Just In Time Production System

(1)

Just In Time Production System

Perencanaan & Pengendalian Produksi

Russell/Taylor Oper Mgt 3/e

What is JIT ?

•

Producing only what is needed, when it is needed

•

A philosophy

•

An integrated management system.

•

JIT’s mandate:

Eliminate all waste.

7 Kind of Waste

1. Over production

2. Waiting

3. Transportation

4. Unnecessary process

5. Inventory

6. Unnecessary movement

7. Rejection

Basic Elements of JIT

1. Flexible resources

2. Cellular layouts

3. Pull production system

4. Kanban production control

5. Small-lot production

6. Quick setups

7. Uniform production

8. Quality at the source

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5

Introduction Procedure

Awareness Revolution

5 S

Flow manufacturing

Kanban Multi processhandling

Leveled Production Quality Assurance Changeover Standard operation Maintenance

& Safety Jidoka

JUST IN TIME

M a n p o w e r R e d u c ti o n V is u a l C o n tr o l In tr o d u c ti o n P ro c e d u re 6

The 5S’s Principle

•

Seiri (

整理

)

=Organization (

Proper arrangement

)

•

Seiton(

整頓

)

=Neatness (Orderliness)

•

Seiso(

清掃

)

=Cleanliness

•

Seiketsu(

清潔

) =Standardization

•

Shitsuke(

仕付け

) =Discipline

7

The 5S’s Principle

•

Seiri

–

putting things in order

–

distinguishing between the necessary and the

unnecessary

–

getting rid of the unnecessary

–

stratification management

8

The 5S’s Principle

• Seiton

–having things in the right places/layout (eliminating searches)

–functional management

• Seiso

–cleaning (is a form of inspection)

–eliminating waste

• Seiketsu

–continually and repeatedly maintaining the above 3Ss

(3)

TI3122-Perencanaan dan

Pengendalian Produksi - Minggu 9 9

The 5S’s Principle

•

Shitsuke

–

doing the right thing as a matter of course

–

practicing good habit and discipline

10

Flow Production

• Goods and material should flow in the factory much as water flows in a river

• But the river (the flow of in process inventory) tends to flood

• High water volume conceals the rocks/problems. Low water volume reveals the rocks /problems

• A factory needs to have a smooth flow of inventory and operations

• Japanese management tends to view inventory as the root of all evil and the likely cause of poor performance in any business activity

Inventory Hides Problems

Poor Quality

Unreliable Supplier Machine

Breakdown Inefficient

Layout

Bad Design

Lengthy Setups

Lower Levels Of Inventory To Expose

Problems

Poor Quality

Unreliable Supplier Machine

Breakdown Inefficient

Layout

Bad Design

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13

Multi-process Operations

• Productivity is important indeed but not as important as respecting the humanity of our workers. Productivity and humanity must coexist in the factory. The factory must find a way to satisfy both productivity and humanity

• People must be trained in the multiple skills to handle several processes

• The assignment where one worker handles 5 different machines/processes is better than the assignment where one worker handles 4 similar machines

14

Multi-process Operations

•

Key points:

–

Establish U shape manufacturing cells

–

Abolish processing islands

–

Make the equipment smaller

–

Standing while working

–

Multiple skills training

–

Separate human work from machine work

–

Human automation (jidoka,

自働化）

and pokayoke

–

Safety first

15

Push and Pull Systems

•

Push system

16

Push and Pull Systems

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17

Kanban System

•

Kanban

–

Card, label, signboard or visible representation

–

The information system controlling the number of

parts

–

Synchronizing production lines and assembly lines

•

Types of Kanban:

