moulds | Additive manufacturing Right: A
conformal cooled core
produced by EOS partner LaserBearbei- tungsCenter
cut cycle times on this part by FWB Kunstst- offtechnik
cooled mould inserts and contour pins. To support this growth, the company is installing a third metal additive manufacturing machine – an Eosint M280 unit from Germany’s EOS. It will be joining an earlier EOS unit and a LaserCusing system from Concept Laser, part of the German Hofmann Innovation Group. Texer Design handles around 300 projects a year on its
existing EOS and Concept Laser additive manufacturing hardware. While each manufacturing system has its own particular benefits, Texer sales manager Marco Andreet- ta says both will only deliver their best performance when used by experienced engineers. “It’s not the machines but the user that makes the difference,” he says. Andreetta says using conformal cooled inserts
delivers typical cycle time reductions of up to 40% and, like Bosco, reports that this is typically achieved along with improved part quality. Many Texer solutions supplement water with air
cooling to remove heat from thin wall sections. While the thermal transfer efficiency of air is poor compared to water, this is more than compensated for by the ability to achieve turbulent flow in the very small channel diameter channels required to access chal- lenging mould areas, says Andreetta. Turbulent flow is critical in achieving good heat removal, he says. Texer also makes extensive use of hybrid manufac-
Below: CAD design of a mould core with conformal cooling
channels by Spritzguss + Formenbau Bergmann
turing technologies to optimise the cost performance balance. Contour pins with diameters or as little as 2.5mm are frequently built onto a standard mould part such as an ejector sleeve to keep the cost down; larger parts may be built onto a pre-machined steel blank. Andreetta says one myth that suppliers of SLM inserts have had to work hard to dispel is that the parts are porous, an impression he believes is created by the rather rough surface finish achieved direct from the machine. “People often mistake surface roughness for porosity but that is not the case,” he says. The part itself is effectively 100% dense, he explains, and the rough ‘direct from the build chamber’ finish requires little more finishing than a conventional machined compo- nent. Texer typically applies a 0.3-0.5mm overbuild to allow for final finishing. The French technology
institutue Pôle Européen Plasturgie (PEP) has been working with metal additive manufacturing techniques for production of conformal cooled moulds for eight years.
The technical facility showed some of 46 INJECTION WORLD | June 2014
its additive manufacturing capabilities on the EOS stand at last year’s K show in Germany, where PEP managing director Luc Utterharghe described additive manufactur- ing technology as a ‘game changer’ for mouldmakers. “Our experiences show that conformal cooling can
help to reduce cycle times in injection moulding by up to 30%. This value can be increased for a process which is using the heat and cool [variotherm] system. It can considerably improve part quality through mould optimisation, at the same time reducing warpage and distortion considerably,” he says. According to Augustin Niavas, business development manager for tooling at EOS, growth in the application of additive manufacturing in injection mould parts is running at double digit rates and has the potential to accelerate further. It is one of the markets the company is aiming its latest metal additive manufacturing system at - the Eosint M290 incorporates a number of new software and process monitoring tools designed to make it easier to produce high quality series parts. “From today’s perspective, I would say we can expect
growth rates of 10% to 15 % per year in injection mould making. Yet, it is very difficult to predict how the additive manufacturing world in tooling will look like in five years. Taking into consideration that further technological developments are to be expected in terms of additive manufacturing hardware, materials and software, growth potentials might even exceed those numbers,” he says. The driver for take up of additive manufacturing will, as with any new technology, be the impact on the bottom line. Niavas says conformal cooling, for example, can improve the stability and uniformity of the moulding process, which helps processors shorten cycle time, cut scrap rates and, ultimately, improve the return on their investment.
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