joeprocess
9th November 2016, 01:41 PM
Taking over on a project for a customer that wants to over-mold a TPU over GF Polypro, without adhesion. (Sounds like Fun, Right!) The production mold would be a two-shot mold. The over-mold is basically a sleeve, but due to the geometry it cannot be applied as a secondary operation.
First prototypes (transfer molded) shown the over-mold to adhere to the substrate, but broke free once sleeve was rotated on substrate. But the substrate was cold when put into the mold for over-molding. This does not represent the correct substrate temperature when the mold goes to two-shot. Once we get the mold and material here we are going to try running the parts as they would run as a two-shot by heating up the substrate to whatever the ejection temperature ends up being.
So on to the question. Has anyone worked with Pulse Cooling in a Two-Shot Application? What do you all think of this technology to get the substrate cooled off enough to prevent bonding? Otherwise, we are going to look at alternate substrate material with higher melt temperatures which will increase the cost significantly.
First prototypes (transfer molded) shown the over-mold to adhere to the substrate, but broke free once sleeve was rotated on substrate. But the substrate was cold when put into the mold for over-molding. This does not represent the correct substrate temperature when the mold goes to two-shot. Once we get the mold and material here we are going to try running the parts as they would run as a two-shot by heating up the substrate to whatever the ejection temperature ends up being.
So on to the question. Has anyone worked with Pulse Cooling in a Two-Shot Application? What do you all think of this technology to get the substrate cooled off enough to prevent bonding? Otherwise, we are going to look at alternate substrate material with higher melt temperatures which will increase the cost significantly.