Thread Whirl Toolholder for Complex Thread Production of Medical Bone Screws

Designed for single-spindle Swiss screw machines, the latest thread whirling toolholder from EXSYS Tool, Inc. (San Antonio, FL) productively machines high-precision OD threads in challenging materials. An inexpensive alternative to dedicated thread whirling machines, this toolholder is ideal for processing micro-components with long, slender thread profiles such as medical bone screws. The ring-shaped toolholder has an adjustable range of zero and 15 deg to accommodate most profile shapes. It employs a maximum input and output rpm of 6,000 1/min and maximum torque output of 13 Nm to threadmill rough stock at extremely high speeds.

Because of its open interface, this toolholder accommodates cutting tool inserts from different suppliers. The chosen inserts, however, must be identical and evenly spaced for the thread whirling process. The cutting edges of these inserts face the toolholder’s opening and rotate around the bar stock to cut an external thread. The machine’s Z-axis longitudinally feeds the toolholder at high speeds, while the bar stock rotates at slow speeds via C-axis control. Each insert then takes its cut of the material as the toolholder whirls around the bar stock. Thread whirling with this toolholder has several advantages over traditional, single-point threading operations. Thread whirling increases tool life by distributing the cutting load over several inserts. The process also cuts threads to their full depths, including full deburr, in one pass. Single-point threading, on the other hand, has one cutting edge, taking the entire cutting load over several passes. Furthermore, in thread whirling, users can freely select their speeds and feeds to suit ideal cutting conditions.

Also, because this toolholder’s cutting action takes place near the machine’s guide bushing, users achieve maximum rigidity during the threading process, which ultimately results in accurate, quality components with high surface finish. This thread whirling toolholder mounts to one of the rotary tool stations on the Swiss screw machine and offers fast cutting tool change outs.

EXSYS is also the exclusive North America supplier of pL LEHMANN rotary tables and has expanded their offering of ultra-high precision products to include the LEHMANN swissClamp modular clamping system that allows operators to mount multiple work pieces on machine tool tables for uninterrupted production and unmanned operations. For use with rotary and standard tables on vertical or horizontal milling machines, the Swiss-manufactured swissClamp modules mount on face plates or directly on worktables. The system extends a shop’s potential part-clamping range from 90 mm to 200 mm – a 40 percent increase in work piece capacity within the same clamping length.

The swissClamp’s four basic modules enable more than 240 possible configurations, including both mono clamping (requiring only one basic body) and duo clamping (where two mono clamps are mounted opposite one another). Configuration options include creating a clamping tower/tombstone on a fourth axis, a horizontal clamping cone that is overhung or with counter bearing, or a clamping bridge on a trunnion table set up where both sides require a different design with mono and duo systems. Operators can also create clamping modules on the fourth or fifth axis. Ideal for a variety of mass production applications in the medical/dental industries, swissClamp is suitable for either strong gripping or light finish clamping applications. For strong gripping, the system achieves rigid, pull down clamping to depths of 3 mm or 6 mm via a mechanical grid on its jaws.

When used for finish clamping, swissClamp’s finish jaws achieve non-rotating, precise parallel clamping with a clamping stroke of approximately 1 mm that prevents indentations and ensures high surface quality. The system enables finish clamping to a depth of 6 mm. The swissClamp system is compact with a simple, yet robust design that makes it easy to clean and offers good chip and coolant flow.

EXSYS Tool, Inc., 11654 Corporate Lake Boulevard, San Antonio, FL 33576, 352-588-4345, Fax: 352-588-4821, [email protected], www.exsys-tool.com.