An innovative steam molding system developed in England and Taiwan is widely used in Asia to improve the surface finish of television frames and may be moving to automotive applications.
The concept involves bringing the mold cavity surface temperature close to the plastic melt temperature to improve the component surface aesthetics. In the RTC process, the mold is heated by flowing steam through channels located close to the cavity surface. Steam is replaced with chilled water in the same mold channels to cool the mold.
The process is called “Rapid Temperature Cycling” by “Steam-Assisted Molding”.
Steam is used because it releases latent heat energy when it condenses to water. The higher the steam temperature the more heat is released.
The technology comes from Gas Injection Worldwide Limited (GIWW Ltd), a UK-based company that was formed in 2007 by its three principle directors (Terry Pearson, Ken Crow and Raymond Foad) who had each been involved with gas-assisted molding for more than 25 years.
Pearson had been involved with several UK technical universities studying methods of heating molds. GIWW made its first prototype RTC steam controller in 2007 and made its first commercial sale the same year. The current system is Version 5.1
In 2009 GIWW introduced its DSG system (Dedicated Steam Generator), which is a small electric boiler placed next to an injection molding machine.
“Initially used by the global LCD TV industry for all high gloss piano black LCD TV bezels, the technology is now finding wider use in applications in the automotive industry and consumer electronics industry,” Foad told The Molding Blog.
In 2008 GIWW started collaboration with a Taiwanese university that had been working on external induction heating technology. GIWW now sells its technology (RTC IHC) outside of China and Taiwan.
“RTC IHC offers numerous benefits compared to other internal induction heating technologies (RocTool’s 3iTec /Caged System) primarily that existing mold tools can be used, power consumption is much less and heating and cooling times (cycle times) are shorter as we are only heating the surface of the mold to a depth of 0.1mm (0.004″),” Foad says.
“To date we estimate that there are over 200 steam molding systems working around the world (predominantly in Asia for TV production) but we can see a major increase in usage for automotive applications for RTC Steam Heating and numerous medical applications for our RTC IHC external Induction Heating technology in the next 3-5 years.”
The RTC Steam Heating technology targets large parts with complex 3D geometry and the RTC IHC External Induction Heating technology is aimed at smaller 2.5D (so-called “two-and-a-half-dimensional” parts.
“We can sometimes get a good synergy by using GAM (gas-assisted molding) technology with RTC,” Foad adds. Foad will be making a presentation titled “Is RTC the long-awaited panacea for injection molded parts?” at ANTEC April 4 in Orlando, FL.