Knock-on benefits

With more than 1,700 different form tools being used in a typical year to service its 38 multi-spindle automatic lathes engaged in turned part production, the switch to the use of wire EDM technology by Rodmatic Multico has enabled special tool costs to be slashed by half. In addition, the volume production operation of the Rodmatic Group, based in Reading, which has one of the largest multi-auto shops in the UK, has been able to reduce its stockholding of tools, while considerably improving response to customers on new components and eliminating sub-contract tool manufacture. "The £80,000 investment in the installation of a Fanuc 0Ii wire EDM (600 UK) is easily the best purchase Rodmatic has ever made, when judged against an immediate return on investment," says Rodmatic Group managing director Brian Steatham. "As our setter/operators get more familiar with the process and technology, bearing in mind it was totally new to us all, having moved from around-the-clock tool production using three optical profile grinders (OPG), new opportunities for savings are now being continually uncovered." The machine was installed at Rodmatic Hytek, the CNC, smaller batch, fast response operation on the same site in Reading, in September 2008. Since then, over the first year, almost 450 different programs have been created for form tools, internal and external recess and special tools, made from both high speed steel (HSS) and brazed carbide. Image: Fanuc Oli wire EDM TOOL LIFE BENEFITS As a result of the changes in process, initial monitoring of tools on each machine has also seen the in-cut life improved by around 10 per cent, due to higher accuracy of form, plus the fact that the cutting action of the EDM wire process does not degrade the cutting surface of the tool. Further savings have been made, due to the flexibility of the process that is able to provide a fast response when a tool is required urgently. A replacement can now be made via an automatic cycle simply by calling up the existing program, which means reserve tooling no longer has to be stocked. Almost as a sideline, the machine has also been designated to cut ring gauges, as well as gauges for groove, form and width checks, which are widely used for components on the production line. "They are considerably cheaper to produce in-house, with the benefit of higher accuracy being achieved through wire cutting, versus the previous grinding methods and sourcing from external toolroom suppliers," explains Mr Steatham. Programming is mainly carried out off-line, using the company's PEPS NC CAM programming system (Camtek), with the tooling module accounting for the appropriate tooling geometry, while speeds and feeds are set at the machine control. Up to 12 tools tend to be mounted at a time on the wire-cut machine's table, taking advantage of the flexibility of the process and giving the choice of producing a range of different tools and/or multiple versions of the same tool in the same manufacturing run. Image: Programmed contours are turned into form tools via wire-cut EDM at Rodmatic The machine is set to run during the day while new programs are created or tool blanks prepared. At the moment, an OPG is still used for regrinds; reserving the wire machine for new tools. Late in the afternoon, the Fanuc is reset, ready for unmanned production between shifts and through the night. Here, the advantage of the automatic wire feed is seen, with this eliminating any need for attendance, while Fanuc's adaptive control adjusts the process to maintain optimised rates of feed. Quite often, as the wire process is a lot faster than the OPG methods, tools are set on the table that will not totally take up a complete night's available production time. In such cases, the setter will input the self-timer, so that the machine starts and then switches off with the job complete as he arrives for work in the morning. As Rodmatic produces over 1 million components a month via its installed base of multi-autos, supplying the fluid power, hydraulic, automotive related and off-road sectors, form tools are critical in creating competitive cycle times and in the maintenance of dimensions of relative features of a component. As the company has also introduced thread rolling wherever possible on the multi-autos in place of tapping, die boxing or chasing, this again creates further savings and contributes to higher quality and productivity, with the form tools providing a greater security of process. CHANGE AT THE RIGHT TIME Over the last 18 months, Rodmatic has been progressively working through the machine shop, rebuilding and updating its machines and switching, where economically viable, from HSS flat form tools to solid carbide tool set-ups. As a result, overall productivity and utilisation of each machine has been improved by around a third as each is re-commissioned, while dimensional consistency, with lower levels of setter involvement, has improved dramatically. "By progressively improving the machine and operational strategy, we are helping to fund the changes we need to remain competitive. Here, the change to wire EDM could not have happened at a more appropriate time," says the managing director, who also highlights one area of spin-off within the Hytek division, where the company has installed two Star CNC sliding-head lathes (Star Micronic GB, a 9-axis SV-32 and 7-axis SR-20 Rlll. Among the contracts being completed on both machines is one for some 40 different types of suspension piston rod for an autosport customer. The parts, up to 16 mm dia and 280 mm long, are turned and threaded at each end, with special flats milled in the single cycle operation. While most companies would resort to single point turning the threaded, undercut and chamfer features, Hytek engineers were able to experiment with potential savings by incorporating wire-cut flat form tools in the sliding-head process. As a result, it has enabled them to cut the overall cycle time by almost 30 per cent. With a working capacity of 700 mm by 600 mm by 255 mm, the Fanuc machine has adequate volume to produce a wide range of components. Indeed, it has even been employed to wire-cut a special coolant manifold for an unusual application on one of its machines, which was cheaper and more convenient to produce versus the toolroom. Plans have already been laid for the future to expand its tool service capability. With the addition of a further C-axis to give a rotary motion, the wire-cut machine will be used to cut circular form tools and multi-diameter combination form cutters for internal forms. "By drawing together a plan of re-engineering our volume production machines, adding a smaller batch CNC capability and adding the capability to be almost self-sufficient on tooling that involves complex forms, we have become significantly more competitive when quoting for new work and are now able to react very quickly to customer needs," Mr Steatham concludes. First published in Machinery, November 2009