Making manufacturable medical devices requires a meeting of the minds
November 1, 2010
At least one stamper is reducing the cost of medical devices by converting machined parts to stamped or stamped/machined parts. Not only is the manufacturer using this innovative approach to reduce cost without sacrificing quality and still meet stringent U.S. Food and Drug Administration (FDA) standards, it sometimes stamps features into the medical devices that could not be made by machining them and tightens tolerances.
Think no one is doing anything about the high costs of health care?
At least one stamper is helping to reduce the cost of medical devices by converting machined parts to stamped or stamped/machined parts. Not only is the manufacturer using this innovative approach to reduce cost without sacrificing quality and still meet stringent U.S. Food and Drug Administration (FDA) standards, it sometimes stamps features into the medical devices that could not be made by machining them and tightens tolerances.
Not bad work if you can get it.
Connecticut Spring & Stamping, Farmington, Conn., a family-owned business founded in 1939, manufactures components and devices for the medical industry segment. Most are hand-held surgical devices such as endoscopic clip appliers, endoscopic stapling equipment, and cauterizers. The manufacturer also makes titanium clips that are applied internally during surgery, ferrules that go into needles, needle guides, and springs.
In many instances, the company both stamps and machines the components or devices, as well as oversees their secondary forming, heat treating, and plating operations. Volumes range from 50 pieces a year to as many as a million pieces a week, depending on whether the components are disposable or go into reusable devices that are resterilized.
The Northeast manufacturer is located in proximity to some of the most prestigious medical facilities in the country, as well as a heavy concentration of precision stamping, machining, and spring-making manufacturing.
“This whole New England area is where manufacturing kind of grew up in this country, so a lot of metal components are made here,” said Steve Dicke, vice president of sales. “Manufacturers were founded on the clock and firearms industries, and that evolved into making more sophisticated parts and components.”
Despite the intense competition, the manufacturer has an enviable client list of FORTUNE 500 companies. It ships parts to 30 countries. The company’s revenues typically are $35 million to $40 million.
The manufacturer performs its engineering in-house, designs and makes all the tooling, and builds all of its own fixturing.
“It allows us to have cross-functional teams—quality, production, and engineering—address particular manufacturability issues,” Dicke said.
Manufacturing Engineer Mark Labbe added, “It improves communication with the customer on the manufacturability issues. Sometimes the customer requests features that cannot be stamped. By having direct communication between the client and the designer, we get better results.”
Manufacturability is discussed in early supplier involvement meetings in which all the design specifications are reviewed so designs can be adjusted. Emphasis is placed on converting machined parts to stampings or combined machinings/stampings, Labbe said.
“We’ll identify the dimensions or materials that are either driving cost or are the most difficult to hold within the manufacturing process. On their side, they identify the most critical dimensions to make the device function effectively and consistently,” Labbe said. “So it’s kind of a meeting of the minds somewhere in the middle, where there’s give and take on both sides to try to get the most manufacturable part at the best cost so that we can produce at a reasonable cost and consistently make good parts within spec.”
By converting a closure device from a machined to a stamped-and-machined device, the company halved the device’s cost, said New Tooling Manager Lou Morelli. The device is used in endoscopic surgery for cutting and cauterizing applications. “It had been a completely machined part, and very expensive originally—$27 apiece.
“We found out what the customer needed and developed secondary tooling to actually make the part. We manufactured fixtures to locate and hold the part to machine it, then stamped and formed the part to specifications,” Morelli said. “We took the customer’s machined part model, remodeled it as a stamping, and showed him an example of what it would be as a stamped part.”
Morelli added, “We’ll take a look at a part that is fully machined. We can take a fully machined part, and maybe with some modifications on the side of the customer, make it a stamped part with machined features.
“It won’t be identical to the machined parts, but we’ll see if we can give them a fully functional part that will closely resemble what they’re getting,” Morelli said.
Some of the give-and-take may be to relax tolerances on the noncritical or less critical features by working closely with the customer, examining the functionality of the instrument, Morelli said. For example, stamping a formerly machined cyclindrical part might require putting a laser-welded seam in it that didn’t exist on the machined part. As long as that seam is not detrimental to the function of the part, it’s a win-win.
Of course, all the instruments and components undergo rigorous safety and quality inspections and testing by the FDA and other agencies. “With most of these medical devices, when it’s new, it has to go through a qualification process that we’re involved with,” Dicke said.
“On all these medical parts—particularly when it’s used in surgery—the development process is very long because of all the necessary approvals,” he continued. “Part of that is working through the functionality and tolerancing of the device from an engineering standpoint, but another big part of it is getting all the approvals necessary, all the way through to the FDA.
“We really try to develop a part that’s fully capable of being held within dimensions, and then we spot-check it for an AQL [acceptable quality level],” Dicke continued. “We use vision systems and so forth to measure parts consistently and quickly. We want to develop a capable process upfront so that 100 percent inspection is not necessary.”
So are any of the 350 employees confident enough in their surgical products to have been on the receiving end of them?
“I have, and it went well,” Dicke said.
Connecticut Spring & Stamping converted a previously machined part to a fully stamped part, added an essential feature, and improved part quality in the process.
A customer wanted to redesign an endoscopic clip applier that previously had been machined by a company it had acquired. The complex, multidirectional instrument had a closure device that emerged at a right angle to the jaw, and the track and the jaw were machined (see Lead Photo).
“Initially the customer was having high internal rejects on the parts. They were having failures of about 7 percent of the instruments, fully assembled,” said Steve Dicke, vice president, sales. Seven percent is a high reject rate for any manufactured product, but especially so on an expensive device costing hundreds of dollars.
“There was a lot of development of the print with our engineering group on what we were going to be able to hold and how the print would have to be modified,” Dicke said.
“The relationship between the grooved guide that guides the clip to other features on the part needed to be redesigned,” Manufacturing Engineer Mark Labbe said. “When the jaw’s groove had been machined, it was a three-sided groove, so the groove had a wall on three sides, but the end of the clip had to be open to machine that groove.
“They came to us to see what we could do with this particular feature. They realized that it was almost impossible to machine the feature they were looking for. To improve the function of the instrument, they had to add a feature—a clip stop into the jaw—that they could not achieve through a fully machined part,” Labbe said,
New Tooling Manager Lou Morelli said, “In machining, where a lot of the variance comes in is the fixturing. You would have to refixture the part multiple times, and you have a little bit of play each time.
“It was not possible for them to consistently fixture this part and machine it. There was too much variation in the process,” Morelli said.
The engineers developed a stamping process to stamp the channel of the jaw into it and hold the tolerance. In addition, they were able to create the groove with a four-sided wall, which was what the customer wanted.
“It starts as a progressive stamping,” Morelli said. “We stamp the overall form and a number of the features initially using the progressive tool. Then we coin the track of the jaw in a different process, fixturing it. We built an automated stamping tool that never lets go of the part. We never refixture it.
“We actually decreased the amount of variation and stamped a much tighter tolerance than they were holding because of the variation inherent in refixturing. We now hold the tolerance within thousandths of an inch,” Morelli said.
Not only did the effort improve the tool, it reduced its cost.
“Our process was faster and cheaper than the machining proc-ess,” Dicke said. “But where we saved our customer the most money was eliminating the fallout.” The product was much more consistent and held to a tighter tolerance.