Lean Manufacturing & Just-in-Time "The most dangerous kind of waste is the waste we do not recognize." - Shigeo Shingo
Raw Material Supplier Final Assembly Customer FGI PUSH Raw Material Supplier Final Assembly Customer FGI PULL Information Flow Material Flow Reducing Waste: Push versus Pull System
Push System • Every worker maximizes own output, making as many products as possible • Pros and cons: • Focuses on keeping individual operators and workstations busy rather than efficient use of materials • Volumes of defective work may be produced • Throughput time will increase as work-in-process increases (Little’s Law) • Line bottlenecks and inventories of unfinished products will occur • Hard to respond to special orders and order changes due to long throughput time
Pull System • Production line is controlled by the last operation, Kanban cards control WIP • Pros and cons • Controls maximum WIP and eliminates WIP accumulating at bottlenecks • Keeps materials busy, not operators. Operators work only when there is a signal to produce. • If a problem arises, there is no slack in the system • Throughput time and WIP are decreased, faster reaction to defects and less opportunity to create defects
Management philosophy • “Pull” system though the plant WHAT IT IS • Attacks waste • Exposes problems and bottlenecks • Achieves streamlined production WHAT IT DOES • Employee participation • Industrial engineering/basics • Continuing improvement • Total quality control • Small lot sizes WHAT IT REQUIRES • Stable environment WHAT IT ASSUMES Kaizen Features of Lean Production
A Little History! • Ford: Design for manufacturing • Start with an article that suits and then study to find some way of eliminating the entirely useless parts. This applies to everything— a shoe, a dress, a house, a piece of machinery, a railroad, a steamship, an airplane. As we cut out useless parts and simplify necessary ones, we also cut down the cost of making. ...But also it is to be remembered that all the parts are designed so that they can be most easily made."
A Little History! • Ohno – put ideas into practice systematically • “When bombarded with questions from our group on what inspired his thinking, Ohno just laughed and said he learned it all from Henry Ford's book."
TPS: Toyota Production System • A system that continually searches for and eliminateswaste throughout the value chain. • Views every enterprise activity as an operation and applies its waste reduction concepts to each activity - from Customers to the Board of Directors to Support Staff to Production Plants to Suppliers.
Muda Elimination of Waste Acronym – CLOSED MITT • Complexity • Labor • Overproduction • Space • Energy • Defects • Materials • Inventory • Time • Transportation
Elimination of Waste • 5S • Group technology • Quality at the source • JIT production • Kanban production control system • Minimized setup times • Uniform plant loading • Focused factory networks
Minimizing Waste – 5S “Good factories develop beginning with the 5S’s. Bad factories fall apart beginning with the 5 S’s.” - Hirouki Hirano
Minimizing Waste – 5S • A place for everything and everything in its place • Not just a housekeeping issue • Critical foundation for • Setup reduction • Pull systems • Maintenance • Inventory management
Minimizing Waste: Group Technology Using Departmental Specialization (Job Shop) for plant layout can cause a lot of unnecessary material movement Note how the flow lines are going back and forth Saw Saw Saw Grinder Grinder Heat Treat Lathe Lathe Lathe Press Press Press
Minimizing Waste: Group Technology Revising by using Group Technology Cells can reduce movement and improve product flow Grinder 1 2 Lathe Press Saw Lathe Heat Treat Grinder Press Lathe A B Saw Lathe
Minimizing Waste: JIT • Only produce what’s needed • The opposite of “Just In Case” philosophy • Ideal lot size is one • Minimize transit time • Frequent small deliveries ??? • Pro’s • Minimal inventory • Less space • More visual • Easier to spot quality issues • Con’s • Requires discipline • Requires good problem solving • Suppliers or warehouses must be close • Requires high quality
Machine downtime Scrap Vendor Change delinquencies Work in orders process queues Engineering design Design (banks) redundancies backlogs Decision Paperwork Inspection backlogs backlog backlogs Minimizing Waste: JIT Inventory Hides Problems
Minimizing Waste – Quality at the Source • “Do it right the first time” • Call for help • Immediately stop the process and correct it vs. passing it on to inspection or repair Andon
Minimizing Waste – Kanban • Signaling device to control flow of material • Cards • Empty containers • Lights • Colored golf balls • Etc
Minimizing Waste – Setup Times • Long setup times drive: • Long production runs • Large lots • Long lead times • JIT requires small lots and minimum kanbans • Setup reduction • Focused efforts • Problem solving • Flexible equipment
Heijunka Minimizing Waste – Plant Loading Suppose we operate a production plant that produces a single product. The schedule of production for this product could be accomplished using either of the two plant loading schedules below. Not uniform Jan. Units Feb. Units Mar. Units Total 1,200 3,500 4,300 9,000 or Uniform Jan. Units Feb. Units Mar. Units Total 3,000 3,000 3,000 9,000 How does the uniform loading help save labor costs?
Minimizing Waste – Focused Factory Networks These are small specialized plants that limit the range of products produced (sometimes only one type of product for an entire facility) Coordination System Integration
TPS – Respect for People • Level payrolls • Cooperative employee unions • Subcontractor networks • Bottom-up management style • Quality circles (Small Group Problem Solving) Keiretsu
TPS – 4 Rules • All work shall be highly specified as to content, sequence, timing, and outcome • Every customer-supplier connection must be direct, and there must be an unambiguous yes-or-no way to send requests and receive responses • The pathway for every product and service must be simple and direct • Any improvement must be made in accordance with the scientific method, under the guidance of a teacher, at the lowest possible level in the organization
Lean Implementation Total Quality Management Product Design Flow Process Empowered Workforce Problem Solving Performance Measurement Stable Schedule Continual Inventory Reduction Kanban Pull Involved Suppliers
Summary and Conclusions… • Lean Production is the set of activities that achieves quality production at minimum cost and inventory • The flow of material is pulled through the process by downstream operations • Lean originated with the Toyota Production System and its two philosophies – elimination of waste, and respect for people • CLOSED MITT forms of waste