Originally Published MPMN October 2009

BREAKTHROUGHS

Cryogenic Process Puts a Freeze on PEEK Implant Burrs

Shana Leonard

A smooth surface is paramount for an implant because the presence of defects such as burrs can seriously endanger patient health. But machine burrs have long been a bane to many medical device OEMs owing to the price and time associated with their removal. With the aim of assisting OEMs to cut costs and increase efficiency, Cryogenic Institute of New England Inc. now offers cryogenic deburring of PEEK implants in a process that removes burrs without compromising part quality or surface integrity.

Able to batch-process small volumes, the Nitrofreeze process entails placing PEEK parts in a basket that is then loaded into the cryogenic deburring system. Next, the implants begin to tumble at a programmed rate while gaseous nitrogen is introduced into the chamber to lower the temperature down to or near the material’s freezing point. Upon reaching the preset temperature, the frozen parts are blasted in a controlled manner with polycarbonate media and continue to tumble for the predetermined period of time.
Although it removes burrs, the clean process is touted by the company as a nonabrasive technique because the surface of the part is not affected. “The burr is going to be frozen because it’s so large; but, it’s only attached at such a small point. The media basically shears it right off,” explains Ryan Taylor, product marketing specialist.
“Even with the parts somewhat tumbling against each other and being shot with media, because the surface is frozen, you don’t have that abrasive effect.”
Taking about a half an hour, the process represents a dramatic improvement in implant burr-removal time compared with hand deburring, according to Taylor. “Several customers told us that they were doing hand deburring and they were taking about 15 minutes per piece, so you can imagine this is much more efficient.”
Repeatability is another advantage of the cryogenic process. Because hand deburring may be performed by different personnel, variation is common among parts. Nitrofreeze, in contrast, ensures repeatability by storing a specific part’s or part number’s parameters so that different batches can be processed under the same conditions.
The process is capable of removing light, thread-hold, and cross-hole machine burrs from complex PEEK parts typically as small as 0.025 in., although smaller components have been processed. Because size is a limitation, the cryogenic process is best suited for precision components, including implants for spinal applications and small joints.

Cryogenic Institute of New England Inc.
Worcester, MA
www.nitrofreeze.com
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