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Timing Is Critical

Today’s rapid prototyping solutions decrease development turnaround and time to market, thereby increasing OEM client satisfaction.

ECA Medical Instruments uses a dedicated design cell team approach to quickly take its standard products or a customer’s design for an orthopedic instrument or complete surgical procedure kit and develop prototypes and engineering validation test instruments. Photo courtesy of ECA Medical Instruments Inc
Think “rapid prototyping” these days and your mind should fill with thoughts of 3-D printing, direct metal laser sintering (DMLS), selective laser sintering (SLS), stereolithography (SLA) and fused deposition modeling (FDM)—all additive manufacturing technologies that rapidly are transforming prototyping into a same-day service. If, however, your thoughts are about how you can reduce the timeline from eight weeks to six weeks, you have some catching up to do.

Time to market is more critical than ever before in the orthopedic market. OEMs expect their manufacturers to have all the rapid-design and production capabilities they need to meet product launch deadlines. Implant manufacturers continue to experience strong pressure from their customers to shorten development cycles and rapid prototyping is the best tool for accomplishing this task. For example, without the use of rapid prototyping, a component might take up to eight weeks to manufacture instead of eight hours with the rapid prototyping process—a gigantic difference when it comes to timeline.

“There is a big push in the orthopedic market to use rapid prototype processes like 3-D printing and DMLS to gain product solutions more quickly, for testing as well as getting early feedback from customers and/or surgeons,” said Daniel Santos, engineering manager for Pro-Dex Inc., an Irvine, Calif.-based contract manufacturer to the medical device industry. “With the ability to gain early feedback through rapid prototyping, these companies are able to make functional prototypes to help evaluate their products in front of the end users, early in the development process. Rapid prototyping processes have advanced to the point where they can generate products made from materials that are equivalent to the final solution.”

“Rapid prototyping allows us to deliver non-human use, full-functional instruments in weeks instead of months,” added Frank Slauenwhite III, director of engineering and new business development for Holmed Corporation, a South Easton, Mass.-based contract manufacturer for medical device companies. “We can go from advanced CAD concepts directly to functioning parts and/or device, bypassing the traditional method of prototype/development methods, yet still maintain product traceability through date-stamped models and minimal documentation.”

By leveraging rapid prototyping machines with in-house molding capability, manufacturers like Holmed Corporation can manufacture production-level devices in compressed schedules, resulting in faster clinical feedback and faster time to market.

“This also helps our customers secure market position and intellectual property protection first,” said Slauenwhite.

While off-the-shelf products always are desired, an increasing number of medical device OEMs want modified standard or fully customized designs. Form, fit, function, and quality must be engineered into the design quickly, and at the lowest possible cost. “Rapid prototyping is a tremendous productivity tool in the design process and can shave weeks off development time and months off the complete design to production process,” said John Nino, president and CEO of ECA Medical Instruments Inc., a Newbury Park, Calif.-based designer and manufacturer of surgical instruments and kits.

Over the last few years DMLS has come down in price and become accurate enough to possibly even surpass traditional machining of components for one-offs and short-run quantities. With a turnaround time measured in days or hours compared to months, more companies are starting to pay attention to the cost benefits of rapid prototyping.

“For example, the new FDM machine, which is more accurate by a factor of 10, may replace nylon SLS as our standard 3-D mock-up prototyping process,” stated Charles Griswold, project manager for Trinity Orthopedics, a San Diego, Calif.-based fabricator of prototypes and short-run surgical instrument components. “FDM machines themselves have reached a price point where more engineering departments can consider buying or leasing one. Simply bringing in-house two components a month that were previously being outsourced for 3-D printing can pay for the lease of the machine.”

There also is an increasing demand for more end-use materials for low-volume applications that can support clinical trials and U.S. Food and Drug Administration (FDA) approvals. This partially is driven by the fact that many companies are reluctant to invest the capital necessary to move immediately into high-volume production, without knowing if the device will be approved. Also launching with a low-volume approach is faster and less expensive initially.

