Hot runnings

An appropriately sensitive control technology that can detect and control even minimal thermal changes in the melt is necessary to reliably process thermally sensitive plastics.

The clean room suitability of hot runner nozzles and systems used today in these environments has been proven in recent years. The now fully developed electric version certainly remains the first choice here. A high degree of automation has become a matter of course in today's hot runner technology. However, says Friederich, "maintainability" and "reliability" must be "considered much more important".

Gallery

Gallery with 5 images

Increasing demands on plastic parts' precision and surface quality

"We see a current trend towards ever-increasing demands in terms of precision and surface quality of plastic components, via customizable injection concepts and thus adaptation to the relevant products," explains Ravan Graubner, sales manager at Witos in Frankenberg/Wangershausen Germany. "Moreover, we improve the quality of plastic parts with steadily ever more advanced drive units, valve gate systems, various capabilities for lateral injection and bolted and pre-finished hot runner systems."

To increase energy efficiency, the company offers its customers electric instead of hydraulic or pneumatic drives. Highly precise control of valve gate lifting plates, an external control unit and permanent position sensing through internal path tracking systems ensure precise cut quality.

In processing thermally sensitive plastics, the company would work toward "permanent advancement of hot runner nozzles and temperature profiles as well as optimal coordination of the installation scenario between hot runner manufacturer and tool maker". Graubner says the company has presented an electric drive particularly designed for clean room applications at the Fakuma. The electric servo motor is fully encased, so that there is no risk of a release of lubricants or media in clean rooms. Compared with hydraulic and pneumatic needle drives, the installation effort for servo motor drives is minimal.

For lateral injection, optimally adapted fully hydraulically balanced systems are recommended. All melt guides by default already come with deflectors preventing "dead corners" in the melt flow. According to Graubner, an optimised heater guide in distributor and nozzles ensures a uniform temperature regulation right down to the nozzle tips. All nozzles can be individually regulated and thus optimally configured for a smooth opening and filling of all cavities.

"For us," concludes Witosa's sales manager, "highly complex applications and a high degree of automation do not conflict with ease of maintenance and reliability. All our systems, no matter how complex, are always designed with a focus on ease of maintenance."

(ID:44036740)