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MAINTENANCE

MANAGEMENT

Prof. DR. Ir. Sukaria Sinulingga, M.Eng

SCHOOL OF POST GRADUATE

UNIVERSITY OF SUMATERA UTARA

MEDAN

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References:

1.Hartmann, E., Successfully Installing Total Productive Maintenance in New Japanese Plant, TPM Press, Pittsburg, 1992.

2.Kister, T.C., and Hawkins, B.,Maintenance Planning and Scheduling Hand Book: Streamline Your Organization For A Lean Environ- ment, 2006

3.Moubray, J., Reliability-centered Maintenance, Industrial Press, 1992

4.Nakajima, S., Introduction to Total Productive Maintenance, Produc-

tion Press, 1988.

5.Nakajima, S., Continuous Improvement in Operation, Elsevier, Pro- duction Press, 2006

6.Pages, E., Spurring Wider Use of On-line Condition Maintenance for Productive Maintenance, Industrial engineering, 1994.

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Topics for Discussion

1. Introduction (maintenance environment and problems)

2. Preventive maintenance

3. Total productive maintenance

4. Predictive maintenance

5. Equipment effectiveness

. Equipment losses

. Maintainability

. Reliability

. Availability

. Quality rate

. Overall equipment effectiveness

6. Maintenance Planning and Scheduling

7. Case studies

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1. INTRODUCTION

1.1 The Purpose of Manufacturing

The purpose of manufacturing (business) is to make and to sell pro- ducts in order to satisfy the customers. Customer satisfaction is determined by the following condition :

. Timeliness of deliveries

. Acceptable product quality

. Reasonable prices of the product

If customers satisfy, then their demands would increase. Should manufacturing company is capable of carrying out production activi- ties efficiently then profits for the business will follow.

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1.2 Equipment Maintenance

• Throughout most of the last four decades, manufacturing was seen by many US managers as a low-status, low-glamour function, somehow below it was maintenance. Maintenance departments in most US companies were understaffed and underfunded. Maintenance was viewed as an overhead cash pit, and certainly never as a way to increase profits or competitiveness. Its role was largely one thing Breakdown Repair.

• BREAKDOWN REPAIR also referred to as repair maintenance is the worst kind of maintenance as it focuses on problems after they have occurred, not on diagnosing the problems to keep them from happening again. Equipment breakdown and malfunction directly contribute to wastes such as product defects, machine waiting, excessive WIP.

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Machine stops

Find, wait for repair person

Diagnose problems

Find spare parts

Repair problem

Test Machine

Machine back in service

Total repair-related downtime

Repair time

The comparison of repair time to total repair-related down time

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1.3 Equipment Problems

Equipment problems have a direct effect on production cost, quality,

and schedules. With each breakdown, one or more operations are

idled, and scheduled completion times are delayed.

Machine

Problems

Possible immediate effects

Ultimate Costs /

Consequences

Malfunction Machine deterioration Shortened machine life

Machine inefficiency High repair cost

Output variability Scrap and reworks

Breakdown Safety hazards Injures

Idled workers Excessive inventories

Idled facilities Scheduled delays

High production costs

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If a machine breaks down, one way to enable the rest of the process to continue is to carry inventories of whatever that machine produces.

Subsequent operations can continue working for as long as the inventory lasts. It is evident that by reducing equipment problems, a company can reduce the inventory, schedule disruptions, defects and the costs associated with these problems. At the same time, it can improve safety and reduce injuries from equipment malfunction.

1.4 Causes of Equipment Problems

Kiyoshi Suzaki (1987) identify 5 causes that act individually or in some combination to cause equipment problems:

1.4.1 Deterioration Moving parts like gears, bearings and belts wear down / breaks and

electrical components burn out. Most kinds of operational equipment eventually deteriorate, but neglect or abuse hastens their deterioration.

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1.4.2 Equipment ill-suited for the purpose.

The equipment is utilized for the purposes other than those of for what it was designed. The material, size, operation of the equipment cannot

handle the expected load, which cause accelerated deterioration, breakage and product defect.

1.4.3 Failure to maintain equipment requirements.

The equipment is dirty, lubricant is not replenished, dust and grime foul the mechanism, and so on.

1.4.4 Failure to maintain correct operating conditions

The equipment is operated at speeds, temperature, pressure etc, in excess of recommended design levels

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1.4.5 Lack of skills of operators, maintenance crew, and setup people

Operators don’t know standard equipment operating procedures and cannot detect or don’t care about emerging equipment problems; maintenance people replace parts but don’t question why breakdowns occur; setup people use the wrong tools, fixture, or adjustment setting; operators, maintenance staffs; setup people, and engineers seldom talk to each other about equipment problems, causes, and solutions.

