10 Lean Systems

OPM 2, 2013-15, Term 3 Prof Kedar P. JoshiT. A. Pai Management Institute, Manipal

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

Lean Systems

Lean systems affect a firms internal linkages between its core andsupporting processes and its external linkages with its customers andsuppliers.

One of the most popular systems that incorporate the generic elementsof lean systems is the just-in-time (JIT) system.

The Japanese term for this approach is Kaizen. The key to kaizen is theunderstanding that excess capacity or inventory hides processproblems.

The goal is to eliminate the 8 types of waste.

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

Eight Wastes or MUDA

Overproduction

Inappropriate Processing / Process waste

Waiting

Transportation

Motion

Inventory

Defects

Underutilized Employees

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

Eight Wastes

1. Overproduction

Manufacturing an item before it is needed.

Building more than what is demanded.

2. Inappropriate Processing / Process waste

Using expensive high precision equipment when simpler machines would suffice.

Excessive or redundant operations.

3. Waiting

Wasteful time incurred when product is not being moved or processed.

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

Eight Wastes

4. Transportation

Excessive movement and material handling of product between processes.

5. Motion

Unnecessary effort related to the ergonomics of bending, stretching, reaching, lifting, and walking.

Unnecessary or excessive human activity.

6. Inventory

Excess inventory hides problems on the shop floor, consumes space, increases lead times, and inhibits communication.

Building more to protect against system problems

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

Eight Wastes

7. Defects

Quality defects result in rework and scrap, and add wasteful costs to the system in the form of lost capacity, rescheduling effort, increased inspection, and loss of customer good will.

8. Underutilization of Employees

Failure of the firm to learn from and capitalize on its employees knowledge and creativity impedes long term efforts to eliminate waste.

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

Eight Wastes or MUDA : Examples

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

Continuous Improvement

Continuous Improvement with Lean Systems

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

Supply Chain Considerations

Close supplier ties

Look for ways to improve efficiency and reduce inventories throughout the supply chain

Supplier proximities Rationalizing number of suppliers Close supplier relationships

JIT II

In-plant representative Benefits to both buyers and

suppliers

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems


Reduce the average level of inventory Pass through system faster (MLT) Create uniform workload and prevent overproduction Increase setup frequency

Small lot sizes

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems


Initial Setup Time

Separate setup into preparation, and actual setup, doing as much as possible while the

machine/process is running (save 30 minutes)

Move material closer and improve material handling (save 20 minutes)

Standardize and improve tooling

(save 15 minutes)

90 min

60 min

45 min

25 min

15 min

Eliminate adjustments

(save 10 minutes)

Training operators and standardizing work procedures (save 2 minutes)

Step 1

Step 2

Step 3

Step 513 min

Step 4

2. Small lot sizes

Set up time reduction

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

Process Considerations

1. Pull method of work flow

Push method

Pull method

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems


1. Pull/Push method of work flow

CENTRAL OPS. PLANNING AND CONTROL SYSTEM

Work

centreDEMANDWork

centre

Work

centre

Work

centre

Instruction on what to make and where to

send it

FORECAST

OR

PULL CONTROL

Work

centre

Work

centre

Work

centre

Work

centre DEMAND

Request Request Request Request

Delivery Delivery Delivery Delivery

PUSH CONTROL

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems


1. Pull method of work flow

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems


2. Quality at the source

Jidoka

Poka-yoke

Andon

Statistical process control Worker involvement Inspect own workQuality circles

Immediate feedback

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems


2. Quality at the source

Jidoka

Andon

1 2 3

8

4

9

5

10 11

6 7

12 13 14STOP BUTTON(STOP THE L INEAUTHOR ITY)

STOP BUTTON(STOP THE L INEAUTHOR ITY)

Abnormality

Station 5

Team Leader

45

Jidoka means "autonomation" or "automation with a

human touch."

Detect a problem and stop production automatically

rather than continue to run and produce bad output.

The principle's origin goes back to 1902 when Sakichi

Toyoda invented a simple but ingenious mechanism

that detected a broken thread and shut off an

automatic loom.

That invention allowed one operator to oversee the

operation of up to a dozen looms while maintaining

perfect quality.

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

Poka- Yoke

Error-proofing, also known as Poka-Yoke, is a technique of preventing errors by designing the process, equipment, and tools so that an operation cannot be performed incorrectly.

