The Motor Running method should be the preferred lubrication procedure for grease-lubricated electric motors requiring relubrication. Adding a measured amount of grease at regular intervals should minimize the amount of grease getting into the windings without adverse affects on motor life.
What happens if you use the wrong grease for electric motors?
Regreasing with the wrong grease can lead to premature bearing failure. Most oil suppliers have grease that is specifically designed for electric motors, which is different from their multipurpose extreme purpose (EP) grease. Grease Incompatibility - Greases are made with different thickeners, such as lithium, calcium or polyurea.
How long should I run the motor after greasing it?
After you've finished greasing and before replacing the relief plug, run the motor for about half an hour. The motor's operating temperature will cause the grease to expand and force any excess grease to be expelled, reducing bearing housing pressure.
What kind of Grease do you use for electric motors?
A significant proportion of equipment manufacturers also specify some type of polyurea grease in their electric-powered machinery. A polyurea-based grease is an excellent grease for electric motors; however, this thickener is incompatible with most other thickeners.
Should I Grease my electric motor bearings?
Regularly greasing your electric motor bearing is an important part of electric motor maintenance. When applied correctly, the right grease will protect your electric motor's bearing against damaging corrosion, reduce wear caused by friction, and act as a seal against contaminants.
How do you grease an electric motor?
Electric Motor Bearing Lubrication ProcedureEnsure the grease gun contains the appropriate lubricant.Clean the areas around the relief and fill fittings.Remove the grease relief valve or drain plug.Grease the bearing with a calculated amount of grease. ... Watch for grease coming out the relief port.More items...
Can you spray lubricant in an electric motor?
Yes, WD-40 is safe to use on electronics. It is used frequently to dry out auto ignition systems as it it non-conductive, displaces water, and lubricates the parts without getting sticky.
What is the best lubricant for an electric motor?
3-IN-ONE Motor Oil is a SAE 20 special blend of high-grade oils engineered for 1/4 HP motors or larger. This long-lasting formula is great as an electric motor oil and lubricant, and can also be used to maintain sewing machines fans, drills, lawn tools, and more.
How often should you grease an electric motor?
When the operating temperature is between 80°C - 100°C (176°F - 212°F), oil should be replaced at least every three months. For critical equipment, it is advisable that lubricating oil be analyzed at least every three months to determine when oil replacement is necessary.
Can I use WD-40 on electric fan motor?
[Never put WD-40 in] any electric motor, even if the rotor is stuck from filthy dried-up lubricant! It not only removes any remaining lube, but it can melt coil wires (the lightly-coated copper wires twisted up in electric motors) and cause an electrical short.
Can you grease bearings while it's running?
Regrease a bearing while the motor is running and hot, or after the motor is removed from service and the grease is still hot. Under operational conditions, the grease is less viscous. Ensure the grease gun contains the right lubricant for the bearings to be regreased.
Do you need to lubricate an electric motor?
Electric motors require lubricants with specific characteristics. Use of the wrong grease often leads to early electric motor failures. The grease consistency preferred for electric motors is normally NLGI 2 or 3, with a base oil viscosity of 100-150 cSt @ 40°C.
How can I make my electric motor quieter?
Capacitors are usually the most effective way to suppress motor noise, and as such we recommend you always solder at least one capacitor across your motor terminals. Typically you will want to use anywhere from one to three 0.1 µF ceramic capacitors, soldered as close to the motor casing as possible.
Where does grease go in a motor?
As observed in the previous test, grease migrated through the gap between the inner cap and the motor shaft and either dripped or was flung off the shaft into the motor winding and end bell.
How to minimize grease in windings?
Adding a measured amount of grease at regular intervals should minimize the amount of grease getting into the windings without adverse affects on motor life.
What is grease relief valve?
Grease relief valves can reduce the amount of grease that enters the motor internals when relubrication is performed while the motor is running at steady-state operating temperature conditions.
What type of bearings are used in motors?
Motors can be equipped with either open-, single- or double-shielded deep-groove ball bearings depending upon the manufacturer's preferences. According to our motor lubrication standard, on motors equipped with shielded bearings, the shields are to be oriented toward the grease cavity in the end bells.
