how to tell what kind of electric motor i have
Table 1: Corporeality of Grease to Use
The general procedure for greasing is every bit follows:
i. Lock and tag out the electric motor
two. Wipe grease from the pressure fitting, clean dirt, debris and pigment around the grease relief plug. This prevents foreign objects from entering the grease cavity.
three. Remove the grease relief plug and insert a brush into the grease relief as possible. This will remove whatsoever hardened grease. Remove the castor and wipe off any grease.
four. Add grease per Tabular array i.
5. Allow the motor to operate for approximately 30 to 40 minutes before replacing the grease relief plug. This reduces the chance that begetting housing pressure will develop.
Bearings should be lubricated at an average frequency equally found in Tabular array 2. Operational environment and type of grease may require more frequent lubrication.
Table 2: Bearing Lubrication Frequency
1 concept that has been presented is that grease volition eventually fill the bearing housing, causing the same problem equally an overgreased begetting. We volition be addressing this detail consequence, as well as a give-and-take of why the motor should be de-energized during greasing, through this paper. We are limiting this paper to a standard deep-groove brawl bearing without shields or seals.
How a Begetting Works
The near common type of bearing is the AFBMA-7 C-3 rated bearing. C-iii relates to the internal clearances of the surfaces of the bearing. In most motor rated bearings, there is a clearance of between 3-five mils (thousandths of an inch) in which lubrication flows to reduce friction and wear of the machined surfaces. The bearing, itself, consists of an inner race, an outer race, balls and a cage which evenly distributes the balls. Mutual bearings are designed to let for a radial load with some limited centric loading. ALL BEARINGS ARE LUBRICATED WITH OIL.
Grease, itself, is an oil sponge. The base of operations (spongy) part of the grease varies depending on the manufacturer, temperature, environment and user preference. The grease holds the oil in break and allows the oil to flow during functioning. The oil compresses between the bearing balls, inner and outer races and the cage, reducing friction. Ball bearings have small, microscopically crude surfaces on the assurance, these surfaces motility the oil, belongings it to the ball during performance.
When likewise much grease is added, the grease is compressed between the bearing surfaces, increasing pressure and resulting with estrus. Also little grease causes the surface friction to increment, resulting with heat. In whatsoever instance, once begetting racket is audible, information technology has failed. Reducing noise by lubrication requires excessive grease, endangering the motor, and giving the technician the false security of extending the motor life when, in reality, additional damage is occurring to machined surfaces.
Bearings may also have shields or seals mounted on them. Bearing shields are metal fittings that have small clearances between the inner race of the begetting and contact the outer race on either side of the balls and cage. The small clearances most the inner race allows some oil and grease to move into the moving parts of the bearing, but prevents particles of large size from passing into the bearing potentially damaging machined surfaces. Sealed bearings accept seal surfaces touching the inner race, while 'non-contact' sealed bearings have extremely shut tolerances betwixt the seal surface and the inner race preventing particles nether several thousandths of an inch. Sealed, and some shielded, bearings are referred to as non-grease able bearings.
What Happens When The Bearing Is Greased With The Motor Running?
Oil is an 'incompressible' fluid, which is important when considering the developing bug within the begetting housing (Figure i) while greasing an operating motor. The 'soap,' or grease medium, acts as a intermission in the oil, although grease is normally represented as a base of operations with an oil intermission. This becomes an important issue in the physical globe of hydrodynamics.
With the bearing housing partially filled with grease, grease is added to the housing. Some of the grease flows through the operating surfaces of the begetting, causing stress. The reduction of clearances causes an increment in friction within the bearings. This will cause the bearing temperature to increase as the bearing surfaces reject the grease medium. Once the temperature drops, the grease is no longer within the bearing surfaces and oil from the grease provides lubrication. The increase in temperature causes a reduction in grease viscosity, assuasive information technology to flow freely, albeit slowly, and excess grease is rejected through the grease plug (grease out). The change in viscosity ensures that enough flow should occur, when the grease plug is removed, and the maintainer does non count on 'grease relief plugs,' the housing should remain less than full, regardless of the number of greasing operations.
Grease that comes into contact with the shaft, bearing cap opening or housing opening (usually less than 0.010 inches) becomes pumped through the openings due to Couetti Flow. This process is the upshot of a turning cylinder (motor shaft) with a shut, stationary, cyclinder (shaft openings) and an incompressible fluid. The excess grease is literally pumped into the motor housing.
What Happens When The Motor Is Not Running?
In the type of begetting that we are discussing, the grease enters the begetting housing. Some grease comes into contact with the bearing surfaces. When the motor is restarted, this backlog grease is ejected from the bearing. The temperature may briefly ascension, then fall, once grease has passed through the begetting. The shear stresses and temperature reduce the viscosity of the grease, allowing it to period.
While some grease is moved into the motor housing, due to Couetti Flow, the corporeality is considerably less than if the motor is operating.
Decision
Electrical motor bearing greasing requires the motor to be de-energized during the procedure. The result is reduced chance of backlog grease entering the electric motor stator, due to Couetti Flow, and reduced viscosity, due to oestrus. Combined with safety issues, proper lubrication can maintain the electrical motor reliability. Therefore, a limited amount of grease should be added to the begetting housing periodically with the grease plug removed.
About the Author
Dr. Penrose is the President of SUCCESS by DESIGN Reliability Services, based in Old Saybrook, CT. He too serves every bit the Executive Director of the Establish of Electrical Motor Diagnostics (IEMD). Starting as an electric motor repair journeyman in the U.s. Navy, Dr. Penrose atomic number 82 and developed motor system maintenance and management programs within manufacture for service companies, the US Section of Energy, utilities, states, military, and many others. Most recently he led the development of Motor Diagnostic technologies within industry every bit the General Manager of the leading manufacturer of Motor Circuit Analysis and Electric Signature Analysis instruments and training. Dr. Penrose taught engineering science at the University of Illinois at Chicago as an Adjunct Professor of Mechanical and Industrial Applied science as well equally serving equally a Senior Research Engineer at the UIC Energy Resource Middle performing energy, reliability, waste stream and production industrial surveys. Dr Penrose has coordinated US DOE and Utility projects including the manufacture-funded modifications to the U.s.a. Department of Free energy's MotorMaster Plus software in 2000 and the development of the Pacific Gas and Electric Motor System Performance Analysis Tool (PAT) projection. Dr. Penrose is a Past Vice-Chair of the Connecticut Section IEEE (Plant of Electrical and Electronics Engineers), a By-Chair of the Chicago Section IEEE, Past Chair of the Chicago Department Capacity of the Dielectric and Electrical Insulation Society and Power Electronics Society of IEEE, is a member of the Vibration Institute, Electric Manufacturing and Coil Winding Association, the International Maintenance Institute, NETA and MENSA. He has numerous articles, books and professional papers published in a number of industrial topics and is a Us Department of Energy (US DOE) MotorMaster Certified Professional, a U.s. DOE Pump Organization Specialist, NAVSEA RCM Level 2 certified, as well as a trained vibration analyst, infrared annotator and motor excursion analyst.
Source: https://reliabilityweb.com/articles/entry/electric_motor_bearing_greasing_basics
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