New cutting tool concepts make small- part machining for the medical industry considerably more efficient, thereby improving productivity. In particular, as sliding-head machines evolve for small- part machining, so, too, do cutting tools in order to provide the performance needed for high machine utilization. Tools for many operations have reached new performance levels recently, but thread-whirling tools and turning with high-pressure coolant both truly exem- plify how far tools have come.
Established Method Upgraded High-volume production of long,
slender screws in high-performance metals—bone screws, for instance—is on the increase, as is the competitive
pressure in manufacturing. Tis typi- cally is the case for medical industry suppliers, where these types of items are machined in growing volumes, and where thread whirling is the established method. Te inherent stability of the process makes it ideal for machining high volumes and demanding metals.
In one bone screw thread-whirling example that involved a half-million units per year, nine times more components were able to be machined before the cutting edge needed changing.
Te primary advancement has been
tool-life extension, which means less machine down-time in production.
Medical Product & Application Specialist Sandvik Coromant US Fair Lawn, NJ
Also, the toughness of the cutting-edge line can be improved to enable a sharper edge to be used and for it to be more se- cure. Taking advantage of the machining advances in other machining areas and developing specific indexable inserts and cutters for whirling small parts lead to improved manufacturing-economic advantages for medical components. Insert advancements have provided
a means for a new take on cutting edges that takes full advantage of the benefits of the thread whirling method. Coated cemented-carbides, for example, have resulted in much longer and more predictable tool life, as well as higher potential cutting speeds. Tis has resulted in higher production output of parts consistently within tolerance and finish levels. New insert grades, such as a PVD/TiAlN coating, have a unique thin coating layer with very good adhe- sion to the insert substrate. Te grade has proved particularly advantageous for the keen edges necessary for thread whirling materials such as those used for bone screws. Operating security and tool handling
New thread- whirling cutter concepts and indexable inserts provide advantages for parts such as bone screws.
38 Medical Manufacturing 2013
are also essential features for achiev- ing higher machining performance in thread whirling. Tool precision deter- mines the quality of insert seating, insert grinding and the ease and reliability in locating the insert correctly every time. Newly developed insert-clamping for thread-whirling cutters has improved the accuracy of cutting edge positioning, machining security and toolchanging simplicity and speed. A smooth tangen- tial cutting action is necessary to ensure the high accuracy and surface finish demanded throughout the process.