nylon 66 overmolding shrinkage Smile
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Posted by: gpolmin

04/16/2006, 23:14:40

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I am molding nylon66 with 35% glass fiber into a gasket carrier followed by overmolding a thermosetting silicone bead onto the nylon66 carrier. The main problem I have is that of secondary shrinkage from the thermoset rubber injection process. I would like to know if there is any method of expanding the parts or permanently elongating the finished parts in any other process besides a new mold that molds a bigger part and allows for a larger shrinkage that takes into account the secondary shrinkage that the carrier body is subjected to from the silicone rubber overmolding process. I have read in a technical article that soaking parts like these nylon 66 with 35% glass fiber in warm water will change the parts but I am not sure if this is a permanent change or a good solution to my problem. If anyone has any information on this problem of double shrinkage and its resolution I can use your assistance Please advise Thank You George

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Re: nylon 66 overmolding shrinkage
Re: nylon 66 overmolding shrinkage -- gpolmin Post Reply Top of thread Forum
Posted by: Kelly_Bramble Administrator, Administrator

04/19/2006, 13:43:06

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I don't think you can stretch parts effectively. In general, your mold should have been manufactured, several test parts made, and your sign-off on the final product before the final heat treating of the mold tool. Shrinkage should have been accounted for by your molder/maufacturer , and thay should be aware that final signoff on the molded part is required and normal.

On a positive note, modifying the mold should be easy enough as you only have to remove material.

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