Testing of Bearings

Download Testing of Bearings

Post on 03-Mar-2015




3 download

Embed Size (px)


<p>TESTING OF BEARING ON SOUND AND VIBRATION QUALITY.</p> <p>Seminar Report on...</p> <p>Testing Of Bearings on Sound and Vibration Quality.</p> <p>A Report By: HIREN R PATEL.M.G.I.T.E.R. NAVSARI Page 1</p> <p>TESTING OF BEARING ON SOUND AND VIBRATION QUALITY.</p> <p>Guidance By:</p> <p>CONTENTSCHAPTER NO.Chapter 1: Introduction. 1.1: What is Bearing? 1.2: Importance. 1.3: Types. 1.4: Damages and Damage types. 1.5: Factors affecting bearing life. Chapter 2: History. 2.1: Historical methods of testing. 2.2: Need of innovation. Chapter 3: Why sound and vibration? Chapter 4: Method introduction. 4.1: Importance of method. 4.2: Component introduction. 4.3: Mechanical set up. 4.4: Working cycle. 4.5: Interface. 4.5.1: I/O card specifications. 4.5.2: P.C. compatibility. 4.5.3: Front end selection. 4.5.4: Back end selection. Chapter 5: Future scope. Chapter 6: Obstacles.M.G.I.T.E.R. NAVSARI Page 2</p> <p>PAGE NO.</p> <p>TESTING OF BEARING ON SOUND AND VIBRATION QUALITY.</p> <p>Chapter 7: References.</p> <p>Record of Tables:-</p> <p>Sr No1 2 3 4 5</p> <p>ContentTABLE OF INDEX.</p> <p>Page Number8 10 18 24</p> <p>TYPES OF BEARINGS. TYPES OF DAMAGES AND REASONS. COMPONENT LIST CARD DETAILS</p> <p>M.G.I.T.E.R. NAVSARI</p> <p>Page 3</p> <p>TESTING OF BEARING ON SOUND AND VIBRATION QUALITY.</p> <p>List of Drawing:-</p> <p>Fig. No.(Fig.A) (Fig.B) (Fig. C) (Fig. D) (Fig. E) (Fig. - F) (Fig. G) (Fig.- H) (Fig.- I) (Fig. J) (Fig. K) (Fig. L)</p> <p>ContentBEARING ELEMENT DETAILS BEARING SYSTEM TYPES OF BEARINGS. TYPES OF DAMAGES HISTORICAL METHOD MECHANICAL SETUP WITH MIC TEST RIG (3D VIEW) TEST RIG (FRONT VIEW) WORKING CYCLE PRESENTATION SOUND TEST SETUP VIBRATION TEST SETUP EXPLODED VIEW OF FRONT END</p> <p>Page Number7 7 9 10 15 19 20 21 22 23 23 27</p> <p>M.G.I.T.E.R. NAVSARI</p> <p>Page 4</p> <p>TESTING OF BEARING ON SOUND AND VIBRATION QUALITY.</p> <p>-: ABSTRACT:Bearings are valuable.... until they go bad, and then they are worthless. But the definition of Bad Condition of Bearing is not standardized yet. To quickly discover what bearings may be salvaged, we offers positive testing machine. Because A Bearing Saved is a Bearing Earned. We tried to compare the bearings on ideal and defective condition on Sound and Vibration factor. For Sound we used microphone and for Vibrations we implemented piezoelectric sensor. Instead of manually comparing we further given the data to computer for automatic test of bearing. By this we reduced manual errors. By this we can predict life very near to actual.</p> <p>M.G.I.T.E.R. NAVSARI</p> <p>Page 5</p> <p>TESTING OF BEARING ON SOUND AND VIBRATION QUALITY.</p> <p>-: CHAPTER 1:INTRODUCTIONIn many industries, ever-increasing demand for high power and high speed with uninterrupted and reliable operation, accurate prediction and control of the dynamic behavior (unbalance response, critical speeds and instability) is increasingly important. The most crucial part of such large turbo machinery is the machine elements that allow relative motion between the rotating and the stationary machine elements i.e. Bearings. Bearings are used in variety of devices, including rotating machinery in the manufacturing industry. Bearing failures account for a large percentage of breakdowns in such machines and can lead to costly downtime. Bearing failure is probabilistic in nature. Because of this, maintenance programs based on set schedules or past performance are not completely effective in preventing failures during operation. Techniques in condition monitoring have been investigated for decades with the aim of determining the actual status of the bearings and replacing them based on that information. We just tried another method for prediction of bearing condition. Quality is the term which decides the company image and that depends on factors such as Machine Downtime, Good Quality Product and many more. As consideration of competition each and every industry is trying for a good AUTOMIZATION.</p> <p>M.G.I.T.E.R. NAVSARI</p> <p>Page 6</p> <p>TESTING OF BEARING ON SOUND AND VIBRATION QUALITY.</p> <p>1.1 What Is Bearing?Bearing is a machine part or device which is mostly used when there is a fixture or machine needs rigid support or when there are two revolving or rotating surfaces are there and they are in contact with each other. Bearing helps both the surface to lower the friction and run system smoothly.</p> <p>General Bearing System (Roller Bearing):</p> <p>(Fig. - A)General Bearing System (Ball Bearing):</p> <p>M.G.I.T.E.R. NAVSARI</p> <p>Page 7</p> <p>TESTING OF BEARING ON SOUND AND VIBRATION QUALITY.</p> <p>(Fig. B) 1.2 Importance:Today there are 90% Elements which are using bearings. So it will be a funny work to list out the applications and justify the importance of bearings.</p> <p>1.3Types of Bearings:-</p> <p>M.G.I.T.E.R. NAVSARI</p> <p>Page 8</p> <p>TESTING OF BEARING ON SOUND AND VIBRATION QUALITY.</p> <p>Types of Bearings:-</p> <p>M.G.I.T.E.R. NAVSARI</p> <p>Page 9</p> <p>TESTING OF BEARING ON SOUND AND VIBRATION QUALITY.