Frequent changeovers determined CNC lathe choice

General engineering company needs as much flexibility in its machine tools as it can get, which is why it sought a CNC lathe to change over quickly and frequently between bar and chuck work.
South Wales based general engineering company D'Arcy Engineering Co needs as much flexibility in its machine tools as it can get and certainly pushes the capacity right to, and often beyond, the limit. As a prime example, its Colchester Tornado 220 two-axis CNC slant bed lathe is used for both bar work up to 65mm diameter and chucking applications to which the proprietor Nigel Allsop maintains: 'We frequently change the machine over from bar feed to chuck or back again inside 10 minutes and we have even stretched its turning capacity from the specified 260mm to 300mm diameter and that's on steel components.' D'Arcy which is a very successful machinist company has its premises on one of the largest business parks in Europe at Llansamlet, just north of Swansea. That said, it still has to work hard to meet its customers demands for quality and delivery in the medical, construction, automotive and general machining sectors which means choosing the right machine for its needs is critical in its success.

Here, the installation of the Colchester Tornado 220 with its integrated MBF 1000 bar feed package bought from Erith, Kent, the new Colchester Sales Technical Centre partner RK International, was seen as important in the plans for future growth.

With a slightly different operation to most subcontract machinists, Allsop has his feet in two camps.

Not only is his general machining operation very successful in supporting locally based international names such as Sony, Bosch and Morganite it has strong links with a prolific local scientific research and development company where it provides a highly successful design for production service.

Set up some 12 years ago D'Arcy employs six people and moved to its current site six years ago when it outgrew its original premises.

At the time of the move, Allsop invested in several CNC machines.

However, to meet the growing production machining requirements for batches that vary between one and 500 parts and especially the fast turnaround the company has to make to customers.

'We then decided to purchase the newly launched Tornado 220,' he says.

Materials now turned on the Tornado 220 include brass, PTFE, engineering plastics and both mild and high tensile steels and while its regular customer base places scheduled orders giving the 'bread and butter' to the business, they tend to be at the top end of the quality spectrum in terms of tolerances and finish.

Allsop describes a recent automotive schedule for aluminium mounting components to be used on high end audio systems in the executive/luxury car market sector.

'These parts had to be machined for the first tier automotive systems manufacturer and had to be totally compliant with their strict drawing and quality demands.

The Tornado met all the requirements for the job and the project was completed with great success,' he says.

D'Arcy's business involvement with the research and development company has placed significant demands on the machine shop on the back of the burgeoning success of a number of products being brought to market.

Here, Allsop' s experience in machining has led to an important boost to this side of the business especially influencing the design for manufacture element, where he can advise and prove the benefit of cost reduction and simplification.

He is also able to help develop features on a design based on the practicality and advantages gained from a particular machine tool, tooling and control system A prime example, which led to gas nozzels, brass pins and mechanical handling equipment for the medical sector being very efficiently produced on the Tornado came out of the design for production development programme.

One particular project, code named Predator, is a gas scavenging system which is currently under development for high quality manual or automatic MIG or TIG welding.

Predator detects the presence of shield gas allowing welding to continue right up to the point when the gas bottles are empty rather than the normal procedure which requires pre-emptive changing of bottles.' The Tornado 220 is powered by a 22kW AC spindle motor which Nigel Allsops' machine setters use to the full explaining that when over capacity turning the 300mm steel billet, the power meter never even moved from its normal position.

The machine was specified with the 3,500 revs/min lower speed option spindle with rapid traverse rates for the VDI 40, 12 station turret being 25m/min in X and 30m/min in Z.

While swing over the bed is 510mm, the maximum turned length is 540mm which is described by D'Arcy's setter as 'very handy' for the exceptional larger part they sometimes have to turn.

According to Allsop, features of the Tornado 220 that have proven to be an excellent bonus is the basic stability of the machine which he puts down to the Duo-stable engineered polymer concrete filled base.

'Even when we put oversize work or really push the machine it is inherently stable,' he says.

And following on to conclude he maintains: 'The thermal properties of the machine are such that it is able to reach operational stability within 10 minutes of start up.'