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Boost reliability to maximise equipment effectiveness

Boost reliability to maximise equipment effectiveness
Rod Bowman, manager for reliability training at The Timken Company, looks at the importance of strategies such as condition monitoring in bearing and lubrication systems to boost reliability.

Does the term 'maintenance' in your company imply sustaining a desired level of equipment and process performance, or simply fixing, painting, and moving things? If the former, then you are one step ahead of many companies today. While there have been various maintenance initiatives introduced over the last 100 years, it is uncommon for a company to latch onto a concept, develop a strategy and ingrain that strategy into the culture of their operations.  

There have been three general ideas that have permeated industry during the last 70 years. Beginning in the 1930s and continuing to the 1960s, most companies operated with a "fix it when it is broke" philosophy. Beginning in the 1960s a slow shift began towards the form of preventative maintenance, which replaced components at fixed intervals regardless of condition. From this, a second generation of thought process began in the 1980s that put a greater focus on safety, more cost-effective maintenance, higher availability and better quality as a result of equipment operating correctly and led to an even more proactive approach to doing maintenance on equipment.

These concepts combine to bring us to today's focus - the continued push to do more with less. This has caused a shift from simply wanting to improve cost, availability and quality to a new more complete view of maintenance and reliability. This view says that a focus on asset performance is not enough. The focus of maintenance must be on the total lifecycle of the asset which will lead to sustainable asset performance. Now, the emphasis is on developing a reliability-focused strategy that aligns with organisational goals to actively address potential failures that will eventually lead to suboptimal results. The alignment of the reliability strategy with overall company goals helps ensure that performance and financial needs are met at the lowest possible cost.

Statistics tell us approximately 50% of downtime could have been avoided or reduced with the appropriate plant condition monitoring systems and practices. Some 30% of downtime could have been avoided by the application of simple plant inspection regimes and 6% by appropriate training. Statistics like this force us to look at condition based maintenance practices. 

Increased asset reliability reduces the need for additional assets or capital investments because you get optimal productivity and longer life from existing assets. You also minimise cost per unit produced as the assets produce more and with reduced defects and waste. There are benefits in minimising (or even eliminating) the labour, material and energy costs associated with inefficiencies. Finally, there is a reduction in safety and environmental incidents which starts from understanding the consequences of failures and how they impact the business. 

In beginning a reliability initiative the most important step is to align the goals with the business goals of the organisation. Once we understand the impact of failures to our business we are better prepared to develop a sound reliability strategy, covering the likes of condition-based (sometimes called predictive) maintenance, preventive maintenance as well as mechanical or procedural redesigns or simply run-to-failure. Another important aspect to a successful reliability program is to ensure that the processes are in place to sustain those goals.  

Since 85% of failure modes that require a maintenance task also require a condition-based task, let's look at how a sound reliability strategy can impact the operations of a maintenance department, in particular its condition-based or predictive maintenance program. It all begins with the creation of consistency. By taking consistent, accurate data readings on the performance of assets, a foundation or baseline is created by which ongoing performance can be measured.

After the baseline is established it becomes possible to monitor changes in the performance of the asset. Regardless of the PdM technology you choose, it becomes possible to compare current state to baseline performance readings. Based on these comparisons, it becomes possible to see trouble signs well in advance of the actual failure and often, before a dip in performance occur. 

PdM practice examples
Regardless of the maintenance philosophy that a predictive maintenance program is founded in, these programs are becoming increasingly more prevalent. The growth in PdM implementations through internal organisations, consultant engagements, mentoring or third-party outsourcing continue to be driven by the need to optimise not only the performance of assets, but the performance of maintenance organisations as pressure mounts to meet objectives with fewer resources. So let's look at some PdM practices.

Vibration analysis is the collection of data from a properly set-up machine and the analysis of this data. The data is collected regularly over a period of time to help determine machine condition by comparing the original baseline to current condition to find obvious outliers. Generally, an accelerometer is mounted on the machinery in close proximity to a bearing (or gear or belt) to measure the amplitude of the vibrations. Using the readings you can not only assess the potential failure of the asset but diagnose the problem based on the data collected.

Lubrication is the number one cause of premature bearing failures. More than 43% of bearing failures result from improper lubrication. Proper lubrication requires using the right types and amount of lubrication for the application as well as ensuring there is no contamination. Lubricants performance can be tested and improved using lubricant condition monitoring. Through a series of laboratory tests, various physical and chemical characteristics can be measured for both used and unused lubricants. These tests can measure viscosity, acid number, water content, oxidation and nitration, particle counts and elemental levels. There are several types of lubrication condition monitoring including wear particle analysis, oil function analysis and equipment condition monitoring. Each of these can help you better understand the state and function of the lubricant. Wear Particle Analysis is a lubrication test that examines the size, shape, composition and concentration of particles suspended in the lubricant. 

By examining these aspects of the contamination it is possible to determine why, what and where the contamination originated. Oil Function Analysis is the careful examination of wear debris and lubricant characteristics. This test can also help indicate the origin of debris and allow conclusions to be drawn about their formation, and as a result, the conditions of inaccessible moving components.

Ultrasonic testing is used for the detection of the high frequency components produced by the sound of operating equipment and most leakage problems. Because all mechanical equipment emits high frequency sounds of some sort, these sounds can be detected and an analysis of the sound can be made to predict failure or spotlight problems that need repair. Common uses for ultrasonic testing include airborne leak detection such as leaks in vacuum systems, compressed air leaks, valve blow bys and integrity issues with seals and gaskets. These types of leaks are usually examined in tanks, pipe systems or large walk-in boxes. 

The measurement of heat energy radiation without contact is the basis for infrared thermography. It is possible to accurately determine the temperature of an object by measuring the amount of its radiated energy. Thermography is most commonly used on electrical components but can also be applied to mechanical problems. 

We can look, too, at electric motor testing. Some 41% of motor failures are bearing related. Most of these failures are diagnosed by vibration analysis but some can be diagnosed by the electric motor testing process. A lot of value to be gained from motor testing both for what can be learned about an asset as well as the fact it can be done with or without the machine being in service. 

It takes patience and persistence to achieve results, but results will come and they will provide you an ROI that will make you and your maintenance team heroes in the eyes of management.
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