LEAN PRODUCTION
Prof. Kaushik Paul
Associate Professor
Operations Area
E-Mail: kaushik.paul@igsm.in
Phone: 43559308
OBJECTIVES
Lean Production Defined
The Toyota Production System
Lean Implementation Requirements
Lean Services
LEAN PRODUCTION
Lean Production can be defined as an integrated set
of activities designed to achieve high-volume
production using minimal inventories (raw materials,
work in process, and finished goods)
Lean Production also involves the elimination of
waste in production effort
Lean Production also involves the timing of
production resources (i.e., parts arrive at the next
workstation just in time)
Here the customer starts
the process, pulling an
inventory item from
Final Assembly
Then subassembly work is
pulled forward by
that demand
Customers
PULL SYSTEM
Vendor
Fab
Vendor
Fab
Vendor
Fab
Vendor
Sub
Final
Assembly
The process continues
throughout the entire
production process and
supply chain
Fab
Sub
FEATURES OF LEAN PRODUCTION
WHAT IT IS
Management philosophy
Pull system though the plant
WHAT IT REQUIRES
Employee participation
Industrial engineering/basics
Continuing improvement
Total quality control
Small lot sizes
WHAT IT DOES
Attacks waste
Exposes problems and bottlenecks
Achieves streamlined production
WHAT IT ASSUMES
Stable environment
THE TOYOTA PRODUCTION SYSTEM
Based on two philosophies:
2.
Elimination of waste
Respect for people
ELIMINATION OF WASTE
1.
Focused factory networks
Group technology
Quality at the source
JIT production
Uniform plant loading
Kanban production control system
Minimized setup times
7
MINIMIZING WASTE:
FOCUSED FACTORY
NETWORKS
Coordination
System Integration
These are small specialized
plants that limit the range
of products produced
(sometimes only one type of
product for an entire
facility)
Some plants in
Japan have as
few as 30 and as
many as 1000
employees
MINIMIZING WASTE: GROUP TECHNOLOGY (PART 1)
Note how the flow lines are going back and forth
Using Departmental Specialization for plant layout can cause a lot of
unnecessary material movement
Saw
Saw
Saw
Grinder
Grinder
Heat Treat
Lathe
Lathe
Lathe
Press
Press
Press
MINIMIZING WASTE: GROUP TECHNOLOGY (PART 2)
Revising by using Group Technology Cells can reduce movement and improve
product flow
Grinder
Saw
Lathe
Lathe
Press
Lathe
Press
Heat Treat
Grinder
Saw
Lathe
10
MINIMIZING WASTE:
UNIFORM PLANT LOADING (HEIJUNKA)
Suppose we operate a production plant that produces a single
product. The schedule of production for this product could be
accomplished using either of the two plant loading schedules
below.
Not uniform
Jan. Units
Feb. Units
Mar. Units
Total
1,200
3,500
4,300
9,000
or
Uniform
Jan. Units
Feb. Units
Mar. Units
Total
3,000
3,000
3,000
9,000
How does the uniform loading help save labor costs?
