maintenance vs maintanability

7/30/2019 Maintenance Vs Maintanability

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Maintenance Vs Maintainability

What is maintenance?

measures taken by the users of a product tokeep it in a operable condition or repair it to aoperable condition

Maintenance is the act of repairing or servicing

equipment


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Maintenance Excellence

Task Coupling alignment

Standards Align motor coupling using

dial gauge or laser method. Straight edge

method is unacceptable

Required best practices

Check the run out of shaft and coupling.Align to equipment specifications and not

to coupling specifications


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Best Maintenance Practices

Indicators of best maintenance practices

* Maintenance persons time covered byWO

* WO generated as a result of PM

* Planned / scheduled work compliances

* Reliability level reached

* Spare parts stock outs

* Overtime to total maintenance time


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Maintenance Excellence

Management Support and measures of effectiveness

Equipment data base

Maintenance tasks and procedures

Maintenance planning and procedures

CMMS

Failure evaluation / continuous Improvement

Personnel skills

Maintenance organization / structure

Work control

Shop stores inventory


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Maintenance Vs Maintainability

What is maintainability ?

Measures taken during the design and

development of a product to include features

that will enhance the ease of maintenanceand will ensure that when used in the field

the product will have minimum down time

and life cycle support cost

Design parameter intended to minimize repair time


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Maintainability

Product Life Cycle Consists with

1. Concept Development Phase

2. Validation Phase

3. Production Phase

4. Operation Phase

1 & 2 Come under Design Process

3 Come under Manufacturing Process

4 Field use


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Downtime of an equipment

Administrative time

Preparation of plans, etc.

Logistic timeWaiting for equipment, etc.

Active repair time

Put in to working condition, testing, etc.


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Active repair time

Failure verification time

Fault location time

Preparation time Part acquisition time

Repair time

Final test time


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Features of maintainability

Increase its serviceability

Increase its reparability

Increase the cost effectiveness ofmaintenance

Product meet the requirements for its

intended use


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Maintainability measures

Mean Time To Repair MTTR

Mean Preventive Maintenance Time

Median Corrective Maintenance Time Maximum Corrective Maintenance Time

Mean Maintenance Down Time


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Maintainability Tools

Failure Mode, Effects and Criticality Analysis FMECA

Structured qualitative analysis of a system,sub system, component or function that

highlights potential failure modes, their

causes and the effects of a failure on system

operation


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Basic steps of FMECA

Understanding system parts operation andmission

Defining each item expected to be

analyzed Identify possible failure mode of each item

Determining the effects of each items

failure for every possible failure mode Identifying methods/procedures for

detecting potential failures


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Maintainability Tools

Fault Tree Analysis FTA

Defines an undesirable state of the system

or product and then analyzes the system orproduct in terms of its operation and

environment, to determine all possible ways

in which the undesirable event can occur.


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Fault Tree Analysis

1. An output fault event occurs if one or

more of the m input fault events occur.

Signify by OR gate logic symbol

2. The output fault event only occurs if all

the m input fault events occur.

Signify by AND gate logic symbol


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Basic steps of FTA

1. Establish the top level fault event

2. Use FTA logic and event symbols and apply

deductive reasoning to identify what could

cause the top level fault event to occur.3. Develop the fall tree to the desired lowest

level, that of the most basic fault events

4. Analyze the completed fault tree qualitativelyand quantitatively.

5. Identify the appropriate corrective measures


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Important consideration of

maintainability design

Interchangeability any component can be

replaced with any similar component

Modularization division of a system or product

in to physically and functionally distinct units toallow removal and replacement

Accessibility easy access to defective

components

Standardization attainment of maximum

practical uniformity in a products design.


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Benefits of Standardization

1.Minimize the variety of parts / components

that the product or system needs

2.Maximize the use of common parts in

different products

3.Minimize the number of different models

and makes

4.Controlling and simplifying inventory and

maintenance

maintenance vs maintanability

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