Product category:
Abrasive machining - manual and CNC machines
News Release from: 600 Centre | Subject: Okamoto ACC 450 DXA surface grinding machines
Edited by the Manufacturingtalk Editorial
Team on 22 May 2002
Programmable surface grinders reduce
lead times
The installation of two programmable surface grinders has allowed toolmaker Tarpey-Harris to reduce lead times by up to 25% and optimise grinding times for dies, moulds and precise parts.
The installation of two Okamoto ACC 450 DXA surface grinding machines by 600 Centre of Shepshed, Loughborough has allowed the Belper-based toolmaker Tarpey-Harris to reduce lead times by up to 25 per cent, have one operator to look after both machines for most of the day and optimise grinding times for a wide range of dies, moulds and precision parts In addition, the company has found the Okamoto machines very easy to operate and to make its purchase justification more significant, the final machine specification worked out 20 per cent less than comparable surface grinders on the UK market
This article was originally published on Manufacturingtalk on 22 May 2001 at 8.00am (UK)
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Established in 1969 as precision engineers and toolmakers specialising in tooling for the investment casting industry, Tarpey-Harris is now part of the Fairbrook Group.
The 32-strong Derbyshire company produces extrusion dies, injection mould tools, rubber mould tools and wax pattern dies that are mainly used for plastics window elements and profiles as well as cladding for buildings.
The wax and rubber tooling it produces is primarily used in the manufacture of seals for hatches, doors and other openings for the aerospace industry.
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However, the company also manufactures injection mould tooling for a range of medical products and provides a component machining subcontract service for an array of different industry sectors.
With over 80 per cent of its machining work involving tool production, grinding is therefore a key process.
So when the company decided to replace a couple of ageing manual surface grinders it looked around for the most suitable machine on the market in terms of performance, accuracy, ease of use and especially set-up and cost effectiveness.
As works director Tony Harris explained: "After seeing an Okamoto 450 DXA in action at a 600 Centre customer, we decided that this machine was ideal for our needs, combining precision with affordability.
Since installation the repeatability, ease of operation and minimal manning requirements of the machines has transformed our business.
I look out of my office window and they are running throughout the day with hardly anybody ever near them." Some 90 per cent of the company's surface grinding work is now channelled through the Okamotos for processing a wide range of die parts, bolsters, die blocks, top plates, ceramic core dies plus a range of blank strips for components which are subsequently profiled by wire-cut EDM.
Work can range from grinding the ends of 3 mm by 5 mm probes right up to quite large bolster elements, measuring 350 mm by 400 mm.
Although the table of the Okamoto ACC 450 DXA is hydraulically actuated, the machine includes a fully automatic grinding cycle controlled via microprocessor with digital readout (DRO) in two axes.
"This provides us with maximum flexibility in terms of just how the machines can be operated," maintains Tony Harris.
Each of the Okamoto grinding cycles tend to be split between various modes of operation for which a quarter accounts for manual and semi-automatic cycles but fully automatic operation is now applied to half the work flow passing though the machine.
Depending on the mix of work, one man can look after the two machines for most of the time and in a typical working day, the operator is only present at the machine for as little as 12 per cent of the time which includes wheel dressing, outlines Tony Harris.
He maintains: "This means we get 16 hours worth of production from the two machines each day with an operator input of around two hours." However, he says: "The biggest single saving has been the ability to measure components directly on the machine using its integral, two-axis DRO.
Here the contribution to productivity is much higher because parts do not have to be removed from the table to perform key measuring tasks and we reckon this reduces our lead times by some 20 per cent.
While the Okamoto's automatic operation, using auto downfeed and crossfeed has proved of major benefit to the company, this feature was not high on the list of priorities when the machine was initially selected.
As Tony Harris recalled: "Coming from purely 'hands on' manual machines, we were not too fussed about automatic cycles.
However, now that we have such an easy to use facility, we are making more and more use of auto cycling on specific types of work because it is dramatically increasing the flexibility of labour.
Combined with quick set-up routines, the Okamoto machines have proved to be a really sound investment and their repeatability is first class." Equipped with 450mm by 150mm magnetic chucks, the Okamoto machines are used on a wide range of tooling work - much of it involving hardened steel elements.
Typical metal removal rates on hardened die blocks, for example, is about 0.5mm and tolerances as tight as two microns are regularly achieved.
Maintains Tony Harris: "Surface finish is another important consideration, particularly on mould type work, and the machines regularly produce finishes to 0.05 micron Ra." The installation of the two Okamoto machines has made a big impact on surface grinding efficiency, accuracy, productivity and cost-effectiveness.
And as Tony Harris concluded: "When we need additional surface grinding capacity we will undoubtedly go back to the 600 Centre, because these two machines have transformed the way we were working.
Without any doubt they have proven to be an excellent value for money investment.".
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