27695562-9-Just-in-Time

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Departemen Teknik Industri FTI-ITB

TI-3122 Perencanaan dan Pengendalian Produksi

Just In Time

Laboratorium Sistem Produksiwww.lspitb.org

©2003

TI3122-Perencanaan dan Pengendalian Produksi - Minggu 9 2


Hasil Pembelajaran

• UmumMahasiswa mampu menerapkan model matematik, heuristik dan teknik statistik untuk menganalisis danmerancang suatu sistem perencanaan dan pengendalianproduksi

• KhususMemahami konsep dan teknik dalam sistem produksijust in time

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Relative Performance in Auto Industry

Toyota Japan(average)

USA(average)

Europe(average)

Deliveries (percent late)1st-tier suppliers2nd-tier suppliers

0.040.5

0.22.6

0.613.4

1.95.4

Stocks (1st-tier suppliers)HoursStock turns (per year)

Na248

3781

13569

13845

1993-94, from Womack and Jones, Lean Thinking



Relative Performance in Auto Industry

Toyota Japan(average)

USA(average)

Europe(average)

ProductivityAssembly1st-tier suppliers

100100

8385

6571

5462

Quality (delivered defects)Assembly (per 100 cars)1st-tier suppliers (PPM)2nd-tier suppliers (PPM)

305400

55193900

612636100

6113734723

1993-94, from Womack and Jones, Lean Thinking

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Hewlett Packard’s CupertinoCalifornia plant

1982(before JIT)

1986(after JIT)

15 days 11.3 hours

$670,000 $20,000

lead time

work in process

no. of back orders

200 2



The Cost Subtraction Formula

• Cost + Profit = Selling Pricethere is no need for improvementthere is no competing procedureconsumer may have no choice

• Profit = Selling Price – Costthe price is determined by the marketprofit is what remains after subtracting cost from pricemaximizing profit means that cost is to be minimized

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The Cost Subtraction Formula

• Cost = Price – Profit

setting a target costthe price is determined by the market profit required is determined by the company



United States of America JapanMarket Research Market Research

Product Characteristics Product Characteristic

Design Planned selling price – desired profit

Engineering Target Cost

Supplier pricing Design Engineering Supplier pricing

Cost

Manufacturing Manufacturing

Periodic cost reduction Continuous cost reduction

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Is JIT a Culture-based System?

• Schonberger, 1982, Japanese manufacturing techniques: Nine hidden Lessons in simplicity, Free Press, New York

The forth lesson: Culture is no obstacle

• Yoshiki Yamasaki (President of Toyo Kogyo)I would ask you never to be self-satisfied, but always to aim for a higher objective. No matter how hard you try, there is no victory if your competitors work harder. I would ask you to continue striving, not only to best the competition but also to keep on improving yourself



ジャストインタイムJust in time

標準作業

Stand. oper.

平準化level prod

流産業Flow mfg

現場改善の基礎Workplace improvement, 5 S

意義改革Awarenessrevolution

少人化

Manpower reduction

目で

見る

管理

Visual management

保全・安全

自働化

段取り替え

多工程持ち

品質保証

かんばん

Jidoka

Change-over

Multiprocesshandling

Maintenance &safety

Qualityassurance

Kanban

Introductionprocedure

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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




• Seiriputting things in orderdistinguishing between the necessary and the unnecessary getting rid of the unnecessarystratification management

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• Seitonhaving things in the right places/layout (eliminating searches)functional management

• Seisocleaning (is a form of inspection)eliminating waste

• Seiketsucontinually and repeatedly maintaining the above 3Ssvisual management




• Shitsukedoing the right thing as a matter of coursepracticing good habit and discipline

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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

PoorQuality

UnreliableSupplier

MachineBreakdownInefficient

Layout

BadDesign

LengthySetups

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Lower Levels of Inventory to Expose Problems

