Product category:
CNC turning centres, mill/turning, multi-tasking centres, horizontal and VTLs.
News Release from: Matsuura Machinery | Subject: Twin-spindle, front-loading CNC lathe
Edited by the Manufacturingtalk Editorial
Team on 12 April 2007
Front loader twin-spindle lathe halves
labour cost
At a supplier of precision transmission components, a twin-spindle, front-loading CNC lathe with gantry loader has halved the labour cost over three shifts, producing 58 clutches/h - a 130% increase.
Having fought back from the 'brink' of closure in 2003, Cramlington Precision Forge (CPF) has since increased its annual turnover by 40% to GBP 4.5 million and plans to quadruple it again within the next five years The 55-employee company is a tier 1 supplier of precision forged rear axle bevel gears, pinions and other transmission components to manufacturers of heavy-duty vehicles in Europe and the USA
This article was originally published on Manufacturingtalk on 21 Jun 2001 at 8.00am (UK)
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Two recent contracts have consolidated the company's position, one from MAN in 2006 worth GBP 1 million annually for the supply of dog tooth sliding clutches; and another GBP 500,000 per year deal in early 2007 to produce bogie gears (a combination of a precision forged differential gear, helical gear and clutch) for Scania.
To cope with the consequent rapid increase in turning, Coalville-based Matsuura Machinery has supplied a Muratec MW200G twin-spindle, front-loading CNC lathe with gantry loader to the Cramlington factory.
It was the firm's first true piece of automated production machinery, although it has for many years operated semi-automatic, six-spindle chucking lathes and an array of stand-alone CNC turning centres.
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Said CPF's managing director, Steve Rose, "When we started turning the MAN clutch forgings, we needed two people to operate a single-spindle CNC lathe and an internal broaching machine, and hourly production output was 25 components.
Now, one operator is able to look after the automated Muratec lathe and the broach, halving the labour cost over three shifts.
Moreover, 58 clutches/h are machined - a 130% increase.
"These impressive figures, together with minimisation of scrap and reduced need for post-machining inspection, will result in rapid return on our investment in this world class cell for clutch manufacture." It was CPF's takeover by Indian company, Sundram Fasteners (TVS Group) and the new owner's willingness to invest in modern machine tools that saved the Cramlington company and prevented the work from being transferred to Hungary.
The reversal in fortunes is an object lesson in the importance of updating manufacturing plant to compete in a global marketplace.
The policy saw the commissioning at CPF in early 2007 not only of the Muratec lathe, but also of a Gleason gear cutter and a 4,000 tonf (40MN) forging press that extends the maximum weight of forgings that can be produced to 30kg.
When researching the best alternative for automated turning, the options of choosing vertical-spindle and single-spindle horizontal lathes were considered, but two machines would have been needed to meet the required production rate.
Both solutions were too costly and so were rejected.
A twin-opposed spindle lathe was not appropriate, as the clutch forging is turned at one end only.
A twin-spindle, front-loading CNC lathe with gantry loader, operated like two separate turning machines, was identified as the most economical method of production.
There are a number of such machines on the market and CPF's manufacturing engineer, Swinhoe, advised that they had considered nine suppliers.
The list was quickly whittled down to one, however, as only the Muratec machine offered spindles of sufficiently high power - 22 kW - to allow a 58mm diameter, indexable-insert tool to drill through the largest 8620H clutch forging in a single pass.
This is a difficult job in solid, case hardenable, nickel-chromium-molybdenum steel.
Before placing the order, Rose and his production team satisfied themselves that machines supplied by Matsuura Machinery have a good reputation amongst users for reliability and longevity.
As the five variants of MAN clutch would tie up the machine for 24h/day, five days a week plus weekend working, uptime was of the essence.
Matsuura also scores exceptionally well for after-sales service, including rapid provision of spares from a large stockholding at the UK company's headquarters and technical centre.
This applies equally to machine tools sold under agency agreements, in this case with Murata Machinery of Japan, as it does to machines built by the Coalville firm's eponymous Japanese parent.
The anecdotal evidence for reliability was confirmed by a visit to a Muratec twin-spindle lathe user - a gear manufacturer in Stockport - whose production engineers were enthusiastic about the equipment and level of support they receive.
The Murata MW200G twin-spindle lathe was delivered to CPF just before Christmas 2006 as a turnkey package, complete with part programs, Iscar tooling and Marposs in-process gauging in the 10-station turrets, and two weeks' on-site training for three CPF operators.
A 30-part run-off was carried out by Matsuura at Cramlington to prove process capability and the system entered full production during the second week in January 2007.
Batches of around 180 forgings are delivered by lift truck to the cell and are loaded by the operator onto the MW200G's 14-station input pallet, which has a capacity to hold 56 of the largest clutch forgings.
At start-up, the gantry-mounted gripper loads a precision forging into the left hand spindle, which grips it on the diameter of the already-forged clutch teeth.
The gantry returns to pick up a second blank, which is similarly loaded into the right hand spindle.
The cutting cycles are consequently staggered, taking just over two minutes per component, allowing the gantry time to offload the first turned component onto a conveyor and replace it with a fresh blank before being required to do the same at the other spindle.
In this way, continuous production is maintained.
Machining operations involve profile turning the outside diameter (OD), facing and boring.
General tolerance is +/-0.1mm, although bore diameter is tighter at 0.05mm total allowance.
To prevent tolerance drift and maintain process capability, offsets are applied automatically by the control to compensate for tool wear.
The OD, length and bore diameter of every fifth clutch is checked using the Marposs gauges, before the component leaves the spindle.
Any part that is not of the required accuracy is taken by the gantry loader to a reject station incorporated within the machine, but this is a rare occurrence.
Turned clutches are transported via the conveyor to a vertical, multi-station broaching machine where the operator loads the parts manually for generation of an internal straight spline.
Current production rate is 3,000 components/week, with one changeover for each of the five clutch variants.
Regular deliveries are made directly to MAN's factory in Munich, Germany.
Concluded Rose, "Automation and lean manufacture are very much the future for CPF, as they allow us to resist international competition.
Following the success of MAN clutch production, we have already looked at turning the back face of the Scania helical gears using spare capacity on the Murata lathe." He said: "We are now about to automate production of differential gears for DAF, for which we are considering ordering a second twin-spindle front-loader from Matsuura.".
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