Introduction to Shaft Alignment

1. Introduction to Shaft Alignment 1.1Basics in shaft alignment 1.2Methods and processes in shaft alignment 1.3Benefits of shaft alignment

Basics in shaft alignment 1.Rotational centers 2.Collinearity 3.Misalignment 4.Measuring misalignment 5.Types of misalignment 6.Alignment tolerances

All shafts, whether they are straight or bent, rotate on an axis called the rotational center. The rotational center forms a straight line. 1. Rotational centers

Two shafts are said to be collinear when their respective rotational centers form a single line. 2. Collinearity

Shafts are misaligned when the two shafts are not collinear. 3. Misalignment

4. Measuring Misalignment Machines are designated as stationary and movable.

The rotational center of the stationary machine is a datum or reference line. 4. Measuring Misalignment

Misalignment is determined by finding the position of the movable rotational center in relation to the stationary in two planes. 4. Measuring Misalignment

Viewed from the top - Horizontal Misalignment Viewed from the side - Vertical Misalignment 4. Measuring Misalignment

5. Types of misalignment Offset misalignment Angular misalignment

Offset misalignment 5. Types of misalignment

Angular misalignment 5. Types of misalignment

6. Alignment tolerances

2. Methods and processes in Shaft Alignment 1.Alignment methods 2.Three stages of alignment tasks 3.Alignment process overview

With all alignment methods measurements are taken at the shafts or couplings. 1. Alignment Methods

Misalignment is corrected at the feet. 1. Alignment Methods

Positions at the feet must be calculated from shaft data or... Success will be dependent on the aligners skills or luck. Many moves will be required. Accuracy will be compromised. 1. Alignment Methods

Mechanical Dial indicators Laser

Mechanical methods Straight edge/feeler gauge method Determine the direction and amount of offset using a straight edge and feeler gauges. Measure the gap at two points 180° apart to determine the direction and amount of angular misalignment.

Dial indicator methods Rim-Face method Reversed-Rim method

Dial indicator, Signs Plunger moves out of the case - negative reading. Plunger moves into the case - positive reading.

©1999 Fixturlaser AB23 Dial indicator, Bar sag Dial indicator bar sag –Weight of the dial indicator and other parts that are overhung –Height of the supporting fixture required to clear the coupling –Span of the indicator bar(s) –Stiffness of the fixture hardware material –Specific geometry of the hardware arrangement

To determine bar sag Mount the fixtures on a rigid mandrel the way they will be mounted during the alignment job. Position the indicator at 12:00 and set the dial to zero. Rotate the fixtures to 6:00 and read the amount of sag. Dial indicator, Bar sag To correct for sag Set the dial to the positive value of sag at 12:00, when the dial is normally zeroed at 12:00 and rotated to 6:00. Set the dial to the negative value of sag at 6:00, when the dial is normally zeroed at 6:00 and rotated to 12:00.

Rim-Face Alignment method The rim dial measures offset The face dial measures angularity

Measuring offset Procedure 1. Set dial to the positive sag value at position #1 (9:00 or 12:00) 2. Rotate both shafts 180 o to position #2. (3:00 or 6:00) 3. Record the reading (TIR) and divide by two. Offset = TIR/2

Measuring angularity Procedure (Rim-Face method) 1.Set dial at 12:00 or 9:00 2.Rotate both shafts 180 degrees 3.Record the reading and divide by diameter of indicator circle. Angularity = TIR / diameter

The position of front & back feet Front Feet position: Back Feet position:

Reversed- Rim alignment method Widely acknowledged as the preferred method of shaft alignment. Both dials measures offset on the Rim. The Angular error is the slope between the two offset values. Easy to plot or calculate the feet correction values.

A between indicator plunges B from the movable plunger to the front bolt centre C between the front and rear bolt centres Reversed-Rim Alignment Method Dimensions

Reversed-Rim Alignment Method Signs Different set-ups effect the sign of the reading differently. Why? The DI:s have the same plus/minus direction but are mounted in reverse Basic set up. No effect on signs.

Zeroing vertically at 12:00 or horizontally at 3:00. –Change the sign of DIM. (Plus to minus, minus to plus) Zeroing vertcally at 6:00 or horizontally at 9:00. –Change the sign of DIS. The DI:s mounted at the same side Reversed-Rim Alignment Method Signs

Measuring vertical misalignment Rotate the dials to 12:00 Set both dials to the positive sag value Rotate both shafts to 6:00 Record the readings Reversed-Rim Alignment Method Measuring

Reversed-Rim Alignment Method Calculations

Move the front feet of the movable machine as you watch the movable indicator move to zero. Move the rear feet of the movable machine as you watch the stationary indicator move to zero. Repeat until both dial indicators read zero

Stationary side offset (S) = Tot. indicator reading 2 = 2.5 Reversed-Rim Alignment Method Measuring example

Movable side offset(M) = Tot. Indicator reading 2 Reverse the sign! = 4.8 Reversed-Rim Alignment Method Measuring example

Reversed-Rim Alignment Method Plotting/Calculation example

Laser systems Single laser systems with a single or double target. Twin laser systems using the Reversed-Rim method.

BALTECH SA-4400 Fixturlaser Laser Kit

Result for horizontal machine

2. Three stages of alignment tasks Pre-alignment –Preparations, Off site (Thermal growth specifications) –Visual checks, On site –On site actions (Checking shaft and coupling run-out) Rough-alignment –Ensure the shafts are in-the-ballpark Precision alignment –Use dial indicator or laser system –Three phases: Measure, Align and Document

Pre-alignment Procedures A. Off-site preparations B. On-site visual checks C. On-site actions, procedure Pre-alignment: How 15 Minutes Can Save Your Time & Money

A. Preparations, off-site Saftey regulations? Working permits? Time limits for production stop? Alignment tolerances? Thermal Offsets? Available space? Shaft rotation? Shims size? Alignment system? Batteries? Specifications?

