FEATURE: ADDITIVE MANUFACTURING


big cost add, not to mention the added time to swap out the lasers.’ To enable this, Optomec exploits a specialised optics train in the LDH 3.X laser deposition head, which keeps the laser light collimated but changes the overall spot size at the workpiece. This enables users to employ the system over a wide range of laser powers, from 500W to 3kW. They can also optimise the process for a range of applications, from low-power thin wall builds to large heavy deposition repairs, cladding, and other applications. ‘There is considerable interest from our customers who want to use the DED process for working with reflective metals,’ Cobbs said. ‘Our new LDH 3.X laser deposition heads with variable optics are already being ordered by new and existing customers, due to the flexibility of optimising the process over a wide range of DED laser powers.’


Making the otherwise unmanufacturable DED blows powdered material through a nozzle into a melt pool created by a laser, which brings its own challenges, potentially damaging the underlying structure. ‘If the laser spot size remains constant and the laser power increases significantly, this can cause the process to start “keyholing”, evaporating elements and basically cutting into, or through, the material,’ said Cobbs. ‘One way to avoid this is to spread


the laser energy density over a larger area, enlarging the laser spot size at the workpiece. We accomplish this with the use of special optics that increase the spot size for optimal DED processing.’ Like Stratasys Direct Manufacturing, Optomec has seen interest in copper DED


from the space sector. Cobbs’ colleague, marketing director Mike Dean, highlighted that Nasa has used copper liners inside Inconel alloy for a combustion chamber for liquid rocket engines. Trumpf’s Buchbinder agreed. ‘Right now,


there’s one market really driving the copper alloys area in additive manufacturing: the rocket area,’ he said. ‘All the burners, really big parts where they use internal cooling, they need thermal conductivity, but also mechanical resistance. That’s why they use copper alloys.’ Other important applications include


producing induction coils for heating in metals such as steel, and lightweight cooling systems for electronics in electric vehicles.


Stratasys Direct Manufacturing offers 3D-printing services using a C18150 copper/ chromium/zirconium alloy


Yet Carter of Stratasys Direct notes it is still early days for the technology. ‘Copper is the newest alloy we’ve brought to market,’ he said. ‘It is currently used for highly custom jobs. We hope to take it to the next level, where we start doing what Stratasys Direct calls serialised production – by no means the quantity of mass production. On the contrary, we’re talking hundreds, if not a few thousand, components. But those developments can take from 18 months to years to develop, especially with a new alloy.’ Stoll and his FAPS colleagues are looking


at a different primary application to the other groups. ‘We are planning to place our research in the power electronics sector, mostly for cooling applications where 3D printing can add great value to the cooling performance. In another branch of research, we are trying to print copper directly on dielectric substrates, like ceramics for power electronic applications.’ And while 3D printing copper is still in its early stages, it’s not far behind the rest of the industry in terms of manufacturing scale. ‘When you look at the great additive manufacturing fairs like Formnext and Rapid Tech, industry is trying very hard to improve the productivity of additive manufacturing,’ Stoll said.


‘I still think additive manufacturing


A cross section of copper, 3D printed using technology developed by Institute for Factory Automation and Production Systems researchers, shows its high density


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will settle down for small and mid-size batch production lines. The aspect of manufacturing parts that aren’t manufacturable in conventional processes, as well as product improvements with such structures, will be, and stay, the strength of additive manufacturing. But additive manufacturing technologies will find more applications in other sectors, for example electronics.’ l


SPRING 2020 LASER SYSTEMS EUROPE 15


Thomas Stoll


Stratasys Direct Manufacturing


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