Living hinge advice

[mikesydwest]

Hi Rick, the images will show all I hope, the length is reduced to a more tolerable dimension, since changing plastic, still not 100%, should be 200 long. still have problem with depressions, which will be something intolerable.

the gate it self is 10mm x10mm, I can get the drawings to you if that helps.

BTW thanks for helping I didn't know where to turn.

regards

Mike

[mikesydwest]

here is the other half of the mould Rick

[bbevc]

Hello!
If the part is too long, try reduce cooling time. i had same problem on similar tool, and i had to reduce cycle time for almost half, from 50s to 33 s. open the mold as soon it is possible, so the part start shrinking when its hot. And reduce holding pressure time, but you will have biger sink marks, i dont know how much it is aceptable. Boris

[mikesydwest]

Hello Boris, the sink marks are very visible - to a point its not acceptable, they have got the length close enough by changing the plastic. Still trying to resolve, not sure about the outcome, can only persist


thanks for suggestions


Michael

[mikesydwest]

BTW, I have read an article, where they have overfilled the mould by leaving it a little open, then whilst still soft (plasticised) closing the mould.

[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