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Precision, Accuracy Among Swiss Machining Benefits

Swiss machining is a precise and high-speed manufacturing process that allows more control, complexity and tighter tolerances than other methods for smaller parts and quantities, with shorter lead times.Its popularity in the orthopaedic device sector is attributed to the precision and accuracy required for the products, down to fractions of a millimeter. In most cases, secondary operations are eliminated and costs are saved since one Swiss machine can mill, drill, ream, saw, etc. 

In addition, as competition in the industry and regulatory guidelines get more stringent, speed to market is more crucial than ever.

With these considerations in mind, device manufacturers and contract manufacturers are seeing real benefits to Swiss machining. What else is shaping this space? BONEZONE spoke with several Swiss machining experts on the supplier side to find out. Participants included:

  • Lowell | Jurrell Baker, Swiss Cell Manager; Phil Allen, Sales/Marketing Director
  • Boston Centerless | Steve Tamasi, CEO
  • Norman Noble | Brian Hrouda, Director of Sales and Marketing
  • Seabrook Medical John Ruggieri, Vice President of Engineering and Business Development

Machining Efficiency

Norman Noble, a contract manufacturer of next-generation implants, utilizes Swiss machining to produce some of the smallest and most complex parts for the medical device industry, including orthopaedic-specific bone screws (cannulated, self-drilling, polyaxial and pedicle).

Norman Noble operates over 55 Swiss-style turning machines, which are located in an independent production business unit over 21,000 square feet in size.“Norman Noble has invested heavily in the technology to perform all turning and milling operations in a single machine to provide a complete part,” says Brian Hrouda, Director of Sales and Marketing. “This eliminates the need for secondary operations, which add cost and almost always negatively impact quality/yield.”

Part of the company’s investment in precision machining includes SynchroFlash, a machining capability that synchronizes Swiss turning, milling and laser machining into one efficient and cost-effective operation. According to Norman Noble, SynchroFlash machining eliminates the start/stop/start nature of producing parts on separate equipment, and is intended to support cost savings, faster production, better quality and higher yields versus competing manufacturing methods that require multiple, separate processes. 

Norman Noble has seen an increase in popularity of Swiss machining in the medical device sector over the last several years, mainly due to an increase in both machine capabilities and need by companies/customers/industry. “We can now make more types of implants using Swiss style equipment,” Hrouda explains. “We are also one of a few companies in the world that can produce nitinol screws and anchor implants on our Swiss turning and milling machines. We also hold tolerances of +/- 0.0005” on neurovascular implants and have the capability to machine parts from nitinol, PEEK and other exotic materials and alloys.”

Machining Precision 

Swiss machining is an integral part of Lowell’s operations. The precision machining contract manufacturer implemented Swiss machining in 2001 and the department has steadily grown over time.“Some of the tolerances are getting so demanding and everything is getting more complex,” says Jurell Baker, Swiss Cell Manager. 

Tolerances lie at the heart of the challenges associated with highly-precise machining processes, like Swiss. “For example, on a bone screw, the transition from the thread portion of the screw to the head of the screw…as those get smaller and smaller, the tolerances get tighter and tighter,” says Phil Allen, Sales/Marketing Director. “That involves smaller tools, higher machine speeds and more potential of tool breakage. All of these things can happen as the parts and tools get smaller and the RPMs get higher.”

Another critical aspect of Swiss machining is the relation between the quality of inputs and the product. In other words, the final product is only as good as what goes in on the front end. “We like to say, ‘Good in and good out,’“ Baker explains. “The materials that we’ve been getting in the last five years or so have been better (as compared to the technology’s infancy). The tooling tolerances have also been getting better.”

Baker also points out that many tools feature new types of coatings, an exciting technology that provides a means for innovation in device manufacturing. “There have been a lot of advancements in the last three to five years in coatings,” Baker says. “Many tool manufacturers will work with you on test cutting. If you have a high-production, high-volume run, you can really get good insight as to what coatings will advance your processes.”Swiss machining also excels in its milling capabilities. Traditionally, once a product has gone through a turning machine, the operator then has to pass it off to a milling machine to do part of the operation. “With Swiss, it’s all-in-one,” Baker says. “This is your best chance for accuracy. Swiss machining is also high volume. Anything you can do to work toward lights-out machining is ideal.”

