Note the encapsulated manifold heater design in this rear view of a 32-cavity hot half. Although this feature seems complex, its use is justified because of its much extended heater life and superior temperature uniformity.

These valve-gated nozzles are designed with replaceable components (including pins) that do not require hot half disassembly.

3. Ease of maintenance - Remember that someone has to work on it. Most hot runner systems are great when they work as intended, however, no system will work indefinitely without requiring some attention and maintenance.

      A seemingly unimportant component can stop working and if not detected and addressed immediately, a small problem can quickly transform itself into a catastrophic failure.

      A good way to reduce this probability is to reduce the number of parts in the system. Not an easy task to accomplish, but easy enough to notice during system evaluation. Easy accessibility to components and wiring is one of the most desirable hot runner assembly features, as is a design that allows nozzle heater and thermocouple replacement from the front of the plates without disassembly of the hot half.

Summary

      Over the years a number of hot runner manufacturers have developed systems that are practical, economical and durable, and that use replaceable components for easy maintenance. Some systems are better-suited for certain applications than others, but selecting the most appropriate system for the job is of vital importance to the mold designer, the mold maker, the molder, the maintenance professional and most of all, the owner of the mold. Educated and informed hot runner system selection will keep all parties smiling.

Contributor

      Sal Benenati is chief operating officer of Orycon Hot Runner Systems. He has been awarded several patents over the past 30 years for controller, manifold and nozzle innovations.

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