Product category:
EDM wire cutting
News Release from: 600 Centre | Subject: Robotised EDM cell
Edited by the Manufacturingtalk Editorial
Team on 28 October 2002
Robotised cell produces powder
compacting dies
A robot, working as part of an unmanned wire cutting electro-discharge machine cell, is providing round-the-clock production of powder compacting die tools.
Dougie is the name given to a Fanuc robot, working as part of an unmanned wire cutting electro-discharge machine (EDM) cell at General Carbide Europe Installed by 600 Centre of Shepshed near Loughborough it is providing round-the-clock production of powder compacting die tools used in a wide array of industries including oil, medical, cold forming and mould tooling
This article was originally published on Manufacturingtalk on 22 May 2001 at 8.00am (UK)
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Why Dougie? Rod Print, Director, explains: "We have a 75 year old general handyman who has been with us for eight years.
He is so fit, he still insists on showing us how he can perform hand stands and beavers away at his duties, non-stop between 8 and 11 each day.
The wire EDM cell is the same - it never stops.
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It works longer than the human Dougie which can be up to 40 hours without a break, which is governed by the 10kg spool of 0.25mm diameter wire running out.
When unmanned at night, we reckon it costs less than the Government minimum wage per hour." General Carbide Europe was set up in 1989 adopting its name from its principal, General Carbide Corporation of America and holds the sole distribution rights for UK and Ireland for supplying sintered tungsten carbide pre-formed blanks.
The blanks are also used by the Daventry operation to produce hard metal products of which 60 per cent are oil industry related.
The company is also changing fast into other sectors such as automotive related and expanding to export markets as far afield as the Far East and China.
Co-directors Rod Print and Mel Knowles have been good customers of 600 Centre having installed two Okamoto IGM-15NC internal grinding machines for grinding the bores of its range of tungsten carbide hard metal wear parts, extrusion dies and powder compaction tablet tooling.
It was when the two directors came along to Productivity Partnerships exhibition at 600 Centre in October 2001 to purchase a third grinder that the concept involving the robot and wire EDM came about.
As they walked around the showroom they saw a demonstration of a robot loading a Fanuc wire EDM which set them on a completely different production tack.
With the Fanuc cell installed, it now runs during the day with minimal attention which tends to focus on loading and unloading pallets and program updating.
But for at least 100 hours a week, it is totally unmanned.
The result is that the final grinding time of dies has been further reduced by half, it had already been reduced by 50 per cent when the CNC Okamoto was installed, and a totally new production strategy means lead times for dies has been cut from between six and seven weeks to under two weeks.
In addition, this has been achieved without increasing labour, and without going to second shift working which the addition of the third Okamoto and a rising order book would have entailed.
The Fanuc cell comprises a Robocut Alpha OiA wire EDM with Series 18i-W control and a Fanuc LR Mate 200i robot.
The robot works between two aluminium pallets peppered with a variety of hole sizes to suit the carbide dies to be machined and a final dip tank to clean the part after processing.
The robot selects the component blank from the pallet, loads it to a common pneumatic fixture for all the dies, the bore of the die is wire cut to the programmed form, unloaded, washed and put back on the pallet.
The various die internal diameters to be machined vary between 5 mm and 11 mm and between 22mm and 38mm in length.
However, all have a common start or core hole of 3mm diameter in the centre.
Bore profiles vary according to customer requirements, which also govern the up to 1,000 component batch sizes.
Following the visit to Productivity Partnerships, the two directors sat down and formulated a production rationale based on producing a series of 15 basic sizes of dies with round and non-round bores that could be provisionally wire cut into stock blanks.
These would then be held in a temporary stockpile and then finished to size according to customer requirements on the Okamoto CNC grinding machines.
"This method," says Mel Knowles, "means the wire EDM cell is run consistently producing blanks in cycle times that vary between 15 minutes and 60 minutes each dependent on the form and are then called-up for finish grinding from stock as required." While appearing very simple in methodology, the application engineering carried out by 600 Centre was critical.
The design of the pneumatic fixture, for instance, is universal to accommodate the complete component range of parts.
Because the Fanuc Alpha has an automatic hole search capability, it is able to find its required start position when the part is loaded.
The two pallets, with nests to hold 250 die blanks, are able to accommodate the complete range of sizes and the dip and rinse station, where the robot cleans the part after processing, further qualifies attention to detail.
So too does the mini-compressor that feeds low-cost air to the machine when running lights-out which allows the main compressor to be switched-off.
According to the type of die being wire cut, some bores are simply increased using the machine's progressive orbiting technique.
However, the simple genius of the cell is the problem of removing the profiled slug that is created when the wire machine has to generate a much larger bore size than can be produced by orbiting.
Here, the programmed cycle follows the load, tank fill, wire feed and profile routine, but the robot then interrupts the cycle by picking-up a tool from the fixturing area.
It then taps out the cut slug, ready for the machine to refeed the wire and follow-on with its final skim cut before being unloaded.
Mel Knowles confirms how he was initially concerned over what would happen if there was variance in the process when unmanned - but he says: "The technology takes care of that.
The adaptive control of the machine takes those concerns away and the corner control software minimises wire deflection which allows the machine to accurately follow the programmed path and reduce wire breakage.
Any wire breakage that does occur is overcome by the automatic refeed while still submerged and the latest Fanuc generator virtually eliminates any effects of surface damage or softening of the tungsten carbide around the cutting zone." And what does handyman Dougie think of his namesake? According to Rod Print: "He was absolutely delighted that we named the robot after him.".
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