A turned parts subcontractor has transformed its business since converting from plug board operated automatics to computer-controlled production lathes.
Poole-based Winton Precision Engineering is a classic example of a turned parts subcontractor that has transformed its business since converting from plug board auto's to computer-controlled lathes. The company's first CNC turning machine was installed in August 1997 and just two years later there were no manual machines on site. Latest acquisition is an Index ABC lathe from Geo Kingsbury.

The machine was installed mid 2000, bringing Winton's tally of CNC turning machines to eight, five of which are bar-fed.

The big difference with the Index lathe, however, is its ability to produce components complete in one set-up, allowing longer runs up to 10,000-off to be produced economically.

To this end, a full length Index magazine for 3.2 metre bar has been fitted.

Said Winton's owner, Peter Kenchington, 'A typical hydraulic coupling that was previously produced from 30 mm hexagonal steel bar in two operations on separate machines used to take a total of 2 minutes 15 seconds.

Now the same part comes off the Index complete in just 50 seconds and this could be improved upon further.

Moreover, there is no work-in-progress taking up space on the shop floor.' The component requires OD turning, undercutting, single point threading, drilling, and turning of an internal cone profile on the front end.

A synchro spindle in the top turret supports the machined end during part-off; then presents the component to end working tools mounted above the spindle for facing, counterboring and chamfering.

Finished components are dropped into a parts catcher and emerge on a conveyor at the right hand side of the machine.

'Much of our work is hydraulic parts for tractors and earthmoving equipment and deliveries have to be just-in-time,' continues Mr Kenchington.

'However, to ensure that we have a buffer stock to guarantee JIT supply, we tend to run off batch quantities sufficient for several months.

This also allows us to benefit from the economy of longer runs once the machine is set up.' Tolerances that Winton is required to hold are fairly open at 50 microns, well within the capability of the Index ABC.

However, with one-hit machining there is no danger of accumulative error due to repeated set-ups, so repeatability of component dimensions throughout a batch is significantly better.

Most parts are produced from steel bar, some in brass, and hexagonal rather than round stock is used to avoid polygon turning of bolt flats.

Nearly every component Winton produces needs a second operation on the reverse end.

In the first 18 months of service operating a double shift, 6 days a week, only 10 different parts were put on the ABC, such is the length of batches and the frequency of repeat runs.

Programming is carried out on the shop floor using the C200-4 CNC.

Peter Kenchington is now looking to expand the variety of components he produces to include diesel fuel injector parts requiring cross hole drilling.

This will allow him to take advantage of the lathe's driven tool capability and increase still further the added-value content of the components he supplies.