Irish engineering firm, Caragh Precision, which specialises in the design and manufacture of medical implants and surgical instruments used in orthopaedics, cardiology, oncology and vascular procedures, has replaced one of its Traub TNL-series sliding-headstock turning centres with a latest-generation model. It was supplied by Kingsbury, sole agent in Ireland and the UK for the German machine builder.
Many of the tightly toleranced medical components are turn-milled on the five Traubs and 15 fixed-headstock CNC turning centres in Caragh’s 40,000 sq ft factory in Galway. Some of the sliding-head machines, which are of 12, 20 and 32 mm bar capacity, have been in use for many years. The oldest, dating back to the late 1990s, was coming to the end of its useful life.
Its replacement, a 20 mm capacity TNL18P delivered in November 2014, is two machines in one. It can produce classical Swiss-type components accurately with a guide bush, which can be removed so that shorter parts may be produced more economically as a result of the reduced remnant length.
Changeover is achieved quickly by releasing the collet that feeds the bar through the guide bush, after which the bar is clamped in the spindle. The material can then be moved 80 mm into and out of the cutting zone using the Z-axis motion of the headstock. The high-torque spindle and powerful driven tools are ideal for machining tough materials, such as those routinely processed by Caragh, including cobalt-chrome, titanium alloy and stainless steels.
A highlight of the TNL18P is the inclusion of two turrets that are rotated as servo-controlled axes, rather than indexed. They may be positioned at any angle through 360 degrees, so multiple toolholders can be used, allowing up to 54 cutters in the working area. All stations can carry either a static turning tool or a live cutter.
Another novel feature is Y-axis simulation, achieved by interpolating the top turret’s rotational and X-axis movements with the main spindle’s C-axis. It allows flats to be milled without the need for a separate Y-axis, providing the facility without the expense of an extra slide.
Other advantages of the machine are a chip-to-chip time under 0.3 second for adjacent turret stations, a 12,000 rpm C-axis counter spindle that moves in X, Y and Z, and seven rear endworking tools, of which three are driven, for completion of simultaneous reverse-end operations.
The Traub TN8i-p control incorporates a 64-bit RISC processor and an additional PLC processor to provide fast data processing and short cycle times. It has an interactive graphical user interface for on-screen programming, automatic synchronisation of the simultaneous front and rear machining operations, and advanced 3D program simulation and diagnostics.
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