Misalignment occurs when the driver and driven equipment shaft’s centre lines are not in a straight line or collinear with one another. Misaligned machines can lead to all sorts of trouble in a facility, from costly unexpected downtimes and increased energy costs to catastrophic equipment damage. Besides higher energy bills, they can also lead to potential safety concerns. Hence, proper shaft alignment is imperative for rotating equipment operating at high speeds.
Correct shaft alignment improves a machinery’s operating lifespan and provides the electric motor with the most efficient power transmission to the driven equipment. By prioritising proper alignment instead of leaving it as an afterthought, organisations not only extend the life of their motors but also free up their maintenance teams to focus on more important matters. Ensuring all equipment is properly aligned means more efficient use of manpower, resources, and replacements because their components last longer.
That said, alignment is not a one-time thing, as they can change over time naturally through normal use. As such, it is important to leverage condition monitoring to collect and analyse data needed to maintain proper alignment.
The consequences of neglecting misalignment
Poorly aligned electric motors and other critical machinery will require more replacement parts than correctly aligned ones, making them more time-consuming and expensive to maintain and diverting labour and parts from other areas. For instance, misalignment may cause seals to break unexpectedly and lead to fluid leaks or damage to other components of the machine. In equipment like generators, damaged seals along the joints in their body may not be fixable in-house and require professional generator overhauling. At times, the seals themselves can be costly to replace as well.
Moreover, misalignment is the primary cause behind excessive vibration and premature failure in components such as couplings, bearings, and shafts. These breakdowns can potentially lead to the failure of other components and prompt unplanned downtimes.
Although flexible couplings have a higher misalignment tolerance than their rigid counterparts, they still have limits and certain requirements. Therefore, they should not be treated as a substitute for proper alignment, and even incorrect coupling choices also contribute to the risk of failure. For example, couplings that are too tolerant of the misalignment of a given application may cause unbalanced rotation or increased vibration.
Electric motors are susceptible to three types of misalignment, namely offset/parallel misalignment, angular misalignment, and combination misalignment, wherein a motor shaft experiences both parallel and angular misalignment simultaneously.
Achieving and maintaining precision alignment
Ideally, installation should not be the end when it comes to ensuring machine alignment;
New equipment must be periodically checked for any changes in alignment in case of settling, especially if they are part of the most production-critical equipment. Maintenance is the perfect time to collect alignment data as it can provide insights on improving alignment over time.
For example, it is vital to determine a machine’s acceptable operating temperatures and record them during normal operations, as heat causes expansion and changes to a machinery’s alignment. Remember that different materials have different expansion rates and thresholds. OEM data often differs from operating conditions in the real world. Thus upon establishing a baseline of temperatures, deviations, if there are any, will stand out.
Alignment is not a fixed state after installation, and misalignments can arise from various conditions and factors, such as load, pressure, vibration, or vibration changes. Condition monitoring can detect such issues before they cause undesired consequences, with vibration monitoring being especially effective. While thermal imaging tools can detect deep components like couplings getting too hot, it does not reveal the cause of their findings. In contrast, vibration data provides a better picture of asset health as certain kinds of vibration and their locations can pinpoint alignment issues.
Successful maintenance teams all leverage condition monitoring to gather real-time asset data. All types of machinery require maintenance intervention at some point, but condition monitoring can reveal insights necessary to detect potential failures before they happen.
Using condition monitoring sensors and analysis software
By having total visibility of the status of their machines, organisations can reduce failures and avoid downtime. This is where condition monitoring programs come in, a cost-effective way of tracking asset health in real-time and assessing the condition of multiple pieces of equipment 24/7 without needing anyone to be physically on-site.
With software and IoT sensors, observing machine condition trends over time and analysing the gathered data is easier. These can produce key insights and paint a full picture of asset health, enabling effective planning and prioritisation for electric motor rewinds and other maintenance efforts. Otherwise, replacing parts before they need replacement wastes materials and labour that could be better allocated elsewhere.
This approach to maintenance increases uptime while reducing spending, which is not the case when relying on a maintenance calendar or reacting to failures after they occur. The former does not accurately correspond to actual asset conditions nor help teams spot quickly progressing issues. On top of that, significant failures can still occur even with regular preventive maintenance.
On the other hand, a reactive maintenance team does not contribute to preventing production hiccups, while a proactive one does. They keep machinery in top condition and ensure high reliability and efficiency for little to no disruptions in operations. With condition monitoring’s real-time knowledge of asset condition, organisations can make the most of their machines and their components thanks to planned repairs that address problems before they cause extensive damage, significantly reducing unplanned downtimes.
Conclusion
In summary, aligning motors and other equipment is not a one-time event, as they can change over time through normal usage. Collecting and analysing machine condition data is key to uncovering these near-undetectable changes and resolving the potential issues they may cause before they escalate. Besides predictive maintenance, condition monitoring and alignment can help ensure a motor’s longevity.
