By Shesby Chabaya, Operations HOD, WearCheck Zimbabwe
The challenge facing the agricultural industry is the need to meet high production targets for the agricultural season versus an unpredictable length (climate change impact) of the wet season. In some cases, this leads to the agricultural season starting off during wet weather, thus exposing the fleet to a considerable amount of operational risk. This operational risk is noticeable on the WearCheck oil analysis reports through the following:
- Repeat or high PQ levels (ferrous density or large wear metal particles) especially in unfiltered drivetrain components.
- High concentration of wear particles observed through the Microscopic Particle Examination (MPE) and ICP (inductively coupled plasma) wear metal test results.
The correlation of the high wear levels with the high incident reports of equipment stuck in the fields as well as the high failure rate mainly on differentials and final drives are indicative of the operational risk affecting equipment.
The oil analysis programme runs throughout the productive season and action plans are implemented through an iterative process of regular oil sampling, development of trends, problem identification, investigation and troubleshooting, corrective action, feedback and review. Trends are analysed on a regular basis with a view to come up with sustainable solutions to any challenges affecting the fleet.
The impact of wet weather operations
Wet weather operations have posed several challenges with the fleet drive trains. The high failure rate on drive trains during the wet season and period following the wet season poses a high risk and therefore provides a compelling reason for a case study and a formulation of strategies to protect the axles/drive trains, minimise failures and improve equipment reliability.
Read also :Effective Oil Analysis, Guaranteed Machinery Uptime
This case study is an analysis of this phenomenon. A number of techniques such as the 5-Why analysis are used to try and get to the bottom or root cause of the problem. Some of the questions asked in this analysis are:
- How are wear patterns spread throughout the year?
- Any seasonal trends?
- Any changes in the lubricant in use?
- Are there any changes in tonnage ferried by the fleet per load?
- Any changes in intensity of operation?
- Is this a fleet-wide problem or only affecting a few machines of the same make & model?
- Are there any changes in operating conditions/road conditions/field conditions and so on?
Where the answer is yes, the 5-Why analysis principle and other techniques are applied to test and critically analyse the aspect or factor, in order to establish the root source of the problem.
Analysis of MPE and wear on differentials and final drives: case study of ZT49 differential (August 2017)
For simplicity of analysis, the case of ZT49 differential is used to illustrate the findings characterising the phenomenon, though the challenges are spread across the fleet.
The differential oil analysis results showed a repeat problem on the Microscopic Particle Examination (six times). Large wear metal particles rose from 1 877MgFe/L (sample 1) to 13 297 MgFe/L (Sample 2) towards the end of the rainy season, see graph below:
Feedback provided by the customer indicates that when the tractor was stuck in the field, the operator repeatedly tried to drive it out, resulting in differential damage before the tractor was eventually pulled out of the field. It was also reported that the tractor had experienced a broken propeller shaft. The differential was then scheduled for replacement.
Oil analysis results show that this trend is commonly experienced across the fleet during periods of wet weather operation as well as periods following the wet season. An analysis of feedback submitted indicated the following common observations:
- High concentration of wear particles
- Chipped gears
- Broken planetary gear carriers
- Broken thrust washers and so on
These are observed upon draining oil or upon inspection, leading to regular differential and final drive overhaul. In some cases, tractors end up losing drive, and broken half shafts are often discovered as a result.
The incident chart below illustrates the distribution of differential failures during the 2017-2018 agricultural season:
As shown in the incident chart, 71% of differential failures occurred during the wet season while 29% occurred during the dry season. In all these failures, broken planetary gear carriers/spiders were discovered upon inspection. All failures were linked to wet weather challenges and/or post wet weather impact of abrasive wear.
The introduction of wear particles in the differentials and final drives resulted in accelerated wear or abrasive wear. The end result is a spiral effect: as more wear particles are generated, the wear rates increase (advanced wear) and in some cases resulting in failures which are costly, especially in terms of downtime and lost production.
It must be noted that the above are only symptoms, not the root cause of the problem at hand. To get to the root source of this phenomenon, we invoked the 5-Why analysis technique:
Toyota’s 5-Why strategy is a good trouble-shooting tool, which can be used in conjunction with the WearCheck oil analysis programme to discover the root cause of a phenomenon. This involves asking a series of “why?” questions until the root cause of the problem is discovered as illustrated below:
Problem – High differential failure rate
- Why? High concentration of wear particles in the oil
- Why? Abnormal wear of components.
- Why? Chipped gears/broken drive train components.
- Why? Tractors stuck in the fields / axle spinning.
- Why? Wet weather operating conditions, slippery roads and fields.
Applied solutions:
A trend in operational challenges has been noticeable over the years. To counter the problem, several strategies have been applied to remove (avoid wet weather operations where possible) or minimise impact (where wet weather operations cannot be avoided.) These strategies are discussed below:
Operator training
The people side cannot be ignored. An operator training programme was implemented to improve vigilance and foster behaviour change amongst the operators. This should be an ongoing project as new operators are employed from time to time.
Continuous improvement of procedures:
Operator procedures are continuously reviewed in response to current challenges. Operators to call for assistance once stuck in the fields and avoid spinning the axles in slippery conditions.
Minimise impact:
- Drain oil to curb the risk of further abrasive wear.
- Take further action to address the root cause of the problem.
This strategy resulted in savings amounting to ZMK363 984 (US$37 100) in cost avoidance (component replacement cost) of potential differential and final drive failures. Savings in reality are more, considering the cost of averted potential downtime which would result in huge loss of tonnage of cane deliveries.
