Synventive Hot Runner Solves Challenging Multi-Component Application for Bosch Power Tools

This lightweight tool was designed for very low vibration for less fatigue in  professional work environments.

The housing for the Bosch GBH 36 V-LI compact professional cordless hammer drill  consists of three separate part sections, molded with three different materials, all produced on one molding machine.

Three Synventive hot runner manifolds with different nozzle and gate styles are an integral part of the application, feeding glass-filled polyamide (PA) 6 in blue (Bosch specific color,  signifying the company’s ‘professional’ brand) and red (Bosch logo), and thermoplastic  elastomer (TPE) for the soft touch handle directly onto the part surfaces and into a cold runner.

The hot runners feed a single, rotating mold that produces all three-part sections of the right and left housing. In the first step the main housing is molded. After the tool rotates in the  second step, the housing parts are overmolded in particular sections. Each cycle produces a separate, finished housing set.

Fig.1: The 2 housings molded with 3 components

The Krauss-Maffei machine used for the application features two injection units and a  Babyplast machine adapted to the tool in an ‘L’ version and used exclusively for molding the smallest part of the application, which includes the raised, red Bosch logo.

A ‘Y’ shaped Synventive manifold with three nozzles (two valve-gate, one open gate, flow bore Ø 12mm) is used to produce the largest parts, a 540 gram housing set. The open gate nozzle starts the fill process, gating into the runner, and the valve gate nozzles are then used to control the weld line on each part. An ‘H’ shaped manifold with four valve gate nozzles produces the 20 gram TPE handle part sections and finally, a separate manifold leg fed from the tool side, with two small valve gate nozzles produces the 4 gram part section with the red Bosch logo at each housing part.

fig. 2: The tool and the 3 hot runner manifolds

“This application was extremely demanding in that it required hot runners with excellent  temperature uniformity to successfully process these temperature sensitive materials,” said Yasim Ipek, Synventive’s sales engineer for this project. “Also very important was gate control for perfect vestige and weld line control on the part surface.”

Synventive worked closely with the molder, Hans Arnold Kunststofftechnik GmbH, and  moldmaker, WGB Werkzeug und Gerätebau Klingenthal GmbH, to provide the solution for this challenging application.

“This was an example of the expertise Synventive provides its customers,” said Ipek. “Our consulting with the toolmaker and molder resulted in the creation of a system that solves a challenging application and provides a stable manufacturing process.”

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