At a Scottish pipe fittings manufacturer, 10 CNC lathes have replaced two-thirds of the 24 cam-type multi-spindle automatics and all of the company's remaining single-spindle cam autos.
At the Dundee, Scotland, factory of Yorkshire Fittings, two-thirds of the 24 cam-type multi-spindle automatics and all of the remaining single-spindle cam auto's, which once totalled 29, have over the past two years made way for 10 German-built CNC lathes from INDEX. Supplied through UK agent, Geo Kingsbury Machine Tools, at a cost of GBP 3 million, the new machines allow Yorkshire Fitting's pipeline components to be produced economically in one hit, 24/7. The investment followed the acquisition of the former IMI Yorkshire Fittings by the Dutch group, Aalberts Industries, in whose flow control division the company now sits.
Output from the Dundee factory, principally parts turned from brass and gun metal bar, finds its way to the company's headquarters in Leeds, to its Barnsley warehouse, and to a plant in a Budapest, all three centres being responsible for assembly of the firm's products.
Since before the Second World War, the fittings that made the company internationally renowned were of the integral-solder ring type for the plumbing and heating industry.
They were followed some years later by compression fittings.
These two styles are relatively simple to machine, whereas the push-in and press fittings introduced over the past 10 years are much more complicated to manufacture.
It was this increased complexity coupled with a dramatic upturn in production volumes for export markets that in 2003 prompted the Yorkshire Fittings management team to reappraise the production facilities in Dundee.
A local project team headed by planning manager, Barry Stewart, was set up to source new equipment.
Annual output is 15 to 20 million units, giving an indication of the scale of the operation.
Cam automatics are fine for turning simple fittings, and indeed still do, but were unable to produce the more complex types economically, if at all, or to the right quality and consistency.
One of the biggest problems was the production of fittings with multiple bore sizes, as the form drills and reamers needed to produce such fittings on cam machines struggled to hold tolerance.
Single-point CNC turning using standard tooling on modern opposed-spindle lathes was clearly the way forward.
With tolerances fairly open at 0.05 to 0.10mm, practically any make of turning machine could have done the job.
Stewart's prime concern was speed, both of machining and of changeover, as savings in cycle and set-up times have a big impact on profitability in this highly competitive, mass production business.
Some batch sizes are up to 50,000-off, which dictated the continued use of six-spindle bar automatics, but with the flexibility of computer-controlled slides.
There are very few suppliers of CNC multis and Stewart concluded that Index was technologically ahead in terms of the ability to set the spindle speed and feed rates independently at each of the six stations.
Productivity is therefore maximised, as optimal settings can be used and there is no need to compromise the machining parameters at any position.
Two Index MS32C CNC multi-spindle automaticss have been installed in the Dundee plant, the first in 2004.
This set the scene for all of the other turning machine purchases, as it was felt that commonality of machine and control system (Siemens in this instance) was desirable to avoid having to cross-train Yorkshire Fittings' shop floor programmer / setter / operators.
Furthermore, by sourcing all 10 lathes from one vendor, advantageous terms could be negotiated.
Commented Stewart, 'Index is well known for its fast-cycling, high production machines, not only the multi's, but also its twin-spindle, twin-turret bar auto's such as the ABC.' He said: 'We were aware of these machines back in the IMI days, as our Norgren division used them.
They are good, versatile turning centres that are quick to set.' He added: 'So we knew they would be ideal for producing our hundreds of types and sizes of fittings up to 54mm diameter in batches of typically 1000- to 5000-off, but exceptionally up to 10,000- and down to 50-off.' A total of six ABC machines have been installed in Dundee, two of them this year.
Other Index purchases in 2006, apart from the second multi, were a V160G vertical, opposed-spindle lathe for producing large parts, and one of the first C65s in the country.
This novel turning machine consists of an upper turret with XYZ axes capable of working at the main and counter spindles, and a lower, twin XYZ turret.
Both are actuated by sets of kinematic rods behind the slant bed.
That Stewart knew, back in 2004, that such machines with advanced specifications were on the drawing board helped to clinch the business for Index and Geo Kingsbury.
The C65 in particular will be able to improve productivity considerably in the sub-65mm diameter range.
Its ability to tow the opposed spindle synchronously behind back-facing tools on the second, lower turret allows three tools to be in cut simultaneously, a capability normally associated with sliding-head lathes.
Stewart says that some mill-turn cycles on the C65 have been reduced by as much as 25% compared with cutting the same part on a conventional, twin-spindle, twin-turret CNC lathe.
Finally, the V160G offers advanced machining capability for producing large fittings up to 130mm diameter, which are being ordered in much larger quantities since the acquisition by Aalberts Industries.
Turned from billets fed from a dedicated bandsaw, the fittings are somewhat atypical in that they require their flats to be milled, rather than polygon turned as on all the other machines.
The self-loading capability of the hanging spindle, whereby the chuck picks billets sequentially from a conveyor and returns the fully machined component, avoids the expense of having to use a separate handling device, such as a robot or gantry loader.
Concluded Stewart, 'The creation in Dundee of Yorkshire Fittings' centre of excellence for turned parts has had a profound effect on our business.
We now have a lean manufacturing plant able to produce all of our components reliably, repeatedly, in tolerance and economically, ensuring that we will continue to be a world leader at the quality end of the pipework fittings industry.'