06 - Chapter 3 _ Flow.ppt

Engineering Management

MSE595LM

Lean Manufacturing

Flow - Definition

 The production system Henry Ford introduced at his Highland

Park, Michigan plant in 1913.

 _{The objective of flow production was to drastically reduce}

product throughput time and human effort through a series of innovations.

 Consistently interchangeable parts so that cycle times could be

stable for every job along an extended line

 The line itself

 _{The reconfiguration of part fabrication tasks so that machines}

were lined up in process sequence with parts flowing quickly and smoothly from machine to machine

 _{Production control system insuring that the production rate in}

The World of Batch-and-Queue

 What happens when you go to your doctor?

• Make appointment days ahead

• Arrive on time and wait in waiting room

• Doctor behind schedule

• Referral to a specialist

• Laboratory tests

• Wait for results

• Treatment or medication given

• Trip to pharmacy or to specialist

• Hospitalization – whole new disconnected processes and waiting

 What happens when you take a flight?

 What happens when you build a custom home?

• As the customer, you pay for all the waiting and rework

 _{The creation, ordering, and provision of any good or any}

How to Obtain Flow?

 _{Think about ways to:}

• Line up all of the essential steps needed to get a job done

• Obtain a steady, continuous flow

• No wasted motions

• No interruptions

• No batches

• No queues

 _{Continuous Flow changes everything:}

• How we work together

• The kinds of tools we devise to help with our work

• The organizations we create to facilitate the flow

• The kinds of careers we pursue

• The nature of business firms and their linkage to each other

The Techniques of Flow

 Step 1: Focus on the actual object

• The specific design

• The Specific order

• The product itself

 _{Step 2: Ignore traditional boundaries of}

• Jobs

• Careers

• Functions and

• Firms

• Form lean enterprise removing all obstacles to the continuous flow

 _{Step 3: Rethink specific work practices and tools}

• Eliminate backflows, scrap, and stoppages so that the design,

order, and production of the specific product can proceed continuously

Example: From Batch to Flow in Bicycles

The Design Step

 Marketing department determined a “need”

 _{Product engineers design a product to serve the need}

 _{Prototype department built a prototype to test the design}

 _{Tooling department designed tools to make a high-volume}

version of the approved prototype

 _{Production engineering figured out how to use the tools to}

fabricate the frame and to assemble the component parts into a completed bike

 Purchasing department arranged to buy the necessary

component parts for delivery to the assembly line once the design was finalized

 The design moved from department to department waiting in the

queue

 _{Frequent reworked or secretly reengineered to deal with}

 _{Create truly dedicated product teams with all the skills required}

to conduct the following in one room in short period of time:

• Value specification

• General design

• Detailed engineering

• Purchasing

• Tooling

• Production planning

 _{Quality Function Deployment (QFD): decision-making}

methodology utilizing “standardized work” to ensure process repeatability

 _{Throughput time accurately measured}

 _{Design methodology continuously improved}

 _{Sales department obtain orders from retailers}

 _{Scheduling department in Operations or Manufacturing work the}

production schedules for the various products

 _{Customers call the Sales department to status late orders}

 _{Sales calls Scheduling}

 _{When customers threaten to cancel orders, Sales and}

Scheduling expedite the orders

 _{Sales and Scheduling had been combined in the early 1990’s}

 _{Computerized systems make instantaneous order changes and}

sometimes electronically transmitted to the customers

 _{Sales and Production Scheduling are core members of the}

product team

 _{In a position to plan the sales campaign as the product design}

is being developed

 _{Sale with a clear eye to the capabilities of the production}

system so that both orders and the product can flow smoothly from sale to delivery

 _{No stoppages in the production system}

 _{Products are built to order}

 _{Only few hours elapse between the first operation on raw}

materials and shipment of the finished item

 _{Orders can be sought and accepted with clear and precise}

knowledge of the system’s capabilities

 _{There is no expediting!}

 Precisely synchronizes the rate of production to the rate of

sales to customers

 _{Takt Time Calculation Example:}

• Customers are placing orders at the rate of 48/day

• Bike factory works a single eight-hour shift

 _{Takt time adjusted as orders increase or decrease over time}

 _{The production slots created by the Takt Time are clearly}

posted on whiteboard or electronic displays (andon boards)

 Lean technique – transparency or visual control – everyone

can see where production stands at every moment

Takt Time

N u m b e r o f B i k e s O r d e r e d

N u m b e r o f H o u r s A v a i l a b l e

B i k e s

H o u r s

B i k e s

H o u r

B i k e

M i n u t e s



4 8





8

6

1

 _{Historic practice was to differentiate production activities by type and}

to create departments for each type of activity.

