How to Fight Angel Hair in Your Material

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Is the distribution box on your Silo getting clogged with angel hair? Are you constantly cleaning the cone/screen and distribution box on your dryer hoppers? Do you clean angel hair off of the Augers in your material & color blenders? If you answered yes to any of these questions, this post might help.

     Angel hair is a nickname for stringers in your material. These stringers are a result of individual material pellets melting when they come in contact with a surface. The pellet gets drawn through a pipe with air. The high velocity of the air moving the pellet through the pipe comes in contact with a surface and skids while it melts from friction which causes a long hair-like string of plastic. That stringer continues down the pipe until it ends up in the silo, day bin, dryer hopper, color blender or molding machine.

What to look for if the stringers are in your silo

When the material was pumped into your silo from the semi-truck load you just received, did you monitor the rate and pressure and velocity as the silo was filled with material?

The pressure should be around 5--but no more than 5 on their gauge. I’ve heard some say 7 but I always tried to keep them at 5 just to be on the safe side. Obviously this depends on what the material is, so this number is for an unfilled Polypropylene.  

Here are a few possible solutions:

1-Have your receiving employee monitor the delivery

2-Install a separate pump to regulate the pressure and velocity

 If you’re having issues with stringers further downstream in your delivery system, you might need to solve the problem a different way.

Make sure that your Vacuum pump is rated for your delivery pipe size.  Also, make sure you do not have 90° Elbows installed in your delivery pipe. These 90° angles can contribute to additional stringers. Please note that the delivery pipe needs to be beaded pipe on the interior of the delivery pipe. This will keep material pellets from skidding down the wall of the delivery pipe.  With these considerations in mind, you should see your problems disappear.

Learn more about how to reduce scrap rates in your injection molding machines.

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Topics: Injection Molding, Plastics Processing, Injection Molding TroubleShooting, Injection Molding Efficiently, reduce downtime, molding defects, angel hair, stringers

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