15

JIT and Lean Operations

McGraw-Hill/Irwin

Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved.

Learning Objectives      

Explain what is meant by the term lean operations system. List each of the goals of JIT and explain its importance. List and briefly describe the building blocks of JIT. List the benefits of the JIT system. Outline the considerations important in converting a traditional mode of operations to a JIT system. List some of the obstacles that might be encountered when converting to a JIT system. 15-2

JIT/Lean Production  Just-in-time (JIT): A highly coordinated processing system in which goods move through the system, and services are performed, just as they are needed,

 JIT   lean production  JIT  pull (demand) system  JIT operates with very little “fat” 15-3

Goal of JIT The ultimate goal of JIT is a balanced system. Achieves a smooth, rapid flow of materials through the system

15-4

Summary JIT Goals and Building Blocks Figure 15.1 Ultimate A Goal balanced rapid flow ing Goals Eliminate disruptions Make the system flexible

Product Design

Process Design

Eliminate waste

Personnel Elements

Manufacturing Planning

Building Blocks

15-5

ing Goals  Eliminate disruptions

 Make system flexible  Eliminate waste, especially excess inventory

15-6

Sources of Waste  Overproduction  Waiting time  Unnecessary transportation  Processing waste  Inefficient work methods

 Product defects

15-7

Kaizen Philosophy  Waste is the enemy  Improvement should be done gradually and continuously  Everyone should be involved  Built on a cheap strategy  Can be applied anywhere

15-8

Kaizen Philosophy (cont’d)    

ed by a visual system Focuses attention where value is created Process oriented Stresses main effort of improvement should come from new thinking and work style  The essence of organizational learning is to learn while doing

15-9

Big vs. Little JIT  Big JIT – broad focus    

Vendor relations Human relations Technology management Materials and inventory management

 Little JIT – narrow focus  Scheduling materials  Scheduling services of production

15-10

JIT Building Blocks  Product design  Process design  Personnel/organizational elements  Manufacturing planning and control

15-11

Product Design  Standard parts  Modular design  Highly capable production systems  Concurrent engineering

15-12

Process Design        

Small lot sizes Setup time reduction Manufacturing cells Limited work in process Quality improvement Production flexibility Balanced system Little inventory storage 15-13

Benefits of Small Lot Sizes Reduces inventory Less rework Less storage space

Problems are more apparent Increases product flexibility Easier to balance operations

15-14

Single-Minute Exchange  Single-minute exchange of die (SMED): A system for reducing changeover time  Categorize changeover activities  Internal – activities that can only be done while machine is stopped  External – activities that do not require stopping the machine

15-15

Production Flexibility  Reduce downtime by reducing changeover time  Use preventive maintenance to reduce breakdowns  Cross-train workers to help clear bottlenecks

15-16

Production Flexibility (cont’d)  Use many small units of capacity  Use off-line buffers  Reserve capacity for important customers

15-17

Quality Improvement  Autonomation  Automatic detection of defects during production

 Jidoka  Japanese term for autonomation

15-18

Production Flexibility  Balance system: Distributing the workload evenly among work stations  Work assigned to each work station must be less than or equal to the cycle time  Cycle time is set equal to the takt time  Takt time is the cycle time needed to match customer demand for final product

15-19

Personnel/Organizational Elements  Workers as assets

 Cross-trained workers  Continuous improvement  Cost ing

 Leadership/project management 15-20

Manufacturing Planning and Control  Level loading  Pull systems

 Visual systems  Close vendor relationships  Reduced transaction processing  Preventive maintenance 15-21

Pull/Push Systems  Pull system: System for moving work where a workstation pulls output from the preceding station as needed. (e.g. Kanban)

 Push system: System for moving work where output is pushed to the next station as it is completed

15-22

Kanban Production Control System  Kanban: Card or other device that communicates demand for work or materials from the preceding station  Kanban is the Japanese word meaning “signal” or “visible record”  Paperless production control system

 Authority to pull, or produce comes from a downstream process. 15-23

Kanban Formula N

=

DT(1+X) C

N = Total number of containers D = Planned usage rate of using work center T = Average waiting time for replenishment of parts plus average production time for a container of parts

X = Policy variable set by management - possible inefficiency in the system C = Capacity of a standard container 15-24

Limited Work in Process  Benefits    

Lower carrying costs Increased flexibility Aids scheduling Saves cost of rework and scrap

 Two general approaches  Kanban – focuses on individual work stations  Constant work in process (CONWIP) – focuses on the system as a whole 15-25

Traditional Supplier Network Figure 15.4a

Buyer Supplier

Supplier

Supplier Supplier

Supplier

Supplier

Supplier

15-26

Tiered Supplier Network Figure 15.4b

Buyer First Tier Supplier Second Tier Supplier

Third Tier Supplier

Supplier Supplier

Supplier

Supplier

Supplier

Supplier

Supplier

15-27

Preventive Maintenance and Housekeeping  Preventative maintenance: Maintaining equipment in good condition and replacing parts that have a tendency to fail before they actually fail.  Housekeeping: Maintaining a workplace that is clean and free of unnecessary materials.

15-28

Housekeeping Five S’s 1. 2. 3. 4. 5.

Sort Straighten Sweep Standardize Self-discipline

15-29

Table 15.3

Comparison of JIT and Traditional

Factor

Traditional

JIT

Inventory

Much to offset forecast errors, late deliveries

Minimal necessary to operate

Deliveries

Few, large

Many, small

Lot sizes

Large

Small

Setup; runs

Few, long runs

Many, short runs

Vendors

Long-term relationships are unusual

Partners

Workers

Necessary to do the work Assets

15-30

Transitioning to a JIT System  Get top management commitment  Decide which parts need most effort

 Obtain of workers  Start by trying to reduce setup times  Gradually convert operations  Convert suppliers to JIT  Prepare for obstacles 15-31

Obstacles to Conversion  Management may not be committed  Workers/management may not be cooperative

 Difficult to change company culture  Suppliers may resist  Why?

15-32

Suppliers May Resist JIT     

Unwilling to commit resources Uneasy about long-term commitments Frequent, small deliveries may be difficult Burden of quality control shifts to supplier Frequent engineering changes may cause JIT changes

15-33

JIT in Services The basic goal of the demand flow technology in the service organization is to provide optimum response to the customer with the highest quality service and lowest possible cost.      

Eliminate disruptions Make system flexible Reduce setup and lead times Eliminate waste Minimize WIP Simplify the process 15-34

JIT II  JIT II: a supplier representative works right in the company’s plant, making sure there is an appropriate supply on hand.

15-35

Benefits of JIT Systems  Reduced inventory levels  High quality  Flexibility  Reduced lead times  Increased productivity

15-36

Benefits of JIT Systems (cont’d)  Increased equipment utilization  Reduced scrap and rework  Reduced space requirements  Pressure for good vendor relationships  Reduced need for indirect labor

15-37

Elements of JIT Table 15.4

   

Smooth flow of work (the ultimate goal) Elimination of waste Continuous improvement Eliminating anything that does not add value  Simple systems that are easy to manage  Use of product layouts to minimize moving materials and parts  Quality at the source 15-38

Elements of JIT (cont’d) Table 15.4

   

Poka-yoke – fail safe tools and methods Preventative maintenance Good housekeeping Set-up time reduction

 Cross-trained employees

 A pull system

15-39

Video: Made for you

15-40

Video: New system

15-41

Video: McDonald’s Process

15-42

Video: Layout Gortrac

15-43