Victory to the Quick

A Ti64 plate and stainless screws made with DMLS. The clear urethane casted “bone” is patient-specific based on CT scanning technology. Photo courtesy of GPI Prototype & Manufacturing Services Inc.


It’s all about speed, because speed is all about cost. Faster prototyping and production mean lower operational costs. Faster prototyping and production also mean faster time to market, which improves market share and generates higher revenues. Even though it’s a pretty simple formula, it’s not easy to achieve—which is why medical device manufacturers and their suppliers continually look for new ways (both technological and non-technological) to cut prototyping and production costs.

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“That’s why early engagement in the product life cycle has become increasingly important,” said Kern Bhugra, president of JunoPacific, a provider of medical device product engineering, prototype and production molding and assembly services with offices in San Francisco, Calif., and Minneapolis, Minn. “We often get engaged early in product development or even the concept stage so we can help develop the product to the client’s functional and aesthetic specifications, with sensitivity to their volume and cost requirements, as well as their prototyping and production needs. This early engagement and partnership also accelerates the speed with which our customers can bring their products to market—an increasingly important factor in the competitive and cost-conscious medical device marketplace.”

Prototyping is a critical step in determining the manufacturability of the final product.

“Prototyping must be designed and developed with production in mind,” added Rudy Pavlik, product development manager for ASI, a Millersburg, Pa.-based contract manufacturer of OEM healthcare products and single-use systems. “Prototypes can at first seem like a perfect solution to what a medical device supplier needs to accomplish; however, if the end product is difficult to manufacture, or requires later changes, it’s no longer a perfect solution. Working in tandem with the customer’s engineering and production teams is essential for creating a process that supports their vision and achieves their objectives.”

Early engagement and input, combined with advanced manufacturing methods, can result in the rapid transition from drawings and models to fully functional prototypes—sometimes within a single day. Such quick turnaround is the result of a deep understanding of the prototype/production process combined with access to cutting-edge additive manufacturing technologies, such as 3-D printing or direct metal laser sintering (DMLS).

Three-dimensional (3-D) printing, for example, traditionally has been used for rapid prototyping for medical devices. However, recent applications are proving that 3-D printing technologies can be used for additive manufacturing of medical components such as femoral trials using DMLS, acetabular cups using DMLS or electron beam melting (EBM) or magnetic resonance imaging scan data for custom patient-specific surgical guides using selective laser sintering (SLS).

“Recently we have noticed a big increase in custom surgical devices,” said Tim Ruffner, vice president of new business development and marketing manager for Lake Bluff, Ill.-based GPI Prototype & Manufacturing Services Inc., which specializes in rapid prototyping and additive manufacturing.
“Typically the surgeon will work directly with a design firm that can create 3-D CAD (computer-aided design) models directly from the surgeon’s sketches. At that point, GPI can then build the device using stereolithography (SLA) to verify design. The surgeon can then approve or make changes to the
design. Following approval from the design, GPI builds the part directly from the 3-D CAD data in stainless steel using the DMLS process. In some cases the parts may need to be milled to a specific tolerance and/or finish prior to sterilization.”

Advances in Additive Manufacturing
Wohlers Associates Inc., an independent consulting firm that tracks rapid product development and additive manufacturing (AM), recently announced that the compound annual growth rate for the additive manufacturing industry was 29.4 percent in 2011 and is expected to grow at a double-digit rate over the next several years.

Additive manufacturing combines powdered materials to make solid objects from 3-D model data, usually layer upon layer, as compared to standard subtractive manufacturing methodologies. Additive manufacturing is used to build prototypes, tooling components and production parts in plastic, metal and composite materials. Thin layers that represent horizontal cross sections of the part are built up using CAD, 3-D scanning or medical scanner data to produce a solid object that often is difficult or impossible to produce any other way because of its geometry or complexity. DMLS, probably the most popular additive metal technology, builds the part or prototype directly from 3-D CAD files. The technology takes a CAD file and slices the object into thin 20-micron (.0007 inches) or 40-micron (.0015 inches) layers. The machine then uses those layers to build the part using a 200-watt fiber optic laser. This locally melts each metal powder layer onto the previous layer, eliminating the need for a binder. The result is a fully dense metal part.