11
MINIMIZING WASTE: INVENTORY
HIDES PROBLEMS
Machine
downtime
Scrap
Work in
process
queues
(banks)
Paperwork
backlog
Vendor
delinquencies Change
orders
Engineering design
redundancies
Inspection
backlogs
Example: By
identifying defective
items from a vendor
early in the
production process
the downstream work
is saved
Design
backlogs
Decision
backlogs
Example: By
identifying defective
work by employees
upstream, the
downstream work is
saved
12
MINIMIZING WASTE: KANBAN PRODUCTION CONTROL
SYSTEMS
This puts the
Once the Production kanban is
received, the Machine Center
produces a unit to replace the
one taken by the Assembly Line
people in the first place
Machine
Center
Withdrawal
kanban
Storage
Part A
Production kanban
The process begins by the Assembly Line
people pulling Part A from Storage
Storage
Part A
system back
were it was
before the item
was pulled
Assembly
Line
Material Flow
Card (signal) Flow
13
DETERMINING THE NUMBER OF KANBANS NEEDED
Setting up a kanban system requires determining the
number of kanbans cards (or containers) needed
Each container represents the minimum production lot
size
An accurate estimate of the lead time required to
produce a container is key to determining how many
kanbans are required
14
THE NUMBER OF KANBAN CARD
SETS
Expected demand during lead time + Safety stock
k=
Size of the container
DL(1 + S )
=
C
k = Number of kanban card sets (a set is a card)
D = Average number of units demanded over some time
period
L = lead time to replenish an order (same units of time as
demand)
S = Safety stock expressed as a percentage of demand
during leadtime
C = Container size
15
EXAMPLE OF KANBAN CARD DETERMINATION:
PROBLEM DATA
A switch assembly is assembled in batches of 4 units from
an upstream assembly area and delivered in a special
container to a downstream control-panel assembly
operation
The control-panel assembly area requires 5 switch
assemblies per hour
The switch assembly area can produce a container of
switch assemblies in 2 hours
Safety stock has been set at 10% of needed inventory
16
EXAMPLE OF KANBAN CARD DETERMINATION:
CALCULATIONS
Expected demand during lead time +Safety stock
k =
Size of the container
DL (1+ S ) 5(2)(1.1)
=
=
= 2.75, or 3
C
4
Always round up!
17
RESPECT FOR PEOPLE
Level payrolls
Cooperative employee unions
Subcontractor networks
Bottom-round management style
Quality circles (Small Group Involvement Activities or
SGIAs)
18
TOYOTA PRODUCTION SYSTEMS FOUR RULES
1.
All work shall be highly specified as to content,
sequence, timing, and outcome
2.
Every customer-supplier connection must be direct,
and there must be an unambiguous yes-or-no way to
send requests and receive responses
3.
The pathway for every product and service must be
simple and direct
4.
Any improvement must be made in accordance with
the scientific method, under the guidance of a
teacher, at the lowest possible level in the
organization
19
LEAN IMPLEMENTATION REQUIREMENTS: DESIGN
FLOW PROCESS
Link operations
Balance workstation capacities
Redesign layout for flow
Emphasize preventive maintenance
Reduce lot sizes
Reduce setup/changeover time
20
LEAN IMPLEMENTATION REQUIREMENTS: TOTAL
QUALITY CONTROL
Worker responsibility
Measure SQC
Enforce compliance
Fail-safe methods
Automatic inspection
21
LEAN IMPLEMENTATION REQUIREMENTS: STABILIZE SCHEDULE
Level schedule
Underutilize capacity
Establish freeze windows
22
LEAN IMPLEMENTATION REQUIREMENTS: KANBAN-PULL
Demand pull
Backflush
Reduce lot sizes
23
LEAN IMPLEMENTATION REQUIREMENTS: WORK WITH
VENDORS
Reduce lead times
Frequent deliveries
Project usage requirements
Quality expectations
24
LEAN IMPLEMENTATION REQUIREMENTS: REDUCE
INVENTORY MORE
Look for other areas
Stores
Transit
Carousels
Conveyors
25
LEAN IMPLEMENTATION REQUIREMENTS:
IMPROVE PRODUCT DESIGN
Standard product configuration
Standardize and reduce number of parts
Process design with product design
Quality expectations
26
LEAN IMPLEMENTATION REQUIREMENTS:
CONCURRENTLY SOLVE PROBLEMS
Root cause
Solve permanently
Team approach
Line and specialist responsibility
Continual education
27
LEAN IMPLEMENTATION REQUIREMENTS:
MEASURE PERFORMANCE
Emphasize improvement
Track trends
28
LEAN IN SERVICES (EXAMPLES)
Organize Problem-Solving Groups
Upgrade Housekeeping
Upgrade Quality
Clarify Process Flows
Revise Equipment and Process Technologies
29
LEAN IN SERVICES (EXAMPLES)
Level the Facility Load
Eliminate Unnecessary Activities
Reorganize Physical Configuration
Introduce Demand-Pull Scheduling
Develop Supplier Networks
30
References: Operations Management for
Competitive Advantage
By Chase, Jacobs & Aquilano, 11e
HOPE YOU ENJOYED THE CLASS. QUESTIONS PLEASE
THANK YOU
