Medical Device Link.

TECHNOLOGY TRENDS

A thread mill developed by Dixi Polytool S.A. improves tool life and implant-thread quality.

Medical manufacturers using titanium or stainless steel in the design of bone implants typically are confronted with tool life and quality issues. Swiss manufacturer of tungsten-carbide tooling Dixi Polytool S.A. (Le Locle, Switzerland; www.dixipolytool.com) has developed a product for threading applications that effectively addresses these concerns.

The company fielded numerous requests from medical manufacturers on how best to solve tool life and quality problems related to the inner threading process, according to Florian Emonin, tooling specialist. “By creating a new thread mill with only two cutting profiles, called a thread whirler, we were able to find a solution to the problem,” says Emonin. “The new geometry reduces the stress applied to the tool during the machining process, providing a better tool life and thread quality . . . without burrs.”

The tooling range consists of a one-pitch single-tooth version (Dixi 1739 for the NIHS standard) and several two-pitch multiple-teeth models (Dixi 1730, 1731, 1735, and 1736 for ISO and UN standards).

These whirling tools can be used in two different machining methods. During the machining of a fixed workpiece, the tool moves in a spiral manner, milling threads into tough materials. The other method involves a rotating workpiece and rotary tool moving in linear interpolation. The latter technique is mainly applied on turning machines and can be used with threads for dorsal or dental implants.

Although whirling techniques will not replace taps or thread mills in conventional applications such as threading mild steel or aluminium, the thread whirling machining method may be advantageous when making threads in particularly tough materials. It can significantly improve the quality of machined interior threads, according to the company.