Excetek supports the top tier at Electro-Discharge

From its impressive facilities in Dudley, Electro-Discharge Limited provides a specialist subcontract CNC wire and spark erosion service to a diverse engineering customer base. With industry leading quality accreditations and a plant capacity list that features over 30 wire and spark erosion machines. These include the latest generation Excetek CNC wire cut machines supplied by exclusive UK agent, Warwick Machine Tools, installed to operate automatically at speed, to close tolerances in a ‘lights out’ environment.

Originally established in 1980, Electro-Discharge initially targeted engineering businesses in the West Midlands. However, continued growth means today its customer base is spread across the UK, and its knowledge and services are also prized by international manufacturing companies.

Since coming under new ownership, as part of the successful MJ Sections group, at the end of November 1999, many changes have taken place within the company. “We have a management team with many years’ experience in the wire and spark industry,” explains General Manager, Rupin Vadera. “We moved to our current purpose-built 7,000 ft2 facility, invested in updated machines to allow for increased capacity, and introduced a shift pattern to meet customer turnaround requirements.”

He recalls: “When I started back in 2000, we had a CAD system and four conventional EDM machines. Today, we use the latest Solid Works, Catia 5, and PEPS CAD/CAM programming software so customer programs or drawings can be emailed in IGES or DXF formats and the exact sizes can be obtained. We now have over 30 wire and spark erosion machine tools installed in our facilities, and where possible the machines are run around-the-clock; 24/7.”

Around 90 per cent of the company’s business is aerospace related so it is no surprise that its quality system is NADCAP accredited to AS7116, AS9100 REV:C, ISO 9001-2008 and Rolls-Royce SABRe9000. And, the 27 highly skilled staff on the shopfloor support the high variety, tight tolerance components that Electro-Discharge’s customers entrust the company to deliver to stringent deadlines. An in-house toolroom produces any electrodes required and also produce bespoke fixturing where necessary, which maintains control over both the quality and timeframe.

Materials machined range from standard carbon steels right through to all the high end exotic alloys used for airframe and aero engine components. High performance alloy components are often ‘free issue’ from the customer and usually are at the end of the manufacturing process, so a high degree of value has already been added to the parts. So, manufacturing procedures have been developed so that mistakes that might lead to a missed delivery to the end customer are minimised.

“When we initially run into capacity issues we had to resolve them quickly,” explains Rupin Vadera. “Although we were aware of the Excetek range we didn’t fully appreciate the capability and functionality offered. We arranged a demonstration at Warwick Machine Tools’ showroom near Kenilworth and everyone was impressed with both the build quality and performance. The price-to-performance ratio is exceptional.”

To meet the component sizes and capacity forecast Electro-Discharge ordered two Excetek V850G CNC wire EDM machines. The large capacity 1,000 litre submerged tank of the V850G is able to take workpieces weighing up to 1,100 kg and measuring up to 1,100 x 850 x 345 mm. Standard axis travels are generous at 800 mm in X, 500 mm in Y and 350 mm in Z, although a larger vertical Z axis can be specified.

Like all the machines in the popular ‘V’ range the V850G features a C-frame structure designed using FEA software to provide exceptional accuracy in the linear axes movements and to minimise any thermal influence. The AC servo motor driven C1 class ball screws are cryogenically treated to minimise the thermal effects of the machine’s ambient operational environment, with high accuracy linear scales fitted for positional feedback.

A key feature for Electro-Discharge’s extended operational hours is the automatic wire feed and threading (AWT) system. Designed to provide continuous unmanned operation around-the-clock, the AWT offers the ability to thread the wire at the point of the breakage. An automated annealing system straightens the wire so that it can be threaded at the break point during machining with almost 100 per cent reliability and without the need to return to the start position. Submerged wire threading is possible, which removes the need to drain and refill the tank. A water jet assist system is available for automatic wire feeds on tall workpiece.

Other optional extras that can be specified for increased machine operating efficiency include remote monitoring via ethernet or internet and Short Message Service (SMS), which will automatically send an alarm message to a mobile phone if the machine stops cutting. For extended operation a 50 kg jumbo wire feeder can also be fitted.

Excetek leave nothing to chance and even the CNC system has been developed in-house, using Windows-based XP-E 64-bit architecture with a 15 inch LCD touch-screen for programming. Excetek says it is easier for operators to understand as they are already familiar with the ‘look and feel’ of the Windows environment. It cuts down the training time required, so one day’s training is all that is required before the operator is competent to program and run the machine. Programming can be done using standard ISO G code or Excetek’s Icon Assistant conversational software, which uses the controls extensive database of cutting technologies.

The control system can also apply offsets to allow for any misalignment during workpiece loading. Before machining an edge finding operation sets the actual position of the raw material, and the control software resets its datum points accordingly.

A new design EF (AC) Electrolysis Free generator system provides improved cutting speeds that are around 10 per cent faster, a maximum cutting speed of 300 mm2/min can be achieved with 0.3 mm diameter zinc coating wire and the optional Excetek high speed cutting circuit. The generator also supports Super Finishing techniques using high frequency technologies on surface finish cutting so a roughness of less than 0.2 micron Ra can be obtained with one cut and four skims.

Rupin Vadera says: “While we were waiting for delivery and installation, WMT provided us with a showroom demonstration machine on loan so that we could keep up with the initial workload that our customers had placed on us. This allowed us to maintain our on time delivery record with our customers. I know the machines are running well as they are often praised during our management meetings.”

The staff at Electro-Discharge have quickly become proficient at programming the user-friendly NC system fitted to the Excetek machines. “Like many engineering companies we could do with more skilled people,” Rupin Vadera states. “We have already inducted three apprentices; they will finish their training programme in April 2017. It is the first time we have taken apprentices on and we will look to add to this pool going forward.”

As well as the aerospace sector Electro-Discharge also supports high precision general engineering companies. “We plan as much as we can but you never know what will come through the door,” Rupin Vadera concludes. “That is why we appreciate the capacity, performance and flexibility of the Excetek EDM machines.”