Just-in-Time (JIT)
JIT philosophy means getting the right quantity of goods at the right place and the right time
JIT exceeds the concept of inventory reduction; it is an all-encompassing philosophy geared to eliminate waste, anything that does not add value
A broad JIT view – or lean production/lean systems – is one that encompasses the entire organization
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Philosophy of JIT
JIT originated in Japan at Toyota Motor Co, fueled by a need to survive the devastation post WWII
JIT gained worldwide prominence in the 1970s
Often termed “Lean Production” or “Lean Systems”
Broad view that entire organization has the same goal – to serve customers
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Philosophy of JIT – cont'd
Everyone should have a broad view of the organization and work toward the same goal, which is serving the customer
JIT is built on simplicity – simpler is better
Continuous improvement – often using kaizen blitz
Visibility – all waste must be visible to be identified and eliminated
Flexibility – to adapt to changes in environment
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Three Elements of JIT
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Three Elements of JIT – cont'd
JIT manufacturing
focuses on production system to achieve value-added manufacturing
TQM
is an integrated effort designed to improve quality performance at every level
Respect for people
rests on the philosophy that human resources are an essential part of JIT philosophy
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Elements of JIT Manufacturing
JIT Manufacturing is a philosophy of value-added manufacturing
Achieved by focusing on these elements:
Inventory reduction – exposes problems
Kanbans & pull production systems
Small lots & quick setups
Uniform plant loading
Flexible resources
Efficient facility layouts
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Role of Inventory Reduction
Inventory = Lead Time (less is better)
Inventory hides problems
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JIT Manufacturing: The Pull System
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Number of Kanbans Required
N = number of containers
D = demand rate at the withdraw station
T = lead time from supply station
C = container size
S = safety stock
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Computing the Number of Kanbans: an aspirin manufacturer has converted to JIT manufacturing using kanban containers. They must determine the number of containers at the bottle filling operation which fills at a rate of 200 per hour. Each container holds 25 bottles, it takes 30 minutes to receive more bottles, safety stock is 10% of demand during LT.
Tip: round up = would provide additional slack
round down = need to make improvements in operations
Click to edit Master text styles
Second level
Third level
Fourth level
Fifth level
Variations on Kanban Production
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Kanban boxes
space on factory floor for storing supplies
Flags (signal kanban)
used to indicate when supplies need to be ordered
Supplier kanbans
brings filled containers to point of usage in factory/picks up empty containers
Small Lot Sizes & Quick Setups
Small lots mean less average inventory and shorten manufacturing lead time
Small lots with shorter setup times increase flexibility to respond to demand changes
Strive for single digit setups- < 10 minutes
Setup reduction process is well-documented
External setup- do as much preparation while present job is still running; thus can be performed while machine is still running
Internal setup- simplify, eliminate, shorten steps involved with location, clamping, & adjustments; requires the machine to be stopped in order to be performed
Ultimate goal is single unit lot sizes
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Uniform Plant Loading
A “level” schedule is developed so that the same mix of products is made every day in small quantities
Leveling the schedule can have big impact along whole supply chain
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Flexible Resources
Moveable, general purpose equipment:
Portable equipment with plug in power/air
Drills, lathes, printer-fax-copiers, etc.
Capable of being setup to do many different things with minimal setup time
Multifunctional workers:
Workers assume considerable responsibility
Cross-trained to perform several different duties
Trained to also be problem solvers
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Effective Facility Layouts
Workstations in close physical proximity to reduce transport & movement
Streamlined flow of material
Often use:
Cellular Manufacturing
Placement of dissimilar machines and equipment together to produce a family of products with similar processing requirements
U-shaped lines
allows material handler to quickly drop off materials & pick up finished work; flexibility
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BUS 363 – Production Operations Management
Improving Layouts Using Work Cells
BUS 363 – Production Operations Management
Improving Layouts Using Work Cells
TQM
Product versus process
Quality in JIT is centered on building quality into the process
Quality at the source – sequential inspection
Jidoka – authority to stop line
Poka-yoke – fail-safe all processes
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TQM
Preventative Maintenance
Regular inspections and maintenance to keep machines operational
Costly, yes but less expensive than unexpected machine breakage.
Work environment
perform maintenance as part of their regular work
Care of equipment and well-trained workers are very important.
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Respect for People
The Role of Employees:
Genuine and meaningful respect for employees
Willingness to develop cross-functional skills
Associates gather performance data; make production and quality decisions
Bottom-round management
consensus management by committees or teams
Quality circles
small volunteer teams that solve quality problems
Everyone is responsible for Quality and preventive maintenance
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Respect for People – cont’d
Lifetime Employment:
Everyone feels secure/is empowered
Everyone is responsible for quality: understand both internal and external customer needs
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Respect for People cont’d
The Role of Management:
Responsible for culture of mutual trust
Serve as coaches & facilitators
Responsible for developing workers
Provide multi-functional training
Facilitate teamwork
Support culture with appropriate incentive system including non-monetary
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Respect for People – cont’d
Supplier Relationships:
Single-source suppliers
Can supply entire family of parts; external factory
Build long-term relationships with small number of suppliers
Suppliers locate near customer
Fewer contracts
Cost and information sharing
Work together to certify processes
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Benefits of JIT
Reduction in inventories
Improved quality
Reduced space requirements
Shorter lead times
Lower production costs
Increased productivity
Increased machine utilization
Greater flexibility
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Implementing JIT
Starts with a company shared vision of where it is and where it wants to go
Management needs to create the right atmosphere
Implementation needs a designated “Champion”
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Implementing JIT – cont'd
Implement the sequence of seven steps:
Make quality improvements
Reorganize workplace
Reduce setup times
Reduce lot sizes & lead times
Implement layout changes
Switch to pull production
Develop relationship with suppliers
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JIT in Services
Many JIT concepts also apply to Service companies
Improved quality such as timeliness, service consistency, and courtesy
Uniform facility loading to provide better service responsiveness
Use of multifunction workers
Reduction in cycle time
Minimizing setup times and parallel processing
Workplace organization
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JIT & Lean Systems: How it all Fits Together
JIT: an overriding philosophy that affects all other business decisions
Quality improvements (chs 5 & 6)
Partnering with suppliers (ch 4)
Changing job designs (ch 11)
Facility layout (ch 10)
Changes in production process (ch 3)
Changes in inventory (ch 12)
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JIT Across the Organization
JIT eliminates organizational barriers and improves communications
Accounting changes or relies on activity-based costing
Marketing by interfacing with the customers
Finance approves and evaluates financial investments
Information systems create the network of information necessary for JIT to function
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C
S
DT
+
=
N
down?
or
up
round
:
Question
containers
kanban
4.4
25
10
(200)(.5)
C
S
DT
N
bottles
10
.5)
0.10(200)(
d)(T)
0.10(deman
S
container
per
bottles
25
C
hour
.5
minutes
30
T
hour
per
bottles
200
D
:
Solution
=
+
=
+
=
=
=
=
=
=
=
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