Training to Increase Capacity 

Boston Centerless, a precision bar materials supplier, specializes in comprehensive Swiss machine training via its SwissAssist program, an asset that the company acquired in 2015 in response to the growing popularity of Swiss machining and lack of skilled laborers. SwissAssist provides detailed instruction, from the basic principles to the most challenging, in medical and aerospace applications.

Through the program, Boston Centerless offers guidance in machine setup and controls; LNS bar feed setting; proper installation of collets and guide bushings; program loading and unloading; program first run, adjustments and offsets; tool selection/touch-off and more.

CEO Steve Tamasi touts increased milling capabilities as the real benefit of Swiss machining. “Because of the technology, you’re able to drop off parts to the customer complete and don’t have to go to secondary operations, which costs money and time. Swiss-type screw machines are so complete, in terms of capabilities; they can be used in situations where it may have taken three or four operations in one. With Swiss machining, all of the relational tolerances and dimensions are in place because they are machined at the same time.” These capabilities are what attract people to these machines,” Tamasi explains. “This is why Swiss machining has been [a rapidly growing] machine tool segment [during] the last 20 years.”

Part of the precision of Swiss machining involves the straightness of the bar stock. “This is critical because if you’re getting whip in the bar and it’s causing vibration, you’re going to have a failure,” Tamasi says. “If for some reason you set the bar at a clearance level that’s less than what the bar needs and a high spot comes through, it can seize the bushing and crash the machine. You’re talking potentially tens of thousands of dollars to repair it, plus all the downtime.”

Tamasi attributes the growth of Swiss machining in medical device manufacturing to a “confluence of capabilities and need. The types of parts that are being made and the types of medical devices, instruments and implants fit the scale and scope of what Swiss machines can handle,” he says. 

Eliminating Material and Cost Waste

Seabrook Medical, part of the Arch Medical Solutions segment within Arch Global Precision, manufactures complex precision-machined orthopaedic instruments and implants for spine, knee, extremities and trauma applications. John Ruggieri, Vice President of Engineering and Business Development, points to the ability to create components in a “done in one” fashion as a reason why Swiss machining has increased in popularity in the medical device sector. “This has helped Seabrook create parts with less total cost where it was not possible previously,” Ruggieri explains.

“Combining machining operations also eliminates much of the waste associated with typical batching and queueing at downstream machining centers. “Ruggieri also identifies overcoming pricing pressure and increased efficiency as other crucial benefits to Swiss machining. “The less a part has to be handled or set up, the better,” he adds. “The Swiss machine is really designed to run nonstop with very little human interaction. This reduces machine wait time as well as operator time, decreasing part cost and increasing the number of parts produced per day. “

The heart of the Swiss machine is the guide bushing. It is the primary means of support for the stock, working to resist vibration and deflection. Guide bushings can be made from different materials, such as Meehanite cast irons (soft) or carbides (hard). “Both can produce a product of the same quality,” Ruggieri explains. “The difference is more about the life span of the bushing and whether it is harder or softer than the stock going through it. The condition of the material itself is a large factor of quality.”

Seabrook Medical uses “centerless ground stock held to a tight diameter, straightness and concentricity tolerances, which results in a stock that has a uniform diameter and finish throughout its length,” Ruggieri says. “A typical Swiss machine is capable of holding 60% of the bar stock tolerance. So if the bar stock has 0.001” of runout, your finished part will still have 0.0006” of that runout. In medical device manufacturing, we are often required to make parts with tolerances of 0.0002”to 0.0005” total tolerance. Therefore the stock we put in, the condition of the guide bushing and its setup are large factors for us to consistently meet those tolerances required.”

Photo courtesy of Lowell 

Supplier Talks is a year-long BONEZONE series in which topics chosen are based on the most-searched capabilities in the ORTHOWORLD® Supplier Directory. We’ll cover Laser Marking in June, followed by Milling in August, Sterilization in October and Micro Machining in December.



Rob Meyer is ORTHOWORLD’s Senior Editor. He can be reached by 
email.

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