Officials of Swiss mold temperature control maker Regloplas AG and its U.S. operation, Regloplas Corp. in St. Joseph, Mich., say pressurized water is the best method for rapid heating and cooling of injection molds, as well as tooling for composites for aerospace parts.
The advantages of rapid heating and cooling of a mold are becoming more well known in North America. They include improved part surface quality and mechanical properties and reduction of mold stresses that can cause warpage.
Regloplas claims pressurized water is more effective than oil, steam and electric cartridge heaters for rapid heating and cooling. Benefits include less injection pressure and clamping force required, longer holding pressure even in areas away from the gate, energy efficiency gains and the possibility of homogenous cooling and fewer scrap parts. It can reduce cycle times.
Markets for Regloplas' Variotherm temperature-control products include injection molding, composites/aerospace, automotive, medical, compounding, food processing, die-casting and tire and rubber.
The top-line Regloplas P230S pressurized water temperature-control unit, introduced at NPE2018, can heat pressurized water up to 446° F. Because the water is under high pressure, it remains liquid and does not turn to steam, Brian Pruitt, sales manager for plastics and medical North America, said.
The P230S offers high-capacity pumping of 10 gallons per minute, with precise pressure control.
The mulfiFlow unit distributes pressurized water to the mold. One multiFlow can run four different water flows in parallel, each running a different temperature, for specific areas of the mold, Pruitt said.
Each circuit is set and monitored separately, fully integrated with the control system. The technician can set the monitoring window according to the specified target values. If the temperature or flow rate goes outside the respective window, the system will trigger an alarm.
Regloplas officials outlined issues with some competing methods. Steam has limited precision on temperature control and requires separate cooling channels that need cold water. Also, a line break can cause potential steam injuries. Oil can use the same channel to heat and cool, but the rate of heating can be slow. Also, energy use is increased because of the oil viscosity. Regloplas officials said oil can be a problem in clean rooms for medical molding. Electric cartridge heaters consume large amounts of electricity and do not offer cooling. The heating elements can fail.
The mold is the key, the company said. The goal is the ability to make very quick temperature changes on the mold cavity surface.
Rapid cycle molding can be retrofitted and applied to any existing mold, if the tool is properly sized and designed. Using conformal inserts --- where the mold channels follow the contours of the part — can direct rapid heating and cooling to problem areas, like a thin wall section. Or in the product design phase, a conformal mold could be configured right from the start for Regloplas technology.
Mold weight should be as light as possible and have good thermal characteristics. Channels should be as close to the surface as possible.
On tooling to make glass-filled composite parts, Regloplas claims its system delivers better strength and structure since it endures a more homogenous orientation of glass fibers. It also reduces weld lines and warpage, and it improves dimensional stability and consistency of injection molded parts, the company said.
Reglopas manufactures the equipment at its headquarters in St. Gallen, Switzerland. The family-owned company employs 90 in Switzerland and more than 200 worldwide.