Millwright-Preventive and Predictive Maintenance | 62 Questions with 100% Correct Answers, Exams of Maintenance Engineering

Download Millwright-Preventive and Predictive Maintenance | 62 Questions with 100% Correct Answers and more Exams Maintenance Engineering in PDF only on Docsity!

Millwright-Preventive and Predictive

Maintenance | 62 Questions with 100% Correct

Answers | Updated & Verified | 2024

Preventive maintenance ✔✔is the periodic inspection and maintenance of plant assets and equipment to uncover conditions that may to equipment failure or shortened life This measures the amount of contaminants per litre of fluid. a. ferromagnetic analysis b. total base number c. infrared tests d. gravimetric level analysis ✔✔d. gravimetric level analysis These tests indicate how much of the oil additives have been depleted a. ferromagnetic analysis b. total base number c. spectographic level analysis d. gravimetric level analysis ✔✔b. total base number This technique is advanced and becomming more common in industry. It determines concentrations of contaminants over a period and accurately predicts the lubricant failure. a. ferromagnetic analysis b. total base number c. spectographic level analysis

d. gravimetric level analysis ✔✔c. spectographic level analysis These tests reveal the amount of general oil degradation. a. ferromagnetic analysis b. infrared c. spectographic level analysis d. gravimetric level analysis ✔✔b. infrared What is a method of determining the condition of lubrication or hydraulic oil? ✔✔Particle Analysis Automatic particle counters APCs or laser particle sizing APS can determine particle size and distribution What is one of the most expensive and dangerous methods of NDT? ✔✔Using X-Rays Harmful gamma and xrays What two kinds of Ultra-Sonic inspection are used in Millwright trade? ✔✔Immersion and Contact Scale, paint and corrosion removal may be required before inpsection Static unbalance is sometimes called (this is when the weighted centerline and shaft axis are parallel but misaligned (shifted) along their length a. force or kinematic unbalance

How is couple unbalance detected? a. when shaft is rotated and 180* phase angle is indicated between ends of arbor b. when shaft is rotated and 180* phase angle is indicated between ends of rotor c. when shaft is rotated and 270* phase angle is indicated between ends of rotor d. when shaft is rotated and 270* phase angle is indicated between ends of arbor ✔✔b. when shaft is rotated and 180* phase angle is indicated between ends of rotor PDM program ✔✔NDE is the main tool in the _______. In this condition the extra weights at either end are unequal and are at opposite ends of the shaft a. force or kinematic unbalance b. couple unbalance c. quasi static d. dynamic unbalance ✔✔c. quasi static The weighted centerline of the rotor and shaft axis do not intersect in the centerline of the shaft This type of vibration or unbalance would be cause if weight is unevenly distributed along the length of the shaft, across the width or at different angles about the radius a. force or kinematic unbalance b. couple unbalance c. quasi static d. dynamic unbalance ✔✔d. dynamic unbalance

the most common type of unbalance, forces are complex and usually involve a computer for correction Abuse, Design deficiencies, Material problems, Wear or age ✔✔Factors that cause failures during the life of machine include the following: 20,000 hertz to 100 kilohertz ✔✔The frequency range for ultrasonic monitoring is from ______ Cobalt 60 ✔✔Radiography uses a source of penetrating radiation, most commonly ______, to shoot through an object and project an image onto a detector or sheet of film. Eddy current inspection ✔✔_________ observes the interaction between electromagnetic fields and metals. a coil of wire ✔✔In an eddy current inspection, electrical cur- rents are induced to flow in the test object by ________ that carries an alternating current. optical borescope ✔✔The ________reaches deep inside a machine, magnifies like a microscope, and has its own light source. Liquid penetrant inspection ✔✔________ is used on the surface of smooth nonporous samples to highlight cracks and gaps that are not visible to the naked eye.

a. priority system b. linkage system c. monintory system d. recods system ✔✔a. priority system This helps to determikne the ugency and the extent of activity needed What are the 3 main facets of priority system of PM? ✔✔High priority-machines that can shut down the plant Next level is machinery that can shut down departments finally decreasing priorites are assigned down to auxiliaty equipment and even random clean up and decoration Vibration is characterized by its ✔✔frequency, displacement, acceleration, phase and pulse or shock vibrations The distance of a vibrating object from its original rest position is called a. speed b. distance c. displacement d. velocity ✔✔c. displacement

