Dan Wheeler, president of Polar Bear Cryogenics Co. in Kalamazoo, Mich., believes mold makers can benefit from cryogenic technology.
As a former race car driver, Wheeler knows what cryogenic treatment can do for engines, such as improving wear characteristics, dimensional stability and resistance to heat deformation.
As a plastics engineer, he would like to prove that cryogenics can enhance the tensile strength, dimensional stability and life of injection molds.
The technology of using liquid nitrogen to strengthen, reduce wear and improve the life of metal components is not new. From researching the technology, Wheeler discovered that it was first used during the Vietnam War on the gearboxes in Huey helicopters.
``One reason why this process hasn't grown too much is that it's not really known why it works,'' said Wheeler. ``Put two metallurgists in a room and they'll start swinging at each other because they can't agree.''
The cryogenic process involves precisely cooling metal parts until they reach minus 300§ F. The temperature is maintained for as long as 40 hours, then the metal is warmed slowly to ambient temperature. The entire process can take 80 hours.
The process is a supplement to heat treating and typically is done after heat treatment.
Wheeler said the cost is based on the weight of the mold components being treated.
One excellent application for the process is in aluminum prototype tooling, he said. A mold that typically has a short life, particularly if running abrasive materials, can be cryogenically treated and the life of the mold extended into long production runs.
Any type of mold steel can be cryogenically treated, including P-20, H-13 or stainless steel, Wheeler said, and it can be particularly effective in any area of the mold where there is a vertical shut-off, where galling typically occurs from two metals that rub together.
``You can make these shut-off areas slippery using cryogenics,'' he said.
Wheeler's company treats engine components for Indy and Winston Cup race cars, but the plastics industry has given him the cold shoulder.
``I go around and visit mold shops, and people look at me like I'm nuts,'' said Wheeler.
Wheeler also tries to attract molding machine and other equipment manufacturers by showing them that cryogenically treated screws, barrels, check rings, granulator blades and other machinery components can have an extended life.
Wheeler suggested that one good way to experiment with cryogenics is to take a two-cavity prototype mold and treat one cavity cryogenically, and leave the second cavity untreated. Then test the wear of both cavities.
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