Lps05 lscheduling

8/13/2018 LEAN SCHEDULING GVC ThS Nguyễn Như Phong nguyenphong.bksg@gmail.com; www.isem.edu.vn Kỹ thuật Hệ thống Công nghiệp ĐH BÁCH KHOA – ĐHQG TPHCM (Tài liệu giảng dạy cho ISE) 2018 LEAN SCHEDULING           Lean scheduling Scheduling concepts The pacemaker Supermarkets RRS Mixed model scheduling Lean batch sizing & EPE Kanban & Pull Material handling route Heijunka & capacity management 11 April 2003 Nguyễn Như Phong 8/13/2018 LEAN SCHEDULING  Scheduling    Push scheduling Pull scheduling Pull sys construction  Building blocks    Workstation Buffer / supermarket Scheduling concepts Nguyễn Như Phong 11 April 2003 Scheduling concepts  Scheduling concepts  enable    most repetitive-production many less-regular-flow plants implement successful lean scheduling sys  11 April 2003 in a value stream Nguyễn Như Phong 8/13/2018 Scheduling concepts  Demand smoothing the starting point  The smoother the demand,    the more stable the production, the easier implement Enable supermarket inventory reduced Nguyeãn Nhö Phong 11 April 2003 Scheduling concepts  Takt time - the drumbeat  Pitch time –    the repeating increment Container moved & material handler circulates Pacemaker   Production scheduled at one single point Other stages pulled / flowing  11 April 2003 in a FIFO sequence the final stage Nguyễn Như Phong 8/13/2018 Scheduling concepts  Kanban   Pull sys Enable the coordination & synchronization of flow   governed by the pacemaker Avoid overproduction & high light problems 11 April 2003 Nguyễn Như Phong Scheduling concepts  Pacemaker schedule  aided by concepts   11 April 2003 RRS Mixed model scheduling Nguyễn Như Phong 8/13/2018 Scheduling concepts  RRS    Runner product – dedicated facilities Repeaters scheduled at regular intervals Strangers fitted around repeaters 11 April 2003 Nguyễn Như Phong Scheduling concepts  Mixed model scheduling     Running the smallest pos repeating batch size down a line One piece flow – ideal Inventory reduced, cell balanced Regularity of flow –  11 April 2003 Making & moving in one repeating sequence all day Nguyễn Như Phong 8/13/2018 Scheduling concepts  Lean batch sizing   Stages involving longer CO operations Governed by the pacemaker   Synchronization maintained Inventories kept low Nguyeãn Nhö Phong 11 April 2003 Scheduling concepts  Material handler   Hold the whole process together Regular route , circulating around the plant   Collect up kanbans,    every pitch increment / round multiple of PI pick needed parts, deliver the requirement Look out any deviation Separate function   11 April 2003 Move parts & prod Make & assemble Nguyễn Như Phong 8/13/2018 Scheduling concepts  Heijunka sys   Leveling at the pacemaker Planning & execution sys    Establish work each pitch increment Authorize the work begin on time Also a problem detection tool 11 April 2003 Nguyeãn Nhö Phong THE PACEMAKER  Single PM     The stage around which whole VS scheduled The heart Avoid amplification problems Create synchronization 11 April 2003 Nguyễn Như Phong 8/13/2018 The pacemaker  Often but need not be a constraint / bottleneck    Well down stream Upstream – pulled Downstream  Flow be FIFO or  Go into FG supermarket Nguyễn Như Phong 11 April 2003 The pacemaker  Rely on as smooth a demand as pos   Operate at / near the pitch increment as the drumbeat Under-capacity scheduling   95% of the pitch time allow little variation Heijunka box –  11 April 2003 scheduling mechanism Nguyễn Như Phong 8/13/2018 SUPERMARKETS & FIFO LANES  Lean aims at one piece flow   Flow takes place bw supermarket Traditionally   Large amount of inv before & after w/s Waiting to move,   waiting for the next operation, buffer SM areas grouped together  enable MH to visit regular routes,  11 April 2003 go shopping for parts Nguyễn Như Phong Supermarkets & FIFO lanes  SM often established at/where     the boundary bw loops of pull VS converge / diverge CONWIP loops meet WIP permission bw w/s    Under visible Kanban control or