</p> <p>(Fig. - C) 1.4 Damages and Damage Types:-</p> <p>Normal Wear</p> <p>Overlay Fatigue</p> <p>Scoring</p> <p>Corrosion</p> <p>Dirt Embedment</p> <p>Cap Shift</p> <p>Distorted Crankcase</p> <p>Oil Starvation</p> <p>Accelerated Wear</p> <p>Hot Short</p> <p>Dirt on Bearing Back</p> <p>Wiped</p> <p>M.G.I.T.E.R. NAVSARI</p> <p>Page 10</p> <p>TESTING OF BEARING ON SOUND AND VIBRATION QUALITY.</p> <p>Fretting</p> <p>Fatigue</p> <p>(Fig. - D) 1.5 Factors Affecting Bearing Life:Bearings in industrial applications continue to fail because of inadequate lubrication caused by lubricant loss, contamination, decomposition and break-down. Lip seals invariably wear out well before the bearing fails, and sealed bearings inherently foreshorten the life of a bearing to the service life of the contained grease (usually only about 3,000 to 5,000 hours for most industrial services).Maintenance professionals may find the following suggestions on how to forestall motor hearing failure obvious, but some new techniques and technologies are available. 1) Lubricate Bearing at Correct Intervals:Despite years of warnings from bearing manufacturers, over lubrication continues to plague many motor bearings. Too much grease can cause overheating of the bearings. The lubrication instructions supplied by the motor manufacturer will specify the quantity and frequency of lubrication. Generally, two-pole motors should be greased twice a year, four-pole and slower motors only once a year.</p> <p>2) Use the Best Available Grease:The most commonly used bearing grease is polypro-based, low-cost, lowperformance, highly compatible lubricant. However, it does not handle water well, a serious drawback for many industrial applications. It reacts readily with water and loses its ability to lubricate bearings. Industrial motor bearings should be lubricated with synthetic-based aluminum complex grease. High-quality grease pays for its additional cost in reduced motor downtime and repair costs. M.G.I.T.E.R. NAVSARI Page 11</p> <p>TESTING OF BEARING ON SOUND AND VIBRATION QUALITY.</p> <p>3) Keep out Moisture:Unless the motor is being hosed down or it operates in a humid environment, shielded motor bearings may not become seriously contaminated with moisture while the motor is running. However, when the rotor is shut down, moisture and condensation can collect on the surface of the bearing components. Eventually, this water breaks through the oil and grease barrier, contacts the metal parts of the bearing, and produces tiny particles of iron oxide. These rust particles make an excellent grinding compound when mixed with the grease. Resulting in premature failure of the bearing because of surface degradation. Preventing water contamination is a major challenge to bearing housing design. Close shaft-to-end bell clearances cannot stop the movement of humid air. Contact seals will quit contacting, resulting in large gaps that allow movement of air and water vapor across the bearing. Vapor-blocking bearing isolators, such as the one illustrated, are among the more successful devices presently available to prevent water vapor from entering a stationary bearing. When the motor shaft is rotating, the isolator opens, eliminating the possibility of friction and wear. However, when the shaft is stationary, the isolator closes, preventing movement of air or water across its face. With no wear from rotating friction, the seal may last indefinitely, and surely as long as the fatigue-failure life of the bearing.5)</p> <p>Keep out Dirt:Lip seals, contact seals, and frequent grease replacement help minimize the amount of dirt and other air-borne abrasives that can contaminate bearing lubricant. These solutions, however, have some drawbacks. Lip seals have a short service life, and frequent grease displacement is expensive and messy. One successful approach to keeping air-borne dirt and liquids out of an operating bearing is to install a labyrinth-type non-contact seal over the bearing housing. These bearing isolators, readily available from suppliers, combine a tortuous labyrinth path with impingement and centrifugal forces to trap and remove airborne dirt and liquid; virtually no contamination can reach the bearing. Because</p> <p>M.G.I.T.E.R. NAVSARI</p> <p>Page 12</p> <p>TESTING OF BEARING ON SOUND AND VIBRATION QUALITY.</p> <p>the bearing isolator is a non-contact device, it will generally be the longestlasting component of the motor. Although not intended as such, a bearing isolator could serve as an emergency sleeve bearing if the primary bearing fails, possibly preventing damage to the motors stator and rotor. In emergency situations, the bearing isolator can allow continued operation for a short time and still prevent the need to rewind the motor when the bearing is replaced. Bearing isolators constructed of bronze or other non-sparking materials also can prevent hazardous sparks that could otherwise occur when the bearings rolling elements fail.