Two directors of a British company called 493K Ltd., held a technical session at Rotoplas'11 in Rosemont, Ill., to introduce its K-Kool, a “dial-in” process control that adjusts the rate of cooling in rotational molding.
Improper cooling can have a big impact on polyethylene, causing shrinkage and warping, according to Nick Henwood. “Problems with dimensional tolerances keeps rotomolding out of some big markets, like automotive and aerospace,” he said.
Henwood explained that a key is balancing the amorphous phase and the crystalline phase of PE, which is semi-crystalline polymer. The rate of cooling will impact that balance, therefore shrinkage and part density. So you want to keep cooling consistent, but in rotomolding that's a real challenge because of changes in ambient air temperature from summer to winter and night and day. And in the cooling stage, rotomolding blows ambient air across the mold.
According to 493K, the best strategy is to apply gentle cooling with a higher level of control by actively cooling the air.
K-Kool makes “controlled fog” that evaporates and cools down the air.
“This is not water cooling. This is controlled cooling and making small changes over the cycle,” said Gareth McDowell, another director.
McDowell said 493K is looking for partners to help develop the K-Kool. The technology can make slow, steady adjustments in air coolness in a controlled manner. It can adjust for changes in ambient air temperature and humidity. Shrinkage can be controlled and predicted, he said.
493K is based in McDowell, the United Kingdom.
Tel. 011 44 28 9335 9922, fax 011 44 87 1528 9022, [email protected].