Dependable production OEE, TPM, and RCM

Antti Salonen antti.salonen@mdh.se

2 © Antti Salonen

Planned production time

Start-up problem

Set-up Break-downs

Planned stopps

Cleaning

Period with small-stops Period with reduced speed

Production

Productive time Unproductive time

How a production shift may look!

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Purpose: ●  Show the disturbances that reduces the productivity of the equipment ●  Show how effective the equipment is used by measuring loss factors ●  Show that improving actions are adequate. ●  Aid in planning of resources and workload

Overall Equipment Effectiveness

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The six big losses

● Failures and break-downs ● Set-up and adjustments

●  Idling and minor stoppages

● Reduced speed

● Defects and rework

● Start-up losses

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Quality rate Performance rate Availability

X X

The OEE-value indicates the total effectiveness in production

What is OEE?

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Value adding

operative time

Overall Equipment Effectiveness (OEE) = Availability x Performance rate x Quality rate

Availability = Planned prod. time – Unplanned stop time

Planned prod. time

Performance rate =

Bought CT x items produced

Available operative time

Quality rate =

Items produced - Defects Items produced

Scheduled working time

Planned production time

Available operative time

Net operative

time

Planning related stopps

Def

ects

Unp

lann

ed

stop

ps

Spee

d lo

ss Idling and minor stoppage

Reduced speed

Defects and rework

Start-up losses

Set-up and adjustments

Failures and breakdowns

OEE calculations Planning factor =

Scheduled time – Planning related stop time

Scheduled time

= (Planning factor) x

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Quality rate = Items produced – defect items 412 pieces - 16 pieces

Items produced 412 st = 0,96 =

Availability = Planned production time – unplanned stop time 400 min - 90 min Planned production time 400 min

= 0,775 =

Performance rate = Bought cycle time x items produced 0,6 min/piece x 412 pieces

Available operative time 310 min = 0,797 =

PfOEE = 0,83 x 0,775 x 0,797 x 0,96 x 100 (%) = 49,2%

OEE calculations

Scheduled working time – planning related stop time Scheduled working time

Planning factor = 480 min - 80 min

480 min = 0,83 =

OEE = 0,775 x 0,797 x 0,96 x 100 (%) = 59,3%

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Three levels of measurement

How to measure ? Depending on purpose and aim with the measuring, the following three levels may be used: Level 1 Total utilization = Pftot x A x P x Q

This level indicates how a plant is utilized compared to maximum available time (24hrs/day, 365 days/year) Level 2 Asset effectiveness = Pf x A x P x Q

This level indicates how effective an asset is used regarding planned working hours Level 3 Equipment effectiveness = A x P x Q

This level indicates how effective a specific equipment is used.

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Calculation of Pftot Theoretical available time (24h/day, 365 days/year) – planning related stop time

Theoretical available time (24h/day, 365 days/year) Planning related stop time is time loss that doesn’t affect the equipment effectiveness. For example hollidays, breaks, meeting time, education, cleaning, waiting time due to surrounding equipment, PM, planned modifications, lack of orders, personell or material. Note. The use of 24h/day, 365 days/year for definition of Theoretical available time is common within process industries where heavy investments occur.

OEE: Total planning factor

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Calculation of Pf Theoretical production time (scheduled) – planning related stop time Theoretical production time (scheduled) Theoretical production time is the scheduled production time when the facility is manned. E.g. 3-shift (ca 110 hours/week), daytime (40 hours/week) Planning related stop time is time loss that doesn’t affect the equipment effectiveness. For example hollidays, breaks, meeting time, education, cleaning, waiting time due to surrounding equipment, PM, planned modifications, lack of orders, personell or material.

OEE: Planning factor

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Quality rate = Items produced – defect items Items produced

Availability = Planned production time – unplanned stop time

Planned production time

Performance rate = Bought cycle time x items produced

Available operative time

PfOEE = Pf x A x P x Q x 100 = %

OEE calculations

Scheduled workingtime – planning related stop time Scheduled working time

Planning factor =

OEE = A x P x Q x 100 = %

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OEE calculation

Calculate the OEE and PfOEE for a production unit under the following conditions: Work hours: 2-shifts, monday– friday Shif hours: Morning shift 06:00 – 14:12

Afternoon shift 13:48 – 22:00, on fridays, the shift ends at 20:00 Breaks: 30 minutes lunch every shift, with no production Meetings: Department meeting every Thursday at 12:48 – 13:48 with no production Preventive maintenance: Every day at 13:48 – 14:00 Production rate: The bought cycle time is 6 minutes per piece. Events during the studied week: Break downs: monday, 08:30 – 10:00

wednesday, 07:00 – 10:12 thursday, 15:30 – 17:24

Produced pieces: 523 of which 3 scrapped beccause of defects.