“The time from concept to market release is very long in the medical device world,” said Jason Bassi, sales executive for Spectrum Plastics Group, a rapid prototyping and production manufacturing company based in Minneapolis, Minn. “With the need for FDA approval, and design verification and validation and process validation all contributing to a longer release cycle, it is not uncommon to see early concepts years before production ever takes place. A lot can happen in that timeframe, including design changes or cancellation of a program. A low-volume approach, either through an additive process or a more traditional manufacturing process such as pre-production molding, can produce the parts for the short term need before making the larger commitment and investment. I think more companies are seeing the value of an FDM, sintered, cast, machined or prototype-molded part as a solution before investing in large capital expenses such as tooling.”

Advances in Technology
Customers want shorter development cycles so that they get products to market faster and beat their competitors. Rapid prototyping gives them this edge by creating design solutions that can be functionally evaluated early in the development process, reducing the overall development cycle.
Griswold notes that companies in the medical device and aerospace industries are using DMLS parts in their finished products.

“It is no longer just a prototype process, it is a production process,” he said. “As a result, 3-D technology is having a noticeable effect on the industries. No longer are shapes designed around casting or machining constraints. Shapes can be more ergonomic and surfaced. Cavities and intricate patterns are becoming more common on parts because rapid prototyping processes can do them out of hand.”

ECA uses a dedicated design cell team approach to quickly take its standard products or a customer’s custom design for an orthopedic instrument or complete surgical procedure kit and develop prototypes and engineering validation test instruments. “We use internal 3-D software such as Solid Works and KeyCreator and finite element analysis (FEA) tools to understand linear and non-linear stress points to help us optimize design and realize productivity gains,” said Nino. “We also use the latest Objet rapid prototyping style 3-D printer for certain product types. In every case we have a documented process that allows us to move rapidly through iterative stages to get the right product that meets demanding torque requirements specifications.”

The rapid prototyping 3-D printer from Israel-based Objet quickly builds representative prototypes from 3-D models. More than 100 materials are available to use for simulating properties ranging from varying grades of rubber to clear transparent glass and engineering plastics, combining high toughness and high-temperature resistance. The Objet printer also can provide “dual shot” capability—that is, it can overlap two computer aided design (CAD) files and print them in different materials, or create a blend of two materials, which is an effective way to simulate overmolding.

Tim Ruffner, vice president of new business development for GPI Prototype & Manufacturing Services Inc., a Lake Bluff, Ill.-based provider of additive manufacturing processes, said that a company called Within provides interesting software that helps with designing acetabular cups for DMLS by creating the porous structure for cups or tibial trays.

The software transforms an existing acetabular cup design into one with a trabecular lattice structure that facilitates osseointegration, which can be generated through additive layer manufacturing. The implant is manufactured from a biocompatible titanium alloy in a single phase using DMLS, with the entire contact surface formed from trabecular lattice. After it is removed from the build plate the part is cleaned and coated with a hydroxylapatite bioabsorbable filler to further stimulate bone growth.
Customers are demanding more fault-tolerant designs that ensure implants and the systems that operate on the implant continue to function, possibly at a slightly reduced level, if a part of the system fails.

“This way the system as a whole is not stopped due to problems either in the hardware or the software, thus avoiding catastrophic failure,” said Reza Sadeghi, chief technology officer for HD Solutions GmbH, a La Jolla, Calif.-based provider of rapid product development and regulatory compliance services. “The implant or the system operating the implant is able to retain its integrity in the presence of damage due to causes such as fatigue, corrosion, manufacturing flaws or impact. Fault-tolerant designs must have a viable alternate load path, both primary and secondary; if the primary fails the system will automatically rely on the alternate load path. Typically the primary has a longer fatigue life and the secondary a shorter one.”

