Which material for forcibly unmolded thrads

[tomysux]

Hello,

does anybody can give me some instructions of forcibly unmolding of the thread. Not to unscrew the thread but to pull it out from the part.

Which grade of PP or PE-HD to use?

... more instructions?

Thanks, Thomas

 

[insideman]

This requires rather shallow broad threads similar to those on a lamp bulb. Then make sure that the part can expand (for a female thread) or contract (for a male thread). Then make the mold and try it. Tinker with the design until it works.

 

[insideman]

Oh yes! Material should probably be almost any grade of PE.

 

[patprimmer]

I think most major PP or PE suppliers produce technical bulitins on this subject, and should be prepared to send you some data if you request it

Regards
pat

 

[tomysux]

What about the processing conditions? I heard that the cycle time must be very short, lower than 6 seconds. At which themperature is possible to eject the part? And how is with shrinkage, warpage and visible marks on the part.

THX Thomas

 

[Soupcat]

tomysux,
It's hard to make a call without seeing the geometry of the part. PP and PE are good materials for 'bumping off' threads but a lot of the mechanics in doing it is down to the design of the mold. When you have the design right obviously you can play around with variables like cycle time and temperature.

Regards

Kieran Fegan

http://www.moulddesigner.com