Tool, die and mouldmaking operations require a skill set that is virtually unique in the machine shop segment. And, as Steed Webzell discovers, the technology is remarkably impressive, too
Ask many manufacturers and they will say toolmaking has emigrated to cheaper economies, typically in the Far East. Sure enough, there was a 'gold rush' to this region some 10-15 years, when companies first realised the size of the wage differential. However, much has changed, particularly in the past five years: not only is the pay disparity now far smaller, but the latest manufacturing technologies are proving a great leveller.
Clearly, getting the right applications, software and engineering support is essential, as Leicester-based Alliance Tooling can verify when it sought to improve a particular aspect of its toolmaking service.
Alliance says the combination of a new Sodick AG60L spark eroder from Sodi-Tech EDM (02476 511677), and switching to the VISI Electrode design module from Vero Software (01189 756084), has generated a marked improvement in the production of its copper electrodes. The company's managing director, Luke Parsons, cites an example of a mould made recently for the trigger of a household cleaning spray.
"We needed 10 different electrodes for the tool, which, previously, would have taken 10 hours to create," he says. "Each electrode used to take an hour to model, but VISI Electrode has reduced this by 80%, with each electrode now taking less than 10 minutes to produce."
Toolmaker Ian Jarvis adds that VISI Electrode has also made his job easier: "Once I'd made a few changes to the fillet radii on the trigger mould, I simply clicked on the faces I wanted to spark and enclosed them with a 3D boundary. They were immediately extracted from the tooling model, providing a quick way to arrive at the required electrode geometry."
New Sodick EDM technology is also proving central to operations at Banbury-based toolmaker, Hanley Precision Tools – the company reports "a quantum leap" in its programming and set-up times. Hanley manufactures multi-cavity and hot runner system moulds. "We are seeing many customers bringing work back from China, fed up with the logistical challenge of having cash tied up in transit and poor lead times," states operations director Mark O'Mahoney. And, as part of a new investment programme, the latest arrivals from Sodi-Tech EDM are an AG600L wire EDM and an AG60L die-sink EDM unit.
"Programming times are at least 50-60% quicker," confirms Mr O'Mahoney. "On the die-sink, we have also found that we no longer need to pre-rough cut cavity forms, making the process much faster, while finishing is now more refined. We have System 3R [02476 538653] technology on both machines for rapid set-up."
There is little doubt of the importance of programming when it comes to complex mould machining. CAM specialist Delcam (0121 766 5544) has an established track record in this sector and has named its 40,000th customer – Lifetime Products, a 1,300-employee OEM with an in-house mould shop, located at Clearfield, Utah, USA.
MOULD TOOL MILLING
For milling its moulds, the company owns a number of machining centres, including two Nexus VNC-510Cs and a Nexus VCS-410A from Yamazaki Mazak (01905 755755), and four VF-9 machining centres and a VS-3 from Haas Automation (01603 760539). The company produced 30 moulds last year, but is working to complete 36 during this year.
Just recently, Lifetime expanded its offerings to include kayaks in its line of outdoor products. The company uses PTC's Pro-E for the design and has since added Delcam's PowerMill CAM software
"What attracted us to PowerMill was the speed with which it can calculate toolpaths," says Dennis Norman, mould design engineer at Lifetime Products. "It is not uncommon for CAM vendors to say they have fast toolpath calculation, but PowerMill backs this up with multi-threading and background processing. It automatically performs complex calculations in the background, while we continue to work on other toolpaths."
Lifetime's range of products, which extend from tables and chairs through to sporting equipment, gardening goods and playground furniture, highlight the sheer extent of items that require moulds. With this in mind, investment in the latest manufacturing technologies for mouldmaking continues unabated, the world over.
For instance, Sridevi Tool Engineers, based at Vasai, near Mumbai, in India, has used WorkNC CAM software from Sescoi (0844 561 7014) to help it make the transition into 5-axis machining. The company produces around 180 moulds a year, up to 40 tons in weight, and specialises in the automotive and white goods markets.
"WorkNC's Global Roughing strategies are very effective," states Abhay Churi, assistant manager in CAM and CNC at Sridevi. "The holder collision check lets us identify what we can safely machine, and rest roughing identifies where material is remaining, enabling us to rapidly remove the large amounts of metal common in the bumper and door moulds we produce. For roughing, we usually start with an 80 mm, 8 mm radius or 66 mm, 8 mm and then work down to a 1 mm ball. For finishing, we normally cut P20 material at between 10,000 and 20,000 rpm."
Back in Europe, in the northeast Romanian town of Iasi, Omco Group is using laser scanning to digitise customers' bottle designs, shortening the lead-time from receipt of order to delivery of cast-iron moulds. An LC50Cx digital line scanner from Nikon Metrology (+32 1674 0100) is fitted to a C3V co-ordinate measuring machine (CMM) in one of Omco's seven mould shops.
Alexandru Geant, quality manager at Omco's Iasi site, says: "Historically, we sent the resin model to the customer for approval, mostly by air. Overall, it used to take up to 14 days to receive any changes needed to the design, plus the go-ahead to start producing the moulds.
"Now, we simply scan resin facsimiles from several angles on the CMM, using the LC50Cx mounted in a Renishaw [01453 524524] PH10M motorised indexing head," he adds. "The resulting point cloud data, an exact digital copy of the physical model, is then sent electronically to the customer. Approval is usually received the same day."
When approved by the customer, the IGES file is loaded into a Delcam CADCAM system. Cutter paths are generated and post-processed for CNC machining the moulds, using a DMG/Mori Seiki (02476 516120) machining centre. In total, lead-time has been reduced by one-third: a considerable commercial advantage in this highly competitive sector.
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Press tools demand no less attention to precision and productivity than mould tools. A case in point can be seen at the West Midlands facility of Cube Precision Engineering. The company has recently installed its largest Hurco (01494 442222) machining centre to date, a 3,200 by 2,100 by 920 mm capacity, bridge-type, vertical-spindle DCX32.
One recent high profile job involved completing work on tools for pressing the door outer panels that go into the new, all-aluminium Range Rover (L405). Other press tools machined on the 3-axis DCX include those for producing the wheel arches for the new Jaguar F-Type (X152).
"Finish machining of large parts was causing a bottleneck, so we opted for a Hurco DCX32, as it was economically priced for a machine with over six cubic metres of working volume," says Neil Clifton, one of three director-owners at Cube. "Despite its size, the machine regularly achieves tolerances of 0.02 mm, together with excellent surface finish."
First published in Machinery, March 2013
Author: Andrew Allcock