B. On-site visual check Machine, serial no. Saftey Available space Foundation condition Bed plate condition Bolt condition Adjustment capability Shims condition Leaks

1.Coupling assembly 2.Mechanical looseness 3.Soft foot 4.Run out 5.Pipe strain 6.Machine temperature 7.Repeatability test C. Pre-Alignment Procedures On-site actions

1. Coupling assembly Assembled according to supplier specification. Slightly loosen the bolts - minimize risk of hanging

2. Mechanical looseness Check looseness in bearings, gears etc. Mount a dial indicator to the shaft/coupling Try to move the shaft by hand for example using a crowbar

Install on a foot the indicator in the vertical direction Losen the bolt Excess of indications of the indicator of value of 0,06mm, speaks about defect SOFT FOOT 3. Check and minimize soft foot before alignment

Replace old and rusty shims, new shims in stainless steel. Avoid home made shims. No more than 3-4 shims under each foot.

Calibrated shims for shaft alignment series BALTECH-23458N (New)

Set up the dial indicator –The dial indicator plunger contacts the hub or shaft to be checked. –It is affixed to any point in space: the machine base, a bearing housing, the adjacent coupling hub (if the coupling is broken). 4. Check run out Measure run out –The shaft to be checked is rotated until the dial indicator reaches a maximum: (+ or -). –The dial indicator is adjusted to zero. –The shaft is rotated again until the dial indicator reaches a maximum: (+ or -). This is the run out value.

5. Check pipe strain Dial indicator set up as in checking run out. Loosen flange bolts to check the effect of pipe strain. Value no more than 0,12 mm

6. Machine temperature Measure the machine temperature Never align during the cool-down process Align in hot or cold conditions Machines that operate at a considerably hotter or colder condition than the ambient room temperature should be thermally compensated. They will grow or shrink as they heat up, or cool off

7. Repeatability test If repetition cant be reached check, 1. Fixtures: Are the fixtures properly tightened? 2. External sources: Foundation, bolts, shims, coupling etc. 3. Internal sources: Mechanical looseness

3. Alignment process overview Alignment correction procedure –Perform pre-alignment checks and corrections –Set up the alignment fixtures or system –Check and correct soft foot –Measure misalignment –Evaluate machinery alignment conditions –Perform precision alignment corrections –Re-measure and document the machinery alignment

Alignment check procedure –Set up the alignment fixtures or system –Measure misalignment –Document and store alignment conditions –Evaluate machinery alignment conditions 3. Alignment process overview

4. Special Tasks Machine train Cardan shaft alignment

Machine train overview Machine train, Power train or multiple drive units –Serie of machines through which power is transmitted. Often part of a critical plant Never start aligning before you know…. The position of each machine. Which machine can not be moved? How much the other machines can be moved. The dynamic movements of each machine.

Machine train overview

Cardan shaft alignment Typical arrangements Roll Gear box Spacer Gear box Cardan shaft Cardan shaft Cardan shaft Motor

Cardan Shaft Alignment Technical principle Cardan error Cardan joint

Cardan Shaft Alignment Technical principle

Cardan shaft alignment Mounting alternatives

Benefits of Shaft Alignment When shafts are misaligned forces are generated at the coupling

Studies over the past ten years indicate that 50% of all machine breakdowns are due to poor alignment. Some surveys indicate that up to 90% of all machines run outside their recommended tolerances Benefits of Shaft Alignment

1.Vibrations 2.Energy savings 3.Wear of mechanical components 4.Production capacity 5.Product quality Benefits of Shaft Alignment

1. Vibrations

When measuring vibrations: Horizontal vibrations indicates imbalance (H) Vertical vibrations indicate a weak or loose foundation (V) Axial vibrations indicate misalignment (A) 1. Vibrations

2. Energy savings The correct alignment can reduce energy consumtion with anything up to 15%, sometimes more.

To calculate savings Measure amperage before and after alignment Find the difference Get motor data Find cost of energy Calculate kW savings with formula below: (volts * amps * pf * 1,732) 1000 kW= 2. Energy savings

Motor: 50 Gz, 380V, 60А, cos( )=0.92 Working: 6000 hours per year (0,20 cent for kW/h) Current use: Mialigned - 54А Alignet - 49А kW = (В А cos 1.732)/1000 Misaligned: (380V 54А )/1000 = 32.7 kW Aligned: (380V 49А )/1000 = 29.7 kW Effect: ( ) 0, = 3600 Euro 2. Energy savings

3. Wear of mechanical components Bearings Increasing the load will result in exponential bearing life reduction Doubling the load will reduce the bearing life to one eight of its design life. Bearing constant Bearing load [ ] 3 L = 10 Expected bearing lifetime is calculated according to:

Seals Poor alignment can cause a 50%-70% reduction of calculated life time. Lubrication problems are often caused by leakage in the seals 3. Wear of mechanical components

Couplings Indications of misalignment: Coupling is getting hot Stacks of rubber or plastic under the coupling or coupling guard Excessive wear of teeth in gear type coupling 3. Wear of mechanical components

4. Production capacity Today a modern production process is depended on high runability. Production stop, loose your money Exceeds by far the cost for the replacement of components.

5. Product quality Decreased vibration levels, reduced loads on mechanical components will have a positive impact on the product it self. Alignment of drives: Paper, Steel, Plastic film

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