Medical shops make the move to more near-net shaped parts

PHOTO COURTESY OF MAZAK

More medical implant and device shops are moving toward using near-net shaped castings and near-net parts produced with additive manufacturing (AM). While doing so enables faster part turnaround times for increased production capacity, near-net shaped parts bring specific requirements in workholding/fixturing and machine tool capabilities.

Near-net shaped parts are closer to finished size, minimizing the material removed during machining to reduce waste and production costs. Most near-net shaped medical parts require only finish machining to bring them to size, eliminating roughing operations and the machine wear they cause, allowing shops to run at higher spindle speeds/feed rates for faster production. It also means medical shops need machine tools with higher speed spindles – those in the 20,000rpm range – and with full simultaneous 5-axis capability to access part features during finishing and provide smooth finishes on complex contoured surfaces.

With 3- and 4-axis machines, medical shops often must stop production to turn or re-clamp a part into a custom-built fixture to handle a compound angle or diagonal part wall. A 5-axis machine can be programmed so the machine’s table tilts or rotates for part feature access for error-free, consistent machine-controlled movement.

As a result, required multiple setups can be finished in two, as these machines can work on five part faces at once. The setup-time improvements alone contribute to much shorter lead times, while increased repeatability prevents damaged or scrapped parts from impacting productivity.

The phrase ‘complex contours’ is commonplace with 5-axis machine technology for a reason – this type of machining makes many parts possible that couldn’t be produced with conventional machines. Nevertheless, 5-axis machines can also expand a medical shop’s capabilities in other ways. In addition to consolidating processes, these machines can also improve product manufacturability.

A component might require multiple parts with tight tolerances for fit and geometric complexities necessary for final assembly. With 5-axis technology, this becomes unnecessary. Contouring, compound angles, and innovative approaches to machining make it possible to produce assemblies as single pieces. Every industry has access to this kind of streamlining, and given the costs of maintaining part families, 5-axis capabilities can result in significant savings.

Medical parts produced from near-net castings and/or AM benefiting from full 5-axis machining include hip and knee replacements, bone screws, and plates as well as precision cast components for dental prosthetics and implants. Precision surgical scalpels and forceps are also common candidates for near-net part processes.

Medical manufacturers apply near-net shape strategies to generate tools tailored for specific surgical procedures; components for devices such as pacemakers, heart valves, and imaging equipment; and small, precise components for minimally invasive surgical tools.

Commonly used medical part materials include titanium and cobalt-chromium alloys. Opting for near-net shaped castings or AM-produced parts also allows manufacturers to cast specialized alloys for specific medical applications.

Near-net shape casting and AM are valuable processes in medical manufacturing, offering material efficiency, precision, and cost savings. They enable production of complex, high-quality medical components with minimal post-processing, essential for the stringent requirements of the medical industry.

As technology and materials continue to advance, near-net shape casting and parts produced with AM will likely play an increasingly important role in manufacturing medical devices and implants as will full 5-axis machining technology. Medical manufacturers will also depend on those machines to generate excellent surface finishes to reduce additional polishing or finishing and for holding the extremely tight tolerances required for medical components.

Most importantly, full 5-axis machines deliver speed and repeatability. Speed is critical as the medical industry moves toward patient-specific implants designed from medical imaging data, while machine repeatability ensures quality and consistency across multiple production runs, critical for medical device reliability.

About the author: Jared Leick is product manager at Mazak.

Mazak
https://www.mazak.com