Industrial Maintenance: Techniques, Models, and Optimization

Posted on Dec 18, 2024 in Other subjects

Maintenance Definition

Maintenance is the set of techniques designed to conserve plant and equipment in service for as long as possible and with maximum efficiency.

Reliability-Centered Maintenance (RCM)

RCM is a technique to develop a maintenance plan, which has some important advantages over other techniques. Initially developed for the aviation sector, where the cost of replacement parts threatened the profitability of companies, RCM provides good results:

• Improved compression performance of the equipment.
• Studying the possibilities of failure of a team and the development of mechanisms that try to avoid them.
• Developing plans for securing the operation of equipment.

Total Productive Maintenance (TPM)

In TPM, some of the tasks normally carried out by maintenance personnel are performed by production workers.

Distinction: System, Plant, Area, Equipment, and Component

• Plant: Work Center
• Area: Area of the plant that has a characteristic in common.
• Equipment: Each of the production units that make up the area.
• System: Set of elements that have a common function within a team.
• Item: Each of the parts of a system.
• Components: Parts into which an element can be subdivided.

Differences Between Significant and Non-Significant Coding Systems

Significant Coding System: The assigned code provides information.

Non-Significant Coding System: Assigns a number or code corresponding to each team, but the number or code does not provide additional information.

The advantage of using a non-significant coding system is the simplicity and brevity of the code. The disadvantage is the difficulty of locating a machine from that code.

The significant coding system provides valuable information on the computer, but adding more information increases the code size.

Types of Maintenance: Definition and Differences

• Corrective Maintenance: Correcting defects that are presented.
• Preventive Maintenance: Maintaining a certain level of service on computers, programming corrections.
• Predictive Maintenance: Monitoring and informing the state permanently and operation of the facility by knowing the values of certain variables.
• Zero Hours Maintenance: Checking the equipment at scheduled intervals before any failure appears. Leaving it as if the computer was new (repairing all items).
• Maintenance in Use: Consists of a series of elementary tasks (taking data, visual inspections, cleaning, lubrication) which do not need extensive education, but only a short training. This is the basis of TPM.

Maintenance Models and Related Tasks

• Corrective Model: Applied to elements with the lowest level of criticality, whose faults are not a problem, either economically or technically. In this type of equipment, it is not profitable to devote more resources and efforts.
• Tasks: Visual inspection, lubrication, repairs.
• Conditional Model: Like the previous model, but also carrying out a series of tests that determine further action. If evidence of an anomaly is discovered, an intervention is scheduled. It is generally used for equipment with a low probability of failure.
• Tasks: Visual inspection, lubrication, condition monitoring, fault diagnosis.
• Systematic Model: Tasks performed no matter what the condition of the equipment. Tests are done, and faults that arise are resolved. Great for teams of average availability and some importance. A team in this model may have systematic maintenance routine tasks that are carried out regardless of the time it takes to run or the state of the elements on which we work.
• Tasks: Visual inspection, lubrication, systematic preventive maintenance, conditional maintenance, breakdown maintenance.
• High Availability Model: The most demanding. Applied to those computers that under no circumstances may suffer a breakdown. The reason is the high cost in production that a fault has. With demand so high, there is no time for maintenance that requires shutdown of equipment. For this, it is necessary to use predictive maintenance techniques that allow us to know the status of the team while it is running.
• Tasks: Visual inspection, lubrication, condition monitoring, fault diagnosis, periodic reset (Stop).

Equipment Classification Based on Criticality

• Critical Equipment: Equipment whose shutdown or malfunction significantly affects firm performance.
• Major Equipment: Equipment whose stop, damage, or malfunction affects the company, but the consequences are bearable.
• Expendable Equipment: Equipment with a minor effect on the results. It will cause a small discomfort, a little change of little consequence, or a small additional cost.

Relationship Between Maintenance Models and Critical Elements

• Critical Equipment: Scheduled maintenance (stops)
• Major Equipment: If the cost is high, scheduled maintenance; if it is low, corrective maintenance.
• Expendable Equipment: Corrective maintenance.

Maintenance Plan Definition

A maintenance plan is a document that contains all scheduled maintenance at a plant that must be performed to ensure the availability levels that have been established. It is a living document; it suffers from continuous changes, the result of the analysis of incidents that occur on the ground and analysis of various indicators.

