OMDEC Optimal Maintenance Decisions Inc. 1 The use of recorded information to improve OEE,...

1OMDECOptimal Maintenance Decisions Inc.Optimal Maintenance Decisions Inc.

The use of recorded information

to improve OEE, reliability, safely, at lowest costby assessing:

1. Failure Data

2. Inspection findings

1. Adjust PM task intervals & PM tasks

2. Assess desirability of additional PM tasks

3. Eliminate unnecessary (over intensive) PM tasks

4. Improve failure response

5. Redesign and Design

In order to

This is a continuous process!


The functions of a CMMS knowledge base1. To determine the types of failures the equipment is actually exposed

to as well as their frequencies

2. To expose the consequences of each failure, ranging from direct safety hazards through serious operational consequences, high repair costs, long out-of-service times for repair, to a deferred need to correct inexpensive functional failures

3. To confirm that functions originally classified as evident (during RCM analysis) are in fact evident to operating personnel during the normal performance of duties

4. To identify the circumstances of failure in order to determine whether the failure occurred during normal operation or was due to some external factor (accidental damage)

5. To confirm that on-condition (CBM) inspections are really measuring the reduction in resistance to a particular failure mode

6. To inform us of the actual rates of reduction in failure resistance in order that we may determine optimum inspection intervals


The Purpose of a Reliability-Centered Knowledge Base

7. To record the mechanism involved in certain failure modes in order to identify new forms of on-condition inspection (CBM) or parts that require design improvement, or improve diagnostic response.

8. To identify those tasks assigned originally as default actions but that do not prove applicable and effective

9. To identify maintenance packages that are generating few trouble reports and are candidates for longer interval schedules

10. To identify items that are not generating trouble reports

11. To record the working ages of assets and components at which failures occur

In summary, the purpose of a Reliability-Centered Knowledge Base is to use all

of the above to

IMPROVE ASSET OEE AT LOWEST COST, SAFELY


The UML Context Diagram

Unified Modeling Language


Data model


Use Case Diagram - Complete the work order form


The UML use case diagram

1. Simplified guidelines and training document,

2. Accessible examples,

3. Supervision, discussion

4. Support,

5. Evolving failure codes ,

6. Revision and Audit capabilty


UML sequence diagram


Anticipated vs. Actual Experience

• Compared failure modes in FMEA to those encountered in the field– Turbofan Engine

Extracted from CaseBank study published in IEEE Paper “Comparison of FMEA and Field Experience for a Turbofan Engine with Application to Case-Based Reasoning”

Failure modes “anticipated”

Overlap of 142 Failure modes610

FMEA

Failure modes “experienced”(LRUs primarily)

727Field

Experience

Quality Loss

Machine

Ma lf u nc ti o n

Process

Operating age since last shop visit (flight hours)C

o ndi

t ion

al p

r oba

bi lt

yof

fai

l ur e

for

200

ho

ur in

t er v

als

1000 2000 3000 40000

0.2

0.4

0.3

0.1Total removals

Functional failures

Potential failures

KPI Incident 1Function,Failure,Cause,Effects,

Consequences

Incident 2Function,Failure,Cause,Effects,

Consequences

…

Incident “n”

Improved maintenance policies

Linked to RCKB

SpotLightCBR

OSISoftPI

Etc…

IVARAEXP

EXAKT

ABB Real-TPI

DLI ExpertAlert


• R(t) is the survival function. (Also called the reliability function.) R(t) = 1-F(t)

• h(t) is the hazard function (At various times called the hazard rate, conditional failure rate, instantaneous failure probability, instantaneous failure rate, failure rate, the inverse of failure resistance, failure risk, and risk.) h(t) = f(t)/R(t)

• MTTF is the average time to failure. (Also called the mean time to failure, expected time to failure, average life.) MTTF = =

Reliability terminology• f(t) is the probability density

function (PDF).

• F(t) is the cumulative distribution function (CDF) It is the area under the f(t) curve from 0 to t.. (Sometimes called unreliability or the cumulative probability of failure.)

