Excetek EDM machine seals support for Veker Extrusions and Gaskets

For nearly two decades Kevin Crossley and his business partner have been successfully running Veker Extrusions and Gaskets. Originally based in Castle Bromwich, the 35-strong company moved to its current 25,000 ft² 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 designs that are as varied as the customer applications they will eventually be used for.  

Many of the extrusions will be 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 different industries. These 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 and the company will run work from 500m upwards, with many typically requiring 30,000m or more.

Kevin Crossley recalls: “When we started we didn’t do any tooling in house, we used a subcontract supplier that would create the extrusion die and carry out any modifications we wanted. As we became busier we wanted to do this ourselves, we had a small bespoke bench-top wire EDM machine made to suit our needs. So we started wire cutting the extrusion dies in-house, the beauty of this was the ability to turn around any modifications overnight. That 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 the different machines available.”

A thorough investigation of the different wire EDM machine tools available pointed Veker to the cost-effective Excetek V350G CNC machine, supplied by exclusive UK agent, Warwick Machine Tools (WMT). With comparative performance levels to Swiss and Japanese wire EDM machines, the V350G offers a cost saving of between £20,000 and £25,000 against any equivalent size machine tool, and the price includes training and installation.

Fitted with a 600 litre tank, it is capable of accommodating workpieces up to 700 x 500 x 215 mm and weighing up to 450 kg. This fully specified wire machine has U and V axis travels of 80 mm and an accuracy of 3 micron over 100 mm. All the standard range of Excetek wire EDM machines feature 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.

Also developed by Excetek, the automatic wire feed and threading system is produced in-house. 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.

Unlike the previous machine, that had a PC-based control and screen operated by simple point-to-point co-ordinates, the V350G is fitted with a CNC system that has been developed using Windows-based 64-bit architecture with a 15 inch LCD touch-screen for programming. This makes it 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.

Dies produced by Veker are mild steel between 10 and 30mm thick as the hot rubber is not harsh, and Kevin 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 worktable at a time so we are far more flexible and efficient.”

He continues: “Some of the dies needed tapers cut into them, which was beyond the ability of our old machine. The new machine is able to cut a +/- 30^o taper. We have been doing this a long time, but there is still a bit of ‘black art’ when it comes to extruding rubber so having the capability of the V350G helps us get the profiles produced exactly right to the customers 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. It often caused problems because some of the small components would break. “We had a situation the other week,” Kevin Crossley states, “we was 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. It was easy to stop the job, make new mandrels overnight and put it back together to 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 paraffin free high accuracy brass wire that, according to Kevin Crossley, provides a good sharp definition: “It is beautiful combination of machine and wire, giving 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.”

Established in Taiwan in 2006, Excetek Technologies focuses solely on wire cut electro discharge machine tool technology. Employing 75 highly skilled staff the company builds around 200 EDM machines per year.