Kortec Inc. of Gloucester, Mass., hopes to bring multigate coinjection technology to the forefront of the injection molding industry. With the use of hot-runner systems, start-up firm Kortec offers a new technology in multigate co-injection. The hot-runner system has separate flow channels for the skin and core materials.
``The two materials are joined at the tip end, within the last inch or so of the nozzle,'' said Presi-dent Paul Swenson. ``The materials are kept from mixing by a combination of nozzle design and how the plastic flows,'' he said.
``Because of the high viscosity of the plastic, it flows in layers. Then in the last inch of the nozzle it's mixed. There's no turbulence, so it flows in layers to the cavity mold,'' Swenson said.
``Also, purging occurs in the final 5 percent filling of the cavity in packing out the part,'' he said. ``When the channels are purged of material, the surface in the gate becomes the skin material.''
Coinjection machines join the skin and core materials in the machine nozzle of the coinjection head and the parts are produced with a cold sprue, Swenson said. But, the production of the parts will be more efficient with the hot-runner system. Swenson added that material would not be wasted as it is in a cold sprue.
``This is why machine-based co-injection has not been widely used: Hot runner molding has not been economical,'' said Swenson. Kortec believes it has overcome these economic disadvantages.
One advantage, Swenson said, is the use of less-expensive materials such as regrind.
``Using engineered-type resins gives a company 20-30 percent material savings,'' he said.
Coupled with the cost of the two-color machines Kortec uses, Swenson believes the customer will ultimately save money with this technology. Overall, the machines cost 50 percent more than a standard injection molding system, but 25-40 percent less than a standard coinjection molding system, the firm said.
Kortec offers the complete turnkey molding cell to its customers, from technical and economic analysis to designing and operating a molding cell to producing a molded part.
Kortec is targeting the automotive, business equipment, housewares and medical industries. The firm has three employees.