ISEN 315
Spring 2011
Dr. Gary Gaukler
Push and Pull Production Control
“Push” system: Determines when and how much to
produce based on forecasts of future demands
“Pull” system: Initiates production of an item only
when the item is requested
Enabling JIT: Pull System
 A pull system uses signals to request
production and delivery from upstream
stations
 Upstream stations only produce when
signaled
 System is used within the immediate
production process and with suppliers
Experiment
JIT Approach – Toyota Production System
• Philosophy:
– 0 defects
– 0 setup time
– 0 inventory
– 0 breakdowns
– 0 leadtime
– Lot size of 1
Toyota production video
Techniques for JIT Implementations
• Five areas of concern:
– Quality
– Resources
– Design
– Production Mix
– Manufacturing
Quality-related Techniques
• Total Quality Management
• Autonomation
• Poka Yoke
Quality
 JIT cuts the cost of obtaining good quality because
JIT exposes poor quality
 Better quality means fewer buffers and allows
simpler JIT systems to be used
Resource-related Techniques
• Flexible labor
• Flexible equipment
Design-related Techniques
• Design for automation
• Design for simplification
• Modularity
Production Mix -related Techniques
• Mixed model production
• Small lot sizes
Manufacturing-related Techniques
• Kanbans
• Setup time reduction
• U-shaped layouts
Reduce Setup Costs
 High setup costs encourage large lot sizes
 Reducing setup costs reduces lot size and
reduces average inventory
 Setup time can be reduced through preparation
prior to shutdown and changeover
Reduce Lot Sizes
Q1 When average order size = 200
average inventory is 100
Inventory
200 –
Q2 When average order size = 100
average inventory is 50
100 –
Time
Implications for Manufacturing
Reduced space and inventory
 With reduced space, inventory must be in
very small lots
 Units are always moving because there is
no storage
Pull vs Push Systems
 By pulling material in small lots, inventory
cushions are removed, exposing problems
and emphasizing continual improvement
 Manufacturing cycle time is reduced
 Push systems dump orders on the
downstream stations regardless of the need