–

Production Kanban

–

Withdrawal Kanban

The Origin Of Kanban

Q = order quantity R = reorder point

= demand during lead time Bin 1 Bin 2

Q - R

R Reorder

Card

Kanban

a. Two-bin inventory system b. Kanban Inventory System

Dual Kanbans

P

W _{Container with withdrawal kanban}

Container with production kanban

P W

P

X X X

X X

Flow of work

Flow of kanban

Kanban Squares

X X _X

X X

X

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Kanban Racks

407 409 410 412

408

411

Signal Kanban

407

408

409

407 408 409

Kanban Post Office

65 66 67 68 69 70 71

72 73 74 75 76 77 78

79 80 81 82 83 84 85

86 87 88 89 90 91 92

93 94 95 96 97 98 99

100 101 102 103 104 105 106

Types Of Kanbans

•

Kanban Square

– marked area designed to hold items

•

Signal Kanban

– triangular kanban used to signal production at the previous workstation

•

Material Kanban

– used to order material in advance of a process

•

Supplier Kanbans

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25

Kanban Golden Rule

• Do not move nonconforming parts to a downstream process

• Ensure that downstream processes withdraw parts from upstream processes in the correct quantity at the right time

• Do not let upstream processes produce more than the quantity of parts withdrawn by downstream processes

• Ensure that production is leveled

• Do not attempt to transmit large demand variation with the Kanban system

• Balance cycle times for smooth production, and constantly improve cells and workstations

Determining Number Of Kanbans

where

–N = number of kanbans or containers

–d = average demand over some time period

–L = lead time to produce parts

–S = safety stock

–C = container size

No. of kanbans = mand during lead time + safety stock container size

average de

N dL S C

Kanban Calculation Example

Problem statement:

d = 150 bottles per hour L = 30 minutes = 0.5 hours dL = (150)(0.5) = 75 S = 10% dL = 10% x 75 = 7.5 C = 25 bottles

Solution:

Round up to 4 (allow some slack) or down to 3 (force improvement)

N dL S C

x ( . ) .

.

150 0 5 7 5 25 75 7 5

25 3.3 kanbans or containers

28

Level Production

•

Making production of various product model and

volume completely even

•

Production scheduling methods: once a month

production, once a week production, once a day

production, and level production

•

Suppose a factory should process the following

products

• Product X: 1000 units per month

• Product Y: 600 units per month

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29

Once a Month Production

Product

Week 1

Week 2

Week 3

Week 4

X (1000)

Y(600)

Z(400)

30

Once a Week Production

Product

Week 1

Week 2

Week 3

Week 4

X

250

Y

150

Z

100

31

Once a Day Production

Product

Week 1

Week 2

Week 3

Week 4

X

50 units

a day

Y

30 units

a day

Z

20 units

a day

32

Quality Assurance

•

Quality assurance is the starting point in building

products

•

Elements where defects most often occur

：

Operator,

material, machine, method, and information

•

Overall plan for achieving zero defects

• Operator: Basic training and multiple skills training

• Material: Preventive inspection

• Machine: Pokayoke and preventive maintenance

• Method: Flow production and standard operations

• Information: Visual control

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33

Pokayoke (Mistake-proofing)

• The pokayoke system possesses two functions: it can carry out 100% inspections and, if abnormalities occurs, it can carry out immediate feed back and action:

–When there is a working mistake, the material will not fit the tool

–If there is irregularity in the material, the machine will not start

–If there is a working mistake, the machine will not start the machining process

–When there are working mistakes or steps left out, corrections are made automatically and machining continues

–Irregularities in the earlier processes are checked in the later process to stop the defective products

–When a step is forgotten, the next process will not start

34

Setup

• Shortening setup time could minimize lot sizes, therefore reduce the stock of intermediate and finished products

• Through small lot sizes, the manufacturing lead times (MLT) of various kinds of products (mixed scheduling) can be shortened

• Through short MLT, the company can adapt to customer orders and demand changes very promptly

• SMED (single minute exchange of dies) is not only a technique but also a concept. It was developed by Shigeo Shingo

• Single minute means that the setup should be performed within 9 minutes 59 seconds

Reducing Setup Time

•

Preset desired settings

•

Use quick fasteners

•

Use locator pins

•

Prevent misalignments

•

Eliminate tools

•

Make movements easier

36

Standard Operations

• Standard operations is an effective combination of workers, materials and machines for the sake of making high quality products cheaply, quickly, and safely

• Basic elements of standard operations: • Cycle time

• Work sequence

• Standard in process inventory

• The principles of motion economy and 3Ms are very useful tools for establishing improving standard operations

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37

JIDOKA

•

Jidoka (

自動化

)

means automation, i.e., a

mechanism where the machine operates by itself

once the switch is thrown but has no feedback

control for detecting errors and no device for

stopping the process if a malfunction occurs.

