Tools of Change
Machining and tooling for orthopedics manufacturing is constantly changing, and OEMs must choose partners that can keep up with it all.
Getting the right machining and tooling for an orthopedics manufacturing job is a delicate and sophisticated task, but one that OEMs sometimes gloss over. That is a mistake. Too often, OEMs design products without any sense of how they will be manufactured, and without any input from manufacturing partners that can offer them valuable advice.
“The overall design strategy is critical to avoid designs where the part is difficult or expensive to produce. It’s important to take these issues into account before you get committed to a definitive path of development,” said Patrick Pickerell, president of Pleasanton, Calif.-based Peridot Corp., a contract manufacturer. “This approach definitely saves customers a lot of money. Unfortunately, it seems that the opposite is more the trend. Someone shows up with everything already determined, and there is no chance to discuss different materials and shapes. Ten years ago, engineers would ask questions of us while they were in the design phase. Now, they are way too busy.”
The problem is that the fabrication of orthopedic parts is not a cookie-cutter process. Instead, they often are designed with very tight tolerances or very odd shapes, and unless these factors are properly accounted for, the resulting part could be expensive and complicated to manufacture, or worse, one that fails during use.
“The tolerances that the orthopedics market requires are the biggest challenge,” noted Pickerell. “The complexity of shapes you see in the orthopedics market is quite different from other markets. There are a lot of 3-D shapes, complex curves, and things of that nature.”
What follows are some tips from orthopedic manufacturing partners that can help eliminate these issues before they arise.
Setting Up
To streamline the orthopedic machining and tooling processes and save money doing it, a collaborative planning process between OEM and supplier should be in place.
“Achieving low costs with high mix, low volume production is a significant challenge,” explained Tom Burns, vice president of business development for Tegra Medical, a contract manufacturer based in Franklin, Mass. “Many OEMs operate on a P.O. (purchase order) to P.O. basis with little long-term planning or communication with the supplier. In some cases, repeat orders will come in for an item that is already scheduled for production. Increasing the original order size would allow for lower setup and inspections costs, and possibly lower material costs as well.”
Orthopedic manufacturing experts from Farmingdale, N.Y.-based Huron Tool and Cutter Grinding Co. said involving all participants early in the process is essential, but can be a considerable roadblock to success due to scheduling.
“You have to communicate with everyoneinvolved with the manufacturing process,” according to the group. “Within every department, you have to set yourself up to win, which means selecting the best tools, inserts, and grinding wheels for the job and using them correctly. With cutting tools, there is a lot of cutting geometry involved to make sure the tool will cut freely enough so the surgeon does not have to use excessive force, but not so aggressive that it pulls itself into the patient. Critical training and experience is necessary as an engineer and cutter grinder to know what will and will not work on each cutting tool.”
Therefore, setting up communication channels and communicating effectively are the first things that an OEM should do once it has selected a partner for its project.
“Make sure all the information needed is correct and available, and provide an engineering contact person that is available to rapidly address the issues that cause problems or delays,” said Duane Audette, director of engineering and estimating for Elk River, Minn.-based Metal Craft and Riverside Engineering & Machining, a custom precision manufacturing and machining operation based in Chippewa Falls, Wis. “Also, being realistic on the time frame it takes to make the product is very important. It seems these days the cart gets put in front of the horse and they determine when they want it before they know when they can actually get it, thus putting the supplier in the position of trying to meet the customer’s needs without negatively impacting their own schedules.”
Pickerell agreed. “When we first meet with an OEM, we are very keen on understanding the customer’s expectations as to tolerances. We need as much information as possible to get a sense as to the cost of producing the part,” he said. “A lot of companies come to us with a 3-D drawing already.”
Burns added that all plans must be reviewed during this very early stage.
“Reviewing the prints, discussing the history and any DFM (design for manufacturability) considerations, and reviewing their inspection plans to ensure good correlation in technique between OEM and supplier are all very helpful,” he said. “Just fostering better communication between the respective teams is very helpful.”
Another helpful hint: Include suppliers in design discussions whenever possible.
“We think it would be great if more OEMs would bring in the supplier during the DFEMA (design failure modes effects analysis) process so the critical nature of the products could be captured, yet non criticals are identified and toleranced as such,” he said. “This way, the cost and inspection efforts are put in the right places and wasted time and effort is reduced, and cost reduction follows.”
One of the reasons this is so important, according to the Huron experts’ response to emailed questions, is that “sometimes it is physically impossible to make what is being drawn. As M.C. Escher demonstrates, just because you can draw it doesn’t mean you can make it. Other times the prints are ambiguous and the manufacturer is left interpreting what someone else wants. Be sure the blueprints are clear so the people on the shop floor do not have to clarify what the customer actually wants when the job is in progress. Communication between product development, manufacturing and quality is key. Also important at this phase is researching the best tools for the job and selecting the best machine as well. ”
Also essential, the panel said, is the concept of teamwork. “In any full production process, it’s all about teamwork, and bouncing ideas and knowledge off one another,” according to the group. “Knowing what tools, inserts, grinding wheels, etc., work best, and all that is needed to do the job right before it even hits the shop floor.”
