In two stations, four materials are injected in six colors.

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Zahoransky mold (above and below) fits seven material feeds into a restricted space.

Mold-Masters valve-gate system for 7-component toothbrush mold.

German injection moldmaker Zahoransky Formenbau GmbH has supplied what it says is the world’s first seven-component injection mold ever built to M+C Schiffer, a German maker of dental-care products. The 16-cavity injection mold for toothbrushes has two injection stations and one loading and removal station located outside the mold. Two different materials in the same color are injected in the first station, while two different TPEs are injected in the second station—one of these is injected in four colors. The latter is said to be a must in the toothbrush market, since they are typically retailed in four colors.

This multi-component mold system eliminates the need for color changes, which can require 2-hr downtime for each change, and material waste for purging. Up to now, the maximum number of components injected in one mold was six, according to Zahoransky. Building a seven-component mold was a major technical challenge, considering that seven injection units had to be connected to the mold in a very restricted space. Seven material feeds, the different processing temperatures of the various materials, and close spacing between nozzles feeding the same cavity were also complicating factors.

Molding is done on a six-component machine from Engel (U.S. office in York, Pa.) with a seventh injection unit from Boy (U.S. office in Exton, Pa.). Mold-Masters, Georgetown, Ont., supplied the hot-runner system. The design allows six or more materials and colors to be integrated in a single runner.