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

An Equipment on ANDON

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems


3. Uniform workstation loads

Takt time

Heijunka

Mixed-model assembly

Lot size of one

Monday Tuesday Wednesday Thursday Friday

AAAAA BBBBB BBBBB DDDDD EEEEE

AAAAA BBBBB BBBBB CCCCC EEEEE

Monday Tuesday Wednesday Thursday Friday

AABBBB AABBBB AABBBB AABBBB AABBBB

CDEE CDEE CDEE CDEE CDEE

5 units

5 units

10 units

Weekly Production Required

Traditional Production Plan

JIT Plan with Level Scheduling

A

B

C

D

E

10 units

20 units

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems


4. Standardized components and work methods

StandardizedWork

Detail of each Process Step

Detail of the Elementsof each Process Step

Work Element Sheet

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems


5. Flexible workforce/ Resources

Capable to do many different things with minimal setup time

Workers assume considerable responsibility

Cross-trained to perform several different duties

Trained to also be problem solvers

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems


6. Automation

7. Total Preventive Maintenance (TPM) Scheduled & daily PM

Operator performs PM

Knows machines

Responsible for product quality

8. Five S (5S) practices

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

1. Five S MethodTABLE 8.2 | 5S DEFINED

5S Term 5S Defined

1. Sort Separate needed from unneeded items (including tools, parts, materials, and paperwork), and discard the unneeded.

2. Straighten Neatly arrange what is left, with a place for everything and everything in its place. Organize the work area so that it is easy to find what is needed.

3. Shine Clean and wash the work area and make it shine.

4. Standardize Establish schedules and methods of performing the cleaning and sorting. Formalize the cleanliness that results from regularly doing the first three S practices so that perpetual cleanliness and a state of readiness are maintained.

5. Sustain Create discipline to perform the first four S practices, whereby everyone understands, obeys, and practices the rules when in the plant. Implement mechanisms to sustain the gains by involving people and recognizing them via a performance measurement system.

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

Designing Lean System Layouts

1. Line flows recommended

Eliminate waste

Workstations in close physical proximity to reduce transport & movement

2. One worker, multiple machines (OWMM)

3. Group technology

Group parts or products with similar characteristics into families

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

One Worker Multiple Machines (OWMM)

One-Worker, Multiple-Machines (OWMM) Cell

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

Drilling

D D

D D

Grinding

G G

G G

G G

Milling

M M

M M

M M

Assembly

A A

A A

Lathing

Receiving and

shipping

L

L L

L L

L L

L

(a) Jumbled flows in a job shop without GT cells

Process Flows Before and After the Use of GT Cells

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

(b) Line flows in a job shop with three GT cells

Cell 3

L M G G

Cell 1 Cell 2

Assembly

area

A A

L M DL

L MShipping

D

Receiving

G

Process Flows Before and After the Use of GT Cells

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

Receiving postKanban card for

product 1Kanban card for

product 2

Fabrication cell

O1

O2

O3

O2

Storage

area

Empty containers

Full containers

Assembly line 1

Assembly line 2

Single-Card Kanban System

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

Storage

area

Empty containers

Full containers

Receiving post

Kanban card for product 1

Kanban card for product 2

Fabrication

cellO1

O2

O3

O2

Assembly line 1

Assembly line 2


OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

Storage

area

Empty containers

Full containers

Receiving postKanban card for

product 1

Kanban card for

product 2

Fabrication

cellO1

O2

O3

O2

Assembly line 1

Assembly line 2


OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

KA

NB

AN

Part N

um

ber:

12

34

56

7Z

Lo

ca

tion

:A

isle

5

Bin

47

Lo

t Qu

an

tity:

6

Su

pp

lier:

WS

83

Cu

sto

mer:

WS

116

1. Each container must have a card

2. Assembly always withdraws from fabrication (pull system)

3. Containers cannot be moved without a kanban

4. Containers should contain the same number of parts

5. Only good parts are passed along

6. Production should not exceed authorization

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

Number of Containers

Two determinations

Number of units to be held by each container

Determines lot size

Number of containers

Estimate the average lead time needed to produce a container of parts

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems


WIP = (average demand rate) (average time a container spends in the manufacturing process)+ safety stock

WIP = kc

kc = d (w + p )(1 + )

k =d (w + p )(1 + )

c

where k = number of containersd = expected daily demand for the partw = average waiting timep = average processing timec = number of units in each container = policy variable

