lean production systems

8/7/2019 Lean Production Systems

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Lean Production

Systems


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Lean Production

An integrated set of activities designedto achieve high-volume productionusing minimal inventories (rawmaterials, work in process, and finished

goods)

Involves the elimination of waste inproduction effort

Involves the timing of productionresources (i.e., parts arrive at the nextworkstation just in time)


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Lean is based on the logic thatnothing will be produced until it isneeded.

E.g. Machineries like Grindingmachines, Lathe CNC machines (costof final product will be high so it is

economically desirable to maintainlow inventories of such products aswell as of the raw material.)


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Pull SystemHere the customer startsthe process, pulling aninventory item from FinalAssembly

Here the customer startsthe process, pulling aninventory item from FinalAssembly

Then sub-assemblywork is pulledforward by that

demand

Then sub-assemblywork is pulledforward by thatdemand

The process continuesthroughout the entireproduction process andsupply chain

The process continuesthroughout the entireproduction process andsupply chain

Customers

Sub

Sub

Fab

Fab

Fab

Fab

Vendor

Vendor

Vendor

Vendor

FinalAssembly


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Features of Lean Production

Management philosophy Pull system though the plant

WHAT IT IS

Employee participation Industrial engineering/basics Continuing improvement Total quality control Small lot sizes

WHAT IT REQUIRES

Attacks waste Exposes problems or difficulties. Achieves streamlined production

WHAT IT DOES

Stable environment

WHAT IT ASSUMES


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The Toyota Production System

Based on two philosophies:

1. Elimination of waste

2. Respect for people


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Seven Types of Waste (Fujio Cho)

1. Waste from Overproduction

2. Waste of Waiting Time

3. Transportation Waste

4. Inventory Waste

5. Processing Waste

6. Waste of Motion7. Waste from Product Defects


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Elements to Address Elimination of

Waste

1. Focused factory networks

2. Group technology

3. Quality at the source

4. JIT production

5. Uniform plant loading

6. Kanban production controlsystem

7. Minimized setup times


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Minimizing Waste:

Focused Factory

Networks

CoordinationSystem Integration

These are small specializedplants that limit the rangeof products produced(sometimes only one type ofproduct for an entirefacility)

These are small specializedplants that limit the rangeof products produced(sometimes only one type of

product for an entirefacility)

Some plants inJapan have asfew as 30 andas many as1000 employees

Some plants inJapan have asfew as 30 andas many as1000 employees


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Minimizing Waste: Group Technology (Part 1)

Saw Saw

Lathe PressPress

Grinder

LatheLathe

Saw

Press

Heat Treat

Grinder

Note how the flow lines are going back and forthNote how the flow lines are going back and forth

Using Departmental Specialization for plant layout

can cause a lot of unnecessary material movement

Using Departmental Specialization for plant layout

can cause a lot of unnecessary material movement


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Minimizing Waste:

Group Technology (Part 2)

Revising by using Group Technology Cells can reducemovement and improve product flow

Revising by using Group Technology Cells can reducemovement and improve product flow

Press

Lathe

Grinder

Grinder

A

2

BSaw

Heat Treat

LatheSaw Lathe

PressLathe

1


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Do it right the first time

When something goes

wrong, stop the processimmediately and address

Workers are trained and

empowered to control theirown process

Minimizing Waste:

Quality at the Source


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Produce what is neededwhen it is needed

Intended for repetitivemanufacturing

Low inventory, ordered only

as needed

Minimizing Waste:

JIT Production


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Minimizing Waste: Inventory

Hides Problems

Work in

process

queues

(banks)

Changeorders

Engineering design

redundancies

Vendor

delinquencies

Scrap

Design

backlogs

Machine

downtime

Decision

backlogsInspection

backlogs

Paperwork

backlog

Inventory

Productivity

Problems


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Work in

process

queues

(banks)

Changeorders

Engineering design

redundancies

Vendor

delinquencies

Scrap

Design

backlogs

Machine

downtime

Decision

backlogsInspection

backlogs

Paperwork

backlog

Inventory

Minimizing Waste: Inventory

Hides ProblemsExample: By identifyingdefective items from a

vendor early in the

production process the

downstream work is

saved

Example: By identifying

defective work by

employees upstream, the

downstream work is

saved


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Minimizing Waste:

Uniform Plant Loading (heijunka)

Not uniform Jan. Units Feb. Units Mar. Units Total

1,200 3,500 4,300 9,000

Uniform Jan. Units Feb. Units Mar. Units Total

3,000 3,000 3,000 9,000

Suppose we operate a production plant that produces a singleproduct. The schedule of production for this product could be

accomplished using either of the two plant loading schedules

below.

Suppose we operate a production plant that produces a singleproduct. The schedule of production for this product could be

accomplished using either of the two plant loading schedules

below.

How does the uniform loading help save labor costs?How does the uniform loading help save labor costs?

or


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What is KANBAN

A system of continuous supply ofcomponents and parts such that workershave what they need, where they need it

and when they need it. KAN CARD

BAN SIGNAL

Therefore KAN + BAN = Signal cards


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Why consider Kanban control?

Lower Inventory investment

Better customer service

Reduce administrative cost


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Manual Kanban

Communication signal from downstream process(customer) to an upstream process (producer)

Visible record (The card is an authorizationThe card is an authorizationfor the next container of material to befor the next container of material to be

produced)produced) Cards indicate standard quantity of production

Maintain discipline of Pull production (AAsequence of kanbans pulls materialsequence of kanbans pulls material

through the process)through the process)


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Kanban

1.1. User removes aUser removes astandard sizedstandard sizedcontainercontainer

2.2. Signal is seen bySignal is seen bythe producingthe producingdepartment asdepartment asauthorization toauthorization toreplenishreplenish

Part numbersPart numbers

mark locationmark location

Signal markerSignal markeron boxeson boxes

Figure 16.8Figure 16.8


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Advantages of Kanban

Allow only limited amount of faulty orAllow only limited amount of faulty ordelayed materialdelayed material

Problems are immediately evidentProblems are immediately evident Puts downward pressure on badPuts downward pressure on bad

aspects of inventoryaspects of inventory

Standardized containers reduceStandardized containers reduceweight, disposal costs, wasted space,weight, disposal costs, wasted space,and laborand labor

lean production systems

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