Types of Prototyping
According to the Merriam-Webster dictionary, "rapid" is defined as "marked by a fast rate of motion, activity, succession or occurrence." It's all relative really, but "rapid prototyping," according to the Society of Manufact
uring Engineers, specifically is "used to directly construct 3-D models and end-use products from electronic data." CAD software is used to build fabrications layer by layer in thin cross sections, according to the society.
Stefan Thundal, industry marketing manager at Arcam AB, a Swedish manufacturer of electron beam melting (EBM) systems, prefers to use the phrase "additive manufacturing" instead of "rapid prototyping." Additive manufacturing is the overall process of making a product by adding materials, which results in virtually unlimited freedom in design and little material waste. Arcam itself does not manufacture prototypes, but it does sell the EBM technology, EBM machines, service, support and metal powders. The EBM technology indeed is used for making prototypes, but Arcam's primary market is customers using EBM for production of medical implants. At present, there are five companies in Europe having CE-certified parts on the market produced with Arcam EBM technology. These products are primary and revision hip implants such as acetabular cups and augments, as well as spinal implants. As of today, several thousand EBM manufactured implants have been implanted, Thundal said.
EBM uses a high-power electron beam, instead of a laser, and the entire process is carried out in a vacuum. According to Thundal, there are several benefits of using EBM:
- EBM allows for an extremely fast beam translation as well as changing focus and power. This contributes to the process control and the high build speed of the EBM process.
- The EBM process is carried out in a vacuum, which means the build environment is carefully controlled, reducing issues with oxygen pickup in the powder. This is a requirement for building implants within chemical specifications.
- EBM is a hot process, meaning that the part is kept at an elevated temperature throughout the build. This results in a stress-relieved part when the build is done, avoiding problems such as distortion under or after the build.
"One of the clearest trends seen in both the orthopedic field and industry-wide is an increased interest in additive manufacturing technologies for real production. These production cases usually evolve around parts with complex geometries. The inherent production challenges of such parts create a drive to look for innovative production methods. In the orthopedic field, we have this situation in two obvious areas-patient-specific implants based on CT data, and press fit standard implants with advanced porous materials," Thundal said.
The EBM process is developed for materials most commonly used for orthopedic implants such as Ti6Al4V (Titanium alloy), Ti6Al4V ELI (Titanium alloy), Grade 2 Titanium and CoCr ASTM F75 (CoCrMO alloy). "Also, to the extent the EBM process is used for prototyping, these are the materials most commonly used within the medical field. Since EBM prototypes are often used for design validations and mechanical testing of new implant designs, the material properties need to fulfill the same specs as parts build with traditional methods," he added.
At Orchid Orthopedics Solutions in Holt, Mich., account manager Jonathan Blocker said his firm receives requests for "straight prototyping" and "project prototyping." Straight prototyping is when the OEM sends the contract manufacturer a print and a desired lead time. Project prototyping is when the contract manufacturer also is involved in the development and design for the prototype.
Determining When to Use Rapid Prototyping
Fort Wayne Metals, a company that specializes in medical grade wire and cable in Fort Wayne, Ind., does not use rapid prototyping because the prototype wouldn't show performance, said Rob Mitchell, product engineer. "We just haven't found where it applied to wire or cable," he said. "We do provide a lot of 3-D models to our customers."
FMI Medical Instruments also has not found a need for rapid prototyping-yet. "Having a prototype that is closer to what the final piece will be seems to be more important than a model of something that may be difficult to evaluate. Rapid prototyping machines can offer a model of something, but it doesn't help us when evaluating the eventual manufacturing requirements and costs of manufacturing down the road," said Peter Browne, sales engineer at Madison, Ala.-headquartered FMI Medical Instruments.
Fort Wayne Metals hasn't yet found a purpose for rapid prototyping at its operation, but it does provide a lot of 3-D models to its customers. Photo courtesy of Fort Wayne Metals. |
Some companies, however, have found a use for rapid prototyping. Blocker at Orchid Orthopedic for example, said his firm uses rapid prototyping, specifically the polyjet 3-D printer, during the contract design process. "It helps greatly with concept generation by giving us rapid iterations. In one of our recent projects, we were able to go through five iterations in one day, so that we could get a presentable design by day's end," Blocker said. The company, however, does not have SLS or DMLS technology.
The benefit is that you can have a functioning prototype within a day or even an afternoon, but there are limitations, he said, including tolerance, and finish machining is required. Additionally, Blocker said, if the design transfer process has started, the technologies don't add anything for a production environment. Finally, material limitations exist.
"Typically, we see these rapid technologies more useful for quick concept iterations than for usable prototypes, and that's why we see SLA [stereolithagraphy] more practical than SLS [selective laser stinting] or DMLS [direct metal laser stinting]. The bottom line is, until these technologies are usable for production, medical devices must still be designed for use in a traditional manufacturing environment. As long as this is true, there will always be a place for the prototype shop," Blocker said.
Customer Requests, Economy Linked
Certainly, medical device companies don't have time to be impractical in such a financially challenging global economy. Time to market and communication are essential requirements for today's device firms.
"OEMs are placing even more value on the relationship between themselves and the companies they do prototyping with," said Browne at FMI Medical. He noted that speed is another factor that is very important for customers. "Customers appreciate our ability to go quickly from prototyping to clinical trials and eventually into production," he said.
