Maintenance Methodology & Systems in Manufacturing : Operations Reserch

Maintanace Methodology & Systems in Manufacturing

Renzil D’cruz

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Maintenance Methodology

• The dictionary defines maintenance as:

“The work of keeping something in proper condition; upkeep.”

• Maintenance is performed to keep equipment and systems running efficiently for at least design life of the components.

• Types of maintenance : Proactive and reactive

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MAJOR MAINTAINENCE METHODS:

• Every facility that produces a consumer product has some requirement for maintenance or upkeep of their machinery.

• Depending upon the product and, to some extent, the size of the

• facility, this maintenance activity may be continuous in nature or periodic.

• Some maintenance activities may consume a significant portion of the facility expenses and manpower.

• Facility maintenance activities generally fall into three categories: Breakdown, Preventive, and Predictive.

• Each category has particular costs associated and specific benefits.

Reactive Maintenance(Breakdown Maintenance)

SYSTEM

• Response to Equipment Malfunctions

CHARACTERISTIS

• Inefficient maintenance department.

• Unpredictable Equipment operation

• All maintenance work unplanned

• Example: Light Bulb replacement

RESULTS

• Steady degradation of equipment performance.

MAINTENANCE DEPARTMENT

RESPONSIBILITY

• Respond to emergencies

• Get production back on line

Reactive Maintenance

• Reactive Maintenance can be described as responding to an event after it has happened.

• Generally categorize by profession.

Locksmith

Glazing

Carpentry Services

Small Building

Works Roofing

Electrical

Plumbing Services

Advantages of Reactive Maintenance (Breakdown Maintenance):

• Low cost.

• Less staff.

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Disadvantages of Reactive Maintenance :

• Increased cost due to unplanned downtime of equipment.

• Increased labour cost, especially if overtime is needed.

• Cost involved with repair or replacement of equipment.

• Possible secondary equipment or process damage from equipment failure.

• Inefficient use of staff resources.

Advancement on a breakdown maintenance program is Preventive Maintenance

• Advancement on a breakdown maintenance program is a preventive program.

• It involves scheduling a regular outage, usually on an annual basis, where the entire machine train or plant is shutdown, or removed from production, for careful inspection and routine replacement of specific parts.

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Advancement on a breakdown maintenance program is Preventive Maintenance

• This method has the highest cost for replacement parts because the facility may have a separate program or department with the sole purpose of maintaining an inventory of spare parts and scheduling outage activity.

• Maintenance costs are reduced because the "annual outage" or "turn around" is usually scheduled for a period when the product demand is low.

• Additional cost savings are realized because manpower and any heavy equipment are scheduled.

Advantages:

• Cost effective in many capital-intensive processes.

• Flexibility allows for the adjustment of maintenance periodicity.

• Increased component life cycle.

• Energy savings.

• Reduced equipment or process failure.

• Estimated 12% to 18% cost savings over reactive maintenance program.

Disadvantages:

• Catastrophic failures still likely to occur.

• Labour intensive.

• Includes performance of unneeded maintenance.

• Potential for incidental damage to components in conducting unneeded maintenance.

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Reliability - Centered Maintenance:

• The Changing World of Maintenance

• Since the 1930's, the evolution of maintenance can be traced through three generations. RCM is rapidly becoming a cornerstone of the third generation, but this generation can only be viewed in perspective in the light of the first and second Generations.

The First Generation:

• The First Generation covers the period up to World War II. In those days industry was not very highly mechanized, so downtime did not matter much. This meant that the prevention of equipment failure was not a very high priority in the minds of most managers. At the same time, most equipment was simple and much of it was over-designed. This made it reliable and easy to repair. As a result, there was no need for systematic maintenance of any sort beyond simple cleaning, servicing and lubrication routines. The need for skills was also lower than it is today.

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The Second Generation:

• Things changed dramatically during World War II. Wartime pressures increased the demand for goods of all kinds while the supply of industrial manpower dropped sharply. This led to increased mechanization.

• The cost of maintenance also started to rise sharply relative to other operating costs. This led to the growth of maintenance planning and control systems. These have helped greatly to bring maintenance under control, and are now an established part of the practice of maintenance.

• Finally, the amount of capital tied up in fixed assets together with a sharp increase in the cost of that capital led people to start seeking ways in which they could maximize the life of the assets.

The Third Generation: • Since the mid-seventies, the process of change in

industry has gathered even greater momentum. The changes can be classified under the headings of new expectations, new research and new techniques.

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RCM - The seven basic questions:

• The RCM process entails asking seven questions about the asset or system under review:

• What are the functions and associated performance standards of the asset in its present operating context?

• In what ways does it fail to fulfill its functions?

• What causes each functional failure?

• What happens when each failure occurs?

• In what way does each failure matter?

• What can be done to predict or prevent each failure?

• What should be done if a suitable proactive task cannot be found?

Functions and Performance Standards:

• Primary functions:

• Secondary functions:

• Functional Failures:

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The RCM process does this at two levels:

• First, by identifying what circumstances amount to a failed state.

• Second, by asking what events can cause the asset to get into a failed state.

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Failure Situations

• Failure Modes:

• Failure Effects:

• What evidence that the failure has occurred

• In what ways it poses a threat to safety or the environment

• In what ways it affects production or operations

• What physical damage is caused by the failure

• What must be done to repair the failure.

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Failure Consequences:

• A great strength of RCM is that it recognizes that the consequences of failures are far more important than their technical characteristics.

• The RCM process classifies these consequences into four groups:

• Hidden failure consequences: .

• Safety and environmental consequences:

• Operational consequences:

• Non-operational consequences:

Failure management techniques

• Proactive tasks:

• These are tasks undertaken before a failure occurs, in order to prevent the item from getting into a failed state. They embrace what is traditionally known as 'predictive' and 'preventive' maintenance, although we will see that RCM uses the terms scheduled restoration scheduled discard and on-condition maintenance.

• Default actions:

• These deal with the failed state, and are chosen when it is not possible to identify an effective proactive task. Default actions include failure-finding, redesign and run-to-failure.

RCM

• Scheduled restoration tasks.

• Scheduled discard tasks.

• Scheduled on-condition tasks.

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Manufacturing processes

• Casting

• Moulding

• Forming

• Machining

• Joining

• Rapid manufacturing

• Other trades

manufacturing processes

Casting

Moulding

Forming

Machining

Joining

Rapid manufact

uring

Systems in Manufacturing

• Production machines and tools

• Material handling and work positioning devices

• Computer system

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Manufacturing Process

• Process or continuous production:

• Mass production:

• Batch production:

• Jobbing production:

• Just-in-Time (JIT)

• Computer integrated

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Maintenance Methodology & Systems in Manufacturing : Operations Reserch

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Transcript of Maintenance Methodology & Systems in Manufacturing : Operations Reserch