It is just as important to make sure that the lubricating oil is kept clean as it is to ensure contaminated oil is not supplied to the pump.
Transfer oil in clean containers and avoid using dirty rags when handling funnels or replacing caps. In some applications, fluid contamination can be a big issue. Seals are important to keep the lubrication in and the pumped medium out. Regularly check any joints or connections that could allow water or contaminants into key mechanical locations of the pump.
If contamination might be an issue, regular lubrication analysis can be performed. To check for dirt or metallic particles, run the pump to mix the lubricant and take a sample from the top of the reservoir. To check for water contamination, let the lubricant settle and take a sample from the bottom of the oil sump to see if water is present. If fluid contamination exists, follow the pump manufacturer's oil servicing instructions for ensuring contaminated oil is replaced with clean oil and filled to the correct level.
Bearing life can be extended on problematic applications where contamination is difficult to control with specialized bearing material heat treatments that offer superior wear resistance. Excessive Loading. Excessive loading can drastically lower bearing life. This can occur due to the following: misalignment, cavitation, flow is well above or below the pump best efficiency point BEP , the bearing is exposed to temperatures above tolerable levels.
When the flow rate is less than 50 percent of BEP, not all of the medium will exit. This creates an irregular distribution of pressure on the impeller, which can result in high radial loads that the bearings must carry.
Check with the pump manufacturer to determine the BEP and recommended flow rates. Excessive heat can be transferred to the bearing rings from the shaft and the housing. Although methods for bearing cooling exist, the inner ring may still expand, creating less clearance between the raceways and rolling elements. This will result in higher contact pressure and reduced bearing life. When anticipated, these conditions can be accommodated for by selecting a bearing with a higher than normal clearance.
However, if too much clearance is provided, the bearings will not be able to maintain pump shaft rigidity. Misalignment commonly occurs when the pump shaft is coupled to the motor shaft.
The coupling will pass reactionary loads to the pump and motor bearing systems. The reactionary loads will differ based on the type and material of the coupling. Misalignment can also occur when the pump temperature rises from ambient temperature to operating temperature. To check for this, run the pump. Once it reaches operating temperature, turn off the pump and check the alignment. If necessary, realign the shafts.
Follow the pump manufacturer's recommendations for proper alignment techniques. Checkpoints Prior to Assembly. Prior to pump assembly, consider these bearing related matters.
Shaft and housing fits vary depending on size, temperature and loading conditions. An oval housing will create an uneven distribution of contact pressure on the bearing rolling elements. Excessively loose shaft and housing fits can lead to creep and fretting on the bore or outer diameter of the bearing rings, eventually resulting in vibration and bearing failure.
Bearing shoulders must be perpendicular to the axis of rotation to prevent misalignment. Bearing experts often work with pump manufacturers in the design process to ensure robust specifications are established for bearings and associated interfaces. Verify that the shaft and housing fits are correct and within the pump manufacturer's specifications. Internal damage to bearings can occur during pump assembly. Exert force only on the bearing ring being mounted during installation.
If your bearings fail, there are multiple things that could go wrong with your electric motor. This section will go over how to inspect the bearings on your motor and prevent unnecessary wear to the bearings. Alignment Make sure the load attached to your motor is aligned properly. Misaligned loads can throw the rotation off balance, straining one or both bearings of the electric motor.
Operational Load Ball bearings are susceptible to load related failure more significantly than roller and spherical roller bearings. Due to the smaller contact surface area, ball bearings are typically suitable for shock load, start and stop or vibrating conditions. Vibration Increasing vibrational impact will dramatically decrease bearing life. Motors attached to drive pulleys with single and multiple V belts will side load the electric motor inboard bearing.
Belt vibration will further expose bearings to damaging conditions. Higher film strength and load resistance reduce the likelihood of spalling. You may have to blow out the motor every so often to keep it free of moisture and small particles that could work their way into the bearings. Guard against water washdowns with full force water hose pressure. If motors are covered with process debris, paper stock, minerals dust etc.
Oily residues can be removed from windings with ultra-pure, high dielectric strength solvents. In all cases after cleaning of the housing, or windings, ensure surfaces are dry and bearings are re-lubricated before restarting the electric motor. High pressure air or water blasting should be avoided. If water rinse off, sanitizing cleaning, or CPI processes are required, electric motor and equipment bearings should be lubricated with waterproof grease. Improved water resistance works in conjunction with good seal design to keep water out of the bearing housing and prevents pitting corrosion.