The distance from one extreme to another is called? a. speed b. amplitude c. displacement d. velocity ✔✔b. amplitude The ___________ of the amplitude is very important especially in slow moving equipment. ✔✔size or magnitude Speed and direction combined are called? ✔✔Velocity When is velocity at a maximum? ✔✔When the direction of travel changes from above the neutral position to below neutral the displacement is zero. (Changing from poitive to negative) Here the velocity is MAXIMUM Velocity is used primarily to detect problems in machinery with frequencies of 600 cpm to _______ cpm? a, 799 b. 500, c. 4600 d. 600,000 ✔✔d. 600,000 cpm Acceleration is a very important parameter to measure in equipment such as turbines because? ✔✔Turbines run at high frequency

a. mobin coil and solenoid b. seismic (moving coil) or piezoelectric c. rotary and dial d. electric and analog ✔✔b. seismic (moving coil) or piezoelectric Piezoelectric transducers have no moving parts, the electricity is generated by vibration pressure upon a ceramic material or crystal These sensors produce voltage proportional to the acceleration of vibration and arre very sensitive to high frequency vibration. Can operate at large range of frequencies but not at low frequencies. a. seismic transducer b. pieloelectric transducer c. accelerometers d. non contact transducers ✔✔c. accelerometers This type of transducer is mounted by threading it into the housing so that there is a gap between the tip and rotating shaft. A DC signal provides a signal proportional to the gap in the tip and the shaft. An AC voltage proportional to vibration is produced. The variation of the signal indicates amount of vibration. ✔✔Non contact For best results this type of transducer mounting is generally considred to be the most accurate but are sometimes difficult or awkward to install. They are time consuming and costly as well. a. magnetic mount b. epoxy mount c. hand held

d. threaded mount ✔✔d. threaded mount This methof of transducer mounting is good for periodic checks but is not considered the most accurate and is not accurate enough for some bearings and other high frequency problems. a. magnetic mount b. epoxy mount c. hand held d. threaded mount ✔✔c. hand held Where are vibration measurements usually taken? a. as close as possible to the shaft b. always in upright position c. perpendicular to the shaft b. as close as possible to the bearing ✔✔as close as possible to the bearing The horizontal/radial postition of measurement is most comonly used for transducer measurement The most common cause of machine vibration is ✔✔unbalance same frequency of the machine amplitude is directectly proportional to amount of unbalance vibration is larger in horizontal than vertical

Frequency double that of machine caused by loose pillow blocks or cracks general looseness many times the frequency, loose bearings found in machine foundations, bolts or anchors Frequency may be that several times of belt caused by? ✔✔worn, loose or mismatched belts frequency same as belt in axial direccction caused by misaligned sheaves same as belt in radial direction = eccentric sheaves How are gear mech frequencies calculated? ✔✔multiply number of teeth by rpm of gear The characteristics of vibrations caused by gear problems are, freq is same as gear (1 x rpm) caused by broken tooth 1 x gmf caused by gear wear, ecccentricity and backlash misalgnment of gear frequency is 2x, 3x x gmf (usually axial) ✔✔The characteristics of vibrations caused by gear problems are, freq is same as gear (1 x rpm) caused by broken tooth

1 x gmf caused by gear wear, ecccentricity and backlash misalgnment of gear frequency is 2x, 3x x gmf (usually axial) This is an unbalance distribution of weight around a rotating axis and one machine defect that is not readily corrected by ordinary maintenance problems a. balance b. unbalance c. misalignment d. arbor cracks ✔✔b. unbalance The amount of the vibration caused by the unbalance depends upon the weight and the rotational speed, the amount of force cause by lack of balance is a. proportional to the gmf b. proporrtional to the gmf squared c. proportional to the rpm d. proportional to the rpm squared ✔✔d. proportional to the rpm squared Doubling the rpm quadruples the force caused by the unbalance centrifugal force= 1.77 x weight x radius x (rpm/1000)^ A long, cylindrical, rotating bar that transmits power ✔✔shaft