Two Tsugami-Mori BS20-III CNC sliding head automatics are now performing continuous 'lights-out' machining on tough spray gun components, formerly produced in the Far East.Two Tsugami-Mori BS20-III CNC sliding head automatics are now performing continuous 'lights-out' machining on tough spray gun components, which were formerly produced in the Far East. RDL Technologies based in Leicester chose the Tsugami-Mori's as the only machines capable of performing the work reliably and unmanned. RDL Technologies wanted a reliable CNC sliding head automatic that would consistently turn and cross-drill precision components from tool steel and stainless steel bar under 'lights-out' conditions.

After searching the market, the company chose two Tsugami-Mori machines from Fredk.

Pollard and Co in Leicester.

'We asked ourselves the question: 'Do you leave a bar-fed CNC automatic running under 'lights-out' conditions machining difficult tool steels and 'sticky' stainless?

'said RDL's Works Manager, Raymond Lockwood.

'With the Tsugami-Mori's, we have had no problems.

We are more than comfortable in running the two machines unmanned.

We re-tool the machines at six in the evening, check them briefly at nine and then let them run 'lights-out' and unmanned through the night.' The main job is a piston and cylinder assembly for a DIY spray gun.

It was this job - a rolling three-year, œ1m contract - which was won on the basis of using a CNC sliding head automatic.

The customer had previously produced the spray gun in the Far East, but had become dissatisfied with quality and delivery.

Nor could any company there really cope with the quantities required.

The work was brought back into the UK and the sub-contact machining put out to open tender.

Although Raymond Lockwood and his brother partner Gary Lockwood - who had partly financed the venture - had grown up on fixed-head machines, they realised the potential of producing the most complex item - the cylinder - in one set-up in a CNC sliding head automatic.

Initial machining trials were carried out and a proposal was put to the OEM.

Once having won the œ1m contract, RDL researched the CNC sliding head automatic market and chose a Tsugami-Mori BS20B-III and BS20C-III to do the work.

Each is equipped with an LNS Hydrobar Express bar loader - the 326 S2 MSC J01D model on the B' machine and the 226 model on the C' machine.

'Once we had the contract sorted out, we put a proposal forward to Fredk Pollard, which was assessed by Simon Pollard (Deputy Managing Director) and Jim Healey (Product Manager),' explained Raymond Lockwood.

'They decided to back RDL and a 'rent-to-buy' agreement was drawn up.

It is a very flexible deal for us.

Payment is structured in proportion to our cashflow and the standing value of each machine.

Simon Pollard liked the idea and was very much in favour of building up such relationships.' 'We chose the Tsugami-Mori machines, partly because they are recognised among turned parts producers as the 'Rolls-Royce' among sliding head automatics,' said Raymond Lockwood.

'In engineering terms, we wanted the extra power of the Tsugami-Mori live tooling.

We had discussed the job with other sliding head automatic suppliers, but they were rather sceptical about the drilling of the cross-holes 'from the solid' using solid carbide drills.' 'Important considerations too were that the Tsugami-Mori machines are easy to change over from different bar sizes.

Everything is at the front end, whereas on other makes, it is all done from the rear.' Raymond Lockwood said that other comparisons such as fast traverse feedrates, spindle power and so on, were 'much of a muchness' from machine to machine.

'We like a good solid machine.

The Tsugami-Mori's are very rigid in structure and have excellent vibration-damping characteristics which helps cross-drilling in materials like tool steels.' Cylinders machined in one set-up.

The cylinder for the spray gun is machined in one set-up from 10mm drawn-and-ground stock of H13 tool steel of 35-40RHC hardness.

Each cylinder is 34mm long and 10mm diameter.

The mating piston is turned down from 5mm drawn-and-ground stock of Type 440C stainless steel.

The cylinders are heat-treated to 50-55 HRC and honed to within a tolerance of 5 micron on diameter.

The pistons are centreless ground to a tolerance of 5 micron.