Sadeghi also indicates that rapid prototyping, coupled with physics based modeling and simulation, is an increasing trend as well. Historically designers had to imagine and then use CAD tools to create shapes that support a set of requirements. Math-based optimization methodologies are fast-evolving and becoming easier to use, which allows designers to take full advantage of the exact properties inherent to the materials being used.

“Topology optimization is one of these math-based approaches,” Sadeghi continued. “The material volume is optimized in a given design space for a given set of loads and boundary conditions, so that the resulting layout meets a required set of performance targets. This optimization method is typically used to arrive at a conceptual design level and later fine-tuned for performance and manufacturability. Topology optimization can also be used to obtain the right distribution of material attributes such as thermal expansion coefficient, piezoelectric coefficients and others. The optimization problem is often solved using sequential linear programming.”

Meeting Customer Demands
Spectrum Plastics Group has increased its ability to provide more low-volume solutions in cast urethane and injection molding to meet customer needs, as urethanes increasingly become accepted by industry as an actual production solution.

“In our protogenic division we really look at urethanes as a production work cell, with separate mold-making, casting and finishing operations, similar to what you’d see in an injection molding environment,” said Bassi. “More advanced materials allow us to provide UL-rated materials for flammability, for example. Common applications have been server bezels, medical monitoring enclosures and specialized instrument cases, where quantities range from 200 to 500 sets per year. Many companies offer this process, and for most it’s the more traditional model-making approach. What’s unique is the shift towards a production mentality, where we’re able to provide higher quantities, repeatable dimensions aided by in-process control charts, multiple-threaded insert options, painting, decorating and even material certifications and first articles.”

More designers and engineers have been added to the staff at ECA Medical Instruments to meet customer needs and enter new medical market segments. The company added Objet 3-D capability, which has helped cut the design-to-manufacturability time in half. “This allows us to save cost, increase throughput and efficiency and become more competitive and add value to our customers,” said Nino. “It enables us to accelerate time to market for our customers, as well our company.”

Pro-Dex has purchased a 3-D printing machine to make components early in the development process so it can evaluate the design, both for function and ergonomics. This also allows the manufacturing department to create fixtures and perform design for manufacturability/design for assembly on the initial design concepts.

“A great example of this is the work holdings for assembly purposes,” said Santos. “With the conventional methods of drawings and 3-D models, the components would need to be manufactured to be able to assemble the units. If the design engineer had forgotten a feature to properly hold the components during assembly (for example, flats to be able to torque a component properly), the parts would have to be reworked and the timeline would be affected. Having a physical representation of all the components and the ability to determine assembly methods early on using 3-D printed components eliminates these types of issues.”

Material Advances
New, advanced materials are being developed that are compatible for rapid prototyping. These enhanced abilities to create components in materials that are equivalent to the final product are motivating more companies to use rapid prototyping services.

One of the biggest challenges for rapid prototyping is keeping up with all of the new material requirements from the OEMs. Aluminum 6061 is a good example—DMLS can produce a generic casted aluminum material that works well for representation purposes but does not mimic the Al 6061 material used in the medical industry.

“The DMLS aluminum may have porosity or structural issues that affect the ability of the part to be anodized properly, resulting in some cosmetic and possible dimensional defects,” said Santos. “The process needs to be further developed and refined so that the Al 6061 material can be produced using the DMLS process, instead of using this current casted grade material.”

There also is greater interest in the increasing variety of polymers, alloys and nanocomposites (or combinations of these) for biomaterials applications in the orthopedics industry. MED610 is a new biocompatible material on the market from Objet for 3-D printing. This rigid material, which is transparent and has superior dimensional stability, is ideal for applications that require prolonged skin contact over 30 days or short-term mucosalmembrane contact for up to 24 hours.

Rapid prototyping continues to be a practical approach for identifying the optimal combination of new materials for new implants. “Forward-thinking companies realize that first to market also means right to market,” said Sadeghi. “Therefore they heavily leverage rapid prototyping tools as well as innovation life cycle management tools, such as Accelrys’ Pipeline Pilot, to develop new materials and products.”