Temperature Monitoring Take temperature readings occasionally to monitor how warm or hot the bearings get. If the bearings are getting too hot, stop using the motor.
Let it cool down and promptly inspect the bearings for damage or contaminants. Over greasing causes as much heat generation as under greasing. Do not assume that excess heat is an over greasing issue.
Consult your lubricant supplier and analyze the bearing operational conditions. In cases of excess heat, be mindful that greasing best practices suggest to re-grease when the motor is running and to remove the lower drain plug while introducing new grease.
The grease plug can be replaced with an open port and tubing or a pressure relief port. Noise Monitoring If you hear any abnormal sounds coming from your motor, you can use ultrasonic detectors to better identify what part of the motor is creating the noise.
Shaft seals and oil rings can contact the bearing housing and create noise unrelated to bearing condition. We recommend a combination of ultrasonic and vibrational analysis monitoring. Listen for any abnormal sounds coming from the motor so you can address the issue before it does any further damage to the other components.
Check oil rings if applicable and keep an eye out for excessive shaft play. Excessive play in the shaft is a good indicator that you have a bearing that is defective or will be soon. The rotor and stator are the heart of your electric motor. Without these components working properly, your motor will function very poorly or not at all.
Here are a few pointers to help you make sure all is well with the rotor and stator. Record the gap sizes at the top, bottom, and both sides at each end. Remember that bearings at rest will allow the rotary assembly to settle slightly due to diametrical clearances in the bearing. Diametrical clearance is the total free movement of the inner race relative to the outer race in a radial plane, also referred to as radial clearance.
Use a feeler gauge to check the gap between the stator and rotor for equal clearance all the way around. For gearboxes, I do something a little different. The drive-side, input bearing is '1' and the opposite end of the input shaft is '2'. I number the bearings on the input side regardless of where the output is as 1,3,5,7. In my reports, I usually use the common terms I don't know there is a 'best' way I like 'menomics' because I am very simple-minded I guess.
Mike, Good topic. I guess one other twist is on vertical motors. Some have solid shafts, couple end on the bottom and some have hollow shafts, couple end on the top.
I guess top and bottom is pretty descriptive though. Pete, I have worked in a couple of motor shops and if you asked me what the front of the motor is, I would say drive end. I am sure just like this topic, different places use different terminology. Thanks, Ronnie. Ronnie Good point. I haven't heard it elsewhere. I printed off CSI's database machine points and handed them to the route techs and asked, "what's that point".
They had been gathering data on that route for 14 months and didn't know. It isn't good enough for 'you' to know your own system; it should be fail-safe enough that you can go and know. Today I created a database for some machine trains consisting of mtr-mtr-GB 3 shft -pinion slave unit - points through 'M'. And another with points through 'O'.
Using this method I've never had a problem nor with the A1 on verticals. Pete's is almost the same and isn't tit-for-tat different. I do it this way as it is simple for simple me and everyone as far as I know in the 's did it this way, so it isn't something I came up with.
I wrote my software that way originally but a few months later increased it greatly to actually identify a point. It'd probably take them an hour or so to do it. If it wasn't for the long description line, the point ID would not be adequate to know what you were on. We use a numbering system here. With 1 bearing always starting with the motor non-drive end, the motor, drive end being 2, then on the driven machine, drive end being 3 then 4 bearing is the non-drive end of the driven machine.
We apply this to inline drive systems, and gear box set-ups as well. The above example is an overhung fan, belt drive. Just another way to approach this so everyone at our plant will be on the same page.
Bell Baton Rouge, LA. How do folks label measurement points when more than one measurement is made at the same point? For example: high and low spectrum ranges, standard and demod or PeakVue spectrum, or high resolution spectrum. Walt, Like many others on this board, we are limited to 3 character identifiers. I also "number" my bearing locations reserving the first character for this. The second character reserved for the measurement plane H,V,A.
I use the same type as Rodney, 1,2,3,etc. With the Entek Odyssey software, you don't have to label the additional points as anything, since once you are on the 1H position, it will take all the redings you label as active for that point.
The filter used tells you what type reading it is.
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