Availability = Planned prod. time – Unplanned stop time

Planned prod. time

Performance rate =

Bought CT x items produced

Available operative time

Quality rate =

Items produced - Defects Items produced

Planning factor = Scheduled time – Planning related stop time

Scheduled time

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OEE: Calculation Scheduled working time 4x16h + 14h = 78h

Planning related stops 2x5x0,5h + 1h + 5x0,2h = 7h

Planning factor (Pf) (78-7h) / 78 = 0,910 Pf = 91,0%

Planned production time 78h-7h = 71h

Unplanned stop time 1,5h + 3,2h + 1,9h = 6,6h

Availability (A) (71 – 6,6) / 71 = 0,907 A = 90,7%

Available operative time 71h – 6,6h = 64,4h

Bought cycle time 6 min / 60 = 0,1h

Produced items 523 st

Performance rate (P) (0,1x523) / 64,4 = 0,812 P = 81,2%

Scrap 3 st.

Quality rate (Q) (523 – 3) / 523 0,994 Q = 99,4%

PfOEE 0,910x0,907x0,812x0,994 0,666 PfOEE = 66,6%

OEE 0,907x0,812x0,994 0,732 OEE = 73,2%

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The following has to be explored: ● Manual loading time included?

● Other limiting factors affecting the cycle time?

● Can several products be produced during one cycle?

● Do different products have different cycle times?

Defining Cycle time

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Defining bought cycle time

● Cycle time according to equipment specification ● Cycle time according to product specification

● Lowest CT in similar equipment

● Lowest CT tested in the equipment

● Theoretically calculated CT

● Lowest measured CT

● Actual CT recalculated with ambition

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Performance rate, P - when producing products with different CT’s

Product Theoretical CT, CTT (min/piece) Produced amount, P (piece) CTT x P (min) Sum CTT x P (min) Available operative time*, T.O.T (min) P = (Sum CTT x P) /T.O.T (%)

0,6 0,7 0,8 0,9 100 150 50 50 60 105 40 45

250 300 83%

P1 P2 P3 P4

* Planned production time – Unplanned stops

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Increased OEE leads to….

● Less disturbances which in turn may lead to •  Improved planning ability •  Reduced risk of quality problems •  More time for developing work

● Released capacity which in turn may lead to •  Alternative to capacity investments •  Increased flexibility •  Decreased operative time •  Decreased number of equipments

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Time for a break?

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OEE in Swedish industry (2002)

10

20

30

40

50

% OEE Interval

35-45 45-55 55-65 65-75 75-85 85-95 % OEE

Electronics Power Chemical

P & P

Steel Mining

Manufacturing industry

60% Average

80%

88% Improvement potential

Practically achievable

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Average OEE = 60,4%

Utilization

Results from a study of 30 Swedish sub suppliers in automotive industry (Nutek, 2008)

For comparison, a number of similar companies in other countries were studied:

Average OEE in other countries = 77%

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39% of the companies measure and analyze time-loss and cause of failures

86% of the companies perform systematic preventive maintenance

Average OEE = 60,4%

Utilization

More findings from the study of 30 Swedish sub-suppliers in automotive industry (Nutek, 2008)

14% of the companies measure and analyze time-loss and cause of disturbances

25% of the companies perform CBM

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My own observations

Poor utilization of the possibilities of analyzing data from CMMS

Most companies fail to regard dependability aspects when investing

Few companies use systematic RCA (Root Cause Analysis)

Few companies use systematic maintenance concepts

Few companies measure the cost of lost production

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Concepts for increasing the dependability of production equipment

TPM; Total Productive Maintenance

RCM; Reliability Centered Maintenance

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TPM – what’s that?

● Total Productive Maintenance ● Total Process Management

● Total Production Management

● And so on….

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TPM - definition

“TPM can be defined as a systematic work method aiming to develop disturbance free processes at lowest possible cost through the commitment of all co-workers” (LCP-Consultants)

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TPM as a philosophy

●  focuses on daily maintenance in manufacturing industries ●  is built on total employee involvement

● born in the Japanese automobile industry.

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TPM – Total Productive Maintenance

● Total Effectiveness ● Total Preventive Maintenance

● Total Commitment

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Why TPM?