In service, the piston reciprocates inside the cylinder for 7-8mm at 100 strokes/sec.

To machine the cylinders, bar is fed forward to a stop in the Tsugami-Mori BS20C-III, centre-drilled, and the bore drilled to halfway using static tooling.

At the same time, the second spindle performs chamfering, and reams the bore of the previous component to within a tolerance of 20 microns and releases the cylinder to the parts catcher.

The sub spindle then moves to a position to pick-up the new cylinder, drills the bore to full depth, while live tooling performs the cross-drilling and machining of a location dimple on the cylinder's perimeter.

The sub-spindle then picks up the cylinder, which is then parted-off from the bar, and takes it to the chamfering and reaming tools while the bar is fed forward again.

The combined operation takes 65.5s.

The pistons are produced in a cycle time of 19.5s on the Tsugami-Mori's BS20B-III.

The bar is fed to a stop, faced and turned and then a 3mm wide groove is plunge form-turned in the circumference.

The sub-spindle then picks up the piston, which is parted off, then presents it for back-end facing.

The tolerance on the relationship between the start of the groove and the front face of the piston is 50 microns.

'Therefore tool life is important,' said Raymond Lockwood.

'We are using grooving tools from Horn, Germany, and we have established the minimum life.

We religiously change the tools after so many components, even if the tool appears to be OK.

You can not take risks when machining parts at 180/h unmanned.' The same philosophy is practised on machining the cylinders.

RDL carried out a lot of tooling development.

For example, it discovered that solid carbide drills proved to be too brittle for the solid drilling of the 5mm bore in H13, and there was a swarf clearance problem.

'The material likes to 'string', so we use a standard Titex cobalt-tipped HSS drill, having optimised speeds and feeds and pecking depth,' said Raymond Lockwood.

The problem with reaming H13 was that a six-fluted reamer, when worn, would pick-up and score the bore.

'We have to leave 30-50 microns on the bore diameter for honing, so we established the very minimum life for the reamer.

Once a reamer has done 2000 cylinders, it is taken out and re-ground.' 'Tool life is very important on a job like this.

The nature of the material demands a strict tool management discipline,' emphasised Raymond Lockwood.

At present, RDL is running the two Tsugami-Mori's on two long 10h shifts/day, seven days/week.

The company is building up a stock of cylinders and pistons for the customer, before entering a into a more routine supply service.

RDL fell very quickly into the setting-up and programming of the Tsugami-Mori's as Raymond Lockwood and his personnel had already some considerable experience of programming fixed-head CNC automatics and were used to running two programs in tandem as required in twin-spindle sliding head automatics.

'The machines are running at capacity, but once we have finished ramping up the customer's stocks - which is part of the contract - we will have established a good base from which to offer a sub-contract service,' said Raymond Lockwood.

'We will be offering a first-class quality job, with on-time deliveries at competitive prices,' said Raymond Lockwood.

'We will not be the cheapest, but we will offer the best.' Tsugami-Mori BS20-III CNC sliding head automatics The TSUGAMI-MORI BS20-III Series has a working bar stock capacity of 6 - 20mm, maximum machining length of 210mm and a spindle speed range of 200-8000 rev/min on the main and sub-spindles.

The main spindle is rated at 2.2/3.7kW and the sub-spindle at 1.5/2.2kW.

The driven spindles for cross-drilling and milling are rated at 0.9kW and 200-5000 rev/min and the driven spindles serving the sub-spindle are rated at 0.5kW and 200-4000rev/min.

The B' variant operates seven OD static tools and three cross-drilling tools.

There are four static and two driven tool stations for ID work and three static tools for back-end machining.

The C variant has five static and three driven tool stations for back-end working.

The CNC used is the GE-Fanuc 18i-TA for five-axes for the B variant and 6 axes for the C variant operation.

Interpolation functions include linear and circular.

There are 32 pairs of programmable tool offsets.