1. Just-In-Time Systems
• 1950’s - Japan produced 30,000 vehicles
less than half a day’s production in the USA
• Principles of mass production did not apply
to these low levels of production
• Eiji Toyoda, President of Toyota, mandated
the elimination of waste in all processes
2. Just-In-Time Systems
• Taiichi Ohno, former shop manager and
eventual Vice-President of Toyota, main
inventor of JIT
• Philosophy states only necessary units be
provided at required quantity at required
time
3. Just-In-Time Systems
Fundamental Elements of JIT
• steady production
• flexible resources
• high quality
• machine breakdowns
• reliable suppliers
• no machine breakdowns
• quick machine setups
• LOTS OF DISCIPLINE
4. Just-In-Time Systems
Toyoda’s mandate to eliminate waste included
non value added tasks such as:
• watching a machine run
• waiting for parts
• counting parts
• overproduction
5. Just-In-Time Systems
Toyoda’s mandate to eliminate waste included
non value added tasks such as:
• moving parts over long distances
• storing inventory
• looking for tools
• machine breakdown
• rework
6. Just-In-Time Systems Elements
• Flexible resources
• Cellular layouts
• Pull production system
• Kanban production control
• Small-lot production
7. Just-In-Time Systems Elements
• Quick set-ups
• Uniform production levels
• quality at the source
• Total productive maintenance
• Supplier networks
8. Just-In-Time Systems Elements
Flexible Resources
• multi-functional workers and general
purpose machines
• Ohno utilized time and motion studies to
analyze every job and machine in plant
• Ohno discovered a relationship between
operating time of a machine and worker
9. Just-In-Time Systems Elements
Flexible Resources
• Ohno began making single operators
operate multiple machines
• This change required:
– machines automatically stopping at end of
process
– jigs & fixtures to hold parts in place
– extra tools located close to operators
Result one operator could run as many as 17
machines (average 5-10)
10. Just-In-Time Systems Elements
Cellular layouts
• groups dissimilar machines to process
family of parts with similar shapes or
processing requirements
• layout is usually U-shaped
• work is moved within a cell (ideally one
unit at a time) from one process to the next
11. Just-In-Time Systems Elements
Cellular layouts benefits
• changes in product mix are easy to
accommodate (dependent on workers route)
• changes in volume can be managed by
adding or subtracting workers to route
• set-up times are low (because all products
are similar)
12. Just-In-Time Systems Elements
Push Systems
• Push Systems - schedules are prepared in
advance and production is moved to next
step whether or not it is needed
• creates inventory between steps
13. Just-In-Time Systems Elements
Pull Systems
• Pull System - take from previous operation
only those items that are needed
• Once output has been taken, production will
re-commence
• Production will replace exact quantity taken
• Forces co-ordination between operations
(no over-production or under-production)
14. Just-In-Time Systems Elements
Kanban (Japanese for “Card”)
• It is used in conjunction with Pull System
• The information included on the Kanban:
– part number
– brief description
– type of container
– unit load (qty/container)
– preceding and subsequent station
15. Just-In-Time Systems Elements
Kanban
• Kanban information does not change during
production
• Same Kanban rotates back and forth to
preceding and subsequent assemblies
• Kanban is associated with the fixed quantity
inventory (Q and R)
17. Just-In-Time Systems Elements
Kanban
• Production Kanban - authorizes production
• Withdrawal Kanban - authorizes movement
(The need for the two types of Kanban are
necessitated by distance. If operations are
close together or always linked Withdrawal
Kanban can be eliminated)
18. Just-In-Time Systems Elements
Different Types of Kanban
• Kanban Square - square where units are
held. If it is empty it signals that production
must begin
• Kanban Racks - operate on the same
principle as squares. ( Have multiple
stations on a rack)
19. Just-In-Time Systems Elements
Different Types of Kanban
• Signal Kanbans - used when inventory is
needed between processes. When a marker
is reached (this is considered R ( re-order
point)), it is placed on a post. This signals
the need for a replenishment order
• Material Kanban - is used to order material
in advance of a process
20. Just-In-Time Systems Elements
Different Types of Kanban
• Kanban Post Office - used to inform
suppliers of orders needed. Will bring order
and check post office for new orders
21. Just-In-Time Systems Elements
Kanban
• Kanban Square - square where units are
held. If it is empty it signals that production
must begin
• Kanban Racks - operate on the same
principle as squares. ( Have multiple
stations on a rack)
22. Just-In-Time Systems Elements
Small Lot Production
• Requires less space and capital investment
• processes can be closer decreasing material
handling requirements
• quality problems are easier to detect
• lower inventory levels reveals process
bottlenecks
• reduces lead time
23. Just-In-Time Systems Elements
Small Lot Production
Lead Time is comprised of four components:
• Processing time - reduces items processed
and efficiency
• Move time - machines close together,
routings are standard or movement is
eliminated
24. Just-In-Time Systems Elements
Quick Set Up
SMED (single-minute exchange of dies)
based on:
• Separate internal from external setup
– internal setup can be performed only when
machine is stopped
– external setup can be performed while machine
is processing
Can save 30-50% in set-up time
25. Just-In-Time Systems Elements
Quick Set Up
SMED (single-minute exchange of dies)
based on:
• Convert internal to external setup
– gathering tools or fixtures
– preheating die
– centering a die
– standardizing a height
26. Just-In-Time Systems Elements
Quick Set Up
SMED (single-minute exchange of dies)
based on:
• Streamline all aspects of a setup
– organizing workplace
– simplifying or eliminating adjustments
– using quick fasteners or pins
27. Just-In-Time Systems Elements
Quick Set Up
SMED (single-minute exchange of dies)
based on:
• Perform setup activities in parallel or
eliminate
– add two people to perform set-up
– standardizing parts or raw materials
28. Just-In-Time Systems Elements
Uniform Production Levels
Reduce variability
• have more accurate forecasts
• level or smooth production across planning
horizon
29. Just-In-Time Systems Elements
Uniform Production Levels
Reduce variability
• Mixed model assembly
– steadies component production
– reduces inventory
– supports pull system
30. Just-In-Time Systems Elements
Quality at the Source
• no inventory to buffer poor quality
• small lots allows operators to inspect for
quality not inspectors
Forms of Visual control
• Jidoka - authority to stop production line
• Andons - call lights that signal quality
problems
31. Just-In-Time Systems Elements
Quality at the Source
• under-capacity scheduling allows time for
planning, training and problem solving
• Poka-yoke - device or system that stops
defects from occurring (eg. machine shuts
down if it over-heats etc.)
33. Just-In-Time Systems Elements
Total Productive Maintenance (TPM)
• breakdown maintenance
• preventive maintenance - history of prior
breakdowns develop regular check-up
schedules
TPM engages the operator to maintain
equipment and perform preventive
maintenance
34. Just-In-Time Systems Elements
Supplier Networks
Supplier Policies
• locate near to customer
• use small, side loaded trucks and ship
mixed loads
• consider establishing small warehouses near
customer or consolidate with other suppliers
35. Just-In-Time Systems Elements
Supplier Networks
Supplier Policies
• use standardized containers
• have precise delivery schedule
• become certified supplier and accept
payment at regular intervals instead of upon
delivery
36. Just-In-Time Systems Benefits
• reduced inventory
• improved quality
• lower costs
• reduced space requirements
• shorter lead times
• increased productivity
37. Just-In-Time Systems Benefits
• greater flexibility
• better relations with suppliers
• simplified scheduling and control activities
• increased capacity
• better use of human resources
• more product variety