CONFORMING TO COMPLEX MOLD SURFACES
For many decades, injection mold designers have employed a tool design technique referred to as “conformal cooling”. In the vast majority of injection molds, mold temperature is controlled via water lines (or steam or oil depending on the properties of the resin used) which are typically drilled into the mold halves following straight pathways and limits how close cooling can be placed to some steel features. Conformal cooling on the other hand is an option that allows water channels to closely “conform” to often complex mold surfaces.
DIRECT METAL LASER SINTERING (DMLS)
In the past twenty years the advent of Direct Metal Laser Sintering (DMLS) made conformal cooling far more feasible. DMLS is an additive manufacturing technology that builds up geometries layer by layer, sintering each subsequent layer to the other. Selective Laser Sintering (SLS) is another technology that’s available, which is different than DMLS but also a strong option. When these technologies first appeared, they were suitable for prototype or lower volume applications but advances in the equipment and steels produced make mold components feasible from either DMLS or SLS. What are the benefits of employing conformal cooling?
DMLS, SLS, and other emerging 3D technologies for metals are faster and more accurate than what was available even two years ago and require less, if any, final machining.
More uniform part cooling and fewer hot spots. From the injection processing perspective, this is the big payoff that drives everything. Uniform and effective cooling eliminates hot spots that can harm part quality and narrow processing windows.
Cooling is the largest portion of most injection cycles and a reduction of up to 50% can have quite an impact on overall cycle times. This efficiency translates into better use of available capacity, whether in relation to a press or tooling, including faster cycle times which are directly linked to reduced costs.
Uniform cooling means better and more consistent control of shrink, tighter Cpk’s, wider processing windows, smoother validations, reduced program risk, and less scrap. All these items taken together add up to a considerable reduction in overall costs even when stacked up against sometimes higher initial tooling investments.
PTA Plastics sees conformal cooling as an increasingly viable option to support a broader range of applications and we have decades of experience with this technique. This is especially important because tools using conformal cooling require a little extra attention versus traditional tools. Corrosion can cause plugged pathways that can be difficult to repair. PTA has invested in equipment to treat and descale cooling lines which reduces the likelihood that a costly component would require replacement. Having past experience with issues of plugged pathways, we understand how critical this can be.
Here at PTA, we are staying abreast of some very recent advancements in 3D steel manufacturing techniques. Not only do these techniques further improve conformal cooling, but also injection mold manufacturing with better lead times, component quality, and strength, to name a few. The pace of change is rapid and we are committed to staying at the forefront of these changes and other technologies.
