Sometimes layering can take a long time — as in millions of years. Take rocks. They’re stacked in layers containing fossils, with the oldest fossils at the deepest layers and the most recent near the top. For scientists and...
February 20, 2014 by Canadian Plastics
Sometimes layering can take a long time — as in millions of years. Take rocks. They’re stacked in layers containing fossils, with the oldest fossils at the deepest layers and the most recent near the top. For scientists and archeologists, it can yield a great snapshot of the Earth’s timeline, but don’t hold your breath waiting for that layering to occur.
Here’s a better way of layering, at least for the manufacturing world: 3D printing (also called additive manufacturing), a process that builds layers to create a three-dimensional solid object from a digital model. To print a 3D object, virtual models from CAD or animation modeling software are taken and “sliced” into digital cross-sections for the 3D machine to successively use as a guideline for printing. During the print process, the 3D printer starts at the bottom of the design and builds up successive layers of material until the object is finished. One big advantage of this technique is its ability to create almost any shape or geometric feature.
It’s not exactly a new technology — the first 3D printer dates back to the mid-1980s — but the cost of 3D printing in the past was expensive and the process tended to be only used by large corporations. The recent development of smaller printers (desktops, even) has made the technology more affordable and accessible to small and mid-sized businesses, however. The result has been as revolutionary for parts makers as the discovery of the first dinosaur fossil was for archeologists way back when. Today, 3D printers are used to create anything from a new toy or motorcycle part to manufacturing prototypes for testing purposes and small-scale commercial production runs. “Before 3D printers existed, creating a prototype was time-consuming, expensive, and required skilled workers and specific machinery,” said James Janeteas, president of additive manufacturer Cimetrix Solutions Inc. “Instead of sending modeling instructions to a production company, advances in 3D printing are allowing businesses to in-source prototype production on a regular basis.”
PERFORMING WITH PLASTICS
While 3D printing technology is used for both prototyping and distributed manufacturing for a wide range of applications — architecture, construction, engineering, fashion, footwear, and jewelry industries, to name a few — it’s particularly well-suited for plastics processing, and seems poised to catch on like wildfire. A January 2014 study by market research firm The Freedonia Group projects that world demand for 3D printing will rise by more than 20 per cent per year between now and 2017, with plastics — in particular ABS, PLA, and nylon — accounting for the majority of materials demand.
Small wonder, then, that machinery makers are already on board. Arburg Inc. threw its hat into the ring in late 2013, for example, with its new Freeformer additive manufacturing system that produces parts using liquid droplets from standard resins, including engineering resins. “Arburg recognized the potential offered by 3D printing many years ago, and it’s not an exaggeration to say that the market is now demanding it,” said Dr. Oliver Kessling, Arburg’s department manager, plastic freeforming. “The Freeformer processes standard — and therefore low-price — plastic granulates such as ABS, PC, PA or TPE. Further materials are possible, depending on the process parameters, and will be specified together with the customers.”
So why, exactly, is the market demanding it? For one thing, 3D printing is a mold-free manufacturing process, thereby doing away with the time, expense, and potential hassles involved in developing mold tooling. Enough said.
Second, the technology can be used by any halfway modern plastics processor. “Any molder making plastic parts with 3D CAD software — of any make, from any vendor — as their source is a good potential user of additive manufacturing,” said Doug Angus-Lee, rapid prototype account manager for 3D printing with Javelin Technologies. “Construction of a model with contemporary methods can take anywhere from several hours to several days, depending on the method used and the size and complexity of the model. Additive systems can typically reduce this time to a few hours. And while traditional techniques like injection molding can be less expensive for manufacturing polymer products in high quantities, additive manufacturing can be faster, more flexible, and less expensive when producing parts on an individual basis or in a small series, whether for short runs, to prove out a part, to get customer approval on a part prototype, or to produce a part to help support tool design.”
