Ejector Pins Location in injection molding

[Selchuk]

Hi there,

I wonder how I determine location of ejector pin in plastic injection molding.

Thanks.

Selçuk GEDİK
Mechanical Engineer

 

[BrianPetersen]

It will help to know if you are attempting to injection-mold buttons for a shirt, or roof panels for a gazebo.

 

[Selchuk]

thanks BrianPeterson.

Did you mean like doghouse geometries(forms) on plastic?

 

[BrianPetersen]

No, I mean you need to give us some information about what it is that you are trying to make and from what material.

A useless question means you'll get useless answers.

 

[3DDave]

Brian - poke a bees nest and the bees come out. Next questions will be about gates, runners, chills, number of cavities, kind of plastic, cycle times, injection pressure, et al.

 

[BrianPetersen]

Surely a question like this comes from someone who is in over their head, but hasn't realized it yet.

Surely such a question is coming from someone junior, in which case, I fail to understand in what way it would be better to ask here than to ask their supervisor or co-worker who has done this a hundred times before and has knowledge of the task at hand. And if said person is attempting to design a set of molds completely on their own and there is no co-worker or supervisor to ask ... oh, boy, are they ever gonna be in trouble.

 

[Selchuk]

Hi Brian,

Some of ejector pins example and what I mean about molding ejector pins you can see on attachment file. The question about where and how I locate ejector pins on the part. And the best location gives me best solution, to not deforme the plastic part when it ejects from the mold. Plastic material PP + M10 you can think. I can calculate the ejector force and I can locate the ejector pins on plastic with my experience. But I wonder about ejector pins location calculation.

I guess you can understand what I want to ask Brian.

Thank you,
Selçuk

 

[MikeHalloran]

Some of the ejector pins you have drawn will require an anti-rotation anchorage in the ejector plate in order to not spoil the part. I have no idea how to do that.

My usual plan is to just tell the molder about the features I want in the part, and to tell him where I don't want to see ejector pin or other marks, and let him figure out how to make the part.

The question you ask is only important if you are the molder, in which case I don't know what to tell you, or if you are working for the molder, in which case you should be asking the molder.



Mike Halloran
Pembroke Pines, FL, USA

 

[ugur17]

Hi Selchuk,

I guess MikeHalloran and BrianPetersen couldn't get it. I am not a supervisor about plastic injection molds but i can say you should choose rib areas for ejector location. That's just a suggestion. Of course there are too many parameters about ejector location.

I am sorry for MikeHalloran and BrianPetersen answers.

Best regards.

 

[Selchuk]

Hi Ugur

You are right. Rib areas is important for eject parts. But I think is it possible a program for ejector pin location that it can gives optimum ejector pressure and optimum location to eject the parts. But I could not find a person like you to understand me.

MikeHalloran I am a molder and I am not supervisor but I am a mold designer. If you do not understand I can send you some more picture like that I send to BrianPetersen. You are second person and you are kidding with me like Brian. What do you think? Is it enjoable for you?

 

[3DDave]

It is not enjoyable for anyone when an unanswerable question is asked. You act as if there is a little paragraph that could be the answer to all molding questions about ejector pins. Do you ask your doctor, what is the best way to perform surgery because you plan to try and need advice?