Flatness on a injection molded part
Flatness on a injection molded part
(OP)
I'm currently trying to finish up a drawing on a injection molded part.
To avoid warpage I was planning on putting down a flatness tolerance on the longitudinal face. I've seen various tolerances talked about with regards to molded parts such as 0.004" / 1".
But I was wondering if that was across the whole width of the part as my understanding would have it or thickness.
Since it's molded part thickness is <0.120" although a complex profile, however the overall width is >18".
To avoid warpage I was planning on putting down a flatness tolerance on the longitudinal face. I've seen various tolerances talked about with regards to molded parts such as 0.004" / 1".
But I was wondering if that was across the whole width of the part as my understanding would have it or thickness.
Since it's molded part thickness is <0.120" although a complex profile, however the overall width is >18".





RE: Flatness on a injection molded part
Four thou per inch allows considerable camber, and is probably not a sufficient spec all by itself.
Flatness over 18" is pretty ambitioous for injection molding anything.
You probably need to learn GD&T so you can express exactly what you want, and what you will not accept, on the face of the drawing without multiple pages of text.
Mike Halloran
Pembroke Pines, FL, USA