Browne added that he is seeing increased competition from smaller, non-ISO 13485:2003-certified shops that want to boost their medical business. But that increased competition has created pricing pressures from medical device firms. Brown said he also is seeing fewer product launches from OEMs.
"These smaller shops can offer fast, relatively inexpensive prototypes because they obviously have a much lower overhead than a company dedicated to medical device manufacturing. This offers the OEM quick, relatively inexpensive prototypes," he explained, adding that smaller shops usually don't have the capability to do the production work. He also said larger contract manufacturers look at manufacturing differently-that his company is constantly attempting to find ways to cut costs, such as reducing operations and setups, once the parts are launched.
Blocker at Orchid Orthopedics said he has noticed that OEMs are undertaking more straight prototyping projects themselves.
"If there is straight prototyping work that must be outsourced, meaning there is either no prototype capability or capacity internally, the company with the lowest shop rate will be king. Think of it like a pack of ravenous wolves that haven't been fed (production), or not well, anyway. These are the shops that are losing to the OEMs' push for vendor consolidation, and as a result, they must do what is needed for survival. Is this industry-wide? Yes. Is this new? No," he said.
From a protyping standpoint, it has been business as usual, according to Blocker. Customers still require their design services and testing through prototyping, he said.
Andrew Nield, director of sales and marketing at C5 Medical Werks in Grand Junction, Colo., a manufacturer of ceramic implant components, ceramic joint replacement components and prototype implant components, said the implantable device market has been "incredibly robust" for C5, with business reaching record growth in 2009.
The company manufactures ceramic implants, ceramic replacements and prototype implants.
He said the best way to speed up prototyping is to "machine a small number of ceramic parts in parallel to tooling. This enables proof of concept work to commence prior to the tooling prototypes."
Mitchell at Fort Wayne Metals said the economy has not affected demand, but has compressed timelines. "Customers cannot afford any lead time for their prototypes. The lead time expectations are
An image from the very core of the EBM process. The high-power electronic beam creates a melt pool in the titanium powder bed. Photo courtesy of Arcam AB. |
increased because the customers are running very lean, and may have waited to order until the allowable timeline is too short," he said. Three years ago, customers were comfortable with four to six weeks for a prototype; that same timeframe, however, is discomforting now because many firms-particularly startups-are unsure about the source of their funding.
It may not be purely economic though. There has been turnover with engineers, and budgets have been decreased for development programs, Mitchell said.
Fort Wayne Metals looks at smaller companies as a priority because many eventually get purchased by large OEMs, Mitchell noted. And those OEMs are increasingly looking to outsource development work.
Thundal said that production customers are more hesitant to invest, and some projects have been put on hold until the economy stabilizes. However, he said, "On the other hand, the medical device field has not seen as dramatic a downturn as many other industries. Arcam is doing quite well, and we are very optimistic looking forward."
Future Prototype
So, what would a future prototype look like?
Thundal said he sees processes and technologies becoming developed specifically for production of certain implants, especially knee and hip components.
Browne at FMI Medical Instruments predicts an even further increase in the strengthening of the relationship between contract manufacturers and design engineers at OEMs. "We may even see the customers we 'partner' with at our facility during early prototyping to better understand the parts, how they will be processed and how they will function," he said.
In addition, Browne thinks less costly materials will be used for prototypes. "I think we'll see more 3-D printing by the developers for the initial design phase before the customer contracts a prototype facility to build a metal part for them, to work through the design R&D issues," he added.
Blocker agrees that communication between outsourcing partners and OEMs will become more important. "Technology is great. If it wasn't for technology, I wouldn't have a phone that can do everything but laser sinter a part out of powder. But the technology is there now, the seamless transition of inputs from the OEM to the prototype facility doesn't exist, at least not on a mass scale. Can we get prototypes back in a day? Yes. But how many days did it take to get a quote? Then write the P.O. [purchase order]? Then send over the files? Then hash out all the issues the prototype shop thinks the OEM didn't think of? Yes, that can happen all in a day, but we all can be better at it."
Nield predicts smaller, more complex features. "Ceramic injection molding will be critical for the implantable device manufacturer going forward," he said.
Mitchell said Fort Wayne Metals will continue to develop faster ways of delivering computer models to customers. "The use of parametric design allows for blueprints of design iterations to be generated quickly. We will be adding various types of machinery to make more involved prototype and production parts. Developing short run machining capability for end effectors is a must," he said.
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Rapid prototyping has its place in the medical device realm, but, according to industry experts, it's not always the most practical method to create prototypes. They say, however, that it is beneficial to have the same firm create the prototype and do the eventual manufacturing of the device. Additionally, communication is becoming increasingly important between outsourcing partners and OEMs, especially with the economic downturn and an increased focus on cost-cutting.
Historical Timeline of Rapid Prototyping
1960s: University of Rochester (N.Y.) Engineering professor Herbert Voelcker, who grew up Tonawanda, N.Y., tries to discover a way in which automated machine tools could be programmed by using the output of a design program of a computer.
1970s: Voelcker creates basic tools that describe 3-D aspects and leads to the earliest theories of algorithmic and mathematical theories for solid modeling. These theories form the basis of modern computer programs that are used for designing mechanical items, but old methods for designing were still in use. (The old method called for a machinist or machine tool controlled by a computer. The metal was cut away and the needed part remained as per requirements.)
1987: Carl Deckard, a researcher from the University of Texas, pioneers layer-based manufacturing. He prints 3-D models by using a laser light for fusing metal powder in solid prototypes, one layer at a time.