Targeting Cushion Size vs. Transfer Position

Andy Routsis
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I was recently asked this question...

e-Mailer
We currently use a target transfer position of 0.25" for all our processes. to avoid uneven barrel wear should we adjust the our standard transfer to something larger?

My Response
A standard cutoff is helpful when initially establishing your fill... but you ultimately want to target a percentage of shot size. When you target a specific cushion value, then you tend to have the same amount of material, and pressure loss, in front of the screw during pack.

Many companies who mold similar products in similar sized machines sucessfully target a specific cushion value. Most molders have the greatest success in targeting a percentage, such as 5% or 10%, of the full shot size.

Additional Thoughts
The transfer position should not have a significant influence on screw and barrel wear... but focusing on a cushion rather than a specific transfer will improve your ability to maintain a solid and reliable injection molding process.

-Andy

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This page contains a single entry by Andy Routsis published on February 22, 2010 11:00 AM.

Torque Values For Larger Molds... was the previous entry in this blog.

Understanding Back-Flow Within the Mold... is the next entry in this blog.

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