MOULDS | TECHNOLOGY
Conformal cooling vs standard cooling
Jay Vang, Customer Success Engineer at Moldex3D Northern America, explains the benefits of using simulation software when designing cooling channels
With the acceleration of 3D printing technology, the realisation of complex (non-conventional) cooling designs is quickly gaining ground in the injection moulding industry. Additive manufactur- ing such as direct metal laser sintering (DMLS) can almost print any imaginable complex cooling circuit design (within the printer platform and print angle limitations) to help control part quality and cycle time. In today’s economy, time is money. In the injection moulding industry, the cooling phase typically determines the length of the overall cycle time. This may be due to factors such as (but not limited to) controlled cooling rate requirements or simply due to the part(s) not reaching safe ejection temperature. Since complex channels can be created near the part surface and hard to reach areas, potential reduction in cooling time and improvement in part quality can be achieved. Using additive manufacturing for conformal
cooling, not only can the designs be complex and contour along the part surface, but it can also potentially be built quicker than with conventional machining. This is even more true for multi-cavity moulds utilising additive manufacturing to build conformal cooling channels.
In conjunction with knowing how conformal cooling can help potentially reduce mould build time, reduce cycle time, and increase part quality, utilising plastic simulation software can help put a relative value in determining the reduction of cycle time and in the improvements of part quality such as distortion. In Fig. 1, direct temperature comparison in the tool can be analysed to determine cooling efficiency and uniformity between a conventional and a conformal spiral cooling channel. Due to conventional cooling design constraints, heat is not removed from the insert and part as efficiently and as uniformly as the conformal cooling design. One factor in minimising warp is to minimise differential shrinkage. With better mould tempera-
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ture uniformity, differential shrinkage can be reduced which again helps minimise warp. Simula- tion results gained at sensor nodes placed on the part surface to determine the temperature profile through an injection moulding cycle allow compari- son of the two cooling channels above. The temperature profile indicates a maximum ∆T of approximately 2-3°C for the case with the confor- mal cooling design, compared to a maximum ∆T of approximately 5-7°C for the conventional cooling design. Because the differential temperature of the part is reduced, the rate that the material of the part freezes and shrinkages are closer and in turn, should yield a part with less warpage. In summary, the utilisation of today’s technology such as vacuum brazing or additive manufacturing to create complex water design to help reduce cycle time and increase part quality is rapidly growing. Coupling conformal cooling design with simulation software can help to prove the validity of conformal cooling in injection moulding and help determine potential ROI. �
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Fig. 1 Simulation results of temperature profile of conventional cooling and conformal
cooling designs of an insert
September 2018 | INJECTION WORLD 47
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