Plant & Works Engineering
The three steps to effective gear oil maintenance
Published:  08 May, 2018

PWE looks at how gear oil changes can be done much more effectively.

In 2013, a report by GE 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 sector is undergoing a digital revolution. Due to developments in sensor technology, cloud computing and connectivity software, factories are becoming increasingly monitored. This interconnectivity helps plant managers determine any maintenance tasks that need doing in advance, based on performance data fed back to a central control point.

Some experts believe that this proactive maintenance will lead to the end of unplanned downtime, which is certainly in the best interests of plant managers. Currently, downtime costs the average factory between 5 and 20 per cent of its productive capacity.

Yet while digitalisation promises unplanned downtime reduction in the future, there are still basic maintenance processes to consider for the time being.

Lubrication and gear oil change is a key example of this. If there is an insufficient amount of gear oil supplying a machine, the equipment is at an increased risk of breakdown. Poor lubrication puts extra wear on the parts and leads to expensive repairs and replacements, while also putting a stop to production, inducing additional costs there.

Inexperienced plant managers may believe that they can simply buy a good gear oil and put it into the system to solve their problems. However, it’s not quite as simple as that. If it is not done effectively, it is worthless buying a high quality gear oil as the machinery can still be damaged.

Fortunately, there is a simple three-step process maintenance engineers can follow when changing gear oil to reduce the risk of damage or downtime.

Timing is key

The first step is choosing the right time to actually 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.

To choose the right time to change the oil, NCH Europe for example developed its NCH Oil Service Program (NOSP), which analyses the gear oil and indicates when an oil change is necessary.

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 there is not too much gear oil used and the machine is not in danger of under lubrication.

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.

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.

Mark Burnett, VP of the Lubricants and Fuel Additives Innovation Platform at global water, energy and maintenance solutions provider NCH Europe says NCH Europe’s Top Blend CS oil has a high percentage of calcium-sulphonate, which is able to repel water to slow the rate of corrosion. It also contains acid neutralisers and oxidative inhibitors, which prevents oil acidity, which would have a detrimental impact on gears and seals if left untreated.

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.

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