Providing high-quality seals and jointing solutions for customers in many leading industry sectors, Veker Extrusions & Gaskets Ltd has established a reputation for high quality and on-time delivery. The company’s recent decision to invest in an advanced CNC wire-cut EDM machine was taken to safeguard these important business values.

For nearly two decades Kevin Crossley and his business partner have been successfully running Veker Extrusions & Gaskets. Originally based in Castle Bromwich, the 35-strong company moved to its current 25,000ft2 facility in Hall Green, Birmingham, around 12 years ago. Here, four extrusion lines operate an extended day shift to provide rubber and neoprene sections in a variety of designs for a diverse range of applications.

Many of the extrusions are processed by the company’s mould shop, where sections are joined together by press-vulcanising the ends together to produce rings, gaskets and frames for customers in industries that include glazing, plumbing and water treatment, construction, marine and passenger rail, as well as second- and third-tier automotive-component suppliers. Extrusion jobs are measured in linear metres; the company will run work from 500m upwards, with many typically requiring 30,000m or more.

Kevin Crossley says: “When we started, we didn’t do any tooling in-house; we used a sub-contract supplier that would create the extrusion die and carry out any modifications we wanted. As we became busier, we wanted to do this ourselves, so we had a small bespoke bench-top wire EDM machine made to suit our needs.

We started wire-cutting the extrusion dies in-house, and this gave us the ability to undertake any modifications overnight. While that machine served us well for about 12 years, it was on its last legs and not reliable enough to support our current workload, so we decided to evaluate a number of new machines.”

Cost-competitive

Veker subsequently selected an Excetek V350G CNC machine from the Taiwanese manufacturer’s exclusive UK agent, Warwick Machine Tools (WMT) (www.warwickmachinetools.co.uk). “The machine’s performance is comparable with Swiss and Japanese wire-cut EDM machines, but it offers a cost saving of £20,000-25,000 against any equivalent-size machine tool — and the price includes training and installation,” says Mr Crossley.

Fitted with a 600-litre tank, the machine accommodates workpieces up to 700 x 500 x 215mm and weighing 450kg; it also has U- and V-axis travels of 80mm and an accuracy of 3µm over 100mm. All the standard range of Excetek wire EDM machines feature a C-frame structure designed using FEA software to provide high levels of accuracy and to minimise any thermal influence.

The AC servo motor-driven C1 class ballscrews are cryogenically treated to minimise any thermal effects relating to the machine’s operating environment; linear scales provide high-accuracy positional feedback.

The Excetek’s automatic wire feed and threading system (AWT) is produced in-house and designed to support continuous round-the-clock unmanned operation.

Moreover, the AWT can 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). Furthermore, submerged wire threading is possible, removing the need to drain and refill the tank.

Control familiarity

Unlike the previous machine, which had a PC-based control and screen operated by simple point-to-point co-ordinates, the V350G is fitted with a CNC system featuring a Windows-based 64-bit architecture and a 15in LCD touch-screen for programming.

This makes the system easy for operators to understand, as most are already familiar with the ‘look and feel’ of the Windows environment. This familiarity cuts down the training time; one day’s training is all that is required before an 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 control’s extensive database of cutting technologies.

Dies produced by Veker are made of mild steel (the hot rubber that they extrude is not harsh) and between 10 and 30mm thick. Mr Crossley says: “The working capacity of the V350G is much larger than we are used to, but we can put a number of dies or other parts such as gears on the table at a time, making us far more flexible and efficient.

“Some of the dies need tapers cut into them, which was beyond the ability of our old machine. The new machine can cut a ±30deg taper.

“We have been in this business some time now, but there is still a bit of ‘black art’ when it comes to extruding rubber, so having the capabilities of the V350G helps us get the profiles exactly right for achieving the customer’s specification.”

Previously, the mandrels required to support the back of the die and create hollow sections in the extrusion would have been produced on a milling machine and a lathe, but these parts often caused problems because some of the small ones would break.

Mr Crossley says: “We had a situation the other week. We were doing a job for a customer and had an inclusion — a bit of metal in the back of the die from the compound. It bent the mandrels, so all the extrusion wall thickness increased. However, it was easy to stop the job, make new mandrels overnight and run the job the next day; it’s good having the capability of the Excetek V350G in-house. Things are a lot quicker now, which is a benefit to us in turning work around.”

The new Excetek V350G is fitted with Erodex Q Cut 0.25mm-diameter paraffin-free high-accuracy brass wire that Mr Crossley says provides a sharp definition: “The combination of machine and wire gives us a better shape on the tool as well, which is better from our point of view when we are extruding, as it provides a nicely defined profile.”