ninth 3D printer was deployed to reach the 500 parts-per-day target. Within four months, 40,000 parts were printed and delivered. The finished product is a part that is glued into the door trim of passenger cars.
The material used was ABS filament from German RepRap, chosen by the customer since ABS has all the required technical properties. One of these properties is resistance to aqueous acids, alkalis, or concentrated hydrochloric and phosphoric acids. ABS allows continuous use at temperatures between -22° and 185° F and does not ignite until a temperature of 752° F is reached.
Mark Neilson, co-owner and co-CEO of In’Tech Industries, is a custom moldmaker and injection molder that entered the rapid manufacturing arena in 2001, and today has a bank of nine Stratasys machines that can spit out 1500 parts per day. In a video made by Stratasys, Neilson remarked that the Continuous Build 3D Demonstrator has helped the company “capture new business for short-run production and for bridging the gap to doing an injection molded product.” This system also gives the company the ability to expand to an unlimited number of machines.
But let’s face it: Will 3D printing truly be a disruptive technology to injection molds and molding? I doubt it. As the technology advances, it can capture some work, such as creating part iterations, test parts and parts for marketing evaluations. It might even be more cost effective for producing low-volume parts than building a mold and molding 1,000 parts, but 3D printing will never replace molds and molding when it comes to high-volume parts.
Additionally, are the polymer end-use parts actually ready for prime time? Are the part dimensions dead-on? Will the parts need post-process finishing, which will add time and cost? Knowing how particular engineers are when it comes to part specifications, can a 3D printer really produce plastic parts that are end-use ready?
3D printing is certainly making headway, particularly in metal printing, and if I were running a machine shop doing CNC metal parts, I’d be a bit worried. It’s a different story when it comes to plastic parts, especially when requirements are in the tens of thousands.