Functional Failure vs. Technical Failure

Functional Failure: Prevents the equipment or system from fulfilling its analyzed function.

Technical Failure: Does not mean that the equipment fails to comply with its function, but it is an abnormal functioning of this.

Distinguish Between Failure Prevention and Failure Mitigation

Avoiding failure is much more expensive than mitigating it. Therefore, try to avoid failures in equipment whose maintenance model is high availability or systematic. Avoidance of failure involves almost always preventing the failure from occurring, while mitigating it means that its effects are minimized.

Preventive Measures to Avoid or Mitigate Failures

Maintenance Tasks: Work can be undertaken to avoid failure or minimize its effects.

• Visual inspections.
• Lubrication.
• Assessment of current performance with proper instruments (online).
• Check offline, with external elements of the team.
• Technical cleaning (conditional).
• Conditional adjustments.
• Systematic replacement of parts.
• Major reviews.

Improvements and/or Modifications to the Facility: Changes in materials, changes in part design, installation of detection systems, changes in facility design, changes in external conditions to the item.

Changes in Operating Procedures: Operating personnel often have a high incidence of problems in a team. This is the most inexpensive and effective damage control.

Changes in Maintenance Procedures: Some failures occur because certain personal interventions are not maintained properly.

Distribution of Time to Repair a Fault and How to Reduce It

• Detection Time: From the origin of the problem to its detection. Reduce by developing fault detection systems and daily inspections.
• Communication Time: From detection to the location of the maintenance equipment. Reduce the time with a flexible communication system.
• Standby Time: From the call until the start of the repair. Reduce with a properly sized template and agile order management.
• Fault Diagnosis: Determine what happens and how to fix it. Reduce by having drawings and manuals available in the vicinity of the equipment.
• Collection of Tools and Technical Means: Located at the site of intervention. Reduce by properly placing the necessary facilities in the workshop.
• Collection of Parts and Materials: Time until the arrival of necessary equipment. Reduce with a properly sized store, with efficient organization, and a fast shopping service.
• Breakdown Service: Time to solve. Reduce with a system of preventive maintenance to avoid breakdowns, and have efficient and well-trained staff.
• Functional Testing: Verify that the machine has been repaired. Reduce by determining which are the minimum tests to check the operation of the machine.
• Commissioning: Time between the solution of the breakdown and entry into service. Reduce the time by having a system of effective communication and agile bureaucratic systems.
• Reporting: Reduce the time by having a good maintenance documentation system.

Classification of Faults According to the Level of Difficulty

• Urgent Faults: Those that can be solved immediately, no waiting, as they cause serious damage to businesses.
• Important Breakdowns: Cause disruption of normal operation of the plant. They can wait until all faults are resolved urgently.
• Faults Whose Solution Can Be Programmed: It may be advisable to wait for a stop of equipment, or simply that the disorder caused is small.

List the Causes of Failures

Material failure, human error by operating personnel, human error by maintenance personnel, abnormal external conditions.

Qualities and Skills Required for Maintenance Personnel

Multipurpose training on technical, training in management and organizational tasks, basic knowledge regarding costs and budgets, monitoring energy conservation, environmental pollution, safety of personnel and materials, and external works.

Reliability Definition

The probability that a machine will work properly under the conditions for which it was designed.

Maintainability Definition

The probability that an industrial system will perform its duties again after a breakdown, or the probability that a fault can be repaired within a given time.

Availability Definition

The probability that a machine operates a service when required.

List Maintenance Functions

Methods, planning, and realization (implementation).

Palliative and Curative Corrective Maintenance

Corrective maintenance is involved when there has been a failure in the machine.

Palliative Maintenance: Arrays, a bet in running on an interim basis, made in situ, sometimes without interrupting the operation of all concerned, which is made in the first level and sometimes on the second level of maintenance.

Curative Maintenance: Repair, done on-site or in a central workshop, sometimes after a settlement has become final, and maintenance has the characteristics of healing. They are made at all levels of maintenance.

Preventive Maintenance: Types and Characteristics

Preventive maintenance is performed to decrease the likelihood of failure.

Types:

• Systematic preventive or scheduled for a stop.
• Preventive round is the regular monitoring of rounds based on material frequency.
• Preventive conditional is one that is testing the machine to know its status or if it suffers any alteration.