【转帖】manufacturing capabilities by feature type

yang686526

manufacturing capabilities by feature type?
does anyone know of any resources anywhere showing the manufacturing capability* of (let's say) a sheet metal emboss, an injection-molded rib, etc.?
*in other words, how tight can tolerances be held for a particular type of feature in a diecast part, sheet metal parts, etc.
thanks in advance.
   dan (on da bass!)
good one, and one i'd been planning on posting at some point.
i've looked on the internet and you can sometimes find information for certain processes but i've not found it all in one document.
i'd love something like the standard surface finish chart (
this is very highly dependent from shop to shop and machine to machine. for instance, i have 2 bridgeport mills in the tool room. i can often achieve tolerances of .0005 with one, whereas the other i'm lucky if i can hit .01. (both are manual).
also, it is going to depend on what you define as tight tolerances. a .0005 tol may be tight for an engine valve, but may be loose as can be for a heart valve.
you really need to consider tol on a case by case basis and a shop to shop basis; and it's highly dependent on your product's requirements.
imho there is too much generalization that is attempted regarding tolerancing.
wes c.
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no trees were killed in the sending of this message, but a large number of electrons were terribly inconvenienced.
oh... and budget
wes c.
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no trees were killed in the sending of this message, but a large number of electrons were terribly inconvenienced.
wes, you are correct.
ideally i design a part based on my experience/function and then the relevant process expert looks at it to suggest changes, including tolerance, that could reduce costs/ease manufacture etc.
back when i worked in a place that had its own machine shop and reasonable quantities of most parts i did this.  in fact for high production parts it was part of the design review.
this is more difficult when you only use external machine shops and are pressed for time.  for some parts it's still appropriate to take the time but but in my situation i have a lot of different mostly relatively simple parts but with low production rates.
so the initial guess is gonna be what you go with a lot of the time and it would be nice to get some information to support the guess.
sometimes the machine shops come back with suggestions, sometimes they just charge to meet your requirements.
we've also had machine shops take it too far, make multiple phone calls etc on how eliminating or changing a certain feature could save money only to find out the saving is only say $20 each on a total run of only 5, the amount of time spent on the phone & investigating the change etc probably cost more than this.
kenat, probably the least qualified checker you'll ever meet...
iso 2768 kind of has this information.