 _{Frame and handle bars:}

• Tube cutting

• Tube bending

• Mitering

• Welding

• Washing

• Painting

 _{Final Assembly of complete bike}

 _{Over time, higher speed machines with higher levels of automation}

were developed for cutting, bending, welding, and painting

 _{Assembly lines to assemble a mix of high-volume models}

 _{Large batches made before changing over to run the next part}  _{Large inventory}

Bicycle Plant Layout and Flow

S T A R T _{S T O C K}T U B E _{C U T T I N G}T U B E D E B U R R _{M I T E R I N G}T U B E S T O R A G E

T U B E B E N D I N G

F R A M E W E L D I N G

1

1 F R A M E

P A R T S S T O R A G E

F R A M E W A S H I N G

2

2 _{P A I N T I N G}F R A M E _{F R A M E A S S E M B L Y}F I N A L

S T O R A G E

F I N I S H E D S T O R E S / S H I P P I N G

E N D C O M P

Engineering Management

Continuous Flow Production

Remember!

•

Make It Flow

•

Feed the Flow

Continuous Flow Production

Definition

•

Flow of products in a level manner through the

production operations. The ideal situation is one

piece flow at and between processes.

•

The intent of flow production is to increase

the velocity of products and make the

Steady Velocity

Traditional: Batch Production (like a meandering stream with many stagnant pools, waterfalls, and eddies)

FLOW:Production:

The right Job and it must keep moving

Layout change

Before

Hobbing

CNC Lathe Dbur. Boring Chamfer _ShaverGear

Hole Boring Manual Deburring Tooth Chamfer Gear Shaving

After

Mill Drill Boring Dbur.

H o b Cham fer Gear Shaver CNC Lathe

Honing _{CNC Mill}

Mill Drill Boring Hob Chamfer Gear Shaver Dbur. Blank Machining Blank Machining Bore Honing Drive Slot

Summary of Benefits

 _{Work flow levels are reduced and progress is visible at a}

glance

 The ability to cross train is enhanced

 _{Work team members take ownership of full process and can}

help each other

 _{Quick problem identification and feedback}  Reduced Cycle Time

 Improved quality through cycle of learning

 Information flow and decision making enhanced  Value-added ratio improved

 Reduces transportation waste  _{Reduces material handling}

 _{Helps to identify root causes of quality problems}  _{Allows for equipment dedication}

Rules for Kanban Systems

1)

Pull from the downstream process (or customer)

drives the system.

2)

All product or inventory is under kanban control.

3)

Only an “empty” kanban authorizes production.

4)

Never pass a known defect downstream.

Purpose of a Kanban System

1)

Authorize production

2)

Authorize movement.

3)

Limits amount of inventory in the system.

Kanban

Is a “signal” that:

The signal can be a:

•

Card

•

Square

•

Box

•

Pigeon hole

•

Light

•

Etc.

•

Electronic Signal

•

Racks

•

Shopping Carts

•

MRK

•

Authorizes production

•

Authorizes movement

•

Limits inventory

•

Drives continuous

How Many Kanbans?

(Lead Time + Safety Time) =

Total Time

Total Time x Production Requirement =

Units in Pipeline

Units in Pipeline

Example

Leadtime

75

Safety Time

14

Total Time

89

Number of months

3

Production monthly requirements

50

Units in the Pipeline

148

Cost of unit

20000

Unit per kanban (container)

25

Number of Kanbans

5.933333

Pull Production System

Definition

•

A customer driven system that produces

and moves a product/service only when the

customer needs it

.

Kanban Example

Who is full?

Kanban

Homework Assignment

 _Questions:

1. Explain what is meant by Continuous Flow Production

2. What is Takt Time? What is Takt Rate? Why is it important to know them?

 _{Read Lean Thinking Chapter 4 - Pull}