I ran across this in a discussion board in the SPE (Society of the Plastics Industry) LinkedIn group… The discussion was about how to make plastics look like metal. I’ll post about that later, but in this discussion, somebody mentions RocTool technology as a way to produce a very high luster surface with a wide variety of filled and unfilled materials, and eliminate painting. So I took a look myself and thought this was rather interesting…
According to an article back in 2006 from Plastics Technology, this technique has been around for a while. By heating the mold, you can control how the melted plastic flows and cools through the cavity, reducing or eliminating weld and flow lines and resulting in a high-quality surface. Of course, this would be using a highly polish (e.g., chrome-plated) cavity. This process was originallydeveloped for long-glass thermoplastic composites to produce large parts with automotive Class A surfaces.
But heating and cooling a 3-ton piece of steel over and over isn’t really the most efficient way to roll, so it hasn’t really been used all that much. However, RocTool’s patented approach heats and cools only the mold surface for much faster cycles than are possible with conventionally heated molds. Turning on electric power to the inductors for only a few minutes heats just a 0.2-mm-deep section of the tool surface while 99.9% of the mold stays cold. RocTool offers the technology for both plastic injection molding as well as composite processing.
You can read more in the Plastics Technology article about how RocTool uses special software to simulate the electromagnetic flows around the mold halves to optimize the mold design and processing. The RocTool site has a bunch of interesting videos that demonstrate the process.
Have any of you out there used this process? I’d be curious to hear your experience with it.