A good orthopedic prototyping process results from early collaboration and constant feedback between OEMs and suppliers.
Contributing Writer
Prototyping is a discipline that presents many challenges. These challenges are magnified when the task is to build a prototype for an orthopedic device. Not only must the materials used in the prototype mimic those that will be used in the device, but the prototype also must have pieces that fit together the right way or the resulting design may not work properly. In addition, the lead times involved often are aggressive, so the prototyping project usually requires a quick turnaround time.
All this must be accomplished without spending too much money, which would defeat the purpose of building a prototype. Therefore, it is important that orthopedic OEMs work closely with prototyping firms to determine the scope of the project and the tools needed to make it succeed.
“One of the goals of prototyping is to spend as little money as possible to get a sense of the part before you spend the big money on it,” said Thom Murphy, director of business development for Vaupell Rapid Solutions, a Hudson, N.H.-based prototyping subsidiary of Vaupell Holdings, Inc., a global contract manufacturer of custom injection molded components and assemblies. “The first step is to have the end in mind. If you can identify how the part is going to be used in the development process and how many you think you might need, that will help us determine how to spend money on prototyping most wisely.”
Obstacles to Success
A miscommunication about the goals of the project could result in a prototype that no one is happy with and does not translate well to the manufacturing environment.
“The challenge is to make sure that it can also be manufactured in a traditional product environment. If you build a prototype that is not manufacturable at the production level, you could be wasting your money,” added Murphy.
Therefore, it is important to get the team responsible for making prototypes involved very early in the design process. Peter Browne, sales engineer for FMI Medical Instruments, a Madison, Ala.-based prototyping firm, said it is crucial that firms like his get involved early in the project to help develop the manufacturability of the part.
“So many customers today are driving their supplier programs through procurement, ultimately restricting the direct contact with engineering groups,” he told Orthopedic Design & Technology.“Getting involved earlier in the prototype/development process benefits the customer by allowing the supplier to help pull cost out of the product by offering design guidance through manufacturing processes. It benefits the supplier by giving earlier insight to newer manufacturing technology that they could add and be prepared for launches and production.”
Adding to the challenge are demands for more sophisticated prototypes, noted Ron Callahan, prototype manager for Orchid Design, a division of Orchid Orthopedic Solutions based in Shelton, Conn. “Engineers can design a slick looking part with swept radii and complex surfaces, but sometimes they just aren’t realistic or cost effective,” he said. “To manufacture the parts to the model/rendering, it often requires a great amount of 3-D machining. Also, the size of the prototypes has diminished in the last few years, requiring smaller tooling and tighter tolerances.”
As a result, said Patrick Pickerell, president of Peridot Corp., a Pleasanton, Calif.-based prototyping firm, time and money often is wasted designing prototypes that are impossible to manufacture for a realistic price. It is crucial, he added, that OEMs seek input from their partners on materials, part shape and assembly issues at the prototyping stage to save both organizations time and money.
The Importance of Collaboration
In order to produce the most realistic prototype at the most reasonable cost, the OEM’s design team and the supplier’s prototyping team must share as much information as possible. Otherwise, the supplier will not know how to build a useful prototype that addresses usability and manufacturability issues.
“Everyone has to understand the intended use of the product and expected surgical procedure,” said Browne. “These answers help paint a picture of the physical parameters the end user will be exposed to, allowing the supplier better insight to assist with manufacturing solutions. Along with this, everyone needs to know about any other ancillary products that might be associated going forward, as well as the project timeline.”
Both teams also need to be on the same page about the goal of the prototype. Should it be a perfect replica of the actual part, or can it be something reasonably close that can give the product development team a good sense of the part’s behavior in real-world conditions? Either way, the cost and timeline implications are essential nuggets of information for prototyping teams.
“In plastics, what we have to do differently is keep in mind that many products have to complete biocompatibility testing before being released into the market,” Murphy said. “Many companies believe you need to start with the actual injection molded part or an exact replica for that reason. But designers should keep in mind that proving design intent or concept before spending money building the actual part has value as well. There are other, less expensive processes that can work for those purposes.”
In addition to intended use, the product’s physical dimensions must fully be disclosed. “We need to verify the physical and technical requirements of the part that you are trying to make,” said Scott Herbert, president of Rapidwerks Inc., a prototyping firm based in Pleasanton, Calif. “What kind of load does it need to bear? What sort of turning, bending, and flexing are involved? What materials do you intend to build it out of?”
The relationship between the design and prototyping teams should be as seamless and as transparent as possible to ensure everyone understands the needs, expectations and requirements of the prototype. A strong relationship can help the teams produce the correct orthopedic component in the best possible way.
“This enables the customer to meet his timescales and ours,” said John Reynolds, tooling manager for Sandvik AB, an international engineering firm with U.S. headquarters in Fair Lawn N.J. “This also gives us a better understanding of the part, to ensure we get the component right first time. Plus, there is no misunderstanding of what is required and what we can achieve.”
An aluminum handle piece as machined on Peridot’s new Mori SeikiNL-2000 Mill/Turn Center. This part previously would have been made in three operations on two different machines, but now is produced in a single operation. Photo courtesy of Peridot. |
It is important for OEMs to understand that multiple iterations are necessary to make the most useful kind of prototype. Patience is essential, particularly when changes are being made on the fly. In addition, customers must ensure that their suppliers can support their production needs, including identifying, hiring and retaining top-tier technicians.
Such collaboration (and patience) can create a more robust feedback loop during the design process.