Implant manufacturers also are eager to try Ti64, which is getting closer to receiving FDA approval. This material is lightweight, corrosion-resistant and biocompatible with good bioadhesion and high specific strength. “With the advocacy of our customers and the ASTM F-42 committee, hopefully the industry will soon receive FDA clearance for using DMLS Ti64 components in implants,” said Ruffner. “The most recent news is that the American Society for Testing and Materials (ASTM) has adopted the standard of F2792-12a—standard terminology for the powder bed fusion process, which includes DMLS. This means that the Ti64 material used with DMLS is now a standard material listed as F2924.”

An increasing number of DMLS materials are production grade or approaching production grade. “Ti64 is a production-grade material and the nylon for the SLS printer is also production grade,” added Ruffner. “The FDM system also produces production-grade polycarbonate/acrylonitrile butadiene styrene blends.”

Nanotechnology and nanomaterials will continue to have a significant impact on rapid prototyping in the future, including faster innovation in material discovery. “Implants with high stiffness, high temperature resistance, excellent dimensional accuracy and good resistance to moisture can be manufactured using nanocomposites,” said Sadeghi. “One such material is Accura Bluestone, with post-cured tensile modulus of up to 11,000 MPa [megapascals] and a flexural modulus of up to 9,000 MPa—these are remarkable properties.”

Looking Ahead
The biggest short-term challenge for rapid prototyping is cost. Even though it’s a more expensive process, rapid prototyping is far faster than standard machining. For example, making a part via additive manufacturing would cost about 30 percent more than making it with standard machining. But the key question is: How valuable is the time that it saves? Both for you and your client?

“You can machine a part at a lower cost and it will take 12 weeks to arrive, but is that better for your needs compared to paying more and having the part within a week?” GPI Prototype’s Ruffner asked. “And some parts can’t be machined at all, so they must be additively manufactured.”

It also is important to educate the customer, who wants to negotiate the best price but is comparing numbers to traditional methods. “Although additive manufacturing is more expensive, it saves a lot of time, works well for highly geometric shapes, reduces or eliminates high tooling costs and also eliminates the need for assembly,” said Ruffner.

Even with these advantages, rapid prototyping costs still need to come down exponentially to be a viable, workhorse alternative for everyday part demands.

“The auto industry pays pennies for parts, which are made in China or Mexico,” said Griswold. “I see no reason why rapid prototyping machines in this country cannot compete with these outsourced, traditionally manufactured parts. As 3-D printers become more popular and their processes optimized, manufacturing inexpensive, complex parts domestically will be more common across all industries. Speed can be further increased with quoting and ordering automation.”

As costs drop and technologies advance, additive manufacturing equipment will cost less and may eventually be able to build full assemblies from multiple materials.

“By becoming cost-competitive with overseas operations, rapid prototyping will bring more manufacturing jobs back to the United States,” added Griswold. “Engineering and corporate management jobs will follow close behind.”

Nino believes that automation of design and speed to market in the engineering to production process will continue to improve. The linking of design engineers with automation tools—whether it is CAD, FEA, rapid prototyping, or other product life cycle management tools—creates an environment where high-quality products can be built faster and more cost-effectively.

“Price pressures are already setting in, so companies that have the core competencies to quickly take client ideas and designs to market will be successful,” said Nino. “Partnering with firms that have the expertise as well as tools, systems and processes will result in success. This is an exciting time to be an orthopedic products designer, especially for single-procedure devices that are taking hold fast and will, over time, come to dominate the instrument and procedural kit segment.”

Santos, too, thinks rapid prototyping machines gradually will replace more conventional manufacturing methods for production over the next few years, giving companies an ability to use products that have been created solely on a rapid prototype machine. “This is happening in other industries and the medical device industry will also likely move in the same direction,” he said. “This will bring more competitiveness to the market place with faster design cycles and product launches.”

Mark Crawford is a full-time freelance business and marketing/communications writer based in Madison, Wis. He can be reached at

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