● Replace routine with development ●  Increased commitment from all co-workers

● Continuous improvements

● Foreseeable operations

●  Improved safety and environment

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TPM Structure

Effectiveness

Continuous improvements

Autonomous maintenance

Planned maintenance

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Education

Organisation and pilot

Policy and goals

Develop a master plan

Management’s decision

Evaluation and new goals

Preparation Implementation

Education and training

Kick-off

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Group activities

Cross functional improvement group

Autonomous maintenance group

Target oriented cross functional group

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Improvement tools

FTA

Identify and evaluate potential weaknesses

Identify causes of failures and their logic connections

Identify, prioritize and analyze failures

Reduce all chronic loss to zero

7QC/QM

PM-analysis

FMEA

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Autonomous maintenance

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Autonomous maintenance

●  Teach the operators to react on cause instead of result ●  By increased kompetence and understanding the operators may:

●  Eliminate minor stoppages

●  Prevent break-downs

●  Secure implemented improvements

●  Improve quality, safety, and environment

●  In the long run operators start to perform maintenance tasks

●  Daliy inspections replaces repair and low frequent controls ●  Implemented through seven well-defined steps

●  Takes long time to implement, often years

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1. Basic cleaning and order

2. Counter meassures at the problem source

3. Standards for cleaning and lubrication

4. General inspection training

5. Autonomous inspection

6. Organize the work environment

7. Autonomous maintenance

Equipment focusing step. Secures the basic condition of the equipment

Focuses the operators. They learn advanced inspection and maintenance techniques

Factory focusing step. From maintenance to control.

Description Competence Repair skills

Understands the relation between

maintenance and product quality

Understands the functions and structure

of the machines

Can find defects and understand the principles for improvements of the equipment

The seven-step ladder

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Planned maintenance

Maintenance planning

Maintenance control

Spare part control

Economy control

Implementation of planned maintenance leads to: - Increased MTBF and MTBM - Decreased MTTR, MWT and M - Closer to 0-faults, 0-stops and 0-accidents

Information feedback

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Activities for improved OEE

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Early equipment management

LCC

Early detection of problems

Experience development MP-design

Basic properties

Acquisition process

Project

Goal and requirements

Structure and process thinking

The included activities are aiming for new equipment to be: • Reliable and producing non defective products. • Easy to mend and set up, and fast to start after set-up changes. • Easy to maintain, and fast to localize faults and repair. • Easy to clean, lubricate and inspect. • Resource efficient and safe.

The process has to goals: • To reach stable, full speed production at start-up. • To, as far as possible, meet the detailed requirements for the equipment.

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Quality maintenance

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Results of TPM at Volvo

Productivity Breakdowns reduced with 90%

OEE increased from 50% to 90%

MTBF increased from 30 minutes to 8 hours

Quality Scrap reduced with 90%

Cost of quality control reduced with 67%

Customer complaints reduced with 75%

Costs Production cost reduced with 30%

Delivery precision Capital bound in WIP and finished goods decreased with 50%

Fulfillment actual/desired delivery time increased to 90%

Delivery precision actual/promised time increased to 100%

Safety Accidents resulting in personal injuries reduced to 0

Accidents resulting in pollution reduced to 0

Commitment Ten times as many suggested improvements

Time for education and training increased with 100%

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RCM has been defined as…

Reliability Centered Maintenance: “a process used to determine what must be done to ensure that any physical asset continues to do what its users want it to do in its present operating context.” (Moubray, 1997, p.7)

RCM – what’s that?

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RCM

Reliability Centered Maintenance, RCM Focuses on construction and development of products and manufacturing systems maintainability and to develop an effective and resource parsimoniuos PM before the product or system is up and running, born in the aircraft industry

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RCM

● RCM is sprung from MSG (Maintenance Steering Group) that has been developed since the 1960s’, for the purpose of the aircraft industry.

● RCM have since also been developed to be used in e.g. the power industry, energy industry, and in some cases also the manufacturing industry.

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RCM

● With RCM methodology one handle the maintenance objectives as early as in the development phase on a consciously, rationally, and planned base. ● One analyses potential failure that can occur on the

developed systems, structures, or components. ● Faults can be classified as obvious or hidden, safety

critical or of considerable financial character.

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RCM is basically about answering… ●  …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? This can be performed through e.g. FMEA and FTA

RCM

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Further reading

Sherwin, D., (2000), “A review of overall models for maintenance management”, Journal of Quality in Maintenance Engineering, Vol. 6, pp. 138-164.

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