In industrial maintenance, several types of maintenance can be highlighted, in this article I will describe the different types, their advantages and disadvantages.
- 1 Preventive Maintenance
- 2 Corrective maintenance
- 3 Predictive Maintenance
- 4 Modifying Maintenance
- 5 Overhaul Maintenance
Preventive maintenance helps prevent the failure of a company’s machines or assets. This maintenance is characterized because it is done with established frequencies. These frequencies are given in terms of the control variable. For this type of maintenance, there are established resources, according to the manufacturers’ recommendations.
Within the preventive maintenance is executed something called maintenance plan. The maintenance plans are created by machine according to the recommendations of the manufacturer. A maintenance plan is composed of standard activities that are executed in a period measured in terms of the control variable that has the machine.
An example may be the maintenance plan that runs on a cart. All procedures that are executed in the vehicle are given in terms of kilometers.
A standard activity, helps to establish that procedures, parts, time and labor, will be invested in the equipment according to the value of the control variable. The standard activity is composed of:
- Tasks to be executed within the activity
- Spare parts to replace
- Type of labor to use (electrical technical personnel, mechanics, painters, lubricators)
- Total execution time of the activity
All the above allows us to make budgets and schedules of resources and equipment. When dates are established for the intervention of the machines with the production area, the availability of the equipment is not affected.
Advantages of preventive maintenance
These are some advantages that we can find in preventive maintenance:
- It is programmed: Preventive maintenance being controlled through the variables and a maintenance plan, you can schedule the stop of the machine without affecting the production schedule.
- Availability of Spare Parts: Same as the previous point; the needs of spare parts can be calculated and the purchase can be requested with a determined time. Helping to avoid making last minute purchases.
- Availability of technicians: The planning of preventive interventions, has included the scheduling of shifts of technicians, therefore, helps to improve shifts and workload of technical staff.
- Decrease corrective maintenance: When preventive maintenance is executed according to a adjusted maintenance plan, corrective maintenance should decrease. This is because it helps prevent unplanned failures.
- Generates savings: Just by decreasing corrective maintenance, a large economic benefit is obtained. The lost time of the machines will be diminished, lowering costs of production and maintenance, in consequence, it will improve the productivity of the company.
Disadvantages of preventive maintenance
There are few disadvantages to be found in preventive maintenance. Perhaps the vulnerability of preventive maintenance is the control variable. If it is not recorded or there are errors, it can drastically modify the programming of preventive activities.
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These errors can advance or delay preventive interventions, generating over costs in exchange of spare parts before time or delays that would lead to a corrective work.
Having a maintenance plan that is not in accordance with the machines is a disadvantage for preventive maintenance; since a mismatch in frequencies will cause the machine to be intervened without the need or never to be checked for a certain element that is important for the operation.
Corrective maintenance consists of repairing the breakdowns as they occur. It is defined as an unscheduled stop that is not in the maintenance plan and generates trauma in the operation and over costs. As these are urgent works, it directly affects the reliability and availability of the equipment.
The personnel in charge of warning of the failures are the users of the equipment themselves and the maintenance personnel is in charge of the repairs. One of the many disadvantages of this type of maintenance is that the user, in most cases, warns of the damage as long as the equipment prevents him from continuing working.
Advantages of corrective maintenance
The advantages that can be highlighted of corrective maintenance are:
- Updating and improvement of preventive plans: Logically, when a machine has a constant failure in one of its elements, that element must be inspected more frequently. Making constant pursuit of the corrective activities of the machine; statistics can be generated; which will give us data of times between failures, used spare parts and time of intervention of the technicians.
- Request warranty from suppliers: Generates claims to the manufacturer of the machine or asset, for imminent failures in manufacturing quality. When a failure occurs it is pertinent to apply techniques to find the initial causes of the failure; and thus be able to make a formal claim to the manufacturer.
Disadvantages of corrective maintenance
Corrective maintenance has many disadvantages. Because corrective maintenance is an emergency, it requires immediate attention from the maintenance department. Therefore, an exhaustive analysis of the cause of the failure cannot be done.
When a corrective maintenance occurs the maintenance area is forced to pay overtime to its technicians and cancel previously scheduled tasks; because the urgency must be attended.
Sometimes the spare parts needed to repair these machines are not in stock. This makes it take longer to repair the damage, which will make the loss of production even greater.
Predictive maintenance consists of permanently knowing the state and functionality of the equipment, through the use of certain techniques. Predictive maintenance is the maintenance that helps to predict the state of a machine; without making a direct intervention on it. The purpose of this maintenance is to be able to intervene the machine or asset at the moment just before it fails.
The actions and/or techniques are applied with the objective of detecting failures and defects of assets in the incipient stages to avoid that the failures are manifested during operation and that they cause emergency stops and dead times causing negative financial impact. Additionally, this maintenance generates savings opportunities in the operation and execution of preventive maintenance.
Advantages of predictive maintenance
Among the advantages to be highlighted in predictive maintenance are:
- Interventions at the right time: Predictive maintenance allows us to intervene at the right time the elements that have to be changed of a machine; which generates savings against preventive maintenance which is handled through established frequencies.
- Increased availability of critical equipment: The results of the implementation of a predictive maintenance program will be reflected in the availability of critical equipment. And these results will have a high impact on production and maintenance costs.
- Improvement of maintenance plans: Predictive maintenance in certain cases can update or modify, certain frequencies established in the maintenance plan, for elements or parts of machines. In addition, it allows testing new parts and making a detailed follow-up of their duration and operation.
Disadvantages of predictive maintenance
The main disadvantage of implementing predictive maintenance is the investment involved. Not only in money but also in personnel training. Many of the techniques used require expensive equipment and specific training of the technicians. Training must be comprehensive, both for the execution and data collection, as well as for the interpretation of results.
One of the types of maintenance that serves to modify the characteristics of the machines to achieve changes in production, or to have greater reliability and availability of equipment. It is performed in several stages of the machines’ life cycle.
When a machine is new, it may need adaptations to start its operation. Or modifications can be made to facilitate maintenance during operation.
Another stage where it is used, is when the equipment is already in operation; and it is done in order to eliminate the causes of the most frequent failures. In this case, modification maintenance originates after a failure analysis has been performed.
Modified maintenance is also performed when the machine reaches the old age stage. At this stage, overhaul maintenance is performed, where parts of the machine are rebuilt to enable them to last another working period after their useful life. In this overhaul maintenance, it is used to make modifications to the original designs and to introduce improvements that serve to production and maintenance.
It consists of checking the equipment at programmed intervals before any failure appears. This review aims to leave the equipment at “zero hours” of operation, in other words, as if the equipment were new.
The overhaul maintenance has to change or repair perfectly the parts with lower reliability. The objective is to increase the availability for an estimated time for the next preventive intervention.
This type of maintenance has a great advantage because it is scheduled. This allows to make budgets of materials, time and labor to be used. In addition to slightly impacting the production area by being able to agree in advance to stop the machine.
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