Throwback Thursday: How to Prevent Hot Runner Leaks

One of the more common concerns still expressed by molders today about hot runner molds is the threat of a leak of molten plastic causing the manifold pocket to fill.  Here is a throwback to an article on leak prevention focused on externally heated hot runner systems.  


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The advantages of quality hot runner molds far outweigh any concerns you should have about their operation and any possible leakage problems. The best advice, according to Husky Injection Molding Systems, is to take time to examine several hot runner designs for performance before making your purchasing decision. Be sure to follow all of the critical dimension requirements in manufacturing and to provide proper training for everyone who might be involved with the system.

There are three key areas of concern regarding leakage prevention: design, manufacturing tolerances and training. While there are options on the nozzle design, there are no options on manufacturing tolerances and proper hot runner training for the workforce.


Choose a hot runner system that provides some method of leakage prevention. Hot runner systems having nozzles with a solid skirt and a significant amount of cold clearance are the ones most likely to leak.


The moldmaker must ensure that the critical dimensions and tolerances in the plates are maintained to provide enough seal-off force once the system is at operating temperature.


Training for all shifts on proper assembly, start-ups and maintenance of hot runner systems is necessary.

Read the full article from Husky Injection Molding Systems here


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