Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/902206
40 | November - December 2017 | www . machinerylubrication.com Paper Machine Oils Lubric a nts used in paper machines are specially formulated to handle the rigors of the applica- tion. ese oils tend to have high levels of additives to combat water contamination and support the loads in working zones. e lubricants generally consist of antioxidants, rust inhibitors and anti-wear additives. In certain cases, they may also have detergent additives to help prevent buildup on machine surfaces due to the breakdown of the oil. Viscosity is the most important physical property of a lubricant and must be properly selected for the application. Paper machine lubricants typically have a viscosity of more than 150 centistokes (cSt). is viscosity allows the oil to be pumped but still provides a thick enough lubricating film to protect the bearings. If the viscosity is too low, the lubricated components will suffer accelerated wear and have a shorter lifespan. Conversely, if the viscosity is too high, additional power is needed to pump the lubri - cant. Temperatures may also run higher due to viscous drag. Demulsibility is another critical lubricant property to consider. e oil must be able to readily separate from any water picked up during its journey through the system. e lubricant should also be able to transport this water to the reservoir or a settling tank, where it sheds the water and continues its way through the lubrication circuit. Contamination Control Filters should be employed on every paper machine circulating system. Without the ability to remove contaminants, the oil and machine surfaces will degrade rapidly. Many paper mills choose filters with a focus on smaller particles, such as 10 microns or less, as they often cause the greatest damage. e selected oil must also be able to pass through the filters at all expected operating temperatures. is is largely a func - tion of the viscosity and viscosity index. Moreover, as oil flows through the filter, the additives must remain in the oil and not be stripped by the filter. Paper machine oils require many additives, so look for lubricants that are filterable and retain their additives during the process. Usage Considerations e intended use of the finished paper product can also be a factor in lubricant selection. In cases where the paper is used for food packaging or hygiene products, food-grade lubricants may be required. is will limit your lubricant options as well as the additives that can be used. Mandatory compliance with the Food Safety Modernization Act (FSMA) has made this issue even more important. Be sure to ask your internal FSMA champion what the best course of action is for minimizing any incidental contact of the lubricant with the product. Grease Lubrication Depend ing on t he paper machine's design, some bearings may be lubricated with grease. ere are specific greases formulated for these applications as well. ey typi- cally utilize a higher viscosity base oil (above 220 cSt), have high water resistance and are white so as not to impact the color of the finished product if any grease would happen to fall onto the paper during its trip through the machine. Automatic Lubrication Although certain paper machines may be greased one point at a time by a lube tech, others are tied into large, centralized greasing systems. ese systems dispense grease from a central reservoir to every point using injectors. e injectors set the volume applied at each point. When automatic greasing systems are employed, the lines and each injector must be inspected to verify that they are working properly. Oil Changes With large volumes of oil at stake, many mills choose to change their paper machine oil based on its condition rather than taking a time-based approach. is allows them not only to get the most life out of their oil but also to track and trend variables like wear debris and contamination. Normal oil analysis test slates can be used to examine the particle count, water content, viscosity, additives and wear metals. Other tests, such as varnish potential, foam tendency and demul - sibility, should also be conducted periodically to look for a breakdown of the base oil or any changes in the oil's physical properties. Lubricant Selection Selecting the right lubricant for any application can be chal- lenging. The same is true for paper machines. As this industry continues to evolve, the lubricants used in these machines will as well. However, by following the simple practice of keeping lubricants clean, cool and dry, you can ensure the best possible life for your lubricants and machines. ML About the Author Wes Cash is the director of technical services for Noria Corpora- tion. He serves as a senior technical consultant for Lubrication Program Development projects and as a senior instructor for Noria's Oil Analysis II and Machinery Lubrication I and II training courses. Wes holds a Machine Lubrication Technicia n (MLT ) Level II certification and a Machine Lubricant Analyst (MLA) Level III certification through the International Council for Machinery Lubrication (ICML). Contact Wes at wcash@ noria.com to learn how Noria can help you implement best practices for lubricating machines at your facility. IN THE TRENCHES By the Numbers: 4,390 paper manufacturing facilities are currently oper- ating in the United States, according to the American Forest & Paper Association