ESKO’s lubrication best practices for paper machines
The primary role of lubricants is simple: reduce the friction between machine elements that move in relation to each other. It is a matter of using the right lubricant (oil or grease), the right way and at the right time to obtain the best preventative measures. Utilizing both oil and grease appropriately are the foundation of an effective machinery lubrication program.
Oil is critical for operating many types of machinery. Manufacturers take care to provide detailed specifications to optimize operation of the machines supplied. It is important to follow those equipment manufacturer recommendations and use the correct lubricating oil for each lubrication point, set of points, or circulating system.
Grease is essentially oil with a thickening agent (‘gel-maker’) added to transform it into a solid, semi-solid or semifluid product. Grease consistency depends on the type and quantity of thickener that the grease contains.
Preventing bearing failure
One of the most significant causes of
unscheduled downtime is bearing failure. Bearings fail because of contamination (moisture and impurities), lack
of lubrication, fatigue and ill-fittings -
either too tight or too loose. There are
ways and means of preventing bearing
failure. These include:
Filtering out moisture and impurities. A steady flow of oil enables filtration of impurities including water, which can break up lubricant films, contributing to overheating and reducing oil performance. Instruments are available to detect moisture condensate and metallic particles in the oil stream.
Consistent circulation. Steady flow in circulating lubrication oil systems can ensure that each individual lubrication point receives a consistent flow of circulating oil, maintaining the right viscosity, reducing friction, and keeping each bearing cool.
Reduce fatigue. Stagnant oil gets hot. A steady flow of oil also ensures that lubrication points stay at proper temperatures and equipment can operate optimally. Temperature measurement and monitoring can predict and prevent undesirable conditions that result in failure or downtime. Monitoring vibration and pressure levels also helps.
Choose the best fittings. Fittings should be not too tight and not too lose. Taking the time to ensure the right fit, alignment and installation of fittings/mountings can prevent denting, cracked rings and excessive wear that can lead to premature failure.
Circulating oil lubrication
Effective process monitoring prevents mechanical breakdowns which
are expensive and disruptive. Automating lubrication monitoring helps ensure
delivery of the appropriate oil throughout a system, ensuring consistent equipment operation based on a
manufacturer’s recommended specifications. Systems can detect and measure
oil flow to critical lubrication points,
monitor oil temperatures, pressures and
vibration levels.
Using flow meters in monitoring systems
Cost-effective oil flow monitoring can
be achieved through oil lubrication products and systems using either positive
displacement (oval gear meters) and/or
variable area flow meters, depending
upon the number and location of monitoring points. Meters combined with
custom monitoring panels can provide
real-time feedback on fluctuations.
In oval gear meters, each complete rotation of the gears represents a specific volume of oil, regardless of viscosity variations which occur at different levels of machine operation. A proximity sensor detects each rotation and sends a signal to the central monitoring system, providing a reliable indication of oil volume at each lubrication point, without the need to recalibrate for viscosity corrections.
Oval gear meters in banks of up to 12 points are equipped with transparent covers providing easy visibility of circulating oil and allow in-line service during operation. Oil flow monitoring stations for up to 64 oval gear meters with an interactive touch-screen display are available for larger oil flow monitoring systems. These monitoring systems allow user definable low, high and operating flow set points with alarms and remote monitoring to PC, DCS and PLC stations. ESKO’s model EGM oval gear meter provides high-visibility of oil flow through a robust transparent cover. The ESKO model EGL oval gear meter panel can be customized for multiple flow points with connections ready for connecting to customer DCS.
Using individual variable area meters or flow meter banks
Individual lubrication points in circulating systems can also be monitored
with single or multi-point flow meter
banks. Various different flow rates
within a meter bank are available with
individual flow control valves. A single
inlet ensures simplified installation. Options include alarms, pressure gauges,
bank configurations and more.
Choosing the right grease
Grease application is an important
aspect of bearing and equipment maintenance. The most important functions
of grease are: lubricate at different temperatures and pressures, seal against
dirt, dust and water, protect against corrosion, reduce vibration and noise, and
longevity in function with consistency.
Grease is typically applied to bearings with specialized equipment that deposits the grease between the rollers in fill percentages recommended by manufacturers, usually in the range of 20% to 40%. Paying attention to grease condition is important too. Proper storage can prevent grease from oxidizing, bleeding, and eliminate contaminants from interfering with its ability to perform as a lubricant. Over time, chemical degradation can cause the oil and thickener to separate, forming a build-up that prevents new grease from working effectively, and contributing to bearing failure. Careful application of grease (to prevent damage to seals) and keeping ports free of excess grease, debris and crusting are also advisable.
Too much or too little grease can shorten bearing life. Over-greasing can cause operating temperature to rise too quickly, especially at high speed operation. Low speed or smaller bearings however, may need more grease in the housing. For optimal bearing life, manufacturer recommendations for both the type and quantity should be followed diligently. Greasing solution to extend bearing life include some of the following. Utilize digital grease meters that mount to existing greasing equipment in order to dispense the correct amounts of grease to each bearing. Connect grease meters with transponders to a PC program to manage planned lubrication amounts for each point and prevent missed points. For continuous monitoring, automated monitoring systems connected to mill systems with pulse inputs are optional. To ensure that no grease is left behind, innovative pneumatic 1:65 grease pumps empty each grease container.
Putting it all together
Information from automatic maintenance monitoring systems can be analyzed as part of a comprehensive preventive maintenance program. It’s
possible to detect equipment problems
when they are minor and can still be
resolved without unwanted downtime.
Consistent and reliable grease application and management also plays a role.
Implementing proactive best practices
for both circulating oil lubrication and
grease lubrication can increase overall
production efficiency and reduce the
number and seriousness of unscheduled
shutdowns. The flow monitoring experts at ESKO are available to share
knowledge and decades of industry experience to assist with putting lubrication practices into action.
