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Medical and electronics industry injection molders can attain a higher degree of process reliability for high-precision valve-gate applications via an electric-drive valve-gate system that's now available with an optional position encoder.

4 Min Read
Hot runner advances: Ewikon unveils electric drive valve gates, slim-line nozzles, and horizontal gating technologies

Medical and electronics industry injection molders can attain a higher degree of process reliability for high-precision valve-gate applications via an electric-drive valve-gate system that's now available with an optional position encoder.

Manufacturer Ewikon says the encoders provide real-time monitoring of valve pin position with an accuracy of 0.01 mm. Also new for the system is a second-generation touch-screen electric drive controller, which monitors the valve-pin position and corrects for any deviation. For instance, the controller will trigger an error message and alarm if the drive fails to reach its position, allowing it to detect gate blockages caused by resin contaminants. The controller shows the current valve pin positions graphically and digitally and allows operators to select for synchronous or sequential control on all drives.

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Ewikon drive encoder

Drive encoder.

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touch-screen controller

Touch-screen control.

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Ewikon valve gate

Electric valve gate.

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Ewikon

Tighter pitch possible.

The system can handle up to 32 drives, and slave units may be grouped together to control larger layouts. In addition to the normal functions, multiple valve-pin positions within one injection cycle are also possible in the standard unit. Various trigger signals can be used to open and close valves, and the signals may be digital from pressure or temperature systems or analog signals such as linear position devices for screw position. Data and settings can be saved on a compact flash card.

Thin to win, nozzle trims the fat
Ewikon  also added a new slim-line nozzle to its High Performance HPS III-S line of standard nozzles, with this design featuring a melt flow bore diameter of 3 mm and only requiring an 11-mm well in the mold. Ewikon notes that the nozzle isparticularly well suited for gating in hard-to-reach areas like near cores, or anywhere internal gating is required. Nozzles may be positioned with a minimum spacing of 12 mm, allowing for very compact mold designs.

The nozzle is available as a hot tip, open tip or valve gate, making it one of the smallest valve gate nozzles on the market, according to Ewikon. The valve-gate version features a valve-pin guide placed in the front area to provide a positive guide of the valve pin at all times, while reducing valve pin and gate wear. The nozzle is available in standard or front-installation versions and comes in lengths from 39 to 189 mm. The front-mount option facilitates ease of installation and servicing since it may be removed from the hot half without hot half disassembly. 

Valve-gated side gating
Need horizontal gating onto a part surface with a valve gate? Ewikon is also now offering its HPS III-MH Multi-Valve Gate System in North America, debuting the technology, which allows gating points on horizontal surfaces close to vertical walls, like flanges of syringes and analysis tubes, at NPE 2012. Based on the its MH Edge Gate Nozzle technology, this product's compact design allows a minimum distance between cavities of 6 mm.

Valve pins are actuated by a synchronous plate that Ewikon says guarantees a simultaneous opening of all gates, which enhances repeatability and balance from cavity to cavity. The combined valve-pin guides and seals are screwed into the cooled standard mold insert and are positioned close to the gate with a free valve-pin length of 5 mm. The company says this guarantees a leakage-free operation and minimum load on the valve pin.

A specially shaped heat conductive element surrounds the valve pin, without contact, near the gate for a homogeneous temperature profile. The heat conductive elements' unique design allows them to be installed in the nozzle from the parting line of the mold. Because of this, split cavity blocks are not required, helping minimize mold costs. This design also facilitates parting line service with maintenance possible without having to take the mold from the machine.

For quick color changes, the nozzle features a streamlined flow channel layout and a melt seal directly at the gate. In multicavity applications, nozzles can be used in conjunction with Ewikon's HPS III T Style manifold with Flow Element Technology.

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