3-D Printing in Metal
Has Additive Manufacturing Truly Come of Age?
Although the technology is still shaking out, metal 3-D printers may soon find a place in the aftermarket alongside other machining practices. The machines employ metal powders and lasers to build 3-D parts layer by layer.
Those who recall the 1967 movie “The Graduate” will remember that the word was “plastics.” Plastics were the future, and that future reached a zenith in recent years with additive manufacturing machines that could “print” 3-D objects in shapely polymers. That future is changing, however, because the new industrial buzzword is “metals”—as in the ability to 3-D print them. But has that latest technology truly come of age? And, more importantly, should SEMA members rush to embrace it?
To review, additive manufacturing begins with a CAD file, much like CNC applications. However, where CNC forms parts by cutting or trimming material away, additive manufacturing uses the CAD data to add and laser-fuse material layer upon layer to painstakingly build a part. Because the material’s delivery or laser device often resembles an inkjet printhead, the technology has been dubbed “3-D printing.” Since the machine builds parts from the ground up, there are few limits to their geometry. Intricate shapes, weaves and even interlocking components are all possible with 3-D printing.
The range of materials for 3-D printing has exploded dramatically in recent years. Machines can already diffuse layers of nylons, rubber compounds and a variety of acrylonitrile butadiene styrene (ABS) plastics, sometimes in combination or even multiple colors. In fact, in addition to ABS, multi-colored acrylonitrile styrene acrylate (ASA) plastics are now also commonly employed to create more durable, weather- and UV-resistant end-use parts. Additive manufacturing is also being used to print flexible electronic circuit boards and embed conductive materials such as wires, filament or circuitry into 3-D objects.
As exciting as all that is, 3-D printing is not presently considered a feasible or economical means of large-scale mass production. While some manufacturers or customizers may print small end-use parts on demand or in limited runs, the technology’s greatest value to industry lays in rapid prototyping and the creation of molds, forms and specialized tooling. For those and other research and development applications, 3-D printing has proven nothing short of revolutionary, significantly cutting the time and costs of conceptualizing and prototyping parts and even lowering barriers of entry for small and startup innovators. The emerging ability to 3-D print in metals adds a whole new dimension to that already high-tech trend.
“Plastic 3-D printing is still a lot more affordable than printing in metal,” explained SEMA Mechanical Engineer Luis Morales. “And plastic will serve great for a hands-on prototype for fitment, making sure that everything is where it’s supposed to be and that there’s nothing in the way of getting a tool in to the part. That said, going into metal 3-D printing is better for actual testing, fatigue analysis and other applications where you need properties of metal such as strength, heat capacity and resistance to certain fluids such as gasoline or diesel fuels—things that plastic can’t hold up to. Plastics can tolerate electricity or some fluids, and some are more heat-resistant, but they aren’t good all-in-one prototypes. A metal 3-D printed part can combine all of those attributes, but the development is still ongoing.”
“One of the things we’ve found is that there are many companies coming to market with 3-D metal printing machines, but technologically speaking, many are not quite there yet, whether it’s the actual machine or the materials,” noted SEMA Senior Director of OE Relations Warren Kosikov, who oversees the SEMA Garage’s explorations of the emerging technology. “Without getting too carried away by the hype, we want SEMA members to know that we’re closely studying the technology for our members. We’re in touch with the various manufacturers and are reaching out to members to see what their needs might be. Factors such as strength and tolerances are going to be key to our industry’s needs. What I’ve been telling folks is that we have to get past ‘cool to have’ and get to ‘need to have.’ We’re sold on the idea of it but not on all the applications or executions yet. Our industry needs to understand that manufacturers are still developing those machines and getting them into the public arena.”
A worker pours metal powder into the chamber of a laser sintering machine. Today’s printers can already work with aluminum, titanium, nickel, stainless steel and a variety of alloys.
Surveying the Technology
In concert with SEMA’s Emerging Trends & Technology Network, Kosikov and Morales have conducted deep research into metal additive manufacturing. Their investigations took them first to last year’s Consumer Electronics Show in Las Vegas and then to the more recent International Machining Technology Show (ITMS) in Chicago, where they identified roughly 50 companies manufacturing metal 3-D printers.
“It really was an eye opener, because we found that the term metal 3-D printing is wide ranging,” Kosikov said. “There are different technologies, different manufacturers and different results. In one case, we discovered a company that uses materials that can’t even be brought into California. However, with those companies and printers in various stages of development, there are not that many now that we would recommend for our industry’s needs.
