Just-in-Time and Lean Systems

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Just-in-Time and Lean Systems
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The Philosophy of JIT - Lean System (Production)

• Central (1st) belief All waste (non value items)
  must be eliminated (started at Toyota Motor Co.)
• excess inventory
• backup equipment
• anything (time, energy, space, human activity)
  that does not contribute to the value of the
  product/service
• Other beliefs
• 2. Broad view that entire organization must focus
  on serving customers
• rather than focusing on their own jobs, employees
  know that they are ALL ultimately responsible for
  serving the customer (eliminate its not my job
  attitude)

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The Philosophy of JIT - Lean System (Production)

• 3. JIT is built on simplicity- the simpler the
  better
• Encourages empl. to think about problems-gtsimple
  sol.
• 4. Focuses on improving every operation- Kaizen
• Continuous improvement An organization is never
  perfect and can always be improved in some way
• 5. Install simple visible control systems
• Make all waste visible open and clean floor
  space
• 6. Flexibility to produce different
  models/features
• Able to change volume
• Able to produce variety of products

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Three Elements of JIT
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I. Elements of JIT Manufact.

• 1.Inventory reduction exposes problems
• 2. Kanbans pull production systems
• 3. Small lots quick setups
• 4. Uniform plant loading
• 5. Flexible resources
• 6. Efficient facility layouts

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1. Role of Inventory Reduction

• Inventory Lead Time (less is better)
• Inventory hides problems

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2. The Pull System
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2. The Pull System

• The amount produced at any one time is the amount
  in one container
• Kanban cards coordinate the pull production
  system
• Production cannot take place unless a container
  is empty and a production kanban has authorized
  production
• A full container cannot be withdrawn unless a
  withdrawal kanban authorizes it

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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 of DT (percent of demand
  during lead time)

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Computing the No. of Kanbans an aspirin
manufacturer has converted to JIT manufacturing
using kanban containers. They wish to determine
the no. 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.Round down improvemen.
in the op. needed Round up excess inventory
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3. 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- lt 10 minutes
• The goal set up time 0 sec. and lot size 1
• Setup reduction process is well-documented
• External tasks- do as much preparation while
  present job is still running
• Internal tasks- simplify, eliminate, shorten
  steps involved with location, clamping,
  adjustments

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4. 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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5. Flexible Resources

• Moveable, general purpose equipment
• Portable equipment with plug in power/air
• E.g. 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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6. Effective Facility Layouts

• Workstations in close physical proximity to
  reduce transport movement
• Streamlined flow of material
• Often use
• Cellular Manufacturing (instead of process focus)
• U-shaped lines (allows material handler to
  quickly drop off materials pick up finished
  work)

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Traditional Process Focused Layout

• Jumbled flows, long cycles, difficult to schedule

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JIT Cellular Manufacturing

• Product focused cells, flexible equipment, high
  visibility, easy to schedule, short cycles

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II. JIT and TQM- Partners

• Build quality into all processes
• Focus on continuous improvement - Kaizen
• Quality at the source- sequential inspection
• Jidoka (authority to stop line)
• Poka-yoke (fail-safe all processes, i.e. prevent
  defects from occurring foolproof)
• Preventive maintenance- scheduled
• Work environment- everything in its place, a
  place for everything

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III. Respect for People The Role of Employees

• Genuine and meaningful respect for associates
• Willingness to develop cross-functional skills
• Actively engage in problem-solving (quality
  circles)
• Everyone is empowered
• Everyone is responsible for quality understand
  both internal and external customer needs
• Associates gather performance data
• Team approaches used for problem-solving
• Decisions made from bottom-up
• Everyone is responsible for preventive
  maintenance

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The Role of Management

• Responsible for culture of mutual trust
• Serve as coaches facilitators
• Support culture with appropriate incentive system
  including non-monetary
• Responsible for developing workers
• Provide multi-functional training
• Facilitate teamwork

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Supplier Relationships and JIT

• Use single-source suppliers when possible
• Build long-term relationships
• Work together to certify processes
• Co-locate facilities to reduce transport if
  possible
• Stabilize delivery schedules
• Share cost other information
• Early involvement during new product designs

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Benefits of JIT

• Smaller inventories
• Shorter lead times
• Improved quality
• Reduced space requirements
• Lower production costs
• Increased productivity
• Greater flexibility

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Implementing JIT

• Implementation needs a designated Champion
• Make quality improvements
• Reorganize workplace
• Remove clutter minimize storage
• Reduce setup times
• Reduce lot sizes lead times
• Implement layout changes
• Cellular manufacturing close proximity
• Switch to pull production
• Extend methods to suppliers

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JIT - Problems

• Companies that use JIT have experienced a variety
  of problems.
• Production systems need to be not only reliable,
  but also flexible to switching on the fly to
  meet an unexpected production change.
• Typical problems involve
• equipment downtime
• the coordination and timing of subassembly
  production
• setup losses
• lack of supply reliability
• use of forecasts in production (push, not pull
  system)

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JIT - Problems (example)

• One of the factories of Aisin, a brake-part
  supplier of Toyota that accounted for 80 of
  Toyotas purchased brake-parts, was destroyed by
  fire. This fire was a major problem since the
  supplier had only a three day supply of parts in
  its warehouse. At the time, both Toyota and
  Aisin were using all of their plants at full
  capacity. It was estimated that Toyota might
  miss selling 50,000 cars as a result of the fire.
  

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JIT in Services

• Most of the JIT concepts apply equally to Service
  companies
• Cellular layouts, product focused, flexible
  employees shorten response times
• Service inventory, paperwork, should be
  eliminated, simplified, examined for waste
• Fail-safe all processes from Orders-Payment
• Team based organizations

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JIT in Services

• McDonalds has implemented JIT in their program
  Made for You. This program, which was
  implemented a few years ago in the restaurants,
  consists of a making food to order. It consists
  of computerized kitchens with the use of some
  robotic technology. For example, machines dump
  fries into a basket, lower the basket into the
  oil and then remove the fries when done. The
  company revamped its point of service software,
  toasters, prep tables and holding bins. The
  prep tables were redesigned for a smooth, more
  efficient, work flows.
• The easiest aspects of JIT to apply in services
  are the use of multifunction workers, cycle time
  reductions, setup time reductions, parallel
  processing, and workplace reorganization.

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Chapter 07 problems

• Problem 2
• a.
• D 10 thermostats per hour
• T 30 minutes ½ hour
• C 5 thermostats per container
• N 1 Kanban (DT)/C 100.5/5
• b.
• S 2 thermostats
• N 1.4 Kanbans (DT S)/C (5 2)/5

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Chapter 07 problems

• Problem 4
• a.
• D (50 units/hour)(1 hour/60 minutes) 0.8333
  units/minute
• T 30 minutes
• C 10 per container
• N (0.8333)(30)/10 2.5 containers
• b.
• As the system improves, the cycle time decreases,
  hence the lead time T decreases, and therefore
  the number
• N (DT S)/C of containers needed decreases (N
  may be rounded down to 2)

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Chapter 07 problems

• Problem 6
• T 305 min. to transport 35 min.
• C 20 units per container
• N 5 containers
• S 20 of the demand during lead time .2(DT)
• N (DT S)/C --gt NC DT S --gt DT NC - S
• DT NC - S NC - DT
• DT DT NC
• (1)DT NC --gt D NC/(1)T
• D NC/1.2T 5(20)/(1.235) 2.38 units per
  minute 142.86 units per hour