Sliding head automatic lathe drastically simplifies allocation of the various machining operations to hip screws machined from bar and for back operations (counter-spindle).

Every year in Europe, roughly 700,000 people suffer a hip fracture, which is frequently linked to osteoporosis. The medical facilities currently available mean that rapid surgical intervention can be conducted to reduce the fracture by applying plates and retaining screws, thereby allowing patients to quickly regain their mobility. The hip screws used for surgery are highly complex parts that require numerous machining operations involving swarf evacuation.

The highly resistant materials used in these implants including stainless steels and titanium often entail several rough-working, finishing and deburring operations.

Without doubt, the best solution in terms of productivity and feasibility is to proceed with the complete machining of the parts in a single chucking operation using one machining unit.

Thanks to the A-line products from Tornos (the Tornos Deco 20a in this case) it is now possible to machine specific parts in minutes.

The Tornos Deco sliding head lathe is fully adapted to this family of parts.

It drastically simplifies allocation of the various machining operations from the bar (main spindle) and for back operations (counter-spindle).

The kinematics of the Tornos Deco (12 numerically controlled axes all with simultaneous interpolation) allow up to 4 tools to be used simultaneously and execution of back-operations is 100% in hidden time.

The lathe and various devices developed to date offer numerous facilities for different types of machining operations, giving finished parts in a single set-up.

The procedure to manufacture hip screws involves turning, centering/drilling/reaming, high pressure drilling to 120 bar, tapping, hexagon broaching/swaging, external hexagon milling, external thread whirling in back-operation mode, deburring, part support and over 20 tools to conduct the numerous operations.

The Tornos Deco 20a sliding head lathe lends itself particularly well to hip screws, due to its dimensional geometry, chucking facility, re-chucking for back-operation and facility to change between main operations and back operations.

* Process improvements - Tornos continually improves its machines for the medical sector and the main technical reason for further improvement to the overall machining process of these difficult materials is to provide the operator with improved versatility and flexibility during setting up work or when retooling.

This can be achieved from pre-adjustable tool systems - available both for the fixed tools and rotating tools.

The setting up or retooling times are significantly reduced, which further reinforces the well-known productivity of the Tornos Deco lathes.

Benefits have also been obtained from the introduction of 'coolant through' tool holders to bring about improved swarf management.

Another addition is the simultaneous machining facility with respect to roughing and finishing (balanced turning), which leads to good swarf management, increased tool life and improved surface quality.

The main sequences for machining a hip screw on the Deco a lathe involve hexagon swaging, external hexagon milling with two tools simultaneously and end piece support, back operation thread whirling in hidden time and back-operation high pressure drilling at 120 bar using a guide bush.