Highly productive centre mill-turns precisely

Twin-turret lathe with C-axis on the spindle for highly productive turn-milling maintains exceptional concentricity for a machine of this class, said the builder.

A new, twin-turret lathe with C-axis on the spindle for highly productive turn-milling has been introduced by Okuma and is offered in the UK by NCMT, sole agent for the Japanese manufacturer.

Called Simul Turn LU300-M, the machine is of 45 degree, slant-bed, box-type design that minimises thermal growth.

When cutting a test piece in the Okuma factory, there was only 10 microns movement over a 25 hour period and maximum out-of-roundness on the spindle rotating at 2,500 rev/min was measured at 0.4 micron.

Such figures are impressive for a machine of this class.

A notable feature is the compact, 7/3kW (20 min/cont) motor that indexes the upper turret and rotates the 12 live tools as well, whereas other turn-mill centres use two separate motors.

The patented design is 92 per cent efficient compared with 82 per cent for a normal induction motor, resulting in energy savings.

An added benefit is the reduction in heat generated within the turret, which is of necessity close to the component being machined.

Station-to-station index time is 0.2 second and the VDI quick-change tools are rotated at infinitely variable speeds from 45 to 4,500 rev/min.

The lower, 8-station turret does not have driven tools.

Cutting capability is 370mm maximum turning diameter by 600mm (optionally 1000mm) centre distance if a tailstock is fitted, the latter having 120mm of quill travel.

Despite the high capacity, the machine occupies just over six square metres of factory space (nine square metres for the 1000mm-between-centres model).

Speed of production is paramount in a competitive market place, so the LU300-M offers 20 and 25m/min rapids in X and Z respectively.

The integral, 22/ 15kW standard motor spindle provides stepless speeds to 5,000 rev/min, or 3,800 rev/min for the large (80mm) bore option.

Control is by Okuma's own OSP-E100L CNC, which is able to learn the user's shop floor practices as each new job is put up on the lathe.

It is an integral part of the company's 'IT Plaza' intranet, utilising a browser to offer guidance on how best to machine the component.

It simplifies the creation of the optimum machining plan, work procedure, tools and cutting conditions, and an on-screen simulation facility allows the program to be checked before it is run.

A larger turn-mill lathe in the same series is available, designated LU400-M, with 420mm diameter turning capacity.

There are also versions of both machines without live stations in the upper turret.

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