“What was really cool to see at the trade shows is that you not only have companies specifically dedicated to making 3-D metal printing machines, but you also have other companies such as Hewlett Packard and General Electric starting to make them,” said Morales. “They weren’t into 3-D printing at all a few years ago, but they see this growing as a technology, and they want to be onboard. There’s a race right now, and the prices are high because of research and development. Will they come down? There’s absolutely reason to believe they will.”
The spectrum of machines currently falls into three price tiers: $150,000-plus, $600,000-plus, and $1 million-plus. Not surprisingly, those tiers represent good, better and best.
“The basic question that a consumer will always ask is how a metal 3-D printed part compares to a raw, machined part,” Morales observed. “That answer varies from system to system, but in general, a metal 3-D printed part is most comparable to a cast part in terms of strength and integrity. While some metal 3-D printed parts carry compatible material and strength properties to machined parts, the weakest points of 3-D printed metal items are their fracture points and fatigue. That means they will only deform to a certain point and may not be ideal for multi-cycle applications.”
However, Morales is quick to add that every form of manufacturing from CNC machining and casting to cutting and welding has its limitations, which generally relate to the materials or geometries of the finished parts. As of now, metal additive manufacturing systems can print in aluminum, titanium, nickel and maraging alloys as well as stainless steels, with the technologies breaking down as follows:
1. FDM Style
This type of system is very similar to the traditional fused deposition modeling (FDM) plastic 3-D printer. Metal-printing FDM systems utilize three separate stations/units to complete a project: print, debind and sinter. The final sinter stage is the critical point, as it shrinks the part down to final size while reducing pore size. The sinter station is what limits the FDM printing envelope to less than 10x10x10 in. (Basically, the larger the size, the more inaccurate the sinter process.) Because FDM is a three-stage process with a smaller printing envelope, FDM systems are more affordable, usually averaging $150,000. While there is nothing wrong with these systems, they are seen as a stepping stone or initial step into the world of metal 3-D printing.
2. Metal Powder Beds
As their name implies, these systems use a bed of metal powder in conjunction with one or more lasers to fuse layer upon layer of metal. The process essentially melts the layers of metal powder together. With print envelopes averaging approximately 11x11x16 in., the build regions of these all-in-one systems are purged with argon gas to displace oxygen. And while these systems deliver the highest density and purest type of metal bonding in the market, they’re among the most expensive to purchase.
Metal 3-D printers can produce parts with complex geometries and could well lead to revolutionary new designs for parts whose current designs are limited by traditional machining.
3. Direct Metal Deposition
This technique accurately releases the metal powder and a laser through separate ports, depositing and fusing the material onto the machine’s base/bed. Behaving similar to welders, these systems boast a major advantage: They can build multi-material parts in a single print. For example, they can produce a half-aluminum, half-steel single part. Some of these machines can also pair with a CNC machine head for post-processing, making them truly all in one. Unfortunately, due to the nature of this process and the complex geometry and the surface finishing involved, such systems are not likely applicable for most specialty-equipment industry uses.
“Some forms of metal 3-D printing have been around for years, but the precision and technique of these new machines are what make them stand out,” Morales said. “In engineering, the step from designing to manufacturing has always been dependent on the manufacturing capabilities and limitations. In other words, not everything that one designs can actually be created. These new machines offer a solution to that problem. With this technology, assemblies can be simplified, complex geometry is achievable, weight can be reduced and topology optimization is no longer just an idea.”
According to Kosikov, metal additive manufacturing is also spreading quickly within the automotive sector—with a number of interesting applications.
“At ITMS, there were multiple metal 3-D printing manufacturers demonstrating work they’re doing for tire companies,” he said. “It was interesting because they could metal 3-D print a tire tread, use it as a mold, make a prototype tire, test it and make any quick changes required before going into full production. So the technology clearly offers a number of benefits for creating molds and tooling.”
Matt Shock, executive director of operations for AddUp, an international supplier of metal 3-D printing technologies, said that current opportunities for the automotive industry are surprisingly wide-ranging. The list includes high-performance parts for racing; prestige, customization, luxury elements and badges; short-run vehicles or special options; prototype and development components; tooling such as a Michelin 3-D sipe tool application; assembly and manufacturing jigs and fixtures; and on-demand spare parts for the aftermarket, especially those now emerging in the antiques and classics segment.
“As metal 3-D printing machine speeds continue to increase, automation is becoming available, and more printable materials continue to be developed,” Shock explained. “In addition, engineers are learning how to design for additive manufacturing—a crucial skill set required to successfully adopt and apply the technology. As that trend continues, metal 3-D printing will begin to play a part in mass production for automotive components targeted and designed to take advantage of the benefits of the technology.”