1.5 The Main Objective of Maintenance

All equipment have design limitations. Often, purchased equipment come with operating manuals that list recommended, normal, and maximum operating conditions. Companies often operate equipment at the maximum condition. Normal operating requirements should be posted at every piece of equipment and operators should run equipment and monitor conditions to ensure that the requirements are not exceeded.

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The main objectives of maintenance may be described as follows:

. To lengthen the usage life of equipment or physical facilities in order

to avoid the investment being increase.

. To ensure that any piece of equipment will always be optimally avai-

lable in order to achieve a reasonable return on investment for the

the business

. To ensure that all equipment and tools be ready to use during emer-

gency.

. To eliminate or minimize equipment - related potential accidents to

the workers

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1.6 Organization of Maintenance Department

1.6.1 Centralized vs Decentralized Maintenance Unit

In traditional plants, a single pool of maintenance people services the entire factory. As a result, maintenance workers never master skills for particular equipment because they are too busy maintaining all equipment as well as lacking of cordial working relationships with operators or managers in particular areas.

They never come to understand the needs of production people and in reverse production people never come to understand the necessity of maintenance other than breakdown repair.

A good arrangement for breaking down interdepartmental barriers is to decentralize the maintenance function, that is to assign maintenance workers to particular areas, process or department in a factory.

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1.6.2 Organizations chart

Facility Department

Facility Planning

Facility Engineering & Drafting

Maintenance Operations

Acquisition & Replacement

Plan and Office Layout

Maintenance Analysis

Custodial Services

Preventive Maintenance

Repair Maintenance

Minor Construction

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1.7 Terminology

. Equipment effectiveness : The multitude of ways equipment influences productivity, costs, and quality. This term is used in reference to individual piece of equipment or to all equipment in a plant

. Equipment loss : Refers to equipment-related resource waste inventory, waiting, defects etc. Nakajima has categorized equipment waste into what he terms the big six losses:

1). Down time from equipment setup and adjustment

2). Downtime from sporadic / chronic equipment breakdown

(These two losses affect the availability of a piece of equipment to perform work). 3). Idling and minor stoppage due to a certain unpredicted obstacles

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4) Reduced speed of operation due to some components are

worn-out

5) Defects caused by variability in equipment performance.

Equipment that is worn-out or near breakdown causes de-

fects and increases process variability. It reduces quality

from nonconforming output that must be reworked or to be

scrapped.

6) Reduced yield caused by nonoptimal operation. Every

time a machine is stopped because of setups, breakdown

or minor interruptions and then restarted, it takes a while

for the machine to reach its normal operating conditions

(speed, temperature, etc). Until then, it produces more

slowly or causes a greater proportion of defective output.

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. Maintainability :The effort and cost of performing maintenance. It is affected by for example, the ease of access to equipment for maintenance, the skill level re- quired to do maintenance, and the availability and convenience of getting spare parts and service. One measure of maintainability is mean time to repair (MTTR). High MTTR is an indication of low maintainability. MTTR is the average time a machine is down:

∑ (Downtime for Repair)

MTTR = --------------------------- Number of Repairs Down time for repair includes time waiting for repairs, time spent doing repairs, and time spent testing and getting equipment ready to resume operation.

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. Reliability : The probability that equipment will perform pro- perly under normal operating circumstances. One measure for reliability (R) is the probability of successful performance or:

Number of Successes R = ----------------------------- Number of Repetitions

The more reliable equipment is, the less likely it will fail. The likelihood of equipment failure is shown with the failure pattern

Wear-out f ailure

Burn-in failure

Time

Fai

lure

pot

entia

l

A

B

C

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. Availability : The proportion of time equipment is actually available to perform work out of time it should be available

. Efficiency : A measure of how well a machine performs while it is running

Pattern A, failure potential (probability of future failure given that so far failure has not occured) is function of age. The older the item, the more likely it will fail.

Pattern B, failure has the so-called bath tube shape. Items having this pattern go through an early burn-in period in which failure potential (infant mortality) isrelatively high (common for electronic components).

Pattern C, items continue to function well regardless of age. This is represented by the constant, uniform failure.

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1.8 Maintenance Management

Maintenance management is a formalized approach to maintaining the currently available machinery and equipment to help them function according to the maintainability and reliability characteristics. It is a management tools and effective to cut down maintenance costs and increasing human productivity, fixed capital productivity and energy productivity.

Maintenance management results in many benefits, including:

. Machine-availability time for production goes up, resulting in higher

outputs and lower machine costs per hour.

. Labor productivity in production areas goes up

. Breakdown maintenance is reduced

. Reduction of overtime

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Total output

Human Productivity = -------------------------

Total human input

Total output

Capital Productivity = ------------------------

Total capital input

Capital input = net stock of structure + plant and equipment cost +

inventory + working capital + land