Technology has evolved to the point that there now are new methods to produce complex projects more efficiently. Pickerell said OEMs must ensure their partners have those capabilities, and should discuss in advance whether they will be needed.
“You need to have productive planning regarding which materials and tools are appropriate for the job,” he said. “For example, when it is appropriate to go with a multi-axis machine to do the whole part at once, and when it might make more sense to push the part down to a lower level of machine and do it in severaloperations. You have to examine your manufacturing strategy, because chances are there will be multiple ways to make the part.”
Before the job begins, the outsourcing partner also should be made aware of various things about the project’s status, explained Burns.
“What is the status of the product? Is it a prototype, clinical build, commercial launch or perhaps an old product line that needs to be cost reduced?” he asked. “What is the forecast for the product and are they open to ideas to realize cost savings?”
The OEM also needs to inform the supplier how the tool will be used, said the Huron team.
“This can help determine proper flute and cutting geometry,” the team wrote in its emailed response. “Will it be on a guide wire or through a fixture? What kind and how much debris needs to get past the cutting edges? Wall thickness of cannulated instruments is also important.”
Taking Advantage of Technology
Several technological advances, especially on the machining side, have made it easier to make orthopedic devices with complex curves, odd angles and tight tolerances. It is important that any partner an OEM chooses to work with is aware of these advances and knows how to employ them.
“Newer five- and seven-axis-configured milling machines have enabled companies to do oddly shaped orthopedic implants in a single operation,” said Pickerell. “Whether this is cost-effective depends on the tolerance level and the shape of the part itself. Sometimes tolerances suffer when you take the part from one work center to another for different operations. In that case, it is better to put it on an exotic machine.”
On the machining side, Audette said Metal Craft has been employing new techniques to make the orthopedic machining and tooling processes more efficient. The techniques include:
• Placing machining centers uniquely to better spread out work to help meet high demands;
• Investing in the latest seven-axis grinding software in an effort to maximize machining capabilities to create more competitive pricing;
• Getting a roll dresser for the grinder that fosters the ability to custom-make wheels (which reduces lead times);
• Having CMM probe automation to aid in inspection at the machine; and
• Having multiple CAD/CAM packages to better accommodate an array of customers.
“Some other things we are looking at are B-axis turning, and multi-axis turn-mill systems, also known as ‘done in one’ systems,” he said.
The Huron panel noted that the latest CNC Swiss machines are equipped with more stations and accessories than their predecessors, which allows the making of a complete part in one operation.
On the tooling side, there has not been as much radical change, though Pickerell noted that some tool inserts have become more sophisticated to keep up with user demands for more complex parts.
Audette said the cutting process has advanced to better handle medical-grade materials.
“We design and manufacture our own specialty end mills and form cutters, along with special insert geometry and multi variable flute end mills in house that are specifically designed for the cutting of medical grade stainless steels,” he said. “That helps reduce manufacturing costs, and provides superior performance and finishes. We also utilize special ground drills in turning centers and Swiss turning centers in lieu of a gun drilling operation to improve efficiency. We have also implemented special tool coatings, insert geometry and multivariable flute end mills.”
Huron’s experts cited recent innovations in cutter grinding.
“In cutter grinding, one advance in particular would be the ‘traveling steady rest,’” according to the group. “It allows easier support of long parts with small diameters.”
In Huron’s Swiss/turning department, the company recently has implemented the use of high-pressure coolant and thread whirling, “which has made some jobs run without chipstops, and threads come off with perfection,” according to the group.
Burns noted that more OEMs have been requesting the use of nitinol because of its shape memory and superelasticity. But nitinol can be very difficult to make, and thus is very expensive. As a result, creative suppliers are developing ways to achieve similar results with lower-cost alternatives.
“We do see nitinol being used more routinely,” he says. “Given the high cost, it is often better to incorporate another lower-cost material into an instrument and utilize a laser weld to gain the performance characteristics desired from nitinol while minimizing the amount of material required.”
Forging Ahead
No matter what machining and tooling methods are being used now for manufacturing of orthopedic parts, chances are something new and better will come along in the near future, and OEMs must be aligned with a partner who knows how to adapt to these rapid changes in technology.
In any manufacturing company or process, if a firm is performing or machining a job the same way with the same tools for two years, it is falling behind, the Huron panel said, adding there is always something new or better coming down the pike.
Pickerell sees this in his own operations, where old methods have been replaced by newer, more efficient ones.
“My old-school sheet-metal and shaping operations are practically dormant,” he said. “Those required a lot of craft and handwork. But things are flying at the more exotic CNC processes. It’s a sea change. The old-school business model is definitely on the downswing now.”
Eric Swain is a freelance writer based in Phillipsburg, N.J. He has covered the medical device industry for 13 years.