</p> <p>5) Other Suggestions:Improved bearing protection and lubrication will reduce downtime and the maintenance costs of electric motors, but other important motor design features contribute to long service life, including over-sized high quality bearings, high-tech winding insulation, superior fan design, high-performance paint (such as epoxy) and a strong, rigid cast iron frame. These features, usually standard or readily available, are found in most industrial-grade severe-duty electric motors. High-performance bearing protection systems. However, are not universally accepted as essential for long motor life. Specifying permanent bearing protection for new motors, or retrofitting isolators onto existing equipment, usually requires initiative on the part of the users maintenance or engineering staff. Permanent, absolute bearing protection has a greater effect on motor life than any other decisions made in specifying, equipping, and caring for electric motors. Keeping bearings lubricated with the right amount of clean, uncontaminated, high-quality lubricant allows bearings in most industrial motors to outlast all other motor components.</p> <p>M.G.I.T.E.R. NAVSARI</p> <p>Page 13</p> <p>TESTING OF BEARING ON SOUND AND VIBRATION QUALITY.</p> <p>-: CHAPTER 2:HISTORYYou may want to look at bearing failures as a means of justification. Can you identify key machines that will shut down production in the event of failure? It doesnt have to be a million dollar machine. An 85 Rs. bearing can stop a production line as quickly as an 85,000 Rs. bearing. However you choose to validate your intentions to the next level, be sure to make a solid business case and have everyone onside. As it is said A BEARING SAVED IS BEARING EARNED man tried a lot of times to predict the life or failure state of bearing.</p> <p>2.1 Historical Methods of Testing: The Reference Bearing (Bearing recommended to be acceptable or of known life value) is to be hanged vertically, using an elastic rubber band, to the rigid support An Instrumented impact hammer is to be used to strike the outer race of the bearing with four (4) repeated light impacts in an any chosen direction at any chosen point. The value of the impact signal is to be taken from the hammer to channel (1) of (at least) Two channel Vibration Analyzer. The response signal of the bearing to each hammer blow is taken through the accelerometer attached (by bees wax) to a point on the bearing at opposite side of the outer race (opposite to striking point).</p> <p>M.G.I.T.E.R. NAVSARI</p> <p>Page 14</p> <p>TESTING OF BEARING ON SOUND AND VIBRATION QUALITY.</p> <p>This accelerometer is connected to channel (2) of the Vibration Analyzer. After averaging of the results of the 4 strikes, the analyzer will show the Transfer Function of the bearing. This Transfer Function will contain the Modal parameters for the first mode of vibration that will be extracted by (BAT) software. Steps 1-4 above are to be repeated for all bearings to be tested. BAT software will make the necessary calculations and will produce a report containing the modal parameters of all tested bearings together with their expected lives relative to the Reference Bearing.</p> <p>(Fig. E)</p> <p>2.2Need of Innovation:M.G.I.T.E.R. NAVSARI Page 15</p> <p>TESTING OF BEARING ON SOUND AND VIBRATION QUALITY.</p> <p>Historically the theoretical estimation of bearing characteristic has always been a source of error in prediction of the dynamic behavior of bearing system. Obtaining reliable estimates of the bearing operating conditions (such as static load, temperature, lubricant etc.) in actual test condition is difficult and leads to inaccuracies. Consequently, physically meaningful and accurate parameter identification is required in actual test conditions to reduce the discrepancy between the measurements and predictions.</p> <p>-: CHAPTER 3:Why Sound and Vibration?Up to now I think you might have understand, what is bearing, how it works, how it is essential and so on. The cause for failure of any machine gives first blame or first doubt on the bearings. So ultimately the bearings are main factor which serves the quality. The cause for bearing failure or near to failure can be described on various criteria such as Temperature Rise Sound Rise Vibration Rise And Many More... Any bearing near to failure may be from any reason gives different sound than the ideal one which ultimately can capture the intention of human. Whenever there is presence of sound vibrations ultimately take place or vice versa. You can call it as Resonance of Bearing. Sound and vibrations are the major and important factors in bearing and they can be monitored very easily. We are not checking them with standards but using the comparative theory on dB calculation. M.G.I.T.E.R. NAVSARI Page 16</p> <p>TESTING OF BEARING ON SOUND AND VIBRATION QUALITY.</p> <p>-: CHAPTER 4:Method Introduction:Considering the quality, human errors must be eliminated or implementation of automatic process must be there. We tried the same by doing atomization in testing process of bearing. In this method the sound is recorded by microphone and vibrations by piezoelectric sensor and this data is fed to computer through ADD ON card. And at computer end or at inspection end there will be comparison and justification of...</p>


View more >