Flatness tolerance machined plate
Flatness tolerance machined plate
(OP)
I have a plate that I want machined that will have fins on both sides. A lid will then be on either side, and sealed from leaking wit an o-ring around the fins. In order to do this I need a really tight tolerance on the flatness. The part would be about 5mm thick once cnc'd, and the dimensions are 190mm x 540mm. Does this thickness make sense, and what kind of flatness could be achieved. Thanks





RE: Flatness tolerance machined plate
RE: Flatness tolerance machined plate
RE: Flatness tolerance machined plate
The shape will make grinding a bit more difficult.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Flatness tolerance machined plate
RE: Flatness tolerance machined plate
I don't get what the purpose is, though. It looks like a heat sink, but covering it up pretty much nullifies any convective cooling.
TTFN

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RE: Flatness tolerance machined plate
RE: Flatness tolerance machined plate
1) How much warpage can the design tolerate
1a) How much deflection can be generated by the fastening scheme
1b) How much compression variation can the o-ring tolerate
1c) How is variation split between this part and the mating parts
2) How much is this going to cost
You could carve the negative version out of the block of material and put the o-ring groove into the faces of this piece so that they remain as flat as when you paid for them and the mating parts would not have fins to prevent making them flat either.
RE: Flatness tolerance machined plate
RE: Flatness tolerance machined plate
Not going to happen.
RE: Flatness tolerance machined plate
RE: Flatness tolerance machined plate
Now, machining the copper to that smooth a finish is just barely possible, but you've been told above several times that it will be very, very expensive to hold those tolerances.
Can you use anything more rigid than a thin sheet of copper foil?
RE: Flatness tolerance machined plate
What you are trying to do will fail without doubt.
RE: Flatness tolerance machined plate
could be done, but it would be VERY expensive, as we once found out when someone did something similar. We had to have the covers lapped, AFTER we had it mostly built.
TTFN

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RE: Flatness tolerance machined plate
RE: Flatness tolerance machined plate
The real world is an insensitive place. It really doesn't care what your hopes or plans were, but marily goes about its future.
See also:
Panama Canal - French version.
Pyramids - first Egyptian version (stepped pyramids).
Nebuchadnezzar: Rules for killing engineers whose buildings failed, killing of.
Liberty ships - Welding, failure of welding under extremely cold weather.
Hoover dam - Death by carbon monoxide, workers in bypass tunnels.
Transcontinental railroad - Nitroglycerine, explosive nature of when dropped
Hotel dance floor - Vibration and holding rods, changing design position of bolts
RE: Flatness tolerance machined plate
RE: Flatness tolerance machined plate
Of course, due to the stiffness provided by the fins, the heat sink body will remain fairly flat in the longitudinal direction within the area covered by the fins.