Metal Additive Manufacturing Conference 2019

Practical research on the implementation of metal additive manufacturing in extrusion tooling applications has been deducted by VIVES University College and the ProPolis research group from KULeuven in Belgium. In polymer extrusion lines, molten plastic is forced through a die to define the rough shape of plastic profiles. Calibration units are positioned right behind the mould; their function is to cool the plastic profiles in order to give them their final and exact shape. This cooling process needs to occur as uniform as possible to prevent geometrical distortion, and as fast as possible to maintain higher production speeds. To achieve this, calibration units feature highly complex cooling channels and vacuum slots. These often intricate channels and slots are very challenging to create using conventional tooling such as CNC-milling and EDM technology, resulting in sub-optimal cooling processes and more complex cooling block assemblies. Where the above subtractive technologies run into their limits, additive manufacturing opens up new possibilities for designers and engineers because of the technology’s geometrical freedom: improved cooling, shorter lead times, faster production speeds and therefore a shorter time to market. These possibilities are explored in the aforementioned research through a number of practical case studies for Belgian extrusion companies. Through thermal simulations, calibration units modelled for conventional CNC machining/EDM are compared to new designs made specifically for additive manufacturing. These simulations provide insight in pressure drops and heat transfer from extrusion profile to cooling water, and therefore aid in the optimisation of cooling channel layout. Once optimised, the new design is printed with selective laser melting technology and tested in production. Measurements on heat transfer are executed and compared to the conventional cooling units, showing great promise for additive manufacturing as an alternative production method for calibration units in polymer extrusion.