Lean Manufacturing & Just-in-Time

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Lean Manufacturing & Just-in-Time"The most dangerous kind of waste is the waste we do not recognize." - Shigeo Shingo


Reducing Waste: Push versus Pull System


Push SystemEvery 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 SystemProduction 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


*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."


A system that continually searches for and eliminates waste 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.TPS: Toyota Production System


Elimination of WasteComplexity Labor Overproduction Space Energy DefectsMudaMaterials Inventory Time TransportationAcronym – CLOSED MITT


*5S Group technology Quality at the source JIT production Kanban production control system Minimized setup times Uniform plant loading Focused factory networks Elimination of Waste


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 – 5SA place for everything and everything in its place Not just a housekeeping issue Critical foundation for Setup reduction Pull systems Maintenance Inventory management


Using Departmental Specialization (Job Shop) for plant layout can cause a lot of unnecessary material movement SawSawLathePressPressGrinderLatheLatheSawPressHeat TreatGrinderNote how the flow lines are going back and forthMinimizing Waste: Group Technology


PressLatheGrinderGrinderA2BSawHeat TreatLatheSawLathePressLathe1Revising by using Group Technology Cells can reduce movement and improve product flow Minimizing Waste: Group Technology


Minimizing Waste: JITOnly produce what’s needed The opposite of “Just In Case” philosophy Ideal lot size is one Minimize transit time Frequent small deliveriesPro’s Minimal inventory Less space More visual Easier to spot quality issuesCon’s Requires discipline Requires good problem solving Suppliers or warehouses must be close Requires high quality???


*Inventory Hides ProblemsMinimizing Waste: JIT


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 repairAndon




Minimizing Waste – KanbanSignaling device to control flow of material Cards Empty containers Lights Colored golf balls Etc


Minimizing Waste – Setup TimesLong 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


*Not uniform Jan. Units Feb. Units Mar. Units Total 1,200 3,500 4,300 9,000Uniform Jan. Units Feb. Units Mar. Units Total 3,000 3,000 3,000 9,000Suppose 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. How does the uniform loading help save labor costs? or Minimizing Waste – Plant LoadingHeijunka


CoordinationSystem IntegrationThese are small specialized plants that limit the range of products produced (sometimes only one type of product for an entire facility)Minimizing Waste – Focused Factory Networks


Level payrolls Cooperative employee unions Subcontractor networks Bottom-up management style Quality circles (Small Group Problem Solving)TPS – Respect for PeopleKeiretsu


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 TPS – 4 Rules


Lean ImplementationEmpowered Workforce Problem Solving Performance MeasurementTotal Quality ManagementFlow ProcessStable ScheduleKanban PullInvolved SuppliersContinual Inventory ReductionProduct Design


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

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Last Updated: 8th March 2018

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