Steps of Alignment 1. Before any coupling alignment first correct the soft foot in individual machine to be coupled i.e. Pump, Motor, Gear etc. Soft Foot Concepts 2. Check for sag calculation of the bracket and the dial gauge for sag correction. Sag Calculation Concepts 3. The different misalignments are to be corrected in sequence with proper dial gauge connections . Misalignment Concepts & Alignment Sequence & Dial Indicator Connections 4. Tighten the foundation bolts to a constant torque value, and start measurement of angular misalignments in vertical plane . Loosen the bolts, put shims accordingly. Again tighten the bolts to constant torque. Repeat the measurements till offset is within tolerance limit. Angular Vertical Alignment Concepts 5. Tighten the foundation bolts to a constant torque value, and start measurement of offset misalignments in vertical plane . Loosen the bolts, put shims accordingly. Again tighten the bolts to constant torque. Repeat the measurements till offset is within tolerance limit. Do not forget to make correction for sag readings. Offset Vertical Alignment Concepts 6. Tighten the foundation bolts to a constant torque value, and start measurement of angular misalignment in horizontal plane . Loosen the bolts, shift machine accordingly. Again tighten the bolts to constant torque. Repeat the measurements till offset is within tolerance limit. Angular Horizontal Alignment 7. Tighten the foundation bolts to a constant torque value, and start measurement of offset misalignments in horizontal plane . Loosen the bolts, shift machine accordingly. Again tighten the bolts to constant torque. Repeat the measurements till offset is within tolerance limit. Offset Horizontal Alignment
What is Soft Foot? Soft Foot means that one or more feet of the machine is bent or poorly manufactured. Type of Soft Foot Remedy Parallel Soft Foot: One or more feet not Measurement with feeler gauge and in same horizontal plane but parallel to application of shims in the soft foot. base plate, i.e. foot ends have vertical distances. Angular Soft Foot: One or more feet Measurement with feeler gauge and are bent and the bottom of the foot is step shimming i.e. 3-5 shims of equal not parallel to the base plate. thickness. Springing Soft Foot: The entire area of Proper base and base plate cleaning the foot does not touch the base plate and finishing, blue matching. Even all due to rusting, oil/ grease, poor the Shims also should also be finishing etc. (The machine acts as if it corrected for this. is on springs) Induced Soft Foot: It is created by Isolation of external forces. E.g. external forces. E.g. vibrations of ducts expansion bellows, flexible couplings and piping due to hammering or etc. otherwise, machine vibrations etc.
Why should soft foot be corrected before misalignment? If the soft foot of individual machines are not corrected and aligned as per procedure, when the foot is tightened down with base plate, it may distort slightly, leading to premature bearing failure. The alignment procedure brings the centerlines of the two machines on same line but can’t correct any soft foot. Aligned with soft foot Pump Motor
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What is misalignment? The two axes of the machines to be aligned are not coincident. What are the types of misalignment? a. Parallel or Offset misalignment: The two axes are parallel but not coincident. The offset may happen in two planes: i. Horizontal plane (Taking top view of machines)
Did you notice the feet are not visible (top view)?
ii.
Vertical Plane (Taking side view of machines)
Did you notice the two feet are visible (side view)?
b. Angular Misalignment: The two axes are inclined to each other. The misalignment may happen in two planes: i.
Horizontal plane (Taking top view of machines)
ii.
Vertical Plane (Taking side view of machines)
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What is dial indicator bracket sag correction? When you do alignment in vertical plane for offset, the sag in bracket due to its own weight and the weight of the dial indicator, adds to the readings for vertical offsets. Thus to correct this, deduct the sag values at top and bottom from corresponding top and bottom value readings during alignment.
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How should the dial gauge be connected for different corrections of misalignments? For angular misalignment, in horizontal or vertical plane, the two faces of couplings are inclined to each other. Hence, distance between two faces at top and bottom for vertical plane are different. Similarly, the distance between two faces at left and right for horizontal plane are different. Thus for vertical angular misalignment, dial gauge pointer should be touching the face of the coupling at top and bottom for readings. Similarly, for horizontal angular misalignment, dial gauge pointer should be touching the face of the coupling at left and right for readings. For offset misalignments, the two faces are parallel, but the rims maintain constant distance. Thus for Vertical offset misalignment the dial indicator pointer should touch the rim of the coupling at top and bottom for readings. Similarly, Thus for Horizontal offset misalignment the dial indicator pointer should touch the rim of the coupling at left and right for readings.
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What should be the sequence of correcting these misalignment types and why? Sequence: 1. Angular misalignment in vertical plane 2. Offset misalignment in vertical plane 3. Angular misalignment in horizontal plane 4. Offset misalignment in horizontal plane
This is to be noted that, before start of any alignment, the foundation bolts are to be tightened to particular torque through torque wrench. For, vertical plane alignments, shims are to be put below legs of the machine, by loosening the bolts. If horizontal plane alignments are done before vertical plane alignment, the shim insertion may result into horizontal plane movements also. Thus, the horizontal plane alignments are lost. That is why this sequence is being maintained.
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1. Angular misalignment in vertical plane: Placing dial gauge as said above that is on faces and taking top and bottom readings. Assuming the dial reading is made zero at top, If bottom reading is –ve, it implies bottom face is farther apart from top face. Hence, shims at front legs to be put. If bottom reading is +ve, it implies bottom face is closer from top face. Hence, shims at rear legs to be put. Shim Thickness, S = (Motor Front and Rear Foot Distance, Fd) X (Bottom Reading, Rb) / (Diameter of dial pointer circle, d) Note: the bottom reading is not divided by 2 here
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2. Offset misalignment in vertical plane : Placing dial gauge as said above that is on rim and taking top and bottom readings. Assuming the dial reading is made zero at top, If bottom reading is –ve, it implies that shaft-2 is lower than shaft-1. Hence, put shims below all four footings of shaft-2. If bottom reading is +ve, it implies that shaft-2 is higher than shaft-1. Hence, put shims below all four footings of shaft-1. Shim Thickness, S = [(Bottom Reading, Rb) – (Bottom reading for sag checking, Rbs)] / 2 Note: the bottom reading is divided by 2 here. Also note sag reading is deducted.
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3. Angular misalignment in Horizontal plane : Placing dial gauge as said above that is on faces and taking left and right readings. Assuming the dial reading is made zero at left, If right reading is –ve, it implies left face is farther apart from right face. Hence, machine to be shifted diagonally accordingly. If right reading is +ve, it implies bottom face is closer from top face. Hence, machine to be shifted diagonally accordingly. Shim Thickness, S = (Motor Front and Rear Foot Distance, Fd) X (Right Reading, Rb) / (Diameter of dial pointer circle, d) Note: the bottom reading is not divided by 2 here.
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4. Offset misalignment in Horizontal plane : Placing dial gauge as said above that is on rim and taking left and right readings. Assuming the dial reading is made zero at left, If right reading is –ve, it implies that shaft-2 is lower than shaft-1 in horizontal plane. Hence, machine to be shifted from one side accordingly. If bottom reading is +ve, it implies that shaft-2 is higher than shaft-1 in horizontal plane. Hence, machine to be shifted from one side accordingly.. Shim Thickness, S = (Right Reading, Rb) / 2 Note: the bottom reading is divided by 2 here. Also note sag reading is not deducted.
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