“During the prototyping process, the group can and often does catch design flaws that might otherwise slip through the cracks,” said Orchid’s Callahan. “One of the most important aspects of prototyping a part of an instrument, for example, is so you can see quickly if the concept is viable and if it will function as needed. As the prototype is being manufactured by the group, working with the engineer will overcome many obstacles that might arise. An internal prototyping shop allows the engineer to test parts running in parallel to the prototyping. As the first prototype comes off the machine, the engineer can test the part to see if it meets the design criteria. If a change is necessary, the engineer can work with the shop and make the appropriate changes. The toolmaker then can run or modify that part or another part, and the engineer can test changes on the fly. Working this way drastically reduces the time for different iterations along with the turnaround time for the next round of prototypes.”
OEMs should be receptive to ideas from the prototyping team in various realms. At Orchid, for example, the prototype team suggests manufacturing changes to the OEM to make the parts more cost effective. While those changes could include processes, material selection or tolerance, they do not change the way the prototype is supposed to function.
Conversely, said Herbert, suppliers that cannot meet an OEM’s demands must explain the reasons for the failure to prevent time and money from being wasted.
Choosing the Right Prototyping Process
One of the keys to a successful prototyping project is agreement between the OEM and the supplier on the kinds of materials and technologies to be used.
“You have to select a material that best replicates the actual product,” said Herbert. “Be aware of new materials on the market and how they may support your need.” In some cases, he noted, the prototype may have to include the material in which the end product will be manufactured. This may not be much of a cost burden if the material is readily available.
The cost of injection molding a part for prototyping purposes may be too expensive, however. That is where a good rapid prototyping process really can come in handy.
“Rapid prototyping is also commonly referred to as additive manufacturing, which is adding layers to a base,” said Vaupell’s Murphy. “At the prototype level, this can be less costly than molding a part. Additive manufacturing typically uses a laser or UV [ultraviolet] light to cure or build a special material into the desired part. We currently utilize SLA [stereolithography apparatus], SLS [selective laser sintering], and DMLS [direct metal laser sintering] technology to serve our clients’ needs in these areas.”
For prototyping plastic parts, there are several processes that can produce a realistic replica without including costly procedures.
“On the plastic side, we can do cast urethane or RTV [room temperature vulcanized] molding. You take a solid model and build the reverse of the part and build a mold out of SLA material,” Murphy explained. “That way, you can get a plastic part out of urethane that can mimic the durometer and color instead of a thermoplastic part, and should be less expensive. But here is where information about product volume and life cycle comes in handy. If you need 50 parts per year, our first recommendation may be to use cast urethane, as the cost of injection molding for a prototype would be prohibitive. But if you’re able to tell us that the life cycle of the product will be five or six years, meaning about 300 parts will be produced, the numbers start to tip where building a traditional tool might make sense.”
Today’s technology helps ensure that different processes can be performed for prototyping purposes and replicated under conventional manufacturing practices.
“The CAD file drawing is imported into our computer-based design. We then convert the file into STL [stereolithography] for prototype manufacture. We ensure that we can manufacture the part correctly,” Reynolds said. “For example, can we achieve what the customer is expecting in terms of tolerance geometry? We load the part into the prototype CAD-based software to orientate the part to get the best build possible to meet the customer requirements. Then depending on which prototype machine we use, we produce the parts on either a follow-the-cast route or the after cast route if we produce a DMLS part.”
Peridot’s new Brightstar laser welding workstation in the clean room. Photo courtesy of Peridot. |
The best way to ensure a proper transition from prototyping to manufacturing is to have the prototyping firm involved early in the process, industry experts said. “If the project is handled properly from the beginning, via design for manufacturability, and is done in a facility that has a prototyping cell that mimics the production cells, this transition is smooth,” Browne said. “If this is the case, the manufacturer can use the same setup procedures, fixturing, programming, etc., if they have helped with the development.”
OEMs should make sure that their suppliers have the latest in multi-axis machining technology.
“Keeping up with the latest in multi-axis machining technology is an expensive proposition, but the newer generation of five-axis CNC centers enable net-shape manufacturing with few if any second operations,” Pickerell said. Acquiring the latest machining technology especially is valuable for firms that deal with compressed lead times and are not concerned about price.
Other technologies on the rise, according to industry observers, are ultra-high-speed micromachining and laser sintering. “I am particularly fascinated with additive processes such as laser sintering that can produce net-shape metal implants by what is effectively a 3-D printing process formerly reserved for plastics,” Pickerell noted. “No tooling is required, and you can make all the changes you want. Implants will be customized to the individual’s anatomy.”
Firms also should determine early on whether their suppliers have the flexibility and capacity to meet the demands of the project.
“We work hard to maintain a two-shift, six-day-a-week prototyping capability that does not interfere with our long term production contracts by utilizing dedicated work centers and personnel,” Pickerell said. “It is a delicate balance between maintaining the ISO 13485 quality system without compromising flexibility and agility.”
Better Early Than Late
An early and detailed consultation with a prototyping supplier can save a lot of aggravation for orthopedic OEMs. The best prototyping projects result from having the proper technology employed with the proper materials on the proper timeline with constant iterations and feedback into the design process.
“A proactive approach by both the orthopedic OEM and their supplier is required,” said Browne. “They need to be on the same page understanding the need and use of the final product. Flexibility also comes to mind as important. The development team must be willing to think outside the box and be open to new ideas that may stray from the norm.”