To provide a higher quality service and take full advantage of unmanned machining, Carousel Precision Engineering has invested in a turnkey CNC turning package from Pollard Mori Seiki.

To provide a higher quality service and take full advantage of unmanned machining, Carousel Precision Engineering, based in Holme-on-Spalding-Moor in York, has invested in a turnkey CNC turning package from Pollard Mori Seiki. A Pollard Mori Seiki SL-203S CNC lathe, served by a 2.5 tonne capacity 4m bar feeder and a bar puller, gives managing director Stephen McCracken the flexibility to machine billet or bar and automatically unload short or long components. Short run batchwork jobs are set up and machined during the daytime hours, then Stephen McCracken sets up the SL-203S to machine long production runs during the night.

Leaning on his design engineering background, he has set up his own telecommunications link with the SL-203S's diagnostics system, so that should a problem occur during unmanned running, the machine will telephone him at home for attention.

Stephen McCracken set up Carousel Precision Engineering in 1995, based on using a Taiwanese CNC two-axis CNC lathe and one vertical machining centre.

Facilities include drilling, grinding, finishing and welding.

Much of the turning work had to be completed in two or three set-ups and often, jobs like chamfering and end facing had to be set up separately.

Customer requests for reduced piece-part costs and higher quality, particularly from hydraulics equipment makers, stimulated Stephen McCracken to seek a top quality, high precision CNC lathe with a back-end turning sub-spindle.

He also wanted a machine that could turn long shaft-like components as well as short ones, and perform chucking work on billets too.

Another requirement was for a cell capable of running for long periods unmanned, and be able to automatically off-load long shafts as well as catch shorter work.

While considering a number of offers, Stephen McCracken was attracted to the Pollard Mori Seiki SL-203S CNC lathe which would fulfil his requirements for a machine capable of turning long shafts as well as short bar work.

Another important consideration was the machine specification and build quality as Carousel Precision Engineering anticipated machining highly accurate components.

The rigidity and vibration-damping characteristics of the SL-203S's structure was also attractive, as Carousel Precision Engineering anticipated machining highly accurate components for the hydraulic pump and valve industry as well as tough stainless steel and non-ferrous alloys - such as titanium threaded rings and 'O' seals.

'It was no small decision to make, to purchase a turning cell for a sum not far short of the company's turnover at the time.' Said Stephen McCracken.

That is where Pollard Mori Seiki stepped in, putting him in touch with local financiers willing to support the project.

Initially the cell was set up at Fredk Pollard's factory in Leicester.

The latest, precision, IEMCA Master 880rF bar feeder and an LNS bar puller/unloader were married to a Mori Seiki SL-203S CNC lathe.

As well as a 12-station turret, the lathe is equipped with a sub-spindle.

The LNS bar puller/unloader can draw turned shafts up to 33mm diameter and 850mm in length through the bore of the sub spindle.

The IEMCA Master 880rF bar feeder can take any diameter and profile section of bar from 5mm to 65mm diameter.

Total capacity is 2.5tonnes - reckoned by Stephen McCracken - to be the largest available for the SL-203S.

The SL-203S also has a maximum turning diameter of 390mm and a 510mm diameter swing over the cross-slide.

'Working as a sub-contractor, one never knows what is going to come through the door, that is why I wanted a machine capable of handling shaft-type work,' said Stephen McCracken.

One of the regular jobs is machining hydraulic cylinder tie-rods, ranging from 450 to 740mm long and machined from 16mm or 19mm diameter bar.

Material is EN1A.

After turning the tiebar outside diameter (OD) and threading the end, the sub-spindle is engaged, having carried out a 'handshake' with the main spindle.

It supports the bar during the parting-off and end-chamfering operation.

A second 'handshake' with the LNS bar puller and the sub spindle causes the completed tie-bar to be pulled through and off-loaded.

'This job used to require two set-ups.

The customer has already noted a quality improvement,' said Stephen McCracken.

'I no longer have to carry out two or three set-ups.

Most of the jobs are now done in one set-up.' Another example is a tooling head for a bar twisting machine.

The 'dumb-bell'-shaped head required two set-ups and around 8 minutes machining time to turn two large diameters of 65mm and a small diameter of 28mm, the latter dimension having to be held to +/-2micron.

This job is machined from 4m, 65mm diameter bar one set-up in the SL-203S in 2.5 min.

The tooling head is first faced and turned in the main spindle, picked up by the sub-spindle, parted-off, and then turned, faced and drilled.

When finished, the parts catcher picks it up.

Before, billets were sawn from 30mm bar, and then machined in two set-ups in the older CNC lathe.

The range of work produced in the SL-203S CNC lathe includes brass, non-ferrous and stainless steel alloys.

One of the toughest jobs carried out so far are titanium sealing rings.

'I chose the SL-203S because of its ability to hold tight tolerances, consistently, during long periods of unmanned machining.

Surface quality is also very important to me,' said Stephen McCracken.

'I did consider other makes, but an important factor is the high resale value the Mori Seiki CNC lathes command.

I expect to get some nine years' useful life from the machine, which compares well with four years of cheaper makes.

The machine's higher residual value certainly made it easier to get the financial support to purchase it.

The SL-203S will also be contributing to the companies own product line.

The impact of the SL-203S on turning steam generation and control gear components is such that Carousel Precision Engineering will be able to offer one-quarter-scale live steam, passenger-hauling traction engines at attractive prices and a one-month factory lead-time.

'As far as my customers are concerned, I am making a statement,' emphasised Steven McCracken.

'I have bought a good quality machine, capable of running unmanned, consistently and reliably, and it is attracting new work for me.' The Mori Seiki SL-203 has a standard turning diameter of 210mm, swing over cross-slide of 510mm diameter and 618mm or 752mm between centres.

Bar work capacity is 52mm or 65mm.

The main spindle speed range is 40 - 4000 rev/min and the drive motor is rated at 11/7.5kW.

The tailstock spindle drive is rated at 7.5/5.5kW.

Through bore in the tailstock spindle is 43mm diameter.

The turret accepts 12 tools and has a station-to-station indexing time of 0.2 sec.

Traverse speeds are18m/min and 24m/min in the X and Z axes respectively.

The control is Mori Seiki MAPPS which features conversational programming.

Routines include soft jaw turning, tool list, program editing, work simulation and maintenance management support.