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5 Sneaky Causes of Hot Runner Contamination

5 Sneaky Causes of Hot Runner Contamination


When cleaning a hot runner, it is an important job to ensure that you are getting consistent parts shot by shot. Using a commercial purging compound is the best way to make sure you can change colors easily and effectively.

There are many ways to get a hot runner clean, but they entail downtime and taking the tool out of the press, which a purge compound can do while still in the machine.

First, you want to make sure the screw and barrel are already clean to ensure that no additional contaminants are added to the hot runner when cleaning.

Here are 5 possible causes of contamination out in a hot runner:

  1. Not cleaning out the hot runner when changing colors or shutting down for the weekend or holiday.

    Using a commercial purging compound is the best way, it gets and keeps the hot runner clean when changing color or shutting down.

  2. Your mold temperature is too low

    When mold temperature is too low, the material cools quicker, which can cause the parts to not fill all the way or the gates to freeze which will create scrap.

  3. Your residence time is too long

    When your processing resin has been inside the hot runner for too long of a time at elevated temperatures the chemical structure breaks down and causes material degradation in the tool.

  4. Your fill speed is too high while injecting

    When injecting the material into the tool too fast it can be enduring more shear than it can withstand, which can cause the molecules to break down easier and cause contamination.

  5. You have insufficient venting on your tool

    If a hot runner tool does not have adequate venting, then the air/material will get trapped inside and can cause burning or short-shotting.

These are five common causes of contamination in your hot runner that can lead to bad parts. If you can prevent these five things from happening to your hot runner tools, you will be able to stop most contamination issues.  If these issues are already occurring, we recommend using a purging compound like PLUS Grade that excels in hot runner cleaning.  High-quality purge compounds will help you get back to running good parts in a fraction of the time.  New to purging? Request a free 10-minute consultation with one of our experienced Purging Experts to make sure you're starting on the right foot and you don't develop bad purging habits. 

Learn more about how to reduce production downtime and protect your profits with a purging compound.

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