Pull System and Kanban

8/12/2019 Pull System and Kanban

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FACULTY OF ENGINEERING TECHNOLOGY

MANUFACTURING ENGINEERING TECHNOLOGY DEPARTMENT

LEAN MANUFACTURING (BETP 3804)Pull System and Kanban

Tan Hauw Sen Rimo



Tan Hauw Sen RimoPULL SYSTEM & KANBAN – LEAN MANUFACTURING BETP 38042

Producing as many as possible (big Lot Size) in

expectation the customer will place order for theproducts

Materials and parts are pushed into the productionoperation before it starts.

Raw materials and parts are planned, scheduled andacquired prior to the start of production.

It creates excessive and unnecessary inventory (rawmaterials and work-in-process)

Push System




Requires top down production instruction Produce in lot/batch

In process stock build up between processes

Lengthy production lead times

Push System Characteristic

Stamping Welding Assembly

WIP WIP Finished Product

Customer

Production Control

O r d e r

Production Schedule




Economic Production Quantity concept : the quantity ofthe product to be made which have minimum cost byconsidering inventory cost and set up cost

The lot size reflects the economic production quantity

“Lots” or “Lot Size” refers to how many items are beingproduced in any given production run.

Lines are “set up” for the production of a given lot size.

In many production lines, only one item at a time can beworked on at any given work station.

A lot size greater than what can be immediately worked oncreates inventory.

Lot sizes greater than what can be worked on results inexcess inventory sitting around idle.

Production Lot Size




Push System creates over production and high inventory

Over production and inventory is expensive(Carrying/holding costs) Reducing inventory saves money

Over production and inventory hides problems that create

inefficiency and increase costs. Capacity problems, late vendor deliveries, imbalanced lines, equipmentproblems…

Reducing over production and inventory makes problemsvisible so they can be corrected.

Problems in Push System




Eliminate wastes by creating Just in Time Production

Produce and deliver ONLY… What is needed

When is needed

In the quantity needed

How to Tackle the Problems




Takt Time Continuous Flow

Pull System

JIT Components

Lean Principles :1. Value

2. Value Stream

3.Flow

4.Pull5. Perfection




Smaller lot sizes

Sequenced production

1 x 1 build one piece flow ideal lot size = 1

Continuous Flow




Continuous Flow

Stamping

Welding

Assembly Inspection

WIP

WIP WIP Finished ProductPush System

• Each operator buildslarge lots at their ownpace

Lean Thinking

• Reduce inventory

• Reduce lead time

• Reduce rework

• Reduce defect

• Better quality

• Better communication




Lead Time Reduction

ProcessCycle Time (Minutes)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

Stamping

Welding

Assembly

Total Lead Time = 26 minutes for total production or 19 minutes for the 1st product

ProcessCycle Time (Minutes)

1 2 3 4 5 6 7 8 9 10

Stamping

Welding

Assembly

Push System

Lean Thinking

Total Lead Time = 10 minutes for total production

or 3 minutes for the 1st product




1. Connect processeswith same Takt Time

2. Processes laid out inorder of operation

3. 1x1 production withinarea

Continuous Flow Design

Process 1 Process 2 Process 3 Process 4 Process 5

WIP WIP WIPWIP Finished ProductRaw Material

Process 1 Process 2

P r o c e s s 3

P r o c e s s 4 P r o c e s s 5

Linier Production Line

U-Shape Workcell




Reduces lead time

Minimizes in process stock

Visually brings problems to the surface

Eliminates build up of defects

Benefits of Continuous Flow




Produce only exactly what needed, when need it and

in the needed quantity Producing based on customer’s order in small lot size

Parts and materials are requested and delivered asthey are needed.

Materials & parts are pulled into the productionoperation when needed.

Pull System




Downstream process

withdraws exactly whatneeded, when need it, andin the needed quantity

Upstream processproduces exactly whatneeded, when need it, andin the needed quantity

Pull System Characeristic

Upstream Process

Store

A

B

C

Downstream Process

Withdrawal Instruction

for component C

Production Instruction

for component C

Replenishempty rack/bin/

container

Taiichi Ohno, early Toyota Engineer, got this ideawhen visited American Supermarket, so this system

also known as Supermarket System

C




1. Store for Material/Parts on hand

[what is needed to produce finished parts/goods]

2. Store for finished parts/goods

[where are completed parts/goods kept]

3. Communication

[what, when, quantity]

Pull System Components




Material Store

Stamping Welding

Material/Parts Material/Parts

Material Store

• All materials needed to build parts/products

[can replenish whatever taken/consumed/sold]

• Located line side of consumer process

[visible pace of consumption/sales]

What is theQuantity?

• USEAGE lot sizes

• Frequency of SUPPLY

• Quantity per container




Finished Parts/Goods Store

Welding Assembly

Finished Parts/Goods Finished Parts/Goods

Finished Parts/Goods Store

• Has all of finished parts/goods

[can replenish whatever taken/consumed/sold]• Located at the end of process

[visible pace of consumption/sales]

What is theQuantity?

• PRODUCTION lot sizes

• Frequency of WITHDRAWAL

• Quantity per container




Communication

Stamping

W e l d i n g

A s s e m b l y

Material/Parts Finished Parts/Goods

F i n i s h e

d P a r t s / G o o d s

Finished Parts/Goods

Customer

Order

Supplier Order




Purpose : Smooth and balanced pace of production

Authorize production and material conveyance Visual check

Control over production

See ahead/behind condition

Process status at a glance

KANBAN -かんばん(看板)

Two Types ofKANBAN

Production Kanban Withdrawal Kanban

a Japanese word which roughly translated means card or ticket.

Key point :It is a communication tool, a signal asking for material or asking for production




Contains all required information for team member tocomplete process efficiently

Additional information to support visual management

KANBAN




Produces what is sold, when it is sold

Contains over production

Gives visual control of production system

Material [quantity, type, location]

Ahead/behind status at a glance

Creates self regulating production schedule

Bottom up schedule driven by customer demand

No need to constantly readjust manual schedules

Pull System Benefits




Known demand is necessary

Problem in one process will shut down the entireproduction

Reducing lot size = Increasing cost (are you agree?)

Relies on consistent supply of material

Relies on equipment/machines availability andreliability

Worker empowerment

Implementation Challenges

Documents

Pull System and Kanban