Published On: Wed, Jul 15th, 2009

EWIKON’s electric drive valve gate combines precision and power

With the electric drive valve gate system with step-motor technology, EWIKON, a developer of hot runner system, offers a clean drive version for standard as well as demanding applications. It is available in three sizes and can be combined with nozzles with flow-channel diameter from 3 mm up to 12 mm, thus covering a broad shot weight range.

The installation of the compact drive units into the mold requires no complex installation geometry. Only simple cable ducts for the input leads must be machined into the clamping plate. Because there is no potential contamination from lubricated compressed air, the system offers an unlimited suitability for cleanroom applications for example in the medical industry.

Compared to electro-magnetic concepts the EWIKON step-motor technology offers decisive advantages. The external operating unit with the matching setup software is designed for operation of up to 8 valve pins and allows full control of the valve pin movement. The valve pin can be positioned with high precision in steps of 0.01 mm so there is no need for a mechanical adjustment of the valve pin length. Furthermore – according to the application requirements – process parameters such as valve pin stroke length, valve pin speed and opening and closing time can be varied by the operator. With a maximum power consumption of only 30 W for the largest version an energy saving operation is ensured.

The closing force of the valve pin stays constant no matter which stroke length is required. Under comparable conditions – the installation dimension of the drive is a good criterion here – it is generally higher than the force that can be generated by electro-magnetic drives, but can be furtherly enlarged by the possibility to vary the valve pin speed. Here a general advantage of step-motor technology becomes obvious. The slower the movement the higher the force generated. So it is possible to start the valve pin closing movement with high speed and then to decrease the speed just before closing the gate. An almost doubled closing force is the result. This makes the step-motor drive suitable for processing of demanding, rapidly freezing materials like Polycarbonate where high closing forces are required for a proper gate sealing.