Why do some parts have extra plastic nodules?

Old 02-06-21, 06:00 AM
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Why do some parts have extra plastic nodules?

This is my first model car (Revell, plastic). Some parts have extra plastic pieces attached that are to be removed, as per the manual. Why are these plastic nodules here? They donít seem to serve any purpose. Iíve attached a photo. Thanks!

Revell Grease Lightning, plastic nodules
Old 02-06-21, 06:30 AM
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Those are the gates when the part was injected molded, the liquid plastic passes into the mold at those points.
Old 02-06-21, 06:35 AM
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Hopefully, this will help explain.

Old 02-06-21, 08:08 AM
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As said above, the cones are left over from the injection molding process. I believe the oval is a riser or 'overflow' to trap bubbles or voids that would ruining the casting.
For small parts, it's not worth the manufacturer's time to remove them-

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