Additive manufacturing opens the door for conformal cooling

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As 3D printing technology continues to advance, the realization of complex, non-conventional, cooling channel designs for tooling are increasingly gaining ground. An additive manufacturing technology like direct metal laser sintering (DMLS) can print almost any imaginable complex cooling circuit design (within the printer platform and print angle limitations) to help control part quality and cycle time, says Jay Vang, customer success engineer at Moldex3d .

In injection moulding, the cooling phase typically determines the length of the overall cycle time. By creating complex channels near the part surface and hard to reach areas, the cooling time may be reduced and an improvement in part quality can be achieved. 

Using additive manufacturing for conformal cooling not allows for more complex circuit designs that contour along the part surface, it also means that the moulds can be built far more quickly than with conventional machining – especially where multi-cavity moulds are concerned. 

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, says Vang.

Figure 1

In Fig. 1, direct temperature comparison in the tool can be analyzed 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 minimizing warp is to minimize differential shrink. With better mould temperature uniformity, differential shrinkage can be reduced, which again helps minimize warp. 

Figure 2

Fig. 2 compares the simulation results at sensor nodes placed on the part surface to determine the temperature profile through an injection moulding cycle comparing the two cooling channels above.

The temperature profile indicates a max ∆T of approx. 2~3°C for the case with the conformal cooling design compared to a max ∆T of approx. 5~7°C for the conventional cooling design. 

Vang: “Because the differential temperature of the part is reduced, the rate that the material of the part freezes and shrinks are closer and in turn, should yield a part with less warpage.”

In other words, taking advantage of the complex conformal circuit design realizable today with additive manufacturing can therefore help reduce cycle time and increase part quality. 

Simulation software can be used to help validate innovative cooling channel designs.

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