Product category:
EDM wire cutting
News Release from: Mitsubishi EDM | Subject: Mitsubishi FX30 wire EDM centre
Edited by the Manufacturingtalk Editorial
Team on 22 March 2001
Wire EDM increases press tool capacity
With the CNC Fanuc and the Mitsubishi FX30 wire EDMs, you have automatic wire threading, so you can load multiple jobs or cut multiple apertures in a job, says Green Bros (UK).
The 'M8 corridor' in Scotland is the home for a large percentage of UK electronics and computer manufacturers It is therefore no surprise that the toolmaker's and subcontract precision engineering companies that support it have embraced new technology in order to meet the demand for high quality products from a very early stage
This article was originally published on Manufacturingtalk on 19 Feb 2001 at 8.00am (UK)
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Fourteen years ago Latkhall-based Green Bros (UK) was one of those companies, and only the second Scottish company to invest in Wire Erosion - what was then, very much a developing technology.
Today, Wire EDM in the shape of a Mitsubishi FX30, plays an important role in shaping this family-owned press tool company, as Co-Director, John Green explained.
'For any press tool maker accuracy is of prime importance to effect a 'best fit'.
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Here at Green Bros, 75-80% of our business is related to the computer industry and therefore the industry's need for ergonomic and aesthetic lines requires us to embrace the best technology available in order to produce press tools with very tight tolerances.
In 1986 our first foray into EDM was the purchase of a Japax Wire Eroder, and although not the 'Rolls Royce' of the industry, it fitted our budget and allowed us to enter the market at an early stage.
We quickly saw that EDM technology would have a great effect on the process of press tool making here at Green Bros and having replaced the Japax machine with a manual Fanuc Wire EDM centre in 1988 we bought two CNC Fanucs in 1995/6.
With our earlier machines, we could only cut a single aperture, then the machine would have to be re-set manually, the wire re-threaded and a new program started.
To cut multiple apertures, the machine would have to be reset for each aperture.
Now, with the CNC Fanucs and the Mitsubishi FX30, you have automatic wire threading, so you can load multiple jobs or cut multiple apertures in a job.
The machines work automatically from aperture to aperture, job to job.
In recent years, larger press tool work had required us to look at extending our Wire EDM facility further, in particular the purchase of a machine with a greater capacity than our Fanuc's.
Controls, filtrationless systems apart, the available technology from the major EDM manufactures is generally speaking on par with one another and although achieving tolerances of +/- 0.0005 was a criterion, size of tank and service were our prime considerations.
Although the Fanuc's have given us no cause for concern they did not offer us a suitable sized machine within their range.
Mitsubishi on the other hand provided us with a front loading submerged wire EDM centre capable of accepting a table weight of 2 tonnes, with the high degree of service we required.' A highly skilled tool design department and extensive CAD/CAM facility running AutoCad 14 generate tool designs for customer approval before sending cutting paths to a server on the shop floor from where operators programme the selected machine.
The operator performs the Wire-EDM programming in which he views apertures and profiles - of one or more individual die pieces - and nests them as sub-routines where possible into one wire-EDM program set-up.
During programming, the operator selects material type - principally mild steel and hardened tool steels - wire type and finish.
In producing a press tool, material is ground and squared up on a Lumsden Grinder before being sent to a CNC milling cell which includes a Mazak horizontal machining centre, capable of accepting tooling up to 4 tonnes.
'We produce the whole of the press tool except pillars and bushes, standard punches and springs.' continued John Green.
'We will bring in the bolsters, preparing top and bottom, drill and tap lifting holes and load up on the Mazak where the remaining work is done in one setting.
Any plates requiring hardening will be sent out for heat treatment.
Every other aspect of press tool manufacture is centred around the EDM cell.' 'In fact,' states John Green, 'whether we are producing a forming tool, piercing tool or progression tool, taking a rough and finish cut to produce punches, die pieces, strippers and punch plates etc, the EDM cell is the profit centre of Green Bros and the Mitsubishi FX30 has allowed us to expanded our capacity.
The four machines are running 24-hours-a-day, 60% of the working week, and with the automatic wire feed on the Mitsubishi, we have the capacity to run a single job up to 60 hours continuous cutting.
Hence we set the long jobs at the weekend.' The Mitsubishi FX30 is a submerged Wire EDM centre of extremely rigid construction, accepting workpieces 1300 x 800 x 345mm.
The entire mechanical structure has been analysed using a supercomputer, and the weight to rigidity ratio greatly improved to achieve high mechanical precision.
Essential requirements of automatic wire feed is reliability and a short cycle time.
The AF3 system uses a thermal wire tip cutting process and a water-jet guidance system, accurately threading 0.1 and 0.15mm diameter wire.
As standard, the Anti-electrolysis (AE) power supply minimises losses in machined surfaces due to electrolytic deterioration or corrosion, enhancing the life of metal dies.
'In terms of time to market' he continued, 'we can produce a full package, chassis, covers, I/O panels, brackets etc, typically 12-16 weeks for our computer customers, although we can prioritise and reduce that time frame.
We also have the facility to try-out each tool and as in the case of Sun Microsystems produce a full capability study.' 'In the early days of Green Bros our highest cost levels lay in the manual work content, such as in fitting and assembly, so we took absolute advantage of the latest technologies available to reduce manual input to press tool manufacture.
We believe we have gained and maintained a competitive edge through new investment and the Mitsubishi Wire EDM is typical of our commitment to our goal.' concluded John Green.
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