Product category:
CNC automatic lathes
News Release from: Citizen Machinery UK | Subject: Citizen M20 sliding head automatic lathe
Edited by the Manufacturingtalk Editorial
Team on 26 November 2002
CNC sliding head auto attracts new
business
Progressive subcontractors are always looking to sharpen-up their performance and seek opportunities to secure new work, a sliding head CNC auto did just that for a Middlesex company.
Progressive subcontractors are always looking to sharpen-up their performance and seek opportunities to secure new work Purchase Engineering in Middlesex is one such go-ahead machining specialist and with the addition of one of the latest Citizen M20 sliding head automatic lathes, supplied by NC Engineering of Watford, the Stanmore-based company has achieved both business objectives
This article was originally published on Manufacturingtalk on 27 Apr 2004 at 8.00am (UK)
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Says joint managing director John Purchase: "We make good use of our Citizen CNC lathes that's why we have 10 running round-the-clock, seven days a week in our sliding head section.
However, despite the impressive speed and all-round performance of these B and L series machines, we still felt we were missing opportunities to attract new work which required heavier milling type operations." He follows on to explain that when Citizen introduced its M20 sliding head lathe with a large and robust lower-mounted turret and forward facing driven tools, they just knew the configuration was a winner to enable them to remove material faster, maintain tolerances and geometric relationships between features.
"It would also allow us to effectively quote for certain types of job where we had been uncompetitive," he said.
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Founded in 1978 and currently employing 40 people, Purchase Engineering produces a range of fairly complex precision turned and milled components for the hydraulic, automotive, medical, electrical, motor sport, bearings, dentistry and nuclear sectors.
Tolerances can be as tight as five microns and around 80 per cent of its turned parts require some sort of milling operation.
Typical components include armatures, bearing races, spindles, connectors and parts for power steering units and diesel pumps.
These are machined in batch sizes between 100 and 30,000.
Installed some 18 months ago, the Citizen M20 has certainly lived up to expectations in terms of speed, versatility, rigidity and performance on work up to 20mm diameter.
This top-of-the-range, 13-axis Citizen lathe has improved machining efficiency on a number of existing projects for Purchase Engineering, reduced setting times and enabled the company to win new business by virtue of its powerful milling capability and flexibility generated from its 80 tool carrying capacity.
As John Purchase outlines: "Around 30 per cent of the work currently being processed on the M20 is new which we just could not have economically produced before on any of our sliding head CNC lathes." A typical set-up carries around 32 tools which are divided between a vertical tool holder, the 10-station turret and a back-machining slide.
Even though the machine has the capacity to accommodate such a large number of tools, quite a few tend to be common across a number of jobs and so are left permanently in position.
This helps speed the changeover between different jobs.
In addition, while the tooling layout of the M20 makes it much easier to access for setting tools, as the working area is larger than other lathes, this has also contributed to the reduction in setting times of about 10 per cent across the range of work.
However, it's the performance of the rigid, 10 driven station electric turret which has proved to be of particular value in the quest for new and more complex machining work at Purchase.
For its powerful milling capacity and ready access to any number of component surfaces enables much higher stock removal rates to be applied and larger end mills and slitting saws to be used.
In the words of John Purchase: "This certainly gives us added flexibility and leads to more cost-effective production." For example, one new component on the M20 is an electrical cable connector for the Formula One racing industry.
Required in a batch of 100,000, these 15mm diameter by 10mm long components are produced from solid aluminium bar and have a 10mm diameter through bore.
While tolerances are generally within 20 microns, the connectors require a relief form machined around the periphery of the three main bayonet locations plus a broached step in each of these fixings.
These features can only be machined using tools located on the M20's lower turret.
Meanwhile the more standard operations require profile turning, slot milling and knurling in a cycle time of approximately 60 seconds.
Says John Purchase: "We just could never have produced these special forms prior to the arrival of the M20." Another new component highlighting the capability of the latest Citizen is a shop fitting, also produced in batches of 100,000.
Measuring 16mm diameter by 20mm long, these brass parts involve basic turning, drilling and the tapping of two 4mm diameter holes and the machining of two slots.
But it is the size and position of these slots, which is best described as 'tricky' and could never have been effectively machined on any other of its sliding head autos due to the adversely long time cycles involved.
"However, the M20 takes all this in its stride and produces complete fittings in a one-hit machining cycle time of 75 seconds," says John Pur chase.
The main, centrally positioned slot measures 9mm wide by 10mm deep and it is the shear size of this feature, that would have caused problems as only fairly small and thin-section slitting saws could have been used on the existing sliding head lathes.
While the second 1.5mm wide by 8mm deep slot is radially positioned at the top end of the fitting, its position would have been hard to access and once again it was just too deep at half the body diameter to be produced using available endmill tooling.
But once again, the rigidity and power of the turret combined with the accessibility it provides, allows the M20 to machine the main slot with an endmill and the peripheral slot with a slitting saw.
The company is a firm believer in the use of automation and unmanned working which is reflected by the fact that only five people are required to look after some 28 CNC machine tools.
The 10 Citizen sliding head CNC lathes are sited together on a 6,000 (square feet) mezzanine floor and they run virtually unattended all the time.
Programming is carried out off-line, while a DNC link transfers part programs as required to all the machines.
With so much experience of automated machining John Purchase sums up the benefits of the M20, that its all-round performance is a factor of the high functionality and its rigid and highly stable design. Request a free brochure from Citizen Machinery UK ...
"The multi-station turret has certainly provided us with a very powerful milling capability which has enabled us to widen our machining scope and win new business.".
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