Manufacturers of large, heavy components are increasingly demanding the capability to machine them in a single set-up to achieve short leadtimes, improve accuracy and reduce work in progress. Aimed at these users is the new Okuma VTM-1200YB from UK agent, NCMT.

The 30 tonne, double column machine has been designed as a cross between a heavy-duty vertical turning and boring facility and a fully featured, 5-axis machining centre. Structurally it is configured as a bed type machining centre but instead of a conventional table it has a 30kW/500rpm/6,000Nm torque turning spindle with 360,000 increment C-axis positioning.

The table has a pair of large cross section X-axis slideways carrying a substantial column with vertical Z-axis slides. These in turn locate a saddle with Y-axis cross slides to support a 37kW/10,000rpm/505Nm milling spindle (B-axis) with HSK-A 100 taper. By locking it using a Curvic coupling, turning operations on components up to 1,200mm diameter by 1,080mm long can be carried out without risk of damaging the bearings.

150° B-axis positioning allows standard tooling to be used in situations where specials might otherwise have to be considered. In addition, it is possible to improve milling efficiency when using ball nose cutters by using the tool at an angle to avoid zero surface speed cutting at the tip. Similarly, angled holes can be produced without the need for special fixtures using a three dimensional coordinate conversion facility within the control software.

The standard tool magazine houses 60 cutters and a common taper standard is used for both milling and turning. Through tool coolant rated at 150 bar ensures efficient cooling and chip control, especially when working with tough materials such as titanium and Inconel.

Axis travels are 1,270mm in X, 1,080mm in Z (vertical), and 1,000mm in Y. Absoscale linear encoders guarantee 0.1µm feedback. Rapid traverse rate is 32m/minute in all linear axes, 20rpm for the 360° C-axis and 19.5rpm on the B-axis. Control is via Okuma's own OSP-P200 CNC system.

During simultaneous 5 axis milling, tool centre point control and Super-NURBS ensures high contour accuracy and surface finish. In combination with Okuma's Thermo-Friendly Concept, even if the ambient temperature changes, a user can achieve accuracies better than 10µm the company claims.

Options include a pallet change system, allowing the machine to be configured as a semi-automated, standalone machining cell.

NCMT
www.ncmt.co.uk