A lot of electric discharge machining previously carried out by Galway Tool & Mould (GTM) has been replaced by high-speed cutting at up to 42,000 rpm on three German-built Roeders machining centres supplied by Hurco Europe, High Wycombe, through its local sales representative in Ireland, Michael Gannon.
Running around the clock
Two of the machines, which are all installed in a temperature controlled environment, have been automated with pallet changers so that they can be operated around the clock, unmanned at night. Owner & Managing Director, GTM, Padraig McFadden said, “As a result of this and other measures, mold lead-times have been cut by up to 20 per cent to typically 14 weeks and we have increased productivity significantly.” The main specialism of the company, which was founded in 1990, is the manufacture of high precision injection molds for the medical, pharmaceutical and high-volume packaging sectors worldwide, from single-impression molds for prototyping to 48-cavity molds for producing complex plastic devices such as inhalers.
In addition, a small number of micro molds are produced to make, for example, miniature rotor gears and screws for medical assemblies or for over molding stents. Components down to 10 mg can be molded to tolerances of ± 0.005 mm, consistently and reliably. The successful working practices implemented by GTM at its Galway factory resulted in a doubling of turnover between 2012 and 2015 and an increase in floor area. There are now 30 employees of whom three are apprentices.
Migration from EDM to high-speed milling is one factor in that success, but others are the opening of a metrology laboratory for tool validation and an in-house trial facility for molds equipped with Fanuc electric molding machines ranging from 100 to 300 ton capacity. McFadden emphasized that customers get a perfect turnkey mold every time, which has been designed, manufactured and tested for process viability, including correct shrinkage allowance.
2007 was a year of change for GTM, which until then derived a large proportion of turnover from automotive mold making. Much of this work rapidly disappeared overseas, notably to China, so McFadden diversified into other areas, particularly the medical industry for which Ireland had become a global manufacturing centre. Characteristic of medical mold work are the requirements for tighter tolerances and better surface finishes as well as shorter lead-times that are normal in the automotive sector.
Demand for shorter lead-times called for high-speed machining
GTM was sparking a lot of small parts for molds, but electrode manufacture is time-consuming and EDM is itself a slow process. The decision was taken to replace as much EDM as possible with high-speed machining using small-diameter, ball nose milling cutters. It was a move that would save 70 per cent of the time needed for this part of the manufacturing process, according to shop floor manager, Mark Walsh. Every mold that passes through the Galway factory now undergoes some high-speed cutting on one of the Roeders.
“Back in 2007 we asked several potential HSC machine suppliers to make test cuts on one of our molds. The Roeders machine beat all the others in terms of speed, accuracy and surface finish,” Walsh said. “It was noticeably better in all areas, partly because the German machine builder was an early adopter of linear motors for the axis drives.”
A Roeders RXP500 3-axis VMC with a 40-tool magazine was duly installed. Despite it having run 24/5 plus extensively at weekends for more than eight years, Walsh confirmed that the machine is just as good today in terms of the accuracies and surface finishes achieved as when it was new.
This level of performance led automatically to the purchase of a second Roeders 3-axis RXP 500 in 2013 to cope with raised production levels. Automation was fitted in the form of an automatic, 8-pallet changer that allows any mix of jobs to be set up and run unattended overnight, or over an entire weekend if longer-running jobs are selected.
During the day, both RXP500s can be attended by one person due to the automation fitted to the second machine. Walsh was palpably enthusiastic when he spoke of how many more hours they were getting out of the spindles for the same number of operator hours.