What is the RPM of a NEMA frame?
This article reviews the results from laboratory testing of a grease-lubricated NEMA-frame, 3,600 rpm electric motor manufactured to IEEE 841 standards and equipped with open deep-groove ball bearings and grease relief valves on bearing housing outlets.
How much grease does a relief valve discharge?
One valve discharged 16 grams of grease, the other 14 grams.
When did Dupont test electric motors?
In August 2001, DuPont conducted tests at an authorized electric motor repair facility in the Mid-Atlantic area, which raised even more questions on the effectiveness of the Motor Running method in preventing/minimizing grease from entering the windings of an in-service motor.
How to grease a motor?
The general procedure for greasing is as follows: 1. Lock and tag out the electric motor. 2. Wipe grease from the pressure fitting, clean dirt, debris and paint around the grease relief plug. This prevents foreign objects from entering the grease cavity. 3.
What Happens When The Bearing Is Greased With The Motor Running?
The ‘soap,' or grease medium, acts as a suspension in the oil, although grease is normally represented as a base with an oil suspension. This becomes an important issue in the physical world of hydrodynamics.
What happens when grease comes into contact with the shaft?
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 result of a turning cylinder (motor shaft) with a close, stationary, cyclinder (shaft openings) and an incompressible fluid. The excess grease is literally pumped into the motor housing.
How does grease enter a bearing?
In the type of bearing that we are discussing, the grease enters the bearing housing. Some grease comes into contact with the bearing surfaces. When the motor is restarted, this excess grease is ejected from the bearing. The temperature may briefly rise, then fall, once grease has passed through the bearing. The shear stresses and temperature reduce the viscosity of the grease, allowing it to flow.
What happens when you add grease to a ball bearing?
When too much grease is added, the grease is compressed between the bearing surfaces, increasing pressure and resulting with heat.
What happens to grease when temperature drops?
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, allowing it to flow freely, albeit slowly, and excess grease is rejected through the grease plug (grease out).
Why does grease increase the temperature of a bearing?
Some of the grease flows through the operating surfaces of the bearing, causing stress. The reduction of clearances causes an increase in friction within the bearings. This will cause the bearing temperature to increase as the bearing surfaces reject the grease medium.
Why should you grease industrial motors?
You're probably familiar with the old saying, "it worked like a well-oiled machine," right? Well, that didn't just come out of nowhere (like that thing about raining cats and dogs)!
Want to see what can happen when you don't grease your motors?
Check out this post and video to see for yourself the carnage that can occur when someone forgets to grease the bearings.
What is the best grease for electric motors?
When searching for a lube type and manufacturer or supplier, there are several things to consider. The following is a list of qualities of a good electric motor grease: 1 Good channeling characteristics 2 NLGI Grades 2 to 3 3 Base oil viscosity of an ISO VG 100 to 150 or more specifically 90 to 120 cSt at 40°C 4 High dropping point, 400°F minimum 5 Low oil bleed characteristics, per D1742 or D6184 6 Excellent resistance to high-temperature oxidation 7 Good low-temperature torque characteristics 8 Good antiwear performance (but not EP)
What happens when a motor is filled with grease?
Motor Casing Full of Grease - If the grease cavity is overfilled, and high pressure from the grease gun is applied, the excess grease can find its way between the shaft and the inner bearing cap and press into the inside of the motor. This allows the grease to cover the end windings of the insulation system and can cause both winding insulation ...
Why is my lubricant starving?
Lubricant Starvation - There are several possible causes of lubrication starvation. The first is insufficient grease being added during installation. The second is inappropriate, elongated relubrication intervals. The third involves the possibility that the oil has separated from the thickener base due to excessive heat.
What happens if grease is different from the grease used in the bearings?
If this grease is different from a grease previously used in the bearings, the previous grease will need to be cleaned out or flushed from the bearings and housings . Make all necessary modifications to the electric motors. This includes adding fittings and making them accessible.
Why is grease important in bearings?
Grease is the lifeblood of these bearings because it provides an oil film that prevents the harsh metal-to-metal contact between the rotating element and races. Bearing troubles account for 50 to 65 percent of all electric motor failures, and poor lubrication practices account for most of these bearing troubles.
