No draft - one face of mold core?

[ttx]

At the risk of providing comic relief....
Is is possible to have one core face completely parallel to the line of pull?
We have a very small plastic part and have (2) datum faces that must be at 90 deg. to one another. Unfortunately, one of the faces is on the mold core. The part face in question is about 8mm x 10mm. Can this be done?

Thanks.

JW

 

[TheTick]

There will be friction and scoring, but it is possible. Since the part is small, you probably will not have too much difficulty.

It helps to provide relief on the cavity side.

Also, if there is draft on the core side opposite (facing) your zero-draft wall, there will be some relief.

 

[ttx]

Tick,
Thanks for the info....
I was planning on adding a healthy draft angle to the opposite core face - I just wasn't sure whether or not this was a "non-starter".

Cheers,

JW

 

[dgowans]

One other thing that may be possible depending on your part design is to adjust your die pull direction such that your 2 datum faces are perpendicular to each other, but the changed pull direction ensures that you have draft. This will most likely affect other areas of the part and you will need to evaluate the feasibility of this approach.

 

[patprimmer]

Straight pull of one side only with a lot of draft on the other is quite feasible so long as the cavity is withdrawn by sideways movement first. This would mean the core and a sliding block for the side would need to be on the moving half.

It can also be done with less trouble with the softer materials by blowing the part of the core with a poppet band air pressure, but once again, the sides of the cavity need to be out of the way.

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.

 

[ttx]

Thanks for the help guys,

Cheers,

JW

 

[TheTick]

Another thing to consider...

It also depends on material. I have molded polypropylene parts with undercuts for snap features (lke Tupperware). With softer materials, you can count on parts deflecting through 0 degree or less.