Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/258778
52 | January - February 2014 | www.machinerylubrication.com Another method involves using a slightly lower viscosity oil during the run-in phase. Along with a lighter load, this can help reduce the severity of the break-in process with generally less wear produced. Although this method works, it also lengthens the break-in period. Combined with the decreased workload, this can cause problems with production goals or process requirements, so it is more often used in situations where spare equipment can be utilized to make up for the loss in capacity. Others believe that machines should be broken in the same manner in which they are expected to operate. While this is typi- cally the industry standard, it can lead to early machine failure if not monitored. All machines will generate wear during the break-in phase; it is how you manage this phase that will determine how long the machine will operate afterward. Oil temperature is also influenced during the break-in period. It will often rise from higher friction and then fall as surfaces smooth and load zones are broadened. This is common with large gearsets. As with all wear debris monitoring, it is important to look at the rate of change and not just the total volume of wear debris. An initial oil sample from a machine may show high iron from machining debris left during the installation process. After a second sample, which may also be high, the focus should be on the rate of change in the metals. This is why tracking hours of runtime between oil samples as well as after adding makeup fluid becomes very important. Perhaps the best example of breaking in a piece of equipment comes from the standard vehicle engine. Several break-in fluids are available that help temper wear on bearings, cams and cylinders. These fluids typically have a higher additive load and a different viscosity than the engine oil. A new engine usually is run at a lighter load (lower speed) for a short period before it is considered road- worthy. Most engines are broken in at the factory prior to being installed in a car. However, many mechanics replace engines and must repeat this process to ensure engine health. A friend of mine experienced this firsthand as he was rebuilding the engine for his drag car. He had just finished putting the final touches on the engine and fired it up. Shortly thereafter, he took the car to the track and lost the engine on his first pass. During the teardown, he discovered most of the bearings were wiped out from what he determined to be a lack of oil. Since the running-in period was so short, the oil didn't have a chance to build up the protective chemical layer on the surfaces to ensure their longevity. In the initial stage of a machine's life, there are a few things to keep in mind. More friction and wear will occur due to the high level of asperities. As the asperities are ground down, the new surface becomes polished, signifying the end of the running-in period. Explore the use of a break-in fluid to help minimize the risk of machine failure and to reduce the amount of wear experi- enced during this time. By vigilant monitoring of wear debris as well as understanding the forces at play during the break-in period, you can ensure that your machines will have a longer life and experience fewer breakdowns. references Salomon, G., DeGee, A.W.J. (1981). "The Running-in of Concentrated Steel Contacts: A System-oriented Approach." The Running-in Process in Tribology. Heilmann, P., Rigney, D.S. (1981). "Running-in Processes Affecting Friction and Wear." The Running-in Process in Tribology. Blau, P.J. (1981). "Studies of the Friction Tran - sients During Break-in of Sliding Metals." The Running-in Process in Tribology. Bloch, H.P. (2009). "Practical Lubrication for Industrial Facilities." Fairmont Press Inc. About the Author Wes Cash is a senior technical consultant with Noria Corporation. He is a mechanical engineer who holds a Machine Lubrication Technician (MLT) Level II certification and a Machine Lubri - cant Analyst (ML A) Level III certification through the International Council for Machinery Lubrica- tion (ICML). Contact Wes at wcash@noria.com. BACk PAGe BAsICs By vigilant monitoring of wear debris as well as understanding the forces at play during the break-in period, you can ensure that your machines will have a longer life and experience fewer breakdowns.