A side-gated hot runner system from Thermoplay promises perfectly round cylinders with even wall thicknesses throughout, very important traits in syringe barrels or pipettes. That application, which Thermoplay and its U.S. distributor, Alba Enterprises, showed off at PLASTEC West 2011 garnered a lot of interest from medically minded show attendees.
Thermoplay notes that parts with long lengths in proportion to their diameter can have difficulty keeping the mold core from shifting during injection, with movement resulting in varying wall thicknesses. By positioning the injection points near the cylinder's open end, Thermoplay says there is less core movement. The company is promoting its new nozzle as a means to replace more traditional "tunnel" sprues used in similar applications.
By placing injection directly into the annular cavity wall, the nozzle structure allows easier machining of the injection system housing within the mold. The nozzle features a double plastic sealing ring, and the lateral injection makes for very clean gate....