Hot Runner Tips

  • Ask your purging compound supplier for a hot runner-friendly grade – complex parts can be molded with many of these grades (see picture).
  • Check with your purging compound supplier on whether or not to use glass filled grades in valve gates, highly polished molds, or hot runners.
  • Always use a purging compound within its, and the production resin’s, recommended processing temperature.
  • Raise manifold heats only if doing so allows you to remain within safe recommended operating temperatures.
  • If possible, apply mold release to the cavities when purging the hot runner system.
  • If color streaking or contamination is observed in certain gate areas, close off all other gates, and inject short shots through each affected gate, one at a time (open mold method only).
  • Purging compounds can pass through gates with clearances similar to those of the resins they are used with.
  • Chemical purges may have success removing deposits from low flow areas within hot runners.
  • When using the open mold method, perform short, high velocity shots to promote turbulence within the hot runner.