Weston EU was looking for a universal machining centre to produce high machining accuracy, present the cutters at different angles and follow variable contour paths to machine complex aluminium wing sections. Based in the UK, Weston EU chose a Unisign Univers 6 vertical machining centre (VMC) to carry out the high speed machining and high metal removal rates from such complex components machined from solid billets. The Univers 6 long-bed VMC is fitted with two rotating/tilting fixtures set up in a pendulum operation, for the continuous five-axis contouring, and achieving virtually 100% spindle up-time.

Each fixture consists of a yoke that is tilted in the X-Z plane from -20deg to +20deg.

AC servo motors using an arc-shaped rack and pinion system on either end of the yoke provide the tilting movement.

The drives are electronically pre-loaded to eliminate drives backlash.

Two NC indexers are mounted on the tilting yoke to rotate the fixture.

The fixture consists of a 760mm X 1300mm cradle, which is mounted between the two NC indexers.

In combination with the tilting movement of the yoke, the rotation of the two NC indexers enable the fixture to be positioned at any angle under the VMC spindle.

The movements are designated A- and B- axis and are interpolated simultaneously with any, or all the X, Y and Z axis, so offering full five-axis machining.

The ram of the Univers 6 has a 25,000 rev/min, HSK-63 E main spindle rated at 55kW.

It features 'hybrid' ball bearings and an automatically variable bearing pre-loading system.

It automatically adapts the spindle to machining loading and increases bearing life.

The ram also features a large integrated water jacket with a refrigerated chilling unit for thermal stabilisation.

Also featured on the Univers 6 is a closed loop control circuit (Vector Control) for controlling the spindle at low speeds, say for rigid tapping.

Machine dimensions include X, Y and Z axis travels of 2000mm (optionally up to 18m), 600mm (optionally 800mm) and 600mm respectively.

Rapid traverse in all axes is 24m/min.

Spindles can be supplied with 27kW/15,000 rev/min, 40kW/25,000 rev/min or, as used by Weston EU, 55kW/25,000 rev/min.