BA341 10th Edition Lecture 10 Outline of Last Lecture I History II The cost of variety III The lean enterprise IV Lean Production V Process Flow VI Systems for Managing Flow VII Process Performance Metrics VIII Little s Law Outline of Current Lecture IX Emphasize JIT production X One Piece Flow XI Kanban Production XII Level Scheduling XIII JIT Layout XIV Other Elements of Lean Production Current Lecture Elements of Lean Production How much WIP should we have High inventory WIP hides problems Lower levels of WIP expose problems o If you adopt lean operations then lower inventory gradually Emphasize JIT production o Employ a Pull production system How are WIP and Throughput Time in a Pull system compared to a Push System Better to adopt the pull system because there is lower inventory and a shorter throughput time A pull system is demand driven Use one piece flow o Move products one unit at a time if possible between workstations to improve throughput These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute o Requires constant effort to reduce setup times One Piece Flow Case 1 assume that parts are transferred 60 units at a time What is the average THt WIP 3 60 180 THr 100 units hr THt WIP Thr 180 100 hr 1 8 h 1 8 60 min 108 min Case 2 assume that parts are transferred 1 unit at a time What is the average THt WIP 3 1 3 THr 100 units hr THt WIP Thr 3 100 hr 0 03 h 0 03 60 min 1 8 min Elements of Lean Production Use Kanban Production Control System Once a kanban i e container is received the Machine Center produces a unit to replace the one pulled by the Assembly Line people The process begins by the Assembly Line people pulling Part A from Storage Determining the Number of Kanban cards containers needed o each container represents the minimum production lot size and o the number of such containers determines directly the amount of WIP in system o K Expected demand during lead time Safety Stock Size of the container DL S C D average demand per period for assembly line downstream L lead time to replenish an order upstream S safety stock expressed in days hours etc of demand C Container size A Kanban example Hobbs Bakery makes cakes that are shipped to grocery stores The bakery wants to change to a kanban system Their data is as follows Daily demand 500 cakes Production lead time 2 days Safety stock 4 hours Workday length 8 hours Container size 250 cakes How many Kanban cards do they need Demand during Lead Time is 500 cakes day 2 days 1 000 cakes Make sure that the time units match Safety Stock is 4 hours of demand i e 500 cakes day 4hrs 8hrs day 500 cakes day 0 5 days 250 cakes again note that units must match Then the number of Kanban containers is 1 000 250 250 1 250 250 5 Another Kanban Example Arvin Automotive makes muffler assemblies composed of a muffler and a catalytic converter The former are made in batches of 10 and the production cell can manufacture a batch in about 4 hours The muffler assembly process averages about eight assemblies per hour Management carries a safety stock equivalent to 75 minutes of demand How many Kanban cards are needed to manage this process The input data is Demand 8 asmbl hr Safety Stock 8 asmbl hr 75mins 60mins hr 8 asmbl hr 1 25hrs 10 asmbl Lead time 4 hrs o Demand during Lead Time is 8 asmbl hr 4hrs 32 asmbl Container size 10 Then the number of Kanban containers is o 32 10 10 42 10 4 2 round up to 5 containers Elements of Lean Production Level Scheduling Heijunka o Goal achieve a smooth stable production flow Why would this be desirable o Idea process frequent small batches rather than a few large batches a k a mixed model jelly bean schedule What does the current layout resemble JIT Layout Group Technology o Group similar products into families o Group processes in work cells o Use this one for lean production this layout is job cells Other Elements of Lean Production Quality at the source andon cord Upgrade housekeeping 5S o Seiri Sorting o Seiton Simplify o Seiso Shine sweep o Seiketsu Standardize o Shitsuke Sustain self discipline Respect for people o Crossfunctional teams sharing info between each department Preventive maintenance o Periodic inspection and repair Standard Work o Use clear standardized consistent task specs Value chain mapping o Map processes and identify value added and non value added activities Continuous improvement Kaizen