just in time - an introduction

8/7/2019 JUST IN TIME - AN INTRODUCTION

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JUST IN TIME

MANUFACTURING PHILOSOPHY


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AGENDA

Introduction

Objectives of JIT

Goals for achieving JIT Key elements of JIT

Key elements to achieve JIT

Other elements of successful JIT


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INTRODUCTION

JIT is a philosophy of manufacturing

based on planned elimination of all wastes and

continuous improvement of productivity. Theideal just-in-time production system produces

and delivers exactly the required number of

each component to the downstream operation

in the manufacturing sequence just at the timewhen that component is needed.


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OBJECTIVES OF JIT

The main objective of JIT is to eliminate thefollowing wastes,

Waste of over production

Waste of transportation Waste of stocks

Waste of making defective products

Waste of waiting

Waste of processing

Waste of motion


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GOALS FOR ACHIEVING JIT

Zero defects

Zero inventories

Zero setup time Zero handling

Zero break downs

Zero lead time


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GOALS FOR ACHIEVING JIT

Reduce lot sizes

Preventive maintenance

Flexible work force Require supply quality assurance

Small lot conveyance


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KEY ELEMENTS TO ACHIEVE JIT

GOALS

PULL SYSTEM PRODUCTION CONTROL

In this system, the order to make and

deliver parts at each workstation comes from

the down stream station that uses those parts.

When the supply of parts at a given

workstation is about to be exhausted, that

station orders the upstream station to produce

the parts and fill again the supply


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KANBAN PRODUCTION CONTROL

SYSTEM

A kanban or pull production control system uses simple,

visual signals to control the movement of materials between work

centers as well as the production of new materials to replenish

those sent downstream to the next work center. Originally, the

name kanban (translated as signboard or visible record)referred to a Japanese shop sign that communicated the type of

product sold at the shop through the visual image on the sign (for

example, using circles of various colors to indicate a shop that

sells paint). As implemented in the Toyota Production System, a

kanban is a card that is attached to a storage and transport

container. It identifies the part number and container capacity,along with other information, and is used to provide an easily

understood, visual signal that a specific activity is required.


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SYSTEM

In Toyotas dual-card kanban system,

there are two main types of kanban:

1. Production Kanban: signals the need to

produce more parts

2. Withdrawal Kanban (also called a "move"

or a "conveyance kanban): signals the needto withdraw parts from one work center and

deliver them to the next work center.


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SYSTEM

Dual-card Kanban Rules:

No parts are made unless there is a production kanban to

authorize production. If no production kanban are in the inbox at a work center, the process remains idle, and

workers perform other assigned activities. This rule

enforces the pull nature of the process control.

There is exactly one kanban per container.

Containers for each specific part are standardized, andthey are always filled with the same (ideally, small)

quantity. (Think of an egg carton, always filled with exactly

one dozen eggs.)


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SYSTEM


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SYSTEM


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SYSTEM


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GOALS

HIGH QUALITY

JIT systems eliminate all defects,

which eliminates the scrap and reworkthat help to provide a smooth flow of

materials through the plant. The quality

is built into the process and is controlled

by workers acting as their own qualityinspectors.


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KEY ELEMENTS TO ACIEVE JIT

GOALS

SMALL BATCH SIZE AND REDUCED

SETUP TIME

Batch size and setup time must beminimized to minimize WIP inventories.

Reduced setup time permit smaller

batches and lower WIP levels. Setup

time may be reduced by the followingapproaches.


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KEY ELEMENTS TO ACIEVE JIT

GOALS

Design the setup tooling and plan the

setup method to permit changeover

procedure as much as possible.

Use time and motion study to reduce the

setup procedure to the fewest possible.

Eliminate or minimize adjustments in the

setup


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GOALS

Use quick acting clamping devices

instead of bolts and nuts.

Use group technology and cellularmanufacturing so that similar part styles

are produced on the same equipment.


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OTHER REQUIREMENTS FOR

SUCCESSFUL JIT PRODUCTION

Stable production schedules

On-time delivery

Defect free components and materials Reliable production equipment

A work force that is capable, comitted

and co-operativeA dependable supplier base


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just in time - an introduction

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