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MACHINE ALIGNMENT.pptx. An Useful Presentation to understand Alignment Requirements
The document covers the topic of machine alignment, detailing the various types of misalignment (parallel, angular, combined) and their impact on machinery performance and vibration. It emphasizes the importance of precise alignment techniques, including checks for soft foot, indicator sag, and dial indicator rigidity, along with methods for detecting and correcting misalignment. Additionally, it discusses the consequences of misalignment on equipment failure, vibration characteristics, and provides guidelines for alignment tolerances and methods used.
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MACHINE ALIGNMENT.pptx. An Useful Presentation to understand Alignment Requirements
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- 2. ALIGNMENT Alignment is theprocess of keeping the Axes of the Driver and The Driven Shafts in ONE STRAIGHT LINE.
- 3. MISALIGNMENT Parallel When theShaft Axes are not in one line but are Parallel, it is termed as Parallel or Radial Misalignment.
- 4. MISALIGNMENT Angular When theShaft Axes are not in one line but intersect at an Angle, it is termed as Angular Misalignment.
- 5. MISALIGNMENT Parallel & angularcombined When the Shaft Axes are not in one line but are Parallel and intersect at an Angle, it is termed as Combined Misalignment.
- 6. MISALIGNMENT Misalignment may be:- • PARALLEL • ANGULAR • COMBINED PARALLEL & ANGULAR.
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- 9. MISALIGNMENT. While Aligning, Careand Adjustments are taken for : •END FLOAT. •TORTIONAL FLEXIBILITY.
- 10. CHECKS BEFORE STARTING ALIGNMENT. •Coupling gap. • Soft foot. • Indicator sag. • Dial indicator rigidity. • Alignment readings. (0°, 90°, 180°& 270°) • Thermal growth. (Steel-0.01mm/m for 1°C rise in temperature.)
- 11. ALIGNMENT : CouplingGap The shaft gap should be in accordance with the coupling manufacturer’s recommendation. Some equipment like Motors have an inherent freedom to float . It should be at the Motor’s magnetic center.
- 12. ALIGNMENT : SOFTFOOT SOFT FOOT is the condition, when all feet of the Pump or Motor are not in one plane.
- 13. ALIGNMENT : How toDetect SOFT FOOT ? • Put Machine on base. • Do not tighten bolts. • Attempt to pass thin Feeler Gauge Blade under a Foot. • If the blade passes, that foot has Soft Foot. • Check other feet.
- 14. ALIGNMENT : How toRectify SOFT FOOT ? • Measure Soft foot gap. • Tighten all hold nuts • Put Dial Gauge on each foot & loosen the Bolt. • If foot rises, put Shims. • Repeat process for each foot. • Always tighten bolts in one sequence.
- 15. Indicator Sag Determine thedifference between the dial indicator reading when it is on top of a shaft as opposed to when it is at the bottom. This is a gravitational effect. It will always be on the negative side. It is to be corrected in top – bottom readings but has no influence on the horizontal readings. Dial Indicator Rigidity The dial indicators as well as the clamps should be fitted as rigid as possible to eliminate sliding and resultant erroneous readings.
- 16. Alignment Readings The dialshould be zeroed at the top for convenience. The coupling bule should be marked at 0°, 90°, 180°& 270° with a reference mark on the equipment such that nuts can be turned by 90° increments. Both the equipment are to be rotated simultaneously in order to eliminate run out. After rotating all four positions make sure that the indicator returns to zero.If not, discard the reading and repeat the procedure.
- 17. Thermal Growth If apump is pumping hot water it will grow due to thermal expansion from cold static condition to the hot running condition. The objective is to operate the machinery in properly aligned when working under normal operating condition. Compensation for these predicted thermal movements can be made by providing some preset offset in the cold static condition.
- 18. ALIGNMENT AND COUPLINGAND ITS EFFECT ON VIBRATION At the beginning of most predictive maintenance programmes, misalignment of direct-coupled machines is by far the most common cause of machinery vibration. In spite of self-aligning bearings and flexible couplings it is difficult to align two shafts and their bearings so that no forces exist which will create vibration. Hence the most widespread mechanical problem in the industry today is misalignment. Although vibration responds to the degree of misalignment there is not a direct 1-1 relationship between the amount of misalignment and amount of vibration.
- 19. Component Failure dueto misalignment: It can cause failure of not only coupling but also bearings and other moving parts of the system itself. Direction of Potentially harmful forces: It is possible that the highest reaction is on the free outboard end instead of coupling end due to increased stiffening.
- 20. Axial Vibration: Misalignmentnormally causes both axial and radial vibration as opposed to unbalance (except overhung rotors). Other sources of High Axial Vibration: Bent shafts, Shaft in resonant whirl, Resonance of same component in axial direction, Worn thrust bearings, Worn helical and Bevel gears, a sleeve bearing motor hunting for its magnetic center, Couple component of dynamic unbalance. Whenever high axial vibration occurs, one should not make a conclusion that the problem is misalignment.
- 21. CHARACTERISTICS OF MISALIGNMENT 2XRPM Vibration: Often misalignment generates a higher than normal 2X RPM vibration which can act not only in the axial direction but also in radial direction. The second operating speed harmonic is caused by asymmetric stiffness in the machine and its supports or in coupling. There is often quite a difference in stiffness around the supporting housing frame, foundation and coupling itself allowing the back and forth motion in each revolution thereby resulting in 2X RPM vibration. Multiple Harmonics: They appear when vibration is more severe. The key distinguishing feature is still the high level of 2X RPM.
