JIT.ppt

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

 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

Fundamental Elements of JIT
 steady production
 flexible resources
 high quality
 machine breakdowns
 reliable suppliers
 no machine breakdowns
 quick machine setups
 LOTS OF DISCIPLINE

Toyoda’s mandate to eliminate waste included
non value added tasks such as:
 watching a machine run
 waiting for parts
 counting parts
 overproduction

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

Elements
 Flexible resources
 Cellular layouts
 Pull production system
 Kanban production control
 Small-lot production

Elements
 Quick set-ups
 Uniform production levels
 quality at the source
 Total productive maintenance
 Supplier networks

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

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)

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

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)

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

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)

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

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)

Elements
Q-R
R
R
Two Bin
Kanban
Re-order Card
Re-order Card
An order is continually
in transit

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)

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)

Elements
 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

Elements
 Kanban Post Office - used to inform
suppliers of orders needed. Will bring order
and check post office for new orders

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)

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

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

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

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

Elements
Quick Set Up
based on:
 Streamline all aspects of a setup
– organizing workplace
– simplifying or eliminating adjustments
– using quick fasteners or pins

Elements
Quick Set Up
based on:
 Perform setup activities in parallel or
eliminate
– add two people to perform set-up
– standardizing parts or raw materials

Elements
Uniform Production Levels
Reduce variability
 have more accurate forecasts
 level or smooth production across planning
horizon

Elements
Uniform Production Levels
Reduce variability
 Mixed model assembly
– steadies component production
– reduces inventory
– supports pull system

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

Elements
 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.)

Elements
Programs that stemmed from JIT
 Kaizen - Continuous Improvement
 Total Employee Involvement

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

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

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

Just-In-Time Systems Benefits
 reduced inventory
 improved quality
 lower costs
 reduced space requirements
 shorter lead times
 increased productivity

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

JIT.ppt

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