PoorQuality

UnreliableSupplier

MachineBreakdownInefficient

Layout

BadDesign

LengthySetups



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

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Multi-process Operations

• Key points:Establish U shape manufacturing cellsAbolish processing islandsMake the equipment smallerStanding while workingMultiple skills trainingSeparate human work from machine workHuman automation (jidoka, 自働化）and pokayokeSafety first



Push and Pull Systems

• Push system

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Push and Pull Systems

• Pull system



Kanban System

• KanbanCard, label, signboard or visible representationThe information system controlling the number of partsSynchronizing production lines and assembly lines

• Types of Kanban:Production KanbanWithdrawal Kanban

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Samples Kanban



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MachiningM-2

AssemblyA-4

Part no.: 7412Description: Slip rings

From : To:

Box capacity 25

Box Type A

Issue No. 3/5



Kanban System

• Production Kanban

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Kanban System

• Withdrawal Kanban



Dual Kanban Systems

• Upstream and downstream operations

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Dual Kanbans

P

W Container with withdrawal kanban

Container with production kanban

PWP

XXX X X

Flow of work

Flow of kanban



Kanban Squares

X X X

XXX

Flow of workFlow of information

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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

whereN = number of kanbans or containersd = average demand over some time periodL = lead time to produce partsS = safety stockC = container size

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

average de

N dL SC

=+

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Kanban Calculation Example

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

Solution:

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

N dL SC

x=

+=

+

=+

=

( . ) .

.

150 0 5 7 525

75 7 525

3.3 kanbans or containers



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– Product Z: 400 units per month

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Once a Month Production

Product Week 1 Week 2 Week 3 Week 4X (1000)Y(600)Z(400)



Once a Week Production

Product Week 1 Week 2 Week 3 Week 4X 250 250 250 250Y 150 150 150 150Z 100 100 100 100

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Once a Day Production

Product Week 1 Week 2 Week 3 Week 4X 50 units a dayY 30 units a dayZ 20 units a day



Leveling Production• Working minutes in day: 8 hours x 60 minutes = 480

minutes• Product X: 480 minutes/50 units = 9.8 minutes per unit• Product Y: 480 minutes/30 units = 16 minutes per unit• Product Z: 480 minutes/20 units = 24 minutes per unit

• The number of products to be processed in day: (50+30+20) units

• Tact time (the time it takes to produce one piece of product): 480 minutes/100 units = 4.8 minutes

• X: 5 units; Y: 3 units; Z: 2 units ===== 10 units every 48 minutes

• Schedule: X-Y-X-Z-X-Y-X-Z-X-Y (repeated this sequence 10 times)

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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– Basic strategy for zero defects: The 5S’s

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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 toolIf there is irregularity in the material, the machine will not startIf there is a working mistake, the machine will not start the machining processWhen there are working mistakes or steps left out, corrections are made automatically and machining continuesIrregularities in the earlier processes are checked in the laterprocess to stop the defective productsWhen a step is forgotten, the next process will not start

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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



The Concept of SMED

• In order to shorten the setup time using SMED, there are 4 major concepts, and 6 techniques for applying the concepts

• These concepts are:Separate the internal setup (requires that the machine be stopped) from the external setup (while the machine is operating)Convert as much as possible of the internal setup to the external setupEliminate adjustment processAbolish the setup itself

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The Techniques of SMED

• The techniques are:Standardize the external setup actions: made into routines and standardizeStandardize only the necessary portions of the machine: since it is very expensiveUse a quick fastener: sliding guide blockUse a supplementary tool: revolving table Use parallel operationsUse a mechanical setup system: air or oil pressure



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

• 3M: Muda ( 無駄) or waste, Mura (斑) or inconsistency, and Muri (無理) or irrationality

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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



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)

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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



Reasons for the accident occurrence

• The worker was not adequately trained• The safety saying was put into the book but not

into the mind of the worker• Safety has not been built into the operational

procedure• The equipment lacked an accident-prevention

device

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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– Continuous evaluation and revision of the standard

operations



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?

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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



Visual Control

Library shelfWork station

Visual kanbansTool board

Machine controls

BetterGood Best

30-50

Howto

sensor

27695562-9-Just-in-Time

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