Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/934530
www . machinerylubrication.com | January - February 2018 | 47 to have a reliable plant. One of the first steps was purchasing a laser alignment tool, but this was only the start. Once we received formal training and began performing more machine alignments, we were able to achieve proper alignment quicker each time. It sure beat the previous methods of using straight edges and dial indicators. We also saw a reduction in failed bearings and couplings across the plant. IDENTIFYING MISALIGNMENT Proper machine alignment can be summed up in a simple state- ment: e shafts are aligned in both the horizontal and vertical planes. Misalignment takes place when the shafts are not parallel or a shaft has an angular misalignment. Parallel misalignment means that an offset of the shafts has occurred. Angular misalignment refers to when the shafts run at an angle to one another. Sometimes both parallel and angular misalignment may be present and need to be corrected. Parallel misalignment can be seen in the horizonal and vertical planes. Vertical misalignment usually can be remedied by adding or subtracting shims from the motor or machine feet. Horizontal misalignment requires side-to-side movement of the motor or machine until the centerlines match. Angular misalignment can also occur in the vertical and horizontal planes. EFFECTS OF MISALIGNMENT The effects of misalignment can be catastrophic to a machine. Coupling damage is the most common symptom. When a technician pulls the coupling halves apart for internal inspection, the grid or teeth may be affected, resulting in replacement of the entire coupling. Of course, this only masks the true problem hidden inside the motor or machine. Misalignment also increases friction along the bearing surfaces, which then turns into increased wear, energy consumption and premature breakdown of the machine. Seals can be damaged during any part of the process and lead to leakage. If the issue exists for an extended period of time, the shaft may be impaired as well. Once the components begin to wear, a simple swap-and-replace is no longer sufficient. If the underlying cause of misalignment is not recog- nized and corrected, the problem will present itself again and again. It's my opinion that misalignment is often overlooked as a root cause of failure. Frequently, the problem is blamed on faulty seals or the bearing installation. It's not until the maintenance profes- sional receives proper training and gains a better understanding of how detrimental shaft alignment is that the issue can be addressed through corrective alignment. PREDICTIVE TECHNOLOGIES There are several predictive technologies that can detect misalign- ment. e most popular options are laser alignment, vibration analysis, oil analysis and thermography. Laser Alignment Laser alignment makes it simple to align shafts with precision and accuracy. It works by using a laser that is directed into another sensor. is sensor feeds data to a device that deciphers the information and then provides you with accurate data to adjust your equipment. Once the laser and sensor are strapped to the driver and driven machine, the shafts are rotated and multiple points are read to determine which direction the driver must move. Laser a lignment tools can take into account the equipment's metallurgy and offer relative metal expansion rates to consider how the machine will expand during operation. A live alignment is also a possibility. For this, the techni- cian aligns the machine as much as possible, then starts the equipment and allows it to reach its operating temperature. After a shutdown, a measurement is immediately taken to establish the machine's thermal expansion. By routinely using laser align- ment on critical equipment, you can make the necessar y adjust- ML