How to grease a bearing?
Grease the bearing with a calculated amount of grease. Slowly add grease to minimize excessive pressure buildup in the grease cavity.
Why does grease overheat?
Overheating Due to Excess Grease -Too much volume will cause the rotating bearing elements to churn the grease, trying to push it out of the way. This results in parasitic energy losses and high operating temperatures, and increases the risk of oil separation and bearing failure.
How Much Grease is Too Much for My Electric Motor?
You are responsible for getting as much as possible out of the electric motors in your facility -- and you know that proper lubrication for your electric motors is a big part of that equation. You've heard that there can be issues with too much grease, but how much is too much? And how do you know when grease needs to be added?
What is grease in motors?
Grease is a semisolid lubricating material comprised of oil suspended in a thickener. Grease does more than just reduce friction in bearings: it helps conduct heat away from the bearing, protects it from contaminants such as dust or moisture, and protects the surface finish by preventing corrosion. The thickener in grease helps it to stay in place and act as a seal for the bearings. Basically, the oil is held within the grease until the motor begins to operate. Once it starts to operate, the oil begins to flow and compress between the various bearing surfaces.
What is an ultrasonic grease caddy?
The Ultraprobe 201 Grease Caddy is an example of just such technology because it allows you to add grease and monitor the grease levels using ultrasound. This supports predictive maintenance and a much more tailored, effective approach to maintaining your motors and power trains.
What happens when grease is overheated?
Overheating will lead to a reduction in the overall effectiveness of the grease.
Why should you not grease bearings?
When you take a smart approach, optimizing how much and when the grease is added, you will see an improvement in the useful life of your equipment, better efficiency , and reduced maintenance costs ...
What is grease table?
There are grease tables -- many of which are posted online -- that will indicate the correct amount of grease to use on certain bearings. You can also calibrate your grease guns so that you know how much grease is added per pump.
How does oil work in a motor?
Once it starts to operate, the oil begins to flow and compress between the various bearing surfaces.
Prior Testing
Recent Testing
- In April 2002, with the assistance of our alliance motor vendor, and other DuPont engineering and mechanical specialists, a comprehensive testing program was carried out at the vendor's Baytown, Texas repair facility. Six test cases, two static and four dynamic, were developed to evaluate the following factors: 1. Motor Stopped vs. Motor Running lubrication method 2. Effecti…
Relief Valve Static Tests
- The first series of static tests were conducted to evaluate the effectiveness of the two approved grease relief valves in controlling/minimizing grease entry into the motor in the Motor Stopped condition. The following test protocol was used: 1. The motor end bell was removed and the motor bearings and grease cavity were packed 100 percent full of the test grease for all test con…
Dynamic Tests
- Test Condition 3 - Motor Stopped Cold Start - Industry-leading Polyurea
In this test condition, the motor, which was at ambient conditions and bearing housing 100 percent grease full, was started on the test bench and allowed to run at its no-load speed of 3,600 rpm. The drive end bearing temperature was recorded at one-minute intervals until the temperat… - Test Condition 4 - Motor Running Normal - Industry-leading Polyurea
In the next test, 15 shots (3/4 ounce) of grease were added slowly to the stabilized, normal-operating motor using a standard hand-operated grease gun. Again the outer race temperature was monitored and the motor components were inspected for excess grease after the test. As o…
Recommendations
- Neither the Reliance positive lubrication system (PLS) with open bearings nor potentially other motors equipped with shielded bearings can prevent the ingression of grease into the motor windings.
- Grease relief valves are most effective in preventing gross overlubrication in the Motor Stopped ambient temperature condition, but may not function during an ambient temperatur…
- Neither the Reliance positive lubrication system (PLS) with open bearings nor potentially other motors equipped with shielded bearings can prevent the ingression of grease into the motor windings.
- Grease relief valves are most effective in preventing gross overlubrication in the Motor Stopped ambient temperature condition, but may not function during an ambient temperature restart, resulting...
- Grease relief valves can reduce the amount of grease that enters the motor internals when relubrication is performed while the motor is running at steady-state operating temperature conditions.
- Grease relief valves should be thought of as "excess lubricant indicators". If grease is observ…
