The rapid progress of 3D printing technology has led to the widespread use of complex (non-traditional) cooling designs in the injection molding industry. Almost any complex cooling circuit design imaginable - within the restrictions of printer platform and print angle specifications - can now be printed using additive manufacturing, such as direct metal laser sintering (DMLS), helping control both cycle time and part quality.
Time is money in the modern economy. In the injection molding industry, the length of the overall cycle time is typically governed by the cooling phase. This could be due to factors such as controlled cooling rate requirements or parts failing to meet a safe ejection temperature. Due to the fact that it is possible to develop complex channels near the part surface and in hard-to-reach areas, potential reduction in cooling times and general enhancements in part quality can now be realized.
Benefits of Conformal Cooling Design
When additive manufacturing is employed in conformal cooling, the designs can be complex (e.g. with contours along the part surface) and can now potentially be constructed quicker than in conventional machining.This is even more true in multi-cavity molds, in which additive manufacturing is already used extensively to develop conformal cooling channels.
Apart from understanding the way in which conformal cooling can help potentially shorten cycle time, minimize mold build time, and enhance part quality; the use of plastic simulation software can also help provide a relative value in ascertaining the reduction of cycle time and in the enhancement of part quality, such as distortion. Figure 1 illustrates ways in which manufacturers can analyze direct temperature comparisons (using the Moldex3D tool) to identify the cooling efficiency and uniformity between a traditional and a conformal spiral cooling channel. In contrast to the conformal cooling design, traditional cooling design constraints result in inefficient and non-uniform removal of heat from the insert and the part.
Figure 1. Simulation results of temperature profiles of a conventional cooling and a conformal cooling design of an insert.
Reduction of differential shrinkage can lead to a reduction in warp. Differential shrinkage can be reduced by ensuring better mold temperature uniformity, which, in turn, helps reduce warp. In Figure 2, simulation results at sensor nodes placed on the part surface have been compared to ascertain the temperature profile using an injection molding cycle comparing the two cooling channels above.
Figure 2. Simulation results of temperature profile at the sensor nodes of a part with a conventional and a conformal cooling design of an insert.
The temperature profile points toward a maximum ∆T of roughly 2~3 °C, in the case of the conformal cooling design, in contrast to a maximum ∆T of around 5~7 °C for the traditional cooling design. Due to the reduction in the differential temperature of the part, the rates at which the material of the part freezes and shrinks are closer and should consequently yield a part with less warpage.
In conclusion, there has been rapid progress in the use of existing technologies, such as additive manufacturing or vacuum brazing, that have allowed manufacturers to develop complex water designs that help minimize cycle time and enhance part quality. The use of conformal cooling design in conjunction with simulation software can help demonstrate the validity of conformal cooling in injection molding and determine potential ROI.
This information has been sourced, reviewed and adapted from materials provided by Moldex3D.
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