Living hinge advice

[chrisprocess]

Try running a warmer mold temp to increase material shrinkage.
Increasing gate size will help a lot, but you can also try increasing pack pressure/time to reduce sinks.
Also make sure your nozzle ID isn't too small; larger nozzle ID will help

I would challenge the part design, a long part like that with varying wall thicknesses is expected to have some sink.
From a processing stand point, turn up back pressure and slow fill speed down to get as much volume in the cavity as you can on first stage fill. Go like 99.999% full then into pack and hold.

[chrisprocess]

Not sure how far you are in your development, or if there's room to modify the design, but a properly designed part will have a uniform wall thickness throughout.
See example of how that thick boss section was done:

[mikesydwest]

I will advise of your suggestions, thanks and here is hoping for some good outcomes.

BTW changing the shape is not a thing we can really do

Mike

[mikesydwest]

I appreciate the help, thanks

anyone have any ideas on a composite PP PE mix, or has anyone tried PE on living hinges ???

Mike

[joeprocess]

It looks to me like it is gated in the thick middle section, then flows through the living hinge and into the thick sections. Packing out a part through a living hinge is not easy at all. Thick to thin to thick. Being the mold is not designed/gated properly for a living hinge anyway I would recommend adding 2 more gates on either side of the living hinge.

For the longest life to a living hinge you would want to try and flow the material perpendicular thru the hinge it will last much longer that way. Flexing the hinge while hot is a common practice to help orientation in the hinge area, but many experts in the hinge business run the mold temperature through the hinge area low in to hold the hinge in a more amorphous state which is more flexible. The more crystalline structure through the hinge area the stiffer and more brittle it will be.

[mikesydwest]

I appreciate the help mate, I will let them know and lets the change.