Developing an effective lubrication strategy02 July 2018

It is predicted that the advent of the Internet of Things (IoT) would eventually lead to the end of unplanned downtime in factories. While we’ve not yet reached this point, plant managers can improve their maintenance systems by following simple steps to minimise unplanned downtime

The Industrial Internet of Things (IIoT) has been lauded as a possible solution to the looming threat of unexpected downtime. The rationale behind this is that smart equipment will be able to provide status updates and alerts to engineers before a breakage occurs. However, this is not an alternative to an effective maintenance strategy, especially in regard to lubrication.

“Adoption of the IIoT has undoubtedly been one of the most eagerly anticipated prospects in manufacturing for some time,” explains Mark Burnett, VP of the lubricants and fuel additives innovation platform of NCH Europe. “Now that it is no longer an abstract concept, it is understandable that many manufacturers consider it the miracle cure for many industrial ills.”

One such ill is unexpected downtime. This is currently a large problem for manufacturing businesses, where even one machine halting production for one minute can result in substantial financial losses. Therefore, any potential solution is highly valued and sought after.
That is why there has been such interest in intelligent systems capable of generating masses of data on critical variables such as temperature, pressure and cleanliness. “By keeping maintenance engineers updated on the status of equipment and predicting upcoming failures, intelligent machinery looks to make life simpler for businesses and engineers alike,” Burnett adds. “However, there is no substitute for an effective maintenance strategy. While systems may be able to forecast repairs, an effective strategy gives maintenance engineers more time between repairs. This is particularly important for processes such as lubrication.”

For example, a steelworks plant will have a lot of machinery with high operating temperatures. If these machines do not have a lubricant with sufficient heat resistance and thermal properties, this can lead to decomposition of base oils and a higher rate of corrosion.
Likewise, pelleting machinery often processes materials such as wood that is prone to producing a substantial amount of dust. These abrasive particles often find their way into the lubricant and accelerate wear.

“While intelligent systems will certainly be able to alert engineers of the need to perform maintenance or change lubricant imminently, they will not be able to accurately diagnose the reason why,” Burnett explains. “The only way to do this is to develop and practise an effective approach to lubrication.”

Lubrication specification
The first step to an effective lubrication strategy is to determine the requirements of the lubricant. To do this, engineers and plant managers should assess the operating conditions of the machinery in question.

“These operations do not necessarily relate to the plant conditions or even the temperature of the machinery itself,” Burnett continues. “However, the operating environment should also be accounted for. A food processing or pelleting plant will be prone to contamination, so it is important that lubricating greases have a composition that nullifies the impact of particulates.”

For machine conditions, the most important variables are operating temperature and load dimensions. For example, if a machine processes heavy material, plant engineers must ensure that it is lubricated sufficiently to perform under the high pressure. This involves selecting a lubricant that has a high load-bearing capacity.

Several things can happen without correct specification. “In some instances an unspecified lubricant will simply deteriorate quickly and need replacing frequently, which in turn increases the cost of operation,” Burnett explains. “Yet in other cases, the lubricant will be unable to handle the load and will deteriorate during the first use. This not only leads to machinery damage but also risks breakage and downtime.
“Of course, even an intelligent system in an IIoT network will only be able to highlight the unusually high operating temperature or breakage after the wrong lubricant has already been applied. Maintenance engineers can pre-empt the problem by understanding what kind of lubricant they need.”

The application process
Even a perfectly specified lubricant is only as effective as its application. Applying too much lubricant is just as bad as applying too little; both cause equipment to fail sooner.

The implications of under-lubrication are clear. Without enough lubricant on a surface area, friction will occur and accelerate wear. Over the course of a production cycle it is not uncommon for high amounts of friction to lead to a complete machine breakage and downtime.

Industrial sensors may be able to alert engineers to an impending failure, but cannot tell them that they are under-lubricating the equipment.
Conversely, many plant engineers take a ‘more is better than less’ approach to lubrication in the hope that it will reduce the frequency of maintenance. Unfortunately, this is not the case. Burnett explains that when equipment is over-lubricated with a grease, the excess volume of lubricant raises the overall operating temperature of the equipment.

“This heightened temperature increases the rate of oxidation, which can cause the build-up of hardened grease deposits on surfaces,” he adds. “These deposits impair the effectiveness of lubrication and can prevent the flow of future products unless properly removed. They also increase the pressure on seals, which results in failure and leakage of lubricant.”

Plant managers and maintenance engineers can avoid these problems by ensuring all engineers know how much lubricant to use. This is information that a lubrication specialist, such as the supplier of the product, can help with.

Status and maintenance
The final step to an effective lubrication strategy is to ensure that machinery is regularly lubricated and that any possible issues, such as grease deposits, are addressed before they cause problems.

This is where the IIoT can help by notifying when equipment is running low on lubricant. While this ensures that maintenance is conducted regularly, engineers must then inspect the application fully to assess whether any further action needs to be taken.

“Undoubtedly, the rise of IIoT is bringing a wealth of benefits to manufacturing businesses, but the elimination of downtime is not strictly one of them,” Burnett concludes.

“What it does offer is an opportunity for engineers to manage and prevent downtime more effectively, which can only be realised with proper planning, the right products and a comprehensive strategy.”