Moldmaker Compact Mould Ltd. currently uses two 3D printers to satisfy these last two demands. “We use additive manufacturing to help our clients develop their products,” said executive vice president Gaston Petrucci. “Some products can be proved from a drawing or from an image that can be rotated on a computer screen, but more and more customers want a prototype they can hold in their hands without having to invest in the tooling to create it. We manufacture bottle prototypes that our customers can use to get approval from their own customers for large-scale production with a full production mold. It’s a complement to our main business at present, but one that’s becoming increasingly popular.”
On a related note, it’s a little known fact that the molds themselves can be created with 3D printing — although these should be used sparingly. “Molds formed by additive manufacturing aren’t going to replace steel or aluminum molds, because you’re not going to get 10,000 parts from them, but they’re useful for making 20 or 50 good parts for prototyping, in that the mold cost is much less than cutting it from steel and the turnaround time is much faster,” said Doug Angus-Lee. “Because of the heat and pressure that the mold has to tolerate, we use a non-porous, digital ABS-like material that has good heat and pressure properties for 3D-printed molds. A sturdier alternative is combining a steel or an aluminum mold base with 3D-printed mold inserts.”
Getting back to the production of plastic parts, another advantage of 3D printing is that, in addition to eliminating the mold, it removes a problem that has bedeviled traditional plastics processing since forever: post-mold warping and/or shrinkage. “Because the plastics material is applied in controlled layers rather than injected all at once, additive manufacturing doesn’t encounter issues relating to warping and shrinkage,” said James Janeteas. “The build envelope in a 3D printer is a precisely controlled temperature environment that creates a very stable part. Accuracy is to within one thousandth of an inch, and the finished part stays that way.”
Additionally, some additive manufacturing techniques are capable of using multiple materials in the course of constructing parts; some are able to print in multiple colors and color combinations simultaneously; and some also utilize supports when building. “Supports are removable or dissolvable upon completion of the print, and are used to support overhanging features during construction,” Janeteas said.
Nor is part size an insurmountable hurdle. “There isn’t always one additive manufacturing machine that’s large enough to produce a single, solid part, but it’s customary in our industry to break down the large assembly,” Janeteas said. “To produce an automotive fascia, for example, the molder breaks the CAD file into segments, 3D prints those segments, and then bonds them together with adhesives and/or mechanical fasteners.”
Finally, don’t be surprised if your design team develops a serious crush. “3D p
rinters make the jobs of designers and part concept teams much easier by allowing them to validate, support, and prove out concepts very early on, using a desktop printer,” said Doug Angus-Lee. “It allows them to design better products, period.”
All of which isn’t to say the technology is perfect, or perfect for every manufacturing scenario. One current handicap involves at least some of these same part designers. “Additive manufacturing removes all of the restrictions and limitations that designers have lived with for decades — they can now do anything they want, but some have a hard time accepting that,” said James Janeteas. “Frankly, some designers don’t know how to design for additive manufacturing, and this remains one of the industry’s challenges. Hopefully, as future generations of designers graduate and enter the workforce, they’ll be better prepared to understand and use the technology.”
And as you’ve probably guessed by now, both fast and large-scale part making are non-starters. “3D printing is not efficient for making large quantities of parts, or for rapid part production,” said Doug Angus-Lee. “The cycle times are obviously much longer than with injection molding — up to 12 hours for a single part, running overnight.”
Materials remain problematic, as well. “The industry is limited to a certain palette of materials that we can print in, so we can’t do everything that every customer wants — we can’t print in Delrin, for example,” Angus-Lee continued. “For simple part prototyping, however, we can usually create a material that will satisfactorily mimic an end-use material, and the palette range is always expanding.”
In the end, you can bet a 3D-printed house on one thing: We’ve barely scratched the technology’s surface. “The bulk of what has been done with 3D printing to date has been in finding ways of replicating traditional ways of manufacturing traditional products in a more efficient fashion,” Angus-Lee said. “Its real potential lies in doing things that can’t be done through traditional means.”
And we won’t have to wait millions of years to find out what they are.