What types of maintenance exist?
We have three types of maintenance that are frequently applied in industries, below you find the definition of each one of them:
- Corrective maintenance: When there is a need for repairs due to breakages. However, until it reaches corrective maintenance, the equipment usually shows several signs of problems;
- Preventive maintenance: Maintenances that are planned based on time. In order to have a pattern, this time is determined with a recurrence, such as every three months;
- Predictive maintenance: These maintenances are defined through data collected from numerous equipment at different times. Thus, with the information provided, it is possible to generate a forecast of when would be the next ideal date for maintenance, considering information from the equipment itself in operation.
What differentiates predictive maintenance from others?
Predictive maintenance differs from others by considering information from the equipment in operation to determine maintenance periods. It is based on projecting the future state of an equipment or system.
Therefore, it is based on the capture of data from specific instrumentation, which checks and analyzes trends in equipment variables.
One of its benefits is the increase in the period of time between maintenance due to equipment breakage (corrective maintenance). And also in maintenance set to take place at certain time intervals (preventive maintenance).
As much as this may seem to be a new subject to some people, predictive maintenance has actually been carried out for many years. In fact, it had already shown productivity results since the 70s. However, it was around the 90s that it had a greater prominence.
What are the main goals of Predictive Maintenance?
The objectives are mainly related to actions with an impact on cost reduction in the industry. In addition, it is important to remember to improve quality and generate greater productivity.
Check out the list of the top 5 goals of predictive maintenance below:
- Define, before breakages or damages, the need for maintenance on a piece of equipment;
- It is not necessary to carry out disassembly for inspection;
- Increase operating time of the equipment;
- Make the most of the lifetime of the equipment;
- Increase equipment reliability.
Therefore, the main focus of Predictive Maintenance is to generate a projection of the status of the equipment and then find failures in an initial period. So that they can be resolved before they progress to a breakdown.
What are the techniques used to perform predictive maintenance?
The techniques aim at analyzing a type of failure. And it is even possible to use more than one technique to increase the assertiveness of the diagnosis.
Below are four of the most used techniques in the industry to perform maintenance:
This analysis focuses on the identification of mechanical defects, being mandatory in predictive maintenance of rotating equipment.
It is possible to identify the root cause of defects that could happen, evolve into breakage and harm the quality of the production line.
Thus, some possible defects to be found by vibration analysis are:
- Electrical problems in engines;
- Structural problems;
- Mass unbalance;
- Misalignment and warping of shafts;
- Bearing wear;
- Gear wear;
- Poor lubrication;
- Loose parts.
In other words, vibration analysis discovers faults through the rates of change of the dynamic forces generated during maintenance. This type of analysis can be done using easily accessible points on the equipment. Therefore, there is no need to stop the equipment.
It is important to be aware that each type of equipment has its own “Original Spectral Signature”. Thus, there are changes in the frequency or amplitude of vibration when the equipment starts to fail.
Thermography analysis records infrared radiation graphically or often with different colorations. It enables monitoring, identification, and recording of changes in the temperature levels of each part of the equipment, generating a thermogram.
With this information, it is possible to detect failures by changing the temperature of the equipment components.
The sensors used for this analysis must be cooled so that the temperatures do not impact the thermogram result, ensuring assertive results.
Currently, there is also the option of using sensors that are capable of producing reliable results without cooling, at room temperature (bolometers). However, the cost of this type of sensor is still quite high.
Thus, in predictive maintenance, this analysis can be used in numerous areas, such as the following types of equipment: static, rotating, piping, electrical, and mechanical.
Oil analysis, unlike others that have sensors, is performed in the laboratory. To perform it, it is analyzed whether the equipment lubricant has debris or contaminating materials in its composition.
By comparing new and used oil analysis results, it is possible to define when the oil should be changed. And with that, it may be possible to stipulate longer intervals for oil changes than the current practice, reducing costs and maintaining quality.
The analysis can be divided into three types:
- Analysis of lubricant properties;
- Contaminant analysis;
- Analysis and monitoring of machine wear.
Some possible defects to be found by oil analysis are:
- Depreciation of additives;
- Wear of equipment components;
- Contaminations in general.
With ultrasound analysis, there is an increase in the frequency of sound waves until they can be heard by the human ear (20kHz).
It is possible to easily identify leaks of air, steam, or even leakage of electrical current and mechanical defects through it. Therefore, there is a cost reduction with waste and it is possible to avoid stopping the production line.
It is also used for different purposes such as measuring distances and detecting objects.
Predictive maintenance as a sustainability action
In addition to all the benefits already mentioned, we also have a positive environmental impact with predictive maintenance. This is because, with the ideal functioning of the equipment, there is also control of energy consumption.
With the application of predictive maintenance, we saw above that other high-cost maintenance, such as corrective, can be reduced in frequency. Which brings benefits related to energy, economic and social issues.
Finally, it is possible to see that the investment in maintenance quickly pays for itself with the reduction of waste. And it can still be seen as a sustainability action, bringing benefits in numerous spheres of industry.