•

Jidoka (

自働化

) means autonomation, i.e., a

mechanism to detect abnormalities or defects and

to stop the line or machine when abnormalities or

defects occur

38

Maintenance and Safety

•

Total productive maintenance (TPM) treating the

causes of breakdowns before the breakdowns

actually happen is the key to achieving zero

breakdowns

•

Accidents happen because of deterioration

•

Stages on the path to breakdown: latent minor

defects, apparent

minor

defects, performing

below expectations, stops intermittently, and

completely stop (breaks down)

Maintenance

•

Four basic maintenance activity:

•Maintenance prevention (MP)

•Preventive maintenance (PM)

•Corrective Maintenance (CM)

•Independent maintenance and improvement

•

The maintenance cycle: MP-PM-CM

•

The CCO (cleanliness, checking and oiling) habit

must be an integral part of the routine tasks

40

Shojinka(

少人化

)

•

Shojinka means to alter (decrease or increase) the

number of workers at a shop when the production

demand has changed (decrease or increase)

•

The prerequisite for realizing shojinka:

•Proper design of machinery layout (U-shaped layout)

•Well-trained and multifunctional workers

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41

Visual Control

• What is being managed and where should people look? ----What are the important points

• What constitutes an abnormality --- What are the standards?

• It is discernible? --- What are the tools used for inspection, and is the inspections easy to do (including easy of

evaluation)?

• What should be done? --- What are the emergency procedures and what are long term remedies?

42

Visual Control Tools

• Make them easy to see from a distance

• Put the displays on the things they are for

• Make them so that anyone can tell what is right and what is wrong

• Make them so that anybody can use them easily and conveniently

• Make them so that anybody can follow them and make them the necessary correction easily

• Make them so that using them makes the workplace brighter and more orderly

• Example: kanban/label, display, marks, andon, color

43

Visual Control

Library shelf Work station

Visual kanbans Tool board

Machine controls

Better

Good Best

30-50

How to

sensor

44

Andon

Mesin A Mesin B Mesin C Mesin D

Tiap mesin mempunyai lampu, dan lampu merah akan menyala untuk m e n u n j u k a n m e s i n y a n g membutuhkan perhatian 1.

Lampu merah juga menyala pada Andon di ruang perawatan 2.

Pekerja perawatan akan menuju tempat terjadinya masalah dengan sesegara mungkin 3.

Ruang Perawatan

M

e

s

in

A

M

e

s

in

D

M

e

s

in

C

M

e

s

in

B

(12)

Kaizen

•

Continuous improvement

•

Requires total employment involvement

•

Essence of JIT is willingness of workers to

–

spot quality problems

–

halt production when necessary

–

generate ideas for improvement

–

analyze problems

–

perform different functions

Trends In Supplier Policies

1. Locate near to the customer

2. Use small, side loaded trucks and ship mixed loads

3. Consider establishing small warehouses near to the

customer or consolidating warehouses with other

suppliers

4. Use standardized containers and make deliveries according

to a precise delivery schedule

5. Become a certified supplier and accept payment at regular

intervals rather than upon delivery

Benefits Of JIT

1. Reduced inventory 2. Improved quality 3. Lower costs 4. Reduced space

requirements 5. Shorter lead time 6. Increased productivity

7. Greater flexibility 8. Better relations with

suppliers

9. Simplified scheduling and control activities 10. Increased capacity 11. Better use of human

resources

Just In Time Production System