- 22. Phase is thebest indicator: Phase behavior in response to misalignment is as given below: Probably the best indicator of misalignment problems is the evaluation of phase across the coupling. When the phase difference across the coupling approaches 180° ( 40° - 50°) misalignment is indicated. The more severe the misalignment the more thus difference will approach 180°. Since it is possible for shafts to have better horizontal alignment , horizontal phase difference may be different from vertical phase difference across the coupling. While examining the phase difference on one of the rotors (just the motor or fan) the radial phase difference for significant misalignment will be 0° or 180° ( 30°). When comparing horizontal phase difference with vertical phase differences on the same rotor about 90% of misaligned machines will show a difference approaching 180°.
- 23. Angular Misalignment: 1. Itprimarily generates high axial vibration particularly at 1X and 2X RPM. 2. Typically when the amplitude of either 2X RPM or 3X RPM exceeds approximately 30% to 50% of that at #X RPM in the axial direction angular misalignment is indicated. 3. Angular misalignment is best detected by 180° phase change across the coupling in axial direction. Parallel Misalignment: 1. It affects radial vibration as opposed to angular which effects axial vibration. 2. It causes phase differences to approach 180° in the horizontal direction. 3. 2X RPM exceeds 50% of 1X RPM. Misaligned Bearings Cocked on Shaft: 1. A cocked bearing will normally generate considerable axial vibration which affects 1X RPM & 2X RPM. 2. If phase is measured in the axial direction at each of a 4 points 90° apart from each other, a cocked bearing will be indicated by 180° phase shift from top to bottom and side to side.
- 24. COUPLING PROBLEMS: Proper interpretationof vibration data provided by the new generation equipment can help to pinpoint some of the coupling problems. 2X RPM will often respond to coupling problems particular a coupling having a spacer too short or too long. In these cases both the radial and axial direction will show a fairly noticeable 3X RPM component. Gear type couplings can experience coupling lock up where the frictional force developed at gear teeth is greater than the applied force causing the coupling to become a rigid member. Friction welding of teeth.
- 25. ALIGNMENT TOLERANCES : MACHINERPM TOLERANCE (mm) <1000 0.08 to 0.11 1000 – 2000 0.05 to 0.10 2000 – 4000 0.025 to 0.05 4000 - 6000 0.013 to 0.025
- 26. METHODS OF ALIGNMENT: • Straight Edge, Feeler Gauge & Level. • Reverse Indicator Alignment (graphic) • Face & Rim Alignment. (graphic) • Across Flex element. (graphic) • Mathematical Method. • Laser Beam Method.
- 27. ALIGNMENT : can bedone in Two stages - 1. PRELIMINARY ALIGNMENT. 2. ACCURATE ALIGNMENT.
- 28. Done with thehelp of • Straight Edge • Feeler Gauge. PRELIMINARY ALIGNMENT :
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- 31. ACCURATE ALIGNMENT with thehelp of DIAL GAUGE
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- 36. Alignment calculations a) Distancecorrections = 700 / 200 = 3.5 3.5 x 0.25 = 0.875 mm shim is to be given under each back foot. b) Corrections when front feet are to be raised :- Distance corrections = 400 / 200 = 2.0 0.25 x 2 = 0.5 mm shim is to be given under each front foot.
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- 43. Reverse Indicator Method Readingon pump. 0.00 - 0.025 - 0.015 - 0.005 Motor Pump
- 44. Pump Motor Reverse Indicator Method Readingon motor. 0.00 + 0.005 + 0.004 + 0.006
- 45. Calculations : Pump Motor Vertical. -0.025 - 0.000 - 0.025 Sag (-)-0.005 (+) - 0.020 / 2 = Vertical. + 0.005 - 0.000 + 0.005 Sag (-)- 0.005 (+) + 0.010/2 = Horizontal. - 0.005 (-) - 0.015 (+) +0.010 /2 = Horizontal. + 0.006 (-) +0.004 (-) +0.002 /2 = - 0.010 + 0.005 + 0.005 + 0.001
- 46. Calculations : Vertical Horizontal. PumpMotor Pump Motor Reading - 0.010 + 0.005 + 0.005 + 0.001 Position on graph. Bottom Bottom Top Bottom
- 47. Pump to motoralignment guide. Vertical (Side view) Horizontal (Top view) Reading on pump Reading on motor Reading on pump Reading on motor + on bottom + on bottom + Near side + Near side - on bottom - on bottom - Near side - Near side + on bottom - on bottom + Near side - Near side - on bottom + on bottom - Near side + Near side Pump shaft Motor shaft
- 48. P M FFBF 0.01 P M FF BF 0.007 0.019 Vertical correction Horizontal correction
- 49. Conclusion : Top –Bottom correction : • The motor shaft : Only the back feet have to be lowered by 0.01” Far – Near correction : • The motor shaft has to be shifted towards far end so that the front feet is pushed by 0.007” and the back feet by 0.019”
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- 53. FACE AND RIMMETHOD
- 57. Across the flexelement.
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