Ejector pins

[mechy20]

Hi All,
I believe I am asking this question in the right forum. I am wondering if it is ok to add an ejector pin location on a cantilever like section of a plastic part.

I am adding this as I would like to ensure the part falls out of the mold, however I am not sure if that ejector pin itself would end up warping the part (cantilever section)

How consistent are the forces from an ejector pin in a mold?

I am relatively new to plastic part design and would appreciate any response...
Thanks,

 

[patprimmer]

Is this the only pin or one of several.

Ejector pins are normally all mounted to the same plate and they move forward in unison so they should not bend the beam if everything is designed and made OK.

Of course from here with a very vague and brief description, I can't say how well designed and made your mould is.

A bad design and or process conditions may well cause distortion or marks on the moulding.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[MikeHalloran]

Your question is appropriate, if you are designing the _mold_.

If you are designing the _part_, you shouldn't specify mold details on the part drawing, unless their location would affect the function of the part. To do that right, you need to talk the molder, or at least _a_ molder, before the part drawing is complete.





Mike Halloran
Pembroke Pines, FL, USA

 

[mechy20]

Thanks all for your replies.
Patprimmer, yes this is one of several pins.

Mike, I am designing the part, but showing the locations of the ejector pins on the drawing based on feedback from the molders. This extra pin location was the one I am planning to request.

So I guess based on your feedback, I can indicate to the molders that they need to ensure no warpage. I just wanted to be sure that I was being reasonable in my expectations.

Thanks again !

 

[patprimmer]

It is very reasonable to expect that the part can be ejected without distortion.

There are other reasons for distortion than position of ejector pins, like differential shrinkage for instance.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[mjh368]

agree with pat, we will assume you are following design guideliness for your beam and rib if there is one.

*If it warps dont blame the ejectors*