Q&A

Problem with glossy readthrough on an ejector pin

Look at the unsupported length of the ejector pin, it may be deflecting under the force from cavity pressure.  Also verify that there are adequate stop buttons behind the ejector plate.  If running with a texture on the “A” side of the mold oftentimes adding the same texture to the face of the ejector pin can help hide the gloss differential on the part.  Contact us at info@kbmoldingsolutions.com for a further in depth review of the mold design and possible root cause.

Having an issue with soft TPU sticking in the mold

TPU (thermoplastic polyurethane) tends to be sticky when molded.  If the surface of the mold, runner or sprue is polished the TPU will severely stick, this material runs much better with a blasted mold surface, including in the sprue.  Also always verify that the material is dry before starting up the machine, TPU is very moisture sensitive.  Thoroughly purge the molding machine before start up, degraded TPU will appear very watery when purged and will stick if injected into the mold.  Contact us at info@kbmoldingsolutions.com to further discuss.

We are adjusting our process to eliminate burning, but what should be done?

Always verify that the mold is clean.  Check for adequate venting throughout the mold, remember that venting can be improved significantly by increasing the vent width and reducing the vent land.  See Injection Molding Advanced Troubleshooting Guide for recommended vent improvements.  For more discussion contact us at info@kbmoldingsolutions.com.

Contact us at info@kbmoldingsolutions.com for input on questions regarding the 4M’s.