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems


Formula for the number of containers

k =Average demand during lead time + Safety stock

Number of units per container

WIP = (average demand rate)(average time a container spends in the manufacturing process) + safety stock

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

Determining the Appropriate Number of Containers

EXAMPLE 8.1

The Westerville Auto Parts Company produces rocker-arm assemblies

A container of parts spends 0.02 day in processing and 0.08 day in materials handling and waiting

Daily demand for the part is 2,000 units

Safety stock equivalent of 10 percent of inventory

a. If each container contains 22 parts, how many containers should be authorized?

b.Suppose that a proposal to revise the plant layout would cut materials handling and

waiting time per container to 0.06 day. How many containers would be needed?

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

Determining the Appropriate Number of Containers

SOLUTION

a. If d = 2,000 units/day, p = 0.02 day,

= 0.10, w = 0.08 day, and

c = 22 units

k =2,000(0.08 + 0.02)(1.10)

22

= = 10 containers220

22

b. Figure 8.5 from OM Explorer shows that the number of containers drops to 8.

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

Application 8.1

Item B52R has an average daily demand of 1000 units. The averagewaiting time per container of parts (which holds 100 units) is 0.5 day.The processing time per container is 0.1 day. If the policy variable isset at 10 percent, how many containers are required?

k =d (w + p )(1 + )

c

= 6.6, or 7 containers

=1,000(0.05 + 0.01)(1 + 0.1)

100

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

Other Kanban Signals

Cards are not the only way to signal need

Container system

Containerless system

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

Other Kanban Signals

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

Benefits of JIT Manufacturing

Shorter lead times

Lower defect rates

Less raw materials inventory

Less WIP inventory

Less finished goods inventory

Enhancements in system flexibility

Reduction in floor space requirements

Improvement in communication

Improvement in employee morale

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

JIT can be effective If

Production system has a flow structure

Set up times are low

Demand is stable

High volume, Repetitive Manufacturing

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

Value Stream Mapping (VSM)

Value stream mapping is aqualitative lean tool for eliminatingwaste

Creates a visual map of everyprocess involved in the flow ofmaterials and information in aproducts value chain

Work plan and

implementation

Future state

drawing

Current state

drawing

Product

family

Value Stream Mapping Steps

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

Value Stream Mapping

Selected Set of Value Stream Mapping Icons

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

Value StreamMapping

A Representative Current State Map for a Family of Retainers at a Bearings Manufacturing Company

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

House of Toyota

A key challenge is to bring underlying philosophy of lean to employees in an easy-to-understand fashion

The house conveys stability

The roof represents the primary goals of high quality, low cost, waste elimination, and short lead-times

The twin pillars, which supports the roof, represents JIT and Jidoka

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

House of Toyota

Highest quality, lowest cost, shortest lead time by eliminating wasted

time and activity

Just in Time (JIT)

Takt time

One-piece flow

Pull system

Culture of Continuous

Improvement

Jidoka

Manual or automatic line stop

Separate operator and machine activities

Error-proofing

Visual control

Operational Stability

Heijunka Standard Work TPM Supply Chain

OP

M 2

, 20

13

-15

, Term 3

Lea

n sy

stems

Need of change in fundamental beliefs about managing operationsCapability Capacity & Utilisation

Planning

Forecasting

Material Supply

Culture

MaterialManMachine

Man MachineMaterial

Monthly / MRP Run

Weekly Daily Hourly

Level Pull

Accuracy

Monthly Weekly Daily HourlyFlowPull

Closed Working in SilosPolicingInformation hoarding

Open Interconnected TeamsDisciplined ThoughtOpen Information sharing

Level ProductionKanban

LeadershipCommander

Crisis Management

CatalystCapability Building

CoachFacilitation

Capability Capacity & Utilisation

Planning

Forecasting

Material Supply

Culture

MaterialManMachine

Man MachineMaterial

Monthly / MRP Run

Weekly Daily Hourly

Level Pull

Accuracy

Monthly Weekly Daily HourlyFlowPull

Closed Working in SilosPolicingInformation hoarding

Open Interconnected TeamsDisciplined ThoughtOpen Information sharing

Level ProductionKanban

LeadershipCommander

Crisis Management

CatalystCapability Building

CoachFacilitation

10 Lean Systems

Documents

Transcript of 10 Lean Systems