HOW DOES IMFLUX LOW PRESSURE MOLDING WORK?
How did P&G convert the not-very-successful 20-year-old Intellimold process into a viable molding process for thin-walled packaging? Intellimold patents describe pressurizing molds with about 200 psi of shop air to control mold filling at constant low pressure. Imflux patents describe molding at low constant pressure of 3000-6000 psi, which is 5-10 times lower than conventional injection pressures of 15,000-30,000 psi. What Intellimold and Imflux appear to have in common is control of mold filling based on maintaining constant pressure in the mold, not on achieving high injection speed.
Imflux’s patented control technology (U.S. Pat. #8980146 and #9321206) claims to alter injection pressure if plastic viscosity changes, so multiple cavities can be filled without short shots or flash. Imflux U.S. Patents # 9289933 and # 9481119 describe a “fluid pressure regulating valve and pressure relief valve” as part of this pressure control, while U.S. Pat. #8911228 describes a “non-naturally balanced feed system” for multi-cavity injection molds with different runner lengths.
The high thermal conductivity of aluminum molds combined with low molding pressure apparently allows co-injection with “more control over the relative velocities of the materials being introduced,” says Imflux patent application WO # 2013126667. The application describes flowing a very thin (0.1 mm) surface layer of a high strength polymer like EVOH or PP together with a layer of an environmentally friendly polymer like PLA, starch and/or postconsumer recycled plastic and achieving overall wall thickness of less than 0.5 mm.
Aluminum molds often don’t have cooling lines. Imflux U.S. patent # 8591219, however, describes aluminum molds with fixed mold plates through which coolant flows. Coolant then goes through a condenser and is sprayed onto an upper mold surface.
Another Imflux patent describes a “simplified evaporative cooling system” (U.S. Pat. # 8591219) with cooling lines in a support plate and projections that allow mold cavities to snap in. U.S. Pat. Applic. # 20150064303 describes “simplified cooling with exotic cooling fluids” in channels in the mold support plate for high output injection molding of consumer products. Other patents describe using “hazardous, dangerous or expensive coolants.”
Imflux low pressure molding also apparently allows higher length/thickness ratios for thin wall molding. U.S. Pat. Applic. # 20130221575 on “Method for Operating a High Productivity Injection Molding Machine” shows low pressure molding of parts with up to 240 L/T vs. 100-200 L/T for high-pressure, conventional injection molding.
In U.S. Pat. Applic. # 20130221575, Figures 5A-5D show a cavity filled by conventional variable pressure injection molding. Figures 6A-6D show cross sections of a thin-wall injection mold cavity filled by Imflux’s constant pressure “high productivity” injection molding.
But analyzing the patents is all guesswork. Imflux technology remains a closely held secret known to dozens of major packaging companies and probably hundreds of processors under non-disclosure. Is it fully commercial? Is it working as well as P&G expected? Does it work with some polymers and not others? Is any company using it voluntarily or is it installed only at P&G subsidiaries and suppliers? Why hasn’t P&G presented actual production data?