High precision EDM machine for cable tie mould manufacture reduces electrode use by 40%

A Japanese-built Makino spark erosion machine has been supplied by the manufacturer’s UK agent NCMT to the Manchester facility of cable management products solutions provider HellermannTyton for producing high precision plastic injection moulds.

The company’s toolroom engineer Rob Pickup, who has 20 years’ EDM (electric discharge machining) experience, says that the super-low wear rate of the copper electrodes using the Makino has cut their usage by around two-fifths, lowering production costs and speeding mould manufacture through the need for fewer electrode changes.

The toolroom in Manchester supplies multi cavitation injection moulds produced mainly using 52 Rc Stavax to meet the demands of the local production operation. The cable ties, fir trees, clips and other cable management solutions produced in the UK factory serve most end user markets.

There are wire-cut EDM machines in the Manchester toolroom and other die-sinkers in addition to the Makino. Spark erosion is inherently a slow manufacturing process and the toolroom is keen to avoid a bottleneck developing as demand for the company’s cable management products continues to rise.

Rob Pickup said, “We wanted to increase sinking capacity, not so much for our higher speed applications but more for producing very high accuracy moulds.

“The radius on the peak of the tooth form is less than 50 microns, so we needed a die-sinker on which electrode wear rate is super-low. We found that performance in the Makino EDNC6, which has probably the best generator on the market.

“An average job here uses up to 15 electrodes on one of our other die-sinking machines, but on the Makino we can rely on that number being reduced to 9.

“It represents a big saving in their manufacture as well as in the copper used and the number of tool changes. Moreover the result is more repeatable, so there is never any rework.”

Rob Pickup singles out the Hyper-i control system on the EDNC6 for particular praise. It is fitted to the Makino’s wire-cut EDM machines as well as its die-sinkers and uses an interface similar to that found on tablets and smartphones. Programs in Manchester are mainly created off-line, but intelligent, intuitive, interactive functions built into the control assist the operator to optimise them at every step of the machining process. They provide easy access to and selection of power settings to produce accurate results in the fastest possible cycle times.

The capability and ease of operation of the Hyper-i control is enhanced by integrated on-board digital manuals, intelligent E-Tech Doctor help functions and an e-learning training system that can be quickly accessed for operator convenience. They are especially useful for assisting operators with less EDM experience, as if a mould is not turning out perfectly, the database can be interrogated to provide the ideal parameters to generate efficient and safe burn routines for continuing the job.

The standard configuration of the EDNC6 utilises a programmable rise-and-fall work tank that sinks below table level to accommodate workpieces up to 1,000 mm x 750 mm. However, the machine installed at HellermannTyton is a wide tank version that supports larger moulds and incorporates a programmable rise-and-fall front door. Access to the work zone is excellent, offering fast workpiece set-up and process monitoring due to the stationary work table. The dielectric reservoir is incorporated into the base casting to improve thermal stability and minimise machine footprint.

Mr Pickup concluded, “The support and applications input from NCMT have been great and so has the performance of the Makino spark eroder. There have been no reliability issues since it was installed and essentially that is what we bought into at the outset.”