“Typical tolerances for DMLS are 0.005 inches on the first inch and an additional 0.002 inches each inch thereafter, but with some fine‐tuning the machines are capable of tighter tolerances,” said Ruffner. “DMLS materials are made from wrought metal that’s been water- or gas-atomized into a fine powder. They are almost identical to current alloys on the market. Most DMLS materials meet or exceed ASTM standards.”

The American Society for Testing and Materials (ASTM) recently announced a new additive manufacturing standard for Titanium-6 Aluminum-4 Vanadium using powder-bed fusion. This 3-D printing process uses electron beams and laser beams to fuse polymer and metal powders in a powder bed to “grow” engineered parts.

“Currently, powder-bed fusion processes can economically replace traditional manufacturing techniques for engineered components that are highly complex or designed to be built via additive manufacturing,” said Shane Collins, managing director of directed manufacturing for ASTM. “The new standard—ASTM F2924—provides the framework whereby the powder bed fusion materials and processes can be controlled and monitored in such a way that satisfies the requirements of safety and performance critical components.”

Collins said that ASTM F2924 first would be used by engineers designing high-value products such as human implants and aerospace components. However, as speed increases and the price of additive manufactured components decreases, the standard will be used by a wider audience for a variety of titanium parts, especially for automotive applications and consumer goods.

“This is great news for the medical industry because we are moving toward additive manufacturing for medical implants,” added Ruffner.

Additive technologies also are used to make porous surfaces to help increase bone growth. Both DMLS and EBM technologies can create pore sizes optimal for bone growth using random or uniform cells. This advancement can eliminate the need for secondary coating or manufacturing processes, as well as quickly create patient-specific, custom-made implants. At present, the U.S. Food and Drug Administration has not approved DMLS or EBM components for implants; however, the technologies can be used to create products in the research and development (R&D) stage or as prototypes.
An increasing challenge for prototyping and production is validating the process and/or educating the engineer on materials that are best suited for the OEM’s needs.

“With all the recent advancements in additive manufacturing, there could be hundreds of material and finish choices for any application,” said Ruffner. “Each AM process has its benefits and its limitations.”
For example, he pointed out that fused-deposition modeling works well for thermoplastic materials but may not be the best for surface finishes. Polyjet is ideal for over-molded prototype parts but may not provide the material specifications engineers are hoping for.

“SLA can give you a great surface finish but might fall short on being production-grade material,” Ruffner said. “SLS will deliver great nylon properties, but you may not want the surface finish it produces. DMLS is great for fully functional metal parts but tolerances aren’t as tight as traditional machining. There are always tradeoffs.”

The technical skills required of production workers who do prototyping are much greater than those needed for ongoing repetitive manufacturing, especially considering the increasing complexity of both the product designs and the tools used to produce them. OEM engineers must work closely with the
additive manufacturer to learn the details about each process and how it affects the appearance and function of the prototype and/or final product.

“Educating and training production operators and technicians, as well as support personnel, will be an increasing challenge in the future,” commented Herb Bellucci, CEO of Pulse Systems, a Concord, Calif.-based contract manufacturer specializing in precision machining services for the medical device industry. “This is the age of the technically savvy worker. Successful employees will be good at math, computers and be willing/able to learn constantly and be flexible. Gone are the days when workers could expect to do the same thing all day, every day. The mindset for success, for individuals and for companies alike, is to grow or get left behind.”

As additive manufacturing continues to develop on multiple levels and in many directions, it will gain more momentum and respect as a method of manufacturing, noted Terry Wohlers in his article “Additive Manufacturing Advances” in the April issue of Manufacturing Engineering magazine.
“Metal parts from some AM systems are already on par with their cast or wrought counterparts,” Wohlers wrote. “As organizations qualify and certify these and other materials and processes, the industry will grow very large. In fact, additive manufacturing is poised to become the most important, the most strategic and the most used manufacturing technology ever.”

As easy as it is to get caught up in the sizzle and glamour of additive manufacturing, Pavlik cautioned that it’s important to not to lose sight of the basics.

“The ease of visualizing a concept with 3-D, computer-generated models, animation and 3-D printing no doubt helps engineers and designers determine the fit, ergonomics and appeal of the future product quickly,” he said. “However, the best approach is to work with the specifications first, get all the functionality, details and goals down on paper, as we did before these technologies came along. Then use the modeling software and prototypes as a visual reference to these, instead of the other way around. We have made a conscious effort to take this traditional step of working through the specifications before we rush to prototypes. This proves to be a cost savings because we have a more realistic prototype in mind from the specifications.”

