Original mould block with cooling tool inserts www.engineeringnews.co.nz 17 limits conformal cooling as only straight lines can be achieved, not lines which followed the contours of the product. When faced with a need for increased cooling, toolmakers create insert with baffles or even helix baffles to accommodate more cooling but complicating operations. Where complex designs require intricate cooling channels the mould can be split in two, channels milled and then the two parts soldered back together making sure the channels were correctly connected. But not only is this process costly and time consuming it offers only straight channels additionally the life of the mould can be shortened due to the deterioration of the soldering. So how can the issues associated with conformal cooling where cooling channels follow the contours of the product be addressed with todays’ technology? Additive Manufacturing (AM) or 3D printing with lasers that melt metal powder is already experiencing successful uptake across a range of industries such as for medical implants, printing titanium light-weight part production, aircraft and drone parts, and more recently 3D printing of car parts. The controlled laser beam melting process in AM follows a computerised CAD design to build a single complex part, removing the need for milling or welds and thereby arriving at a better, more reliable product. A well-publicised example undertaken by General Electrics Aviation in 2016 was the printing of a fuel nozzle for the CFM LEAP engine as a single piece rather than eighteen separate parts that originally had to be joined together. The benefits of a single 3D printing fuel nozzle are numerous including a reduction in weight: the nozzle is 25% lighter than its predecessor; a simpler design as there is only one part; while the design features have more intricate cooling pathways and support ligaments that will result in an increase of five times in durability. Spurred by these small but significant improvements and the opportunity to improve productivity while harnessing costs, GE Aeronautics made a substantial commitment to additive manufacturing of 3D printed aircraft engine parts at the end of 2016, a change that represents a major paradigm shift from traditional manufacturing. But GE is not alone. The emergence of additive manufacturing is offering the automotive industry new possibilities. The engineering team at Renault Trucks are looking at how to boost the performance of the DTI 5 4-cylinder Euro-6 step C engine. By using the new CAD design freedoms offered with 3D printing they have been able to optimize parts and reduce the number of assembly operations. Already the rocker arm has been redesigned and printed as a lighter part, and tested I the DTI 5 engine. The Renault Truck engineers agree 3D AM is disruptive technology that will certainly impact the future of the automotive industry in a number of ways, a situation already being considered by Audi. Audi is looking at AM to improve economies of scale. Manufacturers currently keep vast stocks of parts that are shipped all over the world as they are required. Many customers have to wait for the dealers to import parts to the accredited service centre which can be time consuming and costly. 3D printing would allow Audi to disrupt the supply chain, by enabling service centres to 3D print the part they require at the point of repair. Already Audi is using SLM Solutions for the development and testing of both new casting technologies and light alloys for the entire pressure-casting process chain for the components body, chassis and transmissions. This use of AM is seen as a disruptive technology but it is also a major game-changer opening new possibilities as well as providing time and cost savings. Across the globe a growing numbers of injection moulders are discovering the benefits of using AM to improve conformal cooling in the injection moulding process. Millions of injection moulded plastic products are already produced with tool inserts made using 3D metal printing. Some toolmakers and injection moulders may hesitate to adopt a new technology as they believe business is fine as it is, but AM conformal cooling won’t actually replace existing processes, it will compliment them. In the past production runs that may have been thought to be too expensive or even impossible can now be tackled, and new design possibilities can attract new business. Use of AM for conformal cooling is a proven or ‘rock-solid’ technology already tested by a number of AM laser system suppliers. The most recent tests have been run by SLM Solutions for ABB Oy, Drives and Controls who produce millions of cabling grommets annually made from thermoplastic elastomer (TPE). In conjunction with the state owned VTT Technical Research Centre of Finland Ltd, six different tooling inserts were designed and printed using an SLM280 laser system. The channel profiles were optimized at the design phase to take account of factors such as the angles of surfaces facing down to reduce the need for supports, a minimum wall thickness between channels and the dimensions and shapes of the channels. The tooling inserts were built in steel 1.2709 and heat treated for the desired harness. Testing of cooling effectiveness revealed the ‘best’ design. The conformal cooling inserts were then placed in the injection mould tool resulting in significant reductions in cooling times from 60 seconds to less than 15 seconds. ABB Oy found an overall reduced cooling time of the (plastic) TPE of some 80%, and shortened cycle time with an overall saving in production time and cost. They experienced less defective products due to a more equal cooling surface - a tremendous benefit to a company that produces millions of grommets each year. Some injection moulders will feel the uptake of 3D printed conformal cooling inserts requires too large an outlay of costs, however, in Australia opportunities for manufacturers to test and trial ideas and even have inserts made exist at the universities. RMIT University’s Advanced Manufacturing Precinct have an SLM Solutions laser system on which the team in 2016 carried out tests to investigate the manufacturability of tool inserts in high-strength H13/DIN 1.2344 tool steel. Using CAD designs to optimize performance they were able to demonstrate the cooling advantages associated with additive manufacturing of conformal cooling mould tools made with an SLM. The team at the Precinct in Melbourne are available to Australian manufacturers to assist, advise and support the area of AM 3D printing with metals. Raymax Applications Pty Ltd is the Australasian distributor of SLM Solutions Group laser systems. The TPE cabling grommet produced with reduced time cycle due to 3D tooling inserts
EN-Apr17-eMag
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