0)( dtttf

0)( dttR

Operating age since last shop visit (flight hours)

Con

ditio

nal p

roba

bilit

y of

fai

lure

for

100

ho

ur in

terv

als

2000 4000 6000 80000

0.2

0.4

0.3

0.1

June – August 1964

Oct. – December 1964

August – Oct. 1964

January – Feb. 1966

May – July 1967October – December 1971

The effects of gradual improvement


Questions

1. What is the optimum reliability state?

2. How quickly can we achieve the optimum reliability state?

3. What actions do we take to accelerate the process? and

4. How do we measure our progress to that end?


Fai

lure

rat

e (f

ailu

res

per

1000

hou

rs)

1963 1965 1971 1972

0.2

0.11967 1969 1970

Date of forecast

0.3

0.60.5

0.8

0.4

0.91.0

0.7

2.0

196819661964

Forecast

Experience

Decreasing failure rate


Refining the maintenance program

Analysis of unanticipated failures

Analysis of results of scheduled tasks

RCM default decisions made in the absence of information

Improvement thru analysis

No other way


Con

ditio

nal p

roba

bilty

of

failu

re f

o r 2

00

hour

inte

rval

s

1000 2000 3000 40000

0.2

0.4

0.3

0.1Total failures FF,PF

Functional failures FF

Potential failures PF

18OMDECOptimal Maintenance Decisions Inc.Optimal Maintenance Decisions Inc. Working age

Con

ditio

nal p

roba

bilit

y of

fai

lure

Failure mode C

Infant mortality Failure mode A

Failure mode B

Total failures

Verified failuresUnverified failures


CBM Effectiveness Comparison

CBM effectiveness is related, ultimately, to how "good" the condition data is.

b


Calendar quarters

Num

ber

of f

unct

iona

l fai

lure

s/qu

arte

r

1971 19730

5

10

1972

Start of borescope inspection, 125-cycle intervals

Inspection interval reduced to 30 cycles

Modification started

Modification completed

Inspection requirement removed

Elimination of CBM

Acquiring Maintenance Information

Using living RCM software

4


MIMS – small mod, big impact


Event type• FF - the ending and renewal of a component (failure mode) due to a

functional failure• PF - the ending and renewal of a component (failure mode) due to having

detected a potential failure in time to avoid the more dire consequences of a FF.

• S - the ending and renewal of a component (failure mode) for any reason other than (functional or potential) failure. (For example preventively replacing the component.)

• B - the beginning of the life of a component in the item (if not FF, PF, or S) • BSA - the beginning of a period of temporary removal (suspended

animation) of a component from the item. • ESA - the return of the same component to the item after a period of

suspended animation • SA - the beginning and ending of a period of suspended animation if

reported on the same work order. • MR - the minor (non-rejuvinating) repair of the item. It does not renew any

components. Sometimes it will impact the monitored data. For example, a calibration, a shaft alignment, an oil change, the balancing of an impeller, and so on.


Creating the Events table with Living RCM

1. Generate a report of all work orders related to the item during the sample period.

2. Update each work order with the significant failure mode(s) and event type

3. Generate the Events table using the CMMS report writer and feed it to the LRCM software.

4. Perform reliability analysis (e.g. Pareto, Weibull, Jackknife, EXAKT)

A policy agent?

Agent

CBM Databases (vibration, oil analysis, control system historian)

CMMS and Process Databases

(events, failures, replacements, minor repairs, mission requirements …)

The “right” decisions

The demonstration

Drive

Unbalanced rotor

Switch

Ramp

Tee

Accelerometer

TeeRampSpring

Spring

Click for movie

ICHM 20/20

Agent

Decision

Deciding on CBM

Preferred policy for 3 reasons - it is often the strategy that is the:

6

1. Least costly

2. Least intrusive

3. Least tolerant of failure

RCM Guide

http://www.omdec.com/wikifiles/rcmWorksheetGuide.pdf


Effects

Effects

Effects

EffectsEquipment

Decision Resourcing

Failed state

Failed state

Failed state

Function

Function

Analysis

•Training• Training resources

•Procurement • Stocking• Lead times • Purchasing decisions

Task

Task

Conseq

ConseqCause

Cause

Cause

Cause

Scheduling one time

•Labor•Skills

•Parts•Consumables•Outside services

•Tools•Test equip

Yearly Sched.

Quarterly Sched.

Monthly Sched.•Task: tools, materials, safety procedures•Task: tools, materials, safety procedures

Planning (one time)

1 2 3 4 5 6, 7


The RCM decision algorithm favors CBM

OMDEC Optimal Maintenance Decisions Inc. 1 The use of recorded information to improve OEE,...

Documents

Transcript of OMDEC Optimal Maintenance Decisions Inc. 1 The use of recorded information to improve OEE,...