Fit tolerance between coupling and pump shaft
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The fit tolerances between many couplings and shafts are transition fits (such as H7/k6, H7/m6, etc.). Sometimes, when the tolerances are processed to their extreme values, the connection can become loose. Dear colleagues, what are the typical fit tolerances for this type of connection that you have encountered?
This post was last edited by Frozen Desert on 2019-2-16 at 16:02. I just checked the manuals for our various types of pumps; the shafts don’t have any markings, but the couplings are all of type H7. Some of our couplings are loose on the shafts, so we simply make uniform notches on the shafts to increase the tightness. A copper sheet can be added to the key, or a set screw can be used as well
For us, overfitting, hot mounting, and disassembly all require hot mounting
When machining a new coupling, the inner hole diameter is 3 to 5 mils smaller than the actual size of the shaft. Hot install. When repairing excessive wear in the inner hole, the following approach can be taken: if the dimensions permit, increase the diameter of the original coupling’s inner hole by 10 to 20 mm. The inner diameter of the new shaft sleeve should be 3 microns smaller than the actual diameter of the shaft, while its outer diameter should be 2 microns smaller than that of the enlarged coupling inner hole. Insert the shaft sleeve into the coupling and weld its ends together; care must be taken to prevent thermal deformation. After cooling, install the coupling by hot fitting
Use an intelligent fully automatic cold welding machine to weld slowly – it’s really a way of wasting time; the welding process must not be rushed
The fit between the coupling’s rear pulley and the shaft is generally a interference fit, with the degree of interference varying depending on the diameter of the shaft.