Charging ahead with production

From its facilities in Dudley, Electro-Discharge 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 more than 30 wire and spark erosion machines.

These include the latest generation Excetek CNC wire cut machines supplied by exclusive UK agent, Warwick Machine Tools, which have been installed to operate automatically at speed and to close tolerances in a lights out manufacturing environment.

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 7,000ft² 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 SolidWorks, 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 24/7.”

Around 90% of the company’s business is aerospace related so it is no surprise that its quality system is NADCAP accredited to AS7116, AS 9100 REV:C, ISO 9001:2008 and Rolls-Royce SABRe9000. The 27 highly skilled staff on the shopfloor support the wide variety of tight tolerance components that the company’s customers entrust to be delivered to stringent deadlines. An in-house toolroom produces any electrodes required and also produces bespoke fixturing where necessary, which maintains control over both the quality and timeframe.

Standard and high-end metals

The materials machined range from standard carbon steels right through to high-end exotic alloys used for airframe and aero engine components. High performance alloy components are often free issued from the customer and usually at the end of the manufacturing process, so a high degree of value has already been added to the parts. This means the company has developed manufacturing procedures so that mistakes that might lead to a missed delivery are minimised.

“When we initially ran into capacity issues we had to resolve them quickly,” says Mr Vadera. “Although we were aware of the Excetek range we didn’t fully appreciate the capability and functionality it 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 1,000ltr submerged tank of the V850G is able to take workpieces weighing up to 1,100kg and measuring up to 1,100 x 850 x 345mm. Standard axis travels are 800mm in X, 500mm in Y and 350mm in Z, although a larger vertical Z-axis can be specified.

Like all the machines in the ‘V’ range the V850G features a C-frame structure designed using FEA software to provide high levels of accuracy in the linear axis movement and minimise any thermal influence. The AC servo motor driven C1 class ballscrews 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% 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 waterjet 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 a Short Message Service (SMS), which will automatically send an alarm message to a mobile phone if the machine stops cutting. For extended operation a 50kg jumbo wire feeder can also be fitted.

Excetek’s CNC system has been developed in-house, using Windows-based XP-E 64-bit architecture with a 15 inch LCD touchscreen 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 needed 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.

Taking control

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% faster – a maximum cutting speed of 300mm²/minute can be achieved with 0.3mm diameter zinc coating wire and the optional Excetek high-speed cutting circuit. The generator also supports superfinishing techniques using high frequency technologies on surface finish cutting so a roughness of less than 0.2µm Ra can be obtained with one cut and four skims.

Mr Vadera comments: “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,” Mr Vadera explains. “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 moving forward.”

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

WARWICK MACHINE TOOLS www.warwickmachinetools.co.uk

ELECTRO-DISCHARGE http://electro-discharge.com