Changing bad gear-oil habits – how engineers can accurately monitor oil condition
14 March 2017
Benjamin Franklin once said, “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 in order 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 are ready and, especially with gear oil changes, failure to get it right often leads to problems. 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 per cent of oil changes happen at the right time. This is not surprising when one considers the fact that 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 actually the quality of the oil itself that must be measured.
This is understandably difficult without a comprehensive approach to industrial gear oil analysis. In order 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, 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.
To this end, NCH Europe has developed the NCH Oil Service Program (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, but it is not the only factor that must be considered to maximise effectiveness. Maintenance engineers can only achieve this by following best practice for changing oil.
Best practice to extend oil life
Advanced insight into gear oil allows engineers ensure that changes happen at the right time to avoid damaging machinery. However, in order to extend oil life and maximise performance, engineers must first clear away contaminants.
One of the most commonly forgotten stages of the oil change process is cleaning the system before refilling with fresh oil. In fast-paced environments, it can be tempting to cut corners and opt for just refilling without cleaning. However, this leads to oil that is ineffective and heavy with contaminants mere hours after use. These contaminants quickly form deposits on metal surfaces in the system, raising operating temperature and reducing power transmission through the gearbox.
To prevent this from occurring, it is imperative that engineers remember to clean their systems before replacing machinery oil. The most efficient and effective way is to use a cleaning product to dissolve the deposits and neutralise any acidic contaminants.
An effective system-cleaning product works by being allowed to run through the system during a brief period of operation. This separates the deposits from the system surface, leaving them suspended in the old oil so they are removed during the oil change. Once the system has been flushed, the final step is the simple process of replacing the fluid with an effective gear oil. To choose an effective product, engineers must consider both the traits of the oil and the problems the application faces.
For example, if the gearbox is prone to accumulating condensation and rusting, it is important that the oil can address this, such as a gear oil solution that employs a higher percentage of calcium-sulphonate technology. This mops up acidity as a result of oxidation; it also contains demulsifiers that separate water from oil to keep gears properly and safely lubricated.
Similarly, problems such as foaming and oil oxidation can also be addressed by choosing a product that contains anti-foam agents and oxidation inhibitors respectively.
For truly effective gear oil replacement, consideration must be paid at every step of the process to determining the best products for an application. This treatment should then be repeated for every subsequent refill. By combining accurate analysis with an effective cleaning solution and a suitable gear oil, maintenance engineers can keep further bad oil-change habits and breakages at bay.
Mark Burnett, vice president of the Lubricants and Fuel Additives Innovation Platform at global water, energy and maintenance solutions provider NCH Europe