drawoh,
I believe what I'm showing is in the standard, the flatness per area is 5.4.2.2 as you noted. Although I believe that means "over any 4" squared area on this surface, hold flatness to .004". Not "in this specific area on the surface". Which is what I want for that callout alone.
The...
That is a good point and what I may end up doing. But I do think it is an interesting question: how do you control just a part of a surface with GD&T. If I needed to mount just one device with a much smoother finish and tighter flatness, it would cost a lot to make the whole plate to that spec
I'm designing a coldplate to mount IGBTs to. The IGBT manufacturer specifies a certain surface finish and "warpage" for the plate, 100um per 100mm. I'm assuming warpage is waviness (mfg is Japanese). I'm also assuming warpage is equivalent to flatness per area, which is how I'm trying to call...
Thank you that is good advice. They were originally handed the CAD and asked to make the drawings, and whoever made them put zero effort into it. That is understandable, it's not their job, but made me hesitant to go to them. It feels like the contract manufacturer just wants a CAD and perfect...
I'm very green and have found myself as the only Mechanical Engineer at a small startup.
Some good work has been done to design a sheet metal assembly (basically a complicated box made of folded parts bolted together). But no thought has been put into tolerances / manufacture. Even the holes...
