When I started my career as a maintenance engineer i got a doubt, is it necessary to align flexible coupling too?? we are using flexible coupling instead of fixed or rigid couplings because they don't have to be aligned??.
Later I read some articles and found some useful information. Today I wanna share this information with you people.
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| Courtecy : T B Woods Inc |
For every coupling its manufacture give some common value of alignment specification:
According to T.B Woods Sureflex Coupling (with an 8je insert)
--> Cost : about $XXX per sleeve or insert
--> Maximum RPM : 4500
--> Parallel Misalignment : 0.020 in
--> Angular Misalignment : 0.094 in (about 0.012"/inch)
Based on these manufactures recommendations the coupling can bear or tolerate some sort of misalignment. and also the insert (i.e rubber) is inexpensive then why we have to go precision alignment??
Because we are aligning shafts -- we are not aligning couplings. The coupling sleeve or Insert that we use can tolerate that misalignment but the bearings on the shafts, oil seals, gears and also shafts can't tolerate.
Sometimes coupling will bend, but also it resists bending, for this it need some good amount of energy to oppose that force. That enegy is produced within itself by:
1) Increased heat due to friction
2) Increase in load on bearings, shafts, and seals.
So finally i got to an conclusion, "is it necessary to align a flexible coupling?"- we should not worry about it but aligning the shafts to precision alignment is necessary. because, by this we will increase the machine life, decrease vibrations, reduce energy consumption and also the couplings life.
