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Inca Geometric has selected a Dugard Eagle 400 lathe to allow it to meet a wide variety of customer requirements.

When the company was considering the purchase of a new, large capacity lathe it had to be a universal specification.

However, topping the essentials of the shopping list of features and benefits were rigidity, a good control system interface and the ability to maintain a good surface finish on aluminium and plastics as well as a range of different steels.

One of the reasons for build quality being very high on the agenda for Inca is a long-standing contract for precision turning components for a customer in aluminium, brass and Perspex that can be up to 550mm in diameter.

Produced in batches of up to 50 a month, the company faces strict quality requirements for the ‘as turned’ surface finish, with the added geometric demands for concentricity, flatness and parallelism.

The heavy duty, 9.5 tonne Dugard Eagle 400 has a swing over the bed of 770mm with a 570mm cutting diameter.

The 26kW spindle is powered by a two-stage gearbox giving up to 2,500 rev/min and the high stability, rigid box ways ensure maximum accuracy and that surface finish is maintained under cutting conditions.

The universal Dugard Eagle 400 lathe was installed in May 2008 and such was the capability of the machine and the support from C Dugard that in August a pre-owned Quaser vertical machining centre with fourth axis and Heidenhain control was installed for further general machining tasks.

18 months before the installation of the lathe, Inca also took delivery of a large TOS W100A horizontal boring machine from C Dugard with Heidenhain five-axis readout to cover the 49in square indexing table and extending quill movements in addition to X, Y and Z.

Inca is very service based, another reason for the installation of the Dugard Eagle 400.

Works manager Tony Clifford describes how it recently had to pick up a large shaft from a power station at midnight, reverse engineer a new part, machine it on the lathe and have it back to the station by 06:00 the following morning ready for its reassembly.

He said: ‘This is where a flexible, universal machine and the Fanuc control pay dividends,’ he said.

A prime example of its production capability is the machining of an aluminium wheel-style component from billets around 555mm diameter by 41.5mm thick.

Originally they were cast, but blow holes were a common problem.

In recommending the switch of raw material to a blank, Inca redesigned the component with its central boss as a separate item to save material which is then machined separately leaving stock material for finish turning.

The boss is then screwed and secured with Loctite into the bore of the main wheel and then finish turned as an assembly with the addition of a screw cut thread on the OD.

Produced in four operations, the profile of the wheel-style component is initially roughed out and bored to accept the central boss then re-chucked and clocked true for the rear to be machined which includes a large scalloped recess in the face.

The rear face is then finish machined and then clamped to a face plate locating precisely from the bore ready for the final profile, to be faced and turned.

The boss is then finish turned true to the bore and threaded.

The part, can be machined from either aluminium or brass and takes around 1hr 15mins to produce but as Clifford says, it is all a matter of product quality not a race against the clock.

Occasionally parts are required in Perspex, which means high levels of care have to be taken to prevent scratching or marking.

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