Burr spec for tubes?
Burr spec for tubes?
(OP)
Morning all- I've recently won some work designing some tube assemblies, and would like a spec for burrs & edges on tube ends. Does anyone know of anything?
Cheers
Simon
Cheers
Simon
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RE: Burr spec for tubes?
RE: Burr spec for tubes?
Mike Halloran
Pembroke Pines, FL, USA
RE: Burr spec for tubes?
Regarding edge breaks, every single machined part drawing I have ever produced, and there have been hundreds of them, had a general note stating something like "Break all sharp edges .005 to .010". And often there are more specific requirements for edge breaks shown on the drawing.
With a tube assembly, where the tubes have very thin walls (ie. around .020") the dimension/tolerance control of edge breaks can be very critical, so that you are not producing a knife edge. There are also situations where it is critical to make sure the sharp inside edges of a hole thru a tube wall is rounded to a specific profile, so that it produces a desired flow coefficient.
RE: Burr spec for tubes?
... and that depends strongly on what mates with the tube end, which is why a general spec couldn't be universal.
E.g. if the tube is to be butt welded, cutting it with a laser may not be a good idea. It doesn't leave burrs, but it does leave a HAZ which will cause the tube to 'weld funny'.
Laser cutting would also be contraindicated for use with a Lenz O-seal fitting, because an o-ring has to ride up and over the tube end. In that case, you'd want a chamfer, or the sort of partially swaged end you get from a hand operated tube cutter.
In any case, you usually want to deburr the inner tube end.
Luckily, there are simple, fast tools, manual and powered, that can do a decent job of chamfering inside and outside, sometimes both at once. Be a little liberal with the tolerance if you can. Nobody wants to pay for measuring chamfers with a micrometer.
Mike Halloran
Pembroke Pines, FL, USA
RE: Burr spec for tubes?