Dawson Precision Components of Oldham has acquired its first Citizen CNC sliding headstock lathe and has been able to allocate multiple-operation work into single set-ups.By the time that Dawson Precision Components of Oldham acquired its first citizen cnc sliding headstock lathe its intentions for the machine were well defined. Its existing manufacturing resources, comprising three machining centres and 10 fixed head lathes could concentrate on larger sized components produced in small batches while the Citizen L20 provided a means of tackling both larger volumes and small sized, intricate jobs that benefit from a single hit machining process. The capabilities of the Citizen L20-VII bought from NC Engineering of Watford, were such that a second, identical, machine was ordered within months followed by a third machine at the end of 2000.
Jobs which had previously required up to four separate machining operations were being completed in a single set-up and machining time on certain components had already been reduced from 8 minutes to just 90 seconds.
Sales manager Paul Dawson comments: 'Machining performance has been very impressive but what has impressed our customers most is the lead time improvement that the citizen machines have allowed.
They may order a batch of 1,800 components but want to call off 200 at a time.
Before we changed to the Citizen method, they would have had to wait at least a week until the entire order was nearing completion before they saw any parts.
Now they can have them in a matter of hours from the machine being set.' Dawson Precision is very much a family business, employing around a dozen family members as well as about 30 others.
It specialises in high precision/high value added component production for a number of first tier suppliers and OEMs in the aerospace, automotive and laboratory equipment sectors.
More recently, it has diversified into production of components for body jewellery.
A full range of ferrous materials including stainless steels, titanium, aluminium alloy and plastics are processed and turning tolerances can be as tight as five microns on diameter.
'We wanted to install sliding head capacity for some years,' Paul Dawson explained, 'but we had postponed the investment until we had larger premises.
But when this failed to happen, we decided to create a space for the first machine.
This more-or-less coincided with us gaining the contract for body jewellery components which are needed in large volumes and because our first machine quickly ran out of capacity, we bought the second.' Much of the work produced on the Citizen machines is complex, and takes full advantage of the cross milling and drilling as well as C-axis spindle positioning.
One task, for instance, involves production of a hexagonal component in 316 stainless steel.
In the absence of 316 being available as a suitable hexagonal bar size, the only option is to mill the required form.
Whereas, the part was previously machined in four operations.
These comprised: turn blank, followed by drilling and roll tapping on a machining centre, milling the hexagon form on a mill and screw cutting the reverse end on a second operation lathe.
The Citizen machines have the flexibility to combine all those tasks into a single set up.
They can also run through the batch of parts unmanned.
Technical director Frank Dawson remarked: 'We'd been looking at sliding head machines for around 20 years, and had been talking to NC Engineering for quite some time.
What finally convinced us to buy from them was the single source responsibility for maintaining and supporting the whole package.' He continued: 'So far as the machines are concerned, the facility to wind through the program with the handwheel at the control and edit at the same time is great.
In fact, we have found the machines are easier to program than some of our conventional machines.
We also like the way that the tooling is arranged to allow swarf to drop away and the milling capabilities of the machine are excellent.
He goes on to explain how one stainless component, shaped a bit like a flag is made.
It starts out as 14.25 mm bar but is milled to create a flat portion measuring 8.4 mm wide by around 3.0 mm thick.
'We're held to 25 microns across the 8.4 mm dimension and there is also a tight tolerance on the thread, which we roll.
On the same job we have to plunge turn from 14.25 mm to 3.0 mm diameter for threading, and again the machine handles it very efficiently.
The machine copes with the whole process without any problem and is so remarkably quiet you don't know its running.' An equally unusual component for the body jewellery trade is a titanium 'cup' that holds a precious stone which is mounted on a threaded shaft.
The machining sequence is to turn and thread the shaft and then turn the sphere form just past its centre line.
A flat is then milled and drilled to form the cup, and the part-off tool used to roughly profile the remainder of the form of the sphere.
The sphere is then simultaneously finished in the sub-spindle while the original shaft turning operation is performed on the main spindle and is then ejected into the parts catcher.
A bar changeover takes less than 20 minutes, with only the barfeed gripper, Citizen collets and guide bush having to be exchanged.
Dawson Precision has also standardised on bar sizes in an effort to avoid too many changes.
'The machines have proved to be an ideal investment,' Frank Dawson concluded.
'We've had no breakdown call-outs and on a lot of jobs are run unattended through the night.
As well as bringing in new business they've proved to be very effective on existing work.
Since we've had them we've only developed around 40 programs but some of those parts have been produced in 10s of thousands.
Having said that, we had one customer that only wanted 15 highly specialised components that included a 0.5 mm diameter nozzle to be drilled to a depth of 14.0 mm.