As applications specialist for SLM Solutions, a Michigan-based machine and powder-bed metal 3-D printer provider, Kyle Adams has an extensive automotive background, including automotive benchmarking, reverse engineering of powertrain systems, and a number of personal project builds. He similarly believes that while technology is developing and costly now, its presence in the automotive sector will only grow.
“Where technology currently is—its general cost for the parts and the speed involved in production—we’re looking at [applications] for the BMW i8, the Bugatti and a few other vehicles that are using this technology in production of vehicles numbering about a couple hundred a year at most,” he said. “As far as mass-produced vehicles, GM is just getting into seatbelt brackets out of metal powder bed, which is really the first use of the technology in the mass production of vehicles. We still need to reach a more cost beneficial point to put it into everyday vehicles.”
Still, he said, metal 3-D printers could easily find a home in the aftermarket.
“A place like Jay Leno’s shop would be a phenomenal place to put a metal 3-D printer, because we’re talking about parts that were hand-designed 80 years ago, and the best you can do is reverse engineer them and 3-D print them,” he said. “Also, the high-end automotive aftermarket would be a really good fit as well, because the cost of the pieces going in are so high that switching over to additive manufacturing doesn’t really increase the cost all that much.”
Adams said that the technology is further ripe for the production of specialty tubing and connectors for exhaust and other systems that are normally hand welded. He likewise foresees metal 3-D printing revolutionizing numerous component designs for higher performance.
“Turbo housings, for example, get super hot,” he said. “If we could introduce some thermal cooling throughout the housing, we could not only get the turbo to run cooler but also increase the life of the turbo and get performance increases through a nontraditional design that’s conceptualized for the additive process.”
Accessing the Technology
While metal 3-D printers are not just for large companies anymore, businesses considering adding them to their shops or outsourcing to an additive supplier will want to carefully weigh costs against benefits, among many other factors. Mainstream suppliers such as SLM Solutions and AddUp are experienced in providing such guidance.
“There is a lot to consider for successfully adopting a metal additive machine or process,” Adams said. “Our engineering team is available to help companies small and large identify where metal additive manufacturing could benefit their business. After the opportunities are identified, our experts assist in the steps required to achieve success with the technology, including design for additive, consulting on health, safety and environmental considerations, materials selection, developing robust and economical print strategies, and post-process heat treatments, machining and metrology.”
|3-D Printing at the SEMA Garage|
The SEMA Garage maintains a state-of-the-art Stratasys 450MC 3-D printer for exclusive SEMA-member use. The unit aids in rapid prototyping and “printing” physical models of products that you can see, touch and test, eliminating costly changes before taking them to production. The printer has a build envelope of 16x14x16 in. and the capability to print in eight different materials with an achievable accuracy of +/- .005-in.
In addition, SEMA Garage staff engineers can work with your 3-D digital part files to control the look, strength and precision of your part, as well as the time, expense and overall efficiency of the print process. They can also assist in printing and combining multiple segments for parts that exceed the print envelope.
For example, popular car builder and “Skidmarks Show” podcaster Jeff Allen recently turned to the SEMA Garage to print a rear spoiler for a ’62 Volvo Amazon project. Boasting a full Corvette chassis and a Lingenfelter engine, the car debuted in the Shell/Pennzoil booth at the 2018 SEMA Show and is slated for auction through Barrett Jackson to benefit the SEMA scholarships program. The SEMA Garage laser scanned the rear of the vehicle to help create a CAD design for the spoiler, which was then printed in two pieces. The pieces were ultimately assembled and added to the Volvo.
SEMA’s 3-D plastic printing is priced at $15 per cu. in., although rates may vary based upon material types. For quotes or further information about rates, scheduling or material, email email@example.com
The SEMA Garage currently owns and operates a Stratasys 450MC plastic 3-D printer for SEMA-member use at the association headquarters in Diamond Bar, California (see sidebar). However, for now the facility will hold off on adding a metal printer until the technology more fully shakes out.
“The association will continue to monitor developments. When it’s time and the right technology is available and priced at a justifiable point, the SEMA Garage may add the capabilities,” explained Kosikov. “Until SEMA makes that decision, we are happy to serve as an information resource for members who want to explore outside metal 3-D printing options.”
“For the right price, these machines could someday become a designer’s wish come true,” Morales added. “There are certain designs and projects where using a CNC may be easier and faster, but the best part of metal 3-D printing is that you can create a one-off product, very similar to your final product, without all the tooling and production costs. One thing is certain: We see the evolution of this technology developing rapidly, and the potential applications will be endless.”