alignment straight tips

7/27/2019 Alignment Straight Tips

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Steps of Alignment

1. Before any coupling alignment first correct the soft foot in individual machine tobe 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 dialgauge connections.

Misalignment Concepts & Alignment Sequence & Dial Indicator Connections

4. Tighten the foundation bolts to a constant torque value, and start measurementof angular misalignments in vertical plane. Loosen the bolts, put shimsaccordingly. Again tighten the bolts to constant torque. Repeat themeasurements till offset is within tolerance limit.

Angular Vertical Alignment Concepts

5. Tighten the foundation bolts to a constant torque value, and start measurementof offset misalignments in vertical plane. Loosen the bolts, put shimsaccordingly. Again tighten the bolts to constant torque. Repeat themeasurements 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 measurementof angular misalignment in horizontal plane. Loosen the bolts, shift machineaccordingly. Again tighten the bolts to constant torque. Repeat themeasurements till offset is within tolerance limit.

Angular Horizontal Alignment

7. Tighten the foundation bolts to a constant torque value, and start measurementof offset misalignments in horizontal plane. Loosen the bolts, shift machineaccordingly. Again tighten the bolts to constant torque. Repeat themeasurements till offset is within tolerance limit.

Offset Horizontal Alignment


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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 notin same horizontal plane but parallel tobase plate, i.e. foot ends have verticaldistances.

Measurement with feeler gauge andapplication of shims in the soft foot.

Angular Soft Foot: One or more feetare bent and the bottom of the foot isnot parallel to the base plate.

Measurement with feeler gauge andstep shimming i.e. 3-5 shims of equalthickness.

Springing Soft Foot: The entire area ofthe foot does not touch the base platedue to rusting, oil/ grease, poorfinishing etc. (The machine acts as if it

is on springs)

Proper base and base plate cleaningand finishing, blue matching. Even allthe Shims also should also becorrected for this.

Induced Soft Foot: It is created byexternal forces. E.g. vibrations of ductsand piping due to hammering orotherwise, machine vibrations etc.

Isolation of external forces. E.g.expansion bellows, flexible couplingsetc.

Why should soft foot be corrected before misalignment?

If the soft foot of individual machines are not corrected and aligned as perprocedure, when the foot is tightened down with base plate, it may distort slightly,

leading to premature bearing failure. The alignment procedure brings thecenterlines of the two machines on same line but cant correct any soft foot.

Motor

Pump

Base Plate

Aligned with soft

foot

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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. Theoffset may happen in two planes:

i. Horizontal plane (Taking top view of machines)

ii. Vertical Plane (Taking side view of machines)

Did you noti

the feet a

not visib

(top view)?

Did you notice

the two fee

are visible

(side view)?


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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 ownweight and the weight of the dial indicator, adds to the readings for vertical offsets. Thusto 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 ofmisalignments?For angular misalignment, in horizontal or vertical plane, the two faces of couplings areinclined 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 forhorizontal plane are different. Thus for vertical angular misalignment, dial gauge pointershould be touching the face of the coupling at top and bottom for readings. Similarly, forhorizontal angular misalignment, dial gauge pointer should be touching the face of thecoupling at left and right for readings.

For offset misalignments, the two faces are parallel, but the rims maintain constantdistance. Thus for Vertical offset misalignment the dial indicator pointer should touch therim of the coupling at top and bottom for readings. Similarly, Thus for Horizontal offsetmisalignment the dial indicator pointer should touch the rim of the coupling at left andright 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 plane3. Angular misalignment in horizontal plane4. Offset misalignment in horizontal plane

This is to be noted that, before start of any alignment, the foundation bolts are to betightened 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 horizontalplane alignments are done before vertical plane alignment, the shim insertion may resultinto 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 madezero 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 atrear 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 onrim and taking top and bottom readings. Assuming the dial reading is made zero attop,If bottom reading is ve, it implies that shaft-2 is lower than shaft-1. Hence, putshims below all four footings of shaft-2.

If bottom reading is +ve, it implies that shaft-2 is higher than shaft-1. Hence, putshims below all four footings of shaft-1.

Shim Thickness, S = [(Bottom Reading, Rb) (Bottom reading for sag checking,Rbs)] / 2Note: the bottom reading is divided by 2 here. Also note sag reading isdeducted.

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3. Angular misalignment in Horizontal plane: Placing dial gauge as said above thatis on faces and taking left and right readings. Assuming the dial reading is madezero 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, machineto 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.

4. Offset misalignment in Horizontal plane: Placing dial gauge as said above that ison rim and taking left and right readings. Assuming the dial reading is made zero atleft,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 horizontalplane. Hence, machine to be shifted from one side accordingly..

Shim Thickness, S = (Right Reading, Rb) / 2Note: the bottom reading is divided by 2 here. Also note sag reading is notdeducted.

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