Draining oil is often done to minimise the impact of abrasive wear, thus giving a lifeline to components. It must be noted that this does not solve the root cause of the problem – further action required.
Read also : Oil sample analysis for Agriculture machinery
Draining oil must be carefully considered and balanced with the need to minimise oil usage and save the environment. There should be a balance between the need to change oil versus the need to reduce oil usage. From a cost perspective, it is argued that draining two litres of oil change is better than the potential cost inflicted by abrasive wear.
It is important to actually consider the real cost of oil change, including the cost of labour, administrative costs, supervision, oil disposal, warehouse overheads, inventory overheads, safety risks, environmental risks and so on.
Planned change versus catastrophic failure
The oil analysis programme is used to closely monitor equipment health and make timely and informed decisions. Planned component changes for example have resulted in huge cost savings mainly accruing from minimised catastrophic failures which are normally associated with losses as a result of unplanned downtime and lost production. This is illustrated in the graph below:
The rule of conversion: With WearCheck, every oil sample is an opportunity to learn and better apply engineering principles to solve any identified challenges with an endeavour to maintain and stay up to date with modern engineering best practices, striving to do better than the previous financial year or season – a continuous improvement approach. The WearCheck oil analysis programme is a dynamic tool. With recurring problems, strategies are put into place to get to the root cause of the problem and prevent it recurring or control it in cases where the challenge cannot be fully eliminated. Where necessary, maintenance procedures are modified accordingly, in line with the new trends discovered.
At WearCheck, we establish partnerships that constantly explore and seek ways of improving current systems, processes and efficiencies or breaking new ground through oil analysis and condition monitoring programmes.
For more information, please visit www.wearcheck.co.za, or email support@wearcheck.co.za
[…] Effective Oil Analysis, Guaranteed Machinery Uptime […]
[…] Effective Oil Analysis, Guaranteed Machinery UptimeThe agricultural industry – grain producers in particular – should adopt oil analysis as one of the main techniques they employ in condition monitoring of their mobile machinery. Given the impact of rising input costs on their revenue – something that is entirely out of their control – the ‘low hanging fruit’ grain producers can utilise is increasing equipment uptime through improving predictive maintenance. By Eric Peters There is no more resounding clarion call for commercial grain farmers in Africa to ensure that their machinery is working optimally at all times than in present economic conditions. The global oil price is rising, triggered by Russia’s “Attack on Ukraine”, based on the recent trend of events. Unfortunately, fertiliser (AN/LAN (28), Ureum (46), and Kaliumchloried) is on a similar price trajectory. High oil prices will result in an increase in input costs like fertiliser and herbicides and insecticides, due to rising transportation costs, as most are imported. Markedly, sanctions against Russia have resulted in low supply of fertiliser globally of which Russia is world’s biggest producer. Consequently, it is incredible to imagine a farming business, weighed down by these factors, experiencing a sudden breakdown of critical lubricated mobile machinery in the throes of productivity. Proactive predictive maintenance The only sure-fire way to pre-empt the occurrence of a costly breakdown of critical machinery is through executing a proactive predictive maintenance plan. Fortunately, farmers have numerous advanced condition monitoring technologies at their disposal for their convenience. It is all a matter of making an informed choice on their exact needs.Read Also: Oil sample analysisAmongst several techniques that are employed in contemporary preventative maintenance is oil analysis. In different industries, oil analysis is now ranked as one of the most effective predictive maintenance interventions by engineers in across industries. Through oil analysis, which assures reliability and availability of machinery, guarantees that equipment is working optimally.Oil analysis involves the scientific analysis of used oil sample and other fluids from mechanical and electrical systems. The data gathered from a machine or component provides insight into the condition of that asset. Then, based on this, a decision is made on whether or not remedial action should be taken on the asset to ensure optimal operating performance and its lifespan. Analysing an oil sample from a machine or a component can be likened to analysing a blood sample from a person: The results determine the health status of the unit, just like the results determine a person’s health.Valuable Machinery downtime can be very costly, seeing the loss of productivity due to downtime, which translates into reduction in revenue, above and beyond unscheduled component replacement costs. Data on the estimated cost is obscure, but one thing is certain – it is astronomical and not worth gambling on. This is without mentioning the safety risks that machine failure can pose to operators or the machine itself when it is involved in an accident. Therefore, it has to be tackled promptly.In a nutshell, if implemented as required, oil analysis in predictive maintenance is a worthwhile step which guarantees the following:‘Low-hanging fruit’This is the time for Africa’s food producers to rise to the occasion, as the continent faces what could be easily – God forbid – the worst food shortage crisis in recent memory. There is a need for the agricultural sector to be aware of its role and gain insight into the value of investment in techniques that increase the availability and reliability of their mobile machinery. This is because their revenue is more likely to take a huge knock – any envisaged increase in food prices may be offset by huge increase in input costs. For this reason, farmers have to seek sustainable means of ensuring that their operations remain sustainable. Farming – food and animal production is a numbers game, where fine margins can make a huge difference. And the low-hanging fruit that is readily available for farmers to explore is predictive condition monitoring. There is a compelling business case for the agricultural industry to adopt oil analysis as one of the main techniques they employ in predictive condition monitoring to guarantee increased mobile machinery uptime.Save my name, email, and website in this browser for the next time I comment. […]
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