Box Out: Changing bad gear oil habits
Benjamin Franklin once said that it is easier to prevent bad habits than to break them. This rings true for the industrial sector, where it is easier to form a habit of good predictive maintenance than to recover from machinery breakage or downtime.

However, this is easier said than done. Predictive maintenance requires constant vigilance to be effective, ensuring that maintenance engineers know when it is the right time to lubricate bearings, apply a rust-preventative coating or treat their water supply. These tasks will vary in frequency, so there can be a steep learning curve to getting it right.

“Unfortunately, we all know that problems do not wait until you’re ready and, especially with gear oil changes, failure to get it right often leads to problems,” says NCH Europe’s Mark Burnett. “Changing oil too soon, for example, leads to higher costs as more changes will be needed than necessary. Conversely, forgetting to change the oil at the right time increases the likelihood of machine damage and breakage, which itself leads to elevated operational costs.”

Despite both extremes leading to increased business costs, only 20% of oil changes happen at the right time. This is not surprising when many variables can determine how regularly oil needs changing. While many engineers may fill up a machine and expect it to require a change after a certain amount of time, it is the quality of the oil itself that must be measured.

“This is understandably difficult without a comprehensive approach to industrial gear oil analysis,” Burnett adds. “To reliably measure the quality of the oil and when a change is due, engineers must identify the quantities of external contamination and metal wear, as well as the general condition of the oil.”

For example, oxidation is a naturally occurring process that affects oil over time. In the presence of oxygen, the oil begins to break down and this reduces the service life of the oil itself. In addition to this, it also produces sludge that makes equipment work harder and drives up operation costs.

If left long enough, the acidity of oxidised oil will steadily increase and result in corrosion and pitting. While this is problematic if left for extended periods of time, this acidity allows more accurate assessment of oil condition.

By measuring increases in the system’s total acid number (TAN), maintenance engineers and plant managers can identify when the oil acidity is reaching the maximum acceptable level and act accordingly.

However, Burnett explains that TAN only accounts for one part of overall gearbox system condition and there are many other considerations such as the operational health of the machinery itself.

“It is crucial that engineers consider all aspects to ensure optimum performance,” he says. “To this end, we have developed the NCH Oil Service Programme (NOSP) to help businesses keep their machinery in working order and their oil changes timely. Samples of gear oil are analysed and user-friendly reports are generated so that plant managers can see accurate results at a glance, giving a clear overview of equipment condition and the TAN of the oil.”

Accurate analysis helps to prevent engineers falling into the bad habit of incorrect oil management. By combining this insight with an effective cleaning solution and a suitable gear oil, further bad oil-change habits and breakages can be kept at bay.

Box out: The three steps to effective gear oil maintenance
1 Timing is key The first step is choosing the right time to carry out the process. Although it may seem like a routine task, only 20% of oil changes happen at the right time. If the oil is changed too frequently, before it needs to be done, it is costly and a waste of labour and oil.
However, if the oil is changed too late, as 40% of changes are, the lubrication will wear off and cause increased wear that may lead to breakdowns, higher operating costs and downtime.

When deciding when to change their gear oil, maintenance engineers must measure external contamination such as the presence of water and dirt. If there are high levels of contaminants, then the gear oil must be changed.

Maintenance engineers should also monitor the wear of the metal and the condition of the oil. Viscosity and oxidation should also be measured.

A good monitoring programme will measure the total base number (TBN), which is the reserve alkalinity or reserve acid neutralisation that is in the oil, as well as the total acid number (TAN), which measures the increase of oil oxidation and the build-up of corrosive acidic compounds.

Over time, the TBN will decrease and the TAN will increase. From the point where the numbers meet, the oil should be changed as it can no longer provide adequate corrosive protection.

Since gear oil is the backbone of many machines in the factory, it’s important to ensure it is working correctly. By using an analytics programme, a plant manager can be assured that the changes are happening at the right time, ensuring that too much gear oil is not used and the machine is not in danger of under lubrication.

2 Cleaning before filling The second step of the process is to effectively clean the gear oil system before refilling with fresh oil. While some plant managers may be used to instinctively filling the machine as soon as it is required, this can make the previous analysis worthless and damage the machine.

If oil is allowed to continually build up, the contaminants in the oil will form deposits on metal surfaces in the system. This raises the operating temperature and reduces the effectiveness of the machine, potentially leading to failure.

To prevent the deposits from building up, maintenance engineers must clean the system to dissolve the deposits and neutralise any acidic contaminants. A cleaning product should be used before the oil is changed, rather than during the change.

The product will then remove the deposits from the inner workings of the machine and suspend them in the oil. When this is changed, the machine is then clean and ready for new oil.

3 Being effective The final step in the gear oil process, once the first two steps are complete, is to choose the right oil to go into the machine. After all, changing the oil at the right time and then ensuring the system is free from contaminants is futile unless the right oil is being used. This means engineers must consider the specific requirements of the machine and its environment.

For example, if a gearbox is used in a damp environment or outside, it can be prone to condensation and water ingress. In this case, the oil should be matched to this environment.

By instructing maintenance engineers to follow these three simple steps, plant managers can be sure that the most essential processes in their plant are running smoothly. Showing caution at the right time to change oil, taking the time to clean the system between changes and choosing the right oil for the machine will all help to reduce the chance of breakdown and subsequent costs of downtime.

Adam Offord

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