Rapid shift: Medical Manufacturing

Courtesy of Solid Concepts

Sample parts made via direct metal laser sintering.

3D printing poised to turn prototyping on its head.

Engineers and product designers have more rapid prototyping choices than an aficionado at an art fair. Stereolithography (SLA), selective laser sintering (SLS), fused deposition modeling (FDM) and direct metal laser sintering (DMLS) are but some of the available additive manufacturing (AM) technologies, which cover a range of materials from nylon, polycarbonate, PEEK (polyether ether ketone) and polypropylene to aluminum, cobalt chrome and titanium.

Say you want to develop the latest and greatest garden gnome. For $600 or so you can log in to your Amazon account, order a 3D desktop printer and be creatingyard ornaments from ABS (acrylonitrile-butadiene-styrene) in no time. But if you’re planning to build a stainless steel army of those cute little dwarves, you’d better have some serious cash in the bank—a metal-capable machine easily costs $750,000.

If you’re not a do-it-yourselfer, there are plenty of service bureaus and specialty shops willing to build whatever design you have up your sleeve. Simply upload a CAD file to one of the many prototyping Web sites, enter credit card information and your latest brainchild will appear on your doorstep a few days later.

Goodbye Old School

It wasn’t always this way. Before 3D printers were developed, having a prototype made was a straightforward process—design the part, send the drawing out for a couple of quotes and award some lucky machine shop a purchase order. Depending on the part complexity, raw material lead time and the preferred vendor’s backlog, your shiny new prototype might arrive in a month or two.

A slow avalanche of change began in the mid-1980s when 3D Systems delivered the first SLA systems. The lure of shorter product development cycles was intriguing, but those early machines cost upwards of $350,000 and were able to manufacture parts from but a few flavors of photopolymer, thus limiting their functionality to foundry patterns and visualization for high-end product development.

As a result, SLA had little impact on machine shops, and traditional prototyping continued unabated for a few years more. Enter FDM, an AM technology that became increasingly prevalent during the early 1990s, one that offered a broader range of materials than SLA and a price tag within the reach of many capital equipment budgets. Still, machine shops had little cause to worry. After all, additive manufacturing was limited to plastic, and everyone knew that prototyping of functional metal parts would always require machining centers, lathes and EDM. Think again.

Big Changes Coming

Over the past few years, the metalworking industry has begun to experience a paradigm shift. DMLS and SLM have been under development even longer than plastic printing, but it wasn’t until recently that these metal-capable technologies became a viable alternative to machined prototypes. At the same time, the AM industry has seen increased consolidation of small prototype houses into “superbureaus,” with hundreds of machines nationwide. Never has the design community had so many choices for prototyping and low-volume production.

One of these is RedEye, a division of AM equipment manufacturer Stratasys Ltd. Product Manager Tim Thellin explained that the RedEye facility in Eden Prairie, Minn., has more than 80 FDM systems, with another 80 or so in operation worldwide. “There’s great interest in 3D printing,” he said. “We work with a number of industries, including automotive, aerospace, medical and defense. Together with our partner facilities, we can manufacture parts for most anyone, out of every thermoplastic material that FDM can produce.”

Courtesy of Linear Mold & Engineering

Linear Mold & Engineering performs maintenance work on an EOS DMLS machine.

Most of RedEye’s orders are still low volume, yet quantities have been on the rise as machines get larger and capacity has been added to support higher volume projects —production runs of 1,000 pieces or more are not unusual. According to Thellin, for anyone who needs engineering-grade plastic components with tolerances no tighter than ±0.005 ” (±0.127mm), FDM is an excellent choice.

Thellin said it’s unlikely AM will be used to crank out millions of the same part, at least not in the foreseeable future. He maintains that AM should be considered a complement to traditional manufacturing processes, not a replacement. This is especially true with metal components. “DMLS is still nowhere near as accurate as machining and typically requires secondary finishing operations.”

Do Me a Solid

The DMLS arm of RedEye is Solid Concepts Inc. That’s not to say the company works exclusively with metal-based AM, however. Project Manager Chuck Alexander said the Valencia, Calif.-based firm is technology-agnostic, utilizing whatever is needed. This includes the full gamut of AM machines, as well as CNC machining and injection molding equipment.

Courtesy of Pro CNC

Endmilling on a gantry-style machining center is one of the final manufacturing steps for this aluminum prototype.

Alexander warned that the manufacturing industry as a whole needs an education on AM’s capabilities. “The disruptive effect additive manufacturing has had on the market is based on how it changes the design process,” he said. “We’re just now starting with a generation of engineers somewhat familiar with additive and 3D printing and what it can do, but we still haven’t even scratched the surface of its potential. AM allows you to do things that you simply can’t do with traditional manufacturing methods.”

Nonetheless, there are some things traditional machining can do that additive manufacturing can’t, Alexander added. “For most applications, we see DMLS as a way to quickly achieve near-net shape, then use CNC machines to attain high-grade surface finishes, close-tolerance holes and precise feature locations. From an accuracy perspective, I compare AM to a precision casting process, where secondary operations are required for critical surfaces.”

Shopping Around

Someone who needs no education on AM’s capabilities is Steve Upton, president of Schmit Prototypes, Menomonie, Wis. Aside from the shop’s 18 CNC machines, there are also two SLA systems, an FDM and an Objet—a PolyJet 3D printer that operates much like a typical inkjet printer. Despite the shop’s large investment in AM equipment, much of the work done on those machines is internal, producing master patterns to create silicone molds for casting urethane parts. While Upton said that’s been the case for years, he noted that customer requests for rapidly built visual models (finished and painted or with only a light finish) have increased sharply. “Using new resins that mimic ABS or polypropylene, many parts that would have required machining before can now be built faster and with less cost via AM.”

Upton pointed out that the machine shop is quite busy, but rapid prototyping is becoming an increasingly competitive market, at least as far as AM-produced parts are concerned. “There are service bureaus with hundreds of machines. This tends to bring the profit margins down quite a bit, so we focus on more complex work and support the prototyping needs of customers with whom we have long-term relationships.”

Courtesy of Pro CNC

Complex prototypes like this require multiple machining operations, fixtures and CAM programs.

Courtesy of Solid Concepts

An impeller wheel is made via DMLS by Solid Concepts from cobalt chrome molybdenum.

Upton’s not alone. Hybrid job shops—those that have picked up a 3D printer or two in hopes of augmenting their existing CNC services with low-cost prototyping—may find it difficult to adjust to this new business model.