Injection Molding
Injection molding continues to be the workhorse technology for plastic parts and products, which increasingly are becoming small, complex, and precision-molded with extremely tight tolerances. As a result, more companies are interested in a technique called scientific molding—a more thorough injection-molding approach that produces higher-quality products by eliminating the guesswork that is sometimes part of the injection-molding process.

“Medical device manufacturers who produce complex, critical-use devices containing precision-molded plastic parts must be certain those parts are defect-free and formed through a highly reliable and repeatable process that can be validated,” said Dan Lindgren, senior project engineer with Kaysun Corporation, an injection molder based in Manitowoc, Wis. “The process must be repeatable across multiple production runs and consistently produce high-quality parts that achieve tight tolerances.”

Compared to traditional molding that may rely on some guesswork to bring parts within specification, scientific molding uses sophisticated data collection and analysis techniques to document the specifications, settings and steps required to ensure reproducibility over time and across equipment. Advanced processing and diagnostic tools are installed on equipment to create a customizable process monitoring and control system for plastic injection molding applications. Important scientific data—including temperature, pressure, material flow rate, material chemistry, cooling time and rate, material moisture rate, fill time and mold conductivity—all are monitored in real time and compared to a “peak” template of values.

“Because all data are recorded, the process can then be replicated as needed, even when production is transferred from one machine to another, with minimal setup time,” indicated Lindgren. “Using a scientific approach to molding results in much higher repeatability and 10 times or greater control compared to traditional molding methods—reducing costs to the OEM by conserving time and materials. The consistency and repeatability in production also makes process validation easier.”

Rapid prototyping, fueled by the latest 3-D CAD technology, speeds production and time to market—always a plus in today’s cost-conscious medtech climate. Photo courtesy of JunoPacific.

One place where DMLS and injection molding intersect is the creation of conformal cooling channels that can significantly reduce molding cycle times and/or help with the stability of parts that need to be dimensionally accurate (parts with warping or sink).


 “Conformal cooling has become a hot commodity within the medical injection-molding community because most medical components are either small or have highly geometric shapes, thus creating issues with cooling within the tool,” said Ruffner. “CNC (computer numerical control) machining for conformal cooling is disadvantaged by straight line drilling. The intersecting
channels, complex coolant routing and zero velocity areas are difficult to manage and the process can’t achieve a controlled or uniform distance from the melt. Secondary sinker EDM (electrical discharge machining) to complement CNC tooling can prove costly, both in
time and money.”

Prototyping must be designed and developed with production in mind. Working in tandem with a customer’s engineering and production teams is essential for creating a process that achieves objectives, experts said. Photo courtesy of ASI.

With conformal cooling, the channels are designed into the mold and follow its complex contours. As the mold is built with DMLS the cooling channels are constructed as well, layer by layer. This results in even cooling of the plastic melt, which minimizes internal stress and results in higher quality with little to no warping or sink marks. Scrap rates also are reduced. Productivity gained in upgrading from a conventional tool to a tool with conformal cooling channels can be in the range of 30 to 60 percent.

Bioresins have emerged as a popular alternative to traditional polyurethane-based plastics. The most durable bioresins are based on polylactic acid (PLA), which can be blended with a variety of petrochemical-based materials including polycarbonate, acrylonitrile butadiene styrene (ABS) and polymethyl methacrylate. It’s also compatible with many fillers, fibers and additives that enhance characteristics such as strength and durability. For example, blending PLA-based bioresin with ABS, polyethylene or co-polyesters reduces brittleness. Bioresins most commonly are used for bio-absorbable implantable devices such as stents.

“PLA-based bioresins are still moving forward in terms of quality and process capability of the material,” said Bhugra. “The ability to load more glass into resins to act as metal replacement parts can also be a great asset to the industry and help drive down the end user cost of medical devices.”

Innovations and Improvements
Computerized solid modeling techniques, such as finite element analysis (FEA), continue to improve the overall productivity and cost-effectiveness of R&D engineering projects. FEA techniques analyze characteristics like strength, durability and flexibility. The FEA process subdivides the product or part into finite-sized units of simple shape that can be tested for stress and strain, resulting in a stress-strain curve or plot. The shape of this curve is distinctive for each material and dependent on the material, as well as the temperature of the material and speed of loading. The final curve reveals the critical properties of the material and is a final test to see if it delivers the properties the designer or engineer is looking for.

