Ask most maintenance techs, and they will say that pretty much every day is a hectic balance between handling emergencies and performing routine maintenance. All it takes is one breakdown to get sidetracked and behind schedule.
Take a look at this list of procedures that should help to reduce the number of fires you have to deal with and to improve reliability.
All rotating equipment that is coupled together needs to be properly aligned to reduce failures, vibration, and energy use. Even brand new equipment should be aligned upon installation. Proper shaft alignment means that the shaft centerlines are co-linear during normal operation; they should create one even line of power transfer from one unit to the next. Do not use coupling surfaces for proper alignment since they do not denote the shafts’ rotation axes.
Despite your best efforts, elements such as thermal growth (if the machinery will move at all as it gets hot from running), piping, and dynamic movement (thrust force, bearing play, vibration, etc.) can result in an Axial Misalignment over time; so be sure to consider the entire system. And please keep in mind, too, that some equipment requires a misalignment to allow for lubrication (gear couplings) or to compensate for thermal growth (compressor motors).
Another common issue called “soft foot” occurs when not all of the mounting feet are in the same plane (all the feet aren’t sitting flat on the base), causing the frame to twist as the foot is tightened.
Most common alignment methods:
FAIR: Straight edge and Calipers may be used to check the parallel and angular alignments, but this is the most inefficient method. Using feeler gauges and a micrometer will improve the results, but it is still not recommended.
BETTER: The Rim and Face method uses a Dial Indicator mounted on one shaft/hub reading from the face of the opposite hub for angular and the outside rim for parallel measurements.
BEST: By far the fastest and most intuitive method, dial indicators are mounted on both shafts /hubs and, along with the detectors and lasers, give vertical and horizontal measurements to quickly zero in an alignment. In addition, they can be used to diagnose soft foot issues. Laser alignment equipment typically comes with customizable reporting capabilities, as well, for historical tracking.
Always follow the manufacturer’s specified equipment tolerances. However, if they are not available, here is a breakdown of the two primary positions - Parallel and Angular – and their suggested alignment tolerances.
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Parallel Misalignment is measured by the distance between the two shafts’ axes when they are not positioned at evenly to create one continuous line. Parallel misalignment is usually measured at the coupling center in mils (1 mil = 0.001 in.).
- Angular Misalignments occur when one or both shafts are mounted in a tilted (sloped) position, so that the ends of the shafts do not meet in a straight flush position. In this scenario, the rise is measured in mils and the run (shaft length) is measured in inches.
2. Proper Lubrication Procedures
Lubrication is a critical component for equipment operations, a fact which is frequently overlooked or underestimated. Not surprisingly, lubrication is a leading cause of equipment failure for multiple reasons. Here are some of the more important issues to consider:
- Lubricants are not created equal. All lubricants are not the same, and should not be used across the board. Each piece of machinery, whether in a hydraulic unit, electric motor, or gearbox, has specific requirements based on, among other things, viscosity, rotation speed, the product being handled, the environment, and industry regulations. Be familiar with your equipment! TECH TIP: Reach out to either the manufacturer or a motor service center for assistance.
Don't overdo it! Too much of a good thing is not a good thing, so don't over grease! If you see grease coming out of the equipment, you may have a leak, or you may be over greasing, which can lead to equipment or bearing failure. Streamline maintenance by choosing one type of grease gun for consistency. Test the gun it to see how much comes out, and determine how many pumps should go into each unit. Marking equipment, especially in larger facilities with multiple shifts, will help to ensure consistent maintenance and cut down on failures.
- Change is not always good. Exercise caution when changing grease or oil; not all products can be mixed together. With so many variations in viscosity, thickening agents, and materials, especially with synthetics, it's best to have the old and new lubricants lab tested for compatibility. If a change is needed, clean out the bearing and unit to remove all traces of the old lubricant.
- Thicker lube doesn't always mean better protection. Application speed, temperature, and load need to be considered when choosing a grease or oil. You may think that smearing on some thicker grease will give more protection when, in fact, it's just gumming up the works. Again, check with the manufacturer or a service center for guidance.
- Looks don't matter. Don't judge a grease or oil on its color – whether blue, white, red, clear, or black. Look at the equipment and applications requirements, speed, temperature, and load to determine the best viscosity and materials needed, then choose the lubricant accordingly.
- Create a protocol. We have seen facilities with grease gunners who routinely pump three shots of grease into every piece of equipment, regardless of whether it needs it or not, because “that’s their job.” Bad idea. Begin by determining each grease gun’s pressure rating and displacement; standardizing on one brand and model is best to establish consistency. TECH TIP: Mark equipment for appropriate fill requirements and keep a log.
3. To Torque or Not To Torque
Tighten as needed to reduce excessive vibration in mechanical equipment; confirm that you have the specified torque requirements with the use of a torque wrench. With sealed equipment, however, make sure that you don’t tighten too much.
Even if something is leaking, applying compression may not be the way to go, and could cause more damage in the end.
Keep the following guidelines in mind when dealing with pressurized equipment:
- Flanges: Manufacturers torque flanges according to standards based on pressure, materials, temperature, etc. Tightening bolts in this case may damage or distort the equipment and cause the leak to get worse.
- Mechanical Seals: A clamped seal ring may become distorted - even a few millionths of an inch out of flatness can lead to leaking. Before tightening - or loosening - the bolts, check the manufacturer's torque requirements.
- Packaging: Leakage is a way of life with packaging, but when leakage increases, tightening should be minimal. Over-torqueing will lead to excessive wear. If minor adjustments don't relieve the problem, then you probably have another problem on your hands.
4. Organize, Train, and Commit
Training everyone on the team is a critical element that is frequently overlooked or handled inconsistently.
Establish a training schedule with refreshers on the most critical procedures, and always with an emphasis on safety. Documentation is important, not only to record what has been covered, but also for employees to have reference materials. Maintain a log book of topics and attendees, and have each person sign that they were in attendance for each training session.
There are multiple avenues for training. Chances are, a lot of your vendors will provide it for free. Check out any organizations that your company belongs to, or research options for industrial training companies.
Probably the most difficult part of creating a training program is committing to it long term.
5. Play Offense not Defense
Preventative Maintenance is ofetn used to maintain equipment reliability, efficiency, and avoid emergency breakdowns with scheduled, periodic inspections. Over time, a baseline is created on which to guage equipment performance and monitor changes, and plan for needed repairs along the way.
Unlike preventative maintenance, predictive maintenance determines equipment conditions with a real time, data driven approach. Instead of routinely scheduled calendar maintenance (that may or may not be needed), predictive maintenance saves time and money by handling machinery on a calculated basis for each piece of equipment.
Most of the common tasks associated with predictive maintenance require test equipment and training. This may not be a problem for larger facilities with the budget and manpower to accommodate; smaller facilities, however, may need to outsource to a company that handles predictive maintenance.
Common Preventative Maintenance Procedures for Electric Motors:
- Vibration Analysis / Monitoring
Using sight, sound, and touch in sensory inspections has long been the standard for monitoring equipment. However, more companies are beginning to understand and appreciate the savings and safety benefits that result from a proper maintenance plan.
