Tolerances on plastic parts
Tolerances on plastic parts
(OP)
Hi,
I have very recently started working on plastic parts design. I would like to know what is a typical error in perpendicularity for a molded part. I am just trying to get an estimate and an educated guess from experts out there would really help.
Thanks
I have very recently started working on plastic parts design. I would like to know what is a typical error in perpendicularity for a molded part. I am just trying to get an estimate and an educated guess from experts out there would really help.
Thanks





RE: Tolerances on plastic parts
General tolerances are +/-.005" per inch, but you can hold about 1/3 of the shrink of the material on critical dimensions if you tune the tool and processing. Depending on the length of your perpendicular features this should give you an idea.
-b
RE: Tolerances on plastic parts
I design plastic widgets for a living, and normally don't consider molded parts as the ideal of precision--better to add sufficient "flex" to your design such that you can work with the relative fluctuation that molded plastic parts can provide.
The structure of your parts matters, too, since you have warping to consider when the part shrinks during cooling. There are several "rules of thumb" guides you can find all over the Internet as general ways to get things done. A little experience goes a long way in getting what you expect.
Jeff Mowry
www.industrialdesignhaus.com
Reason trumps all. And awe transcends reason.
RE: Tolerances on plastic parts
The charts identify both standard commercial tolerances and fine tolerances. By consulting with a molder you should be able to establish tolerances that meet your design needs and are achievable by the molder.
RE: Tolerances on plastic parts
Matt
CAD Engineer/ECN Analyst
Silicon Valley, CA
http://sw.fcsuper.com/index.php
RE: Tolerances on plastic parts