Hot runner control

These controls represent the reference class of today s hot runner control systems, depending on the accuracy, functionality, ease of use, and adaptability. All control functions can be easily adapted to the Windows-like user interface. Fault analysis and diagnosis of the hot runner system are possible as well as master-slave configurations and loading of drawings or photos into the user-friendly touch-screen display for intuitive adjustment of the nozzles and hot runner block control areas. 

It is important in this or any other heat stability test to mold the natural resin as a control. Some resins, especially acrylonitrile butadiene styrene (ABS), darken considerably when heated above a particular threshold temperature. In the case of ABS, the butadiene rubber component may begin to go yellow and dark over 450°F. Although the customer may set its machines below 450°F barrel temperatures, shear heating or heating in the hot runner manifold could yield local melt temperatures in excess of 500°F and burn the natural resin. 

Figure 6.34 Construction and temperature control curve for an externally heated hot-runner nozzle.

Runners are the ehannels through which the polymer melt is fed into the mold cavities from the eyhnder nozzle. In a multicavity mold, it is necessary to fill all the mold cavities simultaneously and uniformly. Control of the size of the runners provides a means of controlling the flow resistance and balaneing the flow into the mold cavities. In most multicavity molds, the runners form part of the mold flame. Consequently, the ejected part is accompanied by the runner system, which must be removed and, in the ease of thermoplastics, reground for reuse. The use of the hot runner mold whereby the runner ehannels are heated to keep the polymer in the molten state, eliminates this need for plastic runner separation and avoids possible generation of scrap material. With proper machine operation, a hot rurmer mold requires a smaller amoimt of melt per shot than an equivalent cold runner mold, leading to redueed injeetion time and faster cycles. 

One development for coinjection equipment was the inclusion of separate hot-runner temperature control systems for the different resins, for example, in order to allow an EVOH core layer to be processed at a temperature 70 C lower than the PET skin layers. Another development was the use of computer simulation to design tooling that manipulates the barrier resin distribution to fortify critical areas such as wall sections. Both wide mouth and narrow neck coinjection stretch blow molded bottles are available. 

The precise controller and gating mechanism of a hot-runner mold. 

These materials have been successfully molded in all types of mold, for example, 2-plate, 3-plate, insulated runner, stack and hot runner, en using the hot manifold type of runnerless mold, the runner channel must be streamlined so that there are no dead spots (nil flow areas) which are likely to cause degradation accurate temperature control of the manifold is essential. To maintain the sparkling clarity of this material, use vacuum smelted steel as this can take a very high polish and is non-porous. 

Master-Shot, Hot runner system, Mold-Masters Masterblend, Feeder control system, Merrick Industries, Inc. 

Cold runners are ejected with the part and trimmed after removal. Hot runners keep the polymer at melting temperature. Finally, the melt is distributed in mold cavities through gates which control polymer flow and isolate mold cavities from the rest of the system... 

E. Schwarzkopf, Electrical Heating Elements in a Hot Runner System and Temperature Control for Them. Published by Hotset Heizpatronen und Zubehor GmbH. [In German ]. 

Hot runner system Staubli Rapid release 1 1 Cascade Control 1 1 Open svstem 1 1 Valve gate 1 1 1... 

A primitive variant of the hot runner is known as an insulated runner. This employs an unheated manifold with very large runners of 20 mm to 35 mm diameter, and relies on the poor thermal conductivity of plastics to ensure that a flow channel in the center of the large runner always remains molten. The insulated runner mold is not capable of precise and consistent control and is now rarely seen. 

Melt enters the cavities in a more controlled condition than with a sprue and runner system, as the temperature control in the hot runner is adjustable to finer limits... 

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