In the area of metal fabrication, tool manufacturers continue to develop creative solutions to small part machining challenges. For example, Pulse Systems has done work in producing parts that combine the capabilities of turning by conventional machining with very fine features cut on a laser, according to Bellucci.

“We’re able to run tubing in our Swiss screw machines and then process on a laser workstation as a secondary operation,” he said.

In response to trends in customer supply chain consolidation, Pulse Systems is moving toward a “value-added” approach to precision metal manufacturing. Rather than focusing on individual components, they are seeking projects that are combinations of parts, requiring multiple capabilities.

“Minimally invasive devices and implants are demanding smaller and smaller parts, with tighter tolerances,” said Bellucci. “We have added CNC machining capabilities for small parts, which opens new business opportunities for us in value-added assembly of welded sub-assemblies. Our new CNC machine tools are specifically configured for small parts, with very fine features. We’re making machined parts .030 inches in diameter or smaller, with features of .001 inch or less and tolerances of a few ten-thousandths of an inch.”

One thing that can slow down prototyping and production is the lead time for raw materials and components. In recent years many suppliers have changed their model from stock to made-to-order. In product development and prototyping, changes frequently take place; delays caused by suppliers also make speed to market challenging.

“ASI is able to manage these challenges through our specialized enterprise resource planning systems,” said Pavlik. “The systems manage and track every raw material and every component necessary for production. Everything is integrated, from our prototype/design phase to production, sterilization and delivery, allowing us to anticipate raw materials in the early stages.”

Parting Thoughts
One of the biggest challenges with prototyping and production is a non-technical one—maintaining clear lines of communication between all parties involved to ensure no small details are missed. Informed, quick decisions have become an absolute necessity for success in the medical device market. Project managers must communicate clearly with OEM engineers, buyers and management, all of whom may have a variety of input; they also must confirm all information is relayed accurately to sub-vendors and that all production issues/solutions are relayed back to the OEM.

This becomes especially complex when there are many sub-assemblies and components, coming from different vendors, which may be scattered around the world in today’s global sourcing market.
“The best way to overcome these communication challenges is to ensure detailed change control is clearly defined and implemented, along with specific team member role and responsibility delineations, in the standard operating procedures (SOPs) for all suppliers and vendors,” said Bhugra.

Although this may seem straightforward, he noted, it is often untested until unusual circumstances arise and an appropriate response becomes dependent on someone’s interpretation, which may be error prone, rather than on detailed SOPs.

“Also, compliance with GMP (good manufacturing practices) and ISO 13485 standards is required to support the framework of effective information transfer,” said Bhugra. “Additionally, ongoing training of staff and new hires must not be overlooked and is an area in which we continually invest.”

Bhugra also indicated that customers are requesting greater visibility into process measurements and assessment of any metric variances. The company has responded by providing customers with specific statistical process control measures such as bioburden testing for work-in-process and clean-room environments, ongoing sterile packaging validations and batch-based qualifications of trays and thermoseals, including peel-strength measurements to ensure low variance.

Bellucci stressed there is nothing “magical” about the current generation of 3-D printing/modeling tools. Despite the impressive ability to produce “good-looking” parts, they are rarely representative of the actual physical characteristics of the part, such as strength of materials, functionality, reliability, etc.
“The high-tech prototyping methodologies can certainly accelerate the process of getting to a workable design, but there is ultimately no substitute for actually making the part by conventional methods,” he said. “It all starts with the CAD tools, which provide the means to develop the models and to communicate them forward to the manufacturing process. The 3-D printers, the CNC machines and mold tool-makers all use those CAD files to do their work.”

Ruffner is excited to see the new materials and advancements in software that allow easier use of additive manufacturing technologies.

“To me, the most exciting part is the potential AM has for bringing jobs back to the U.S.,” he said. “OEMs and contract manufacturers that embrace the need for additive manufacturing will need to hire new staff to run the equipment, etc. The coolest part about prototyping is seeing a part go from design to production—if companies are prototyping then they are innovating, which means they are making new products that will create more jobs and boost the U.S. economy.”

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