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Just-in-Timeand

Lean Systems

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Basic Idea

Minimizing inventory and smoothing the flow ofmaterials so that material arrived just as it wasneeded or just in time.

Doing more with less less inventory, fewer workers,less space.

JIT/ Lean production/ Toyota production system-Used interchangeably

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A)Attacks waste

B) Exposes problems and bottlenecks causedby variability

C)Achieves streamlined production

What Does Just-in-Time Do?

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Waste is anything other than the minimum amount

of equipment, materials, parts, space, and workers

time, which are absolutely essential to add value tothe product.

-Shoichiro Toyoda

President, Toyota

1995 Corel Corp.

Eliminating Waste

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Overproduction

Waiting- Idle time, storage (add no value)

Transportation-moving material b/w plants,work centers, handling more than once

Overprocessing- work on products that add novalue

Inventory- unnecessary raw material, work in

process, finished goods

Unnecessary motion- of equipments or people

Product defects- returns, warranty claim,

rework, scrap

Types of Waste

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B) Remove Variability

-Deviation from the optimum process.

-Less variability in a system, Less waste in system

- Caused by tolerating waste or by poor management

- Variability in customer demands, due to poorproduction process that allows employees to produce

improper quantities

Note: JIT and inventory reduction- effective tools foridentifying causes of variability

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Inventory Hides Problems Just as Water in a Lake

Hides Rocks

Scrap

Setup

time

Late

deliveries

Quality

problems

Process

downtim

e

Scrap

Setup

time

Late

deliveries

Quality

problem

s

Process

downtim

e

Inventory

level

Inventory

level

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Streamlined Production

Drive down the cycle time

Use pull system pull a unit to where it is needed just as it is needed

- Signals to request production in small lot sizes

As inventory is removed, problems become evident.

Removing cushion of inventory reduces investment ininventory and cycle time.

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JIT Techniques:

Suppliers: Few vendors, good relation with suppliers,strong supply chain network, quality deliverieson time, directly to work areas

Layout: Work-cells; group technology, flexible machinermultifunctional workers, Organized workplace,reduced space for inventory

Inventory: small lot sizes, low setup time, specializedparts bins

Scheduling: zero deviation from schedules, uniform

production levels, Kanban system

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Quality production: Statistical process control, quality

suppliers, quality within the firm

Employee empowerment and commitment

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Kanban: Japanese word for card.

Each Kanban contains basic information such as partnumber, brief description, type of container, quantity per

container, preceding station, subsequent station.

Sometimes the kanban is color-coded to indicate rawmaterials or other stages of manufacturing.

Associated with fixed quantity inventory system. Acertain quantity Q, is ordered. The reorder point R isdetermined so that demand can be met while an orderfor new material is being processed. Reorder point

Kanban 2-bin system

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corresponds to demand during lead time.

2-bin system: two bins are maintained

1stbin contains: Q-R 2nd bin contains: R

At the bottom of 1stbin is an order card that describesthe item, supplier and quantity Q.

When 1stbin is empty, card is removed and sent tosupplier as a new order.

While order is being filled, quantity in 2nd bin is used.

When the 2nd bin is empty, new order will arrive andboth bins will be filled again.

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Kanban Signals PullMaterial Through the Process