CONWIP or DBR 11 April 2003 Nguyễn Như Phong 8/13/2018 Supermarkets  WIP in SM  Types     Ordinary SS needed carter uncertainty demand BS needed carter process uncertainties A little more helps highlight the causes of problems 11 April 2003 Nguyễn Như Phong Supermarkets  FG SM    Wall of shame  demand management & schedule stability Need regard the inventory dynamically Clear marker sys shows excess inventory 11 April 2003 Nguyễn Như Phong 10 8/13/2018 Kanban  Number of Kanban cards  The general rule on Ks    Start loose w a generous amount of SS Move toward tight K gradually but steadily The no K calculated on a safe assumption   Comfortably sufficient inv in the replenishment loop Ohno warning about excessive no.Ks  Loosing the responsive feel of a pull sys Nguyễn Như Phong 11 April 2003 Kanban  Number of cards  Traditional 2-bin sys ROP = D*LT + SS N = ROP/Q      N rounded up Assuming K card   D: demand rate during LT LT: placing an order  receiving delivery Q: container quantity sent as soon as the first part removed from the container Often better think of safety LT N = D*(LT + ST)/Q 11 April 2003 Nguyễn Như Phong 47 8/13/2018 Kanban  Number of cards w CO   LT = CO + Batch RT + QT + Delivery time EPE cycle the interval bw running a prod   Not include delivery time & safety time Delivery time linked w MH cycle / pitch time N = D*(EPE+DT+ST)/Q Nguyễn Như Phong 11 April 2003 Kanban  Number of cards  for assembly operations / suppliers  Repetitive assembly operations N = D*(LT + ST)/Q    11 April 2003 No CO Demand expressed in units/d LT Nguyễn Như Phong 48 8/13/2018 Kanban  LT  time required      to go through all nec steps from placing receiving the order Elements of run, wait, move Run time fill the container Wait time –   pre&post waiting movement Waiting on the K board / mailbox  before the order actioned Nguyễn Như Phong 11 April 2003 Kanban  Number of cards  for assembly operations / suppliers N = D*(LT + ST)/Q  Parts obtained from ext sup   LT the expected delivery ST –    11 April 2003 Uncertainty in delivery, quality, breakdown, distruption Moving from loose tight pull SS somewhat allowed in the rounding up calculation Nguyễn Như Phong 49 8/13/2018 Kanban  K weakness  Assume    repetitive production fairly level schedule Schedule not level  Significant buffer inventories idle lengthy periods,   waiting be pulled Further complications     Routings vary significantly bw prod.s Variation in processing time Unbalanced lines & temporary bottlenecks Sometimes more inv than MRP push sys Nguyễn Như Phong 11 April 2003 Kanban  No.Ks depends on demand     Demand changes  NoK changes Unstable envi  adding / subtracting Ks Takt changes  NoK changes  vigilant schedulers MRP used generate the required NOK   11 April 2003 MRP philosophy : job shop rather than flow shop Fine planning not execution Nguyễn Như Phong 50 8/13/2018 CONWIP  Constant WIP   Link the last proc w the first by a multistage signal sys Cards      Work completed at the end of a route   not operate bw each pair of w/s follow the prod / batch through all the stages sent the first proc as the prod / batch completed at the last authorize the start of a new batch equivalent amount let in the route beginning The amount of work calculated in terms of the beginning Nguyễn Như Phong 11 April 2003 CONWIP   CONWIP card not prod specific Beautifully simple but robust sys  Inventory automatically accumulates   in front of temporary bottleneck Less inv than stage by stage kanban 11 April 2003 Nguyễn Như Phong 51 8/13/2018 CONWIP  CONWIP loop –   Assembly line, cell, factory Establish a CONWIP loop   Start w loose inv and tighten UB = required LT * TT  Established bw supermarket  Set up components & end items  several loops making up a value chain Nguyễn Như Phong 11 April 2003 CONWIP  Categories of priority   FIFO used Hot CONWIP cards  11 April 2003 jump the queue at the first operation / buffers Nguyễn Như Phong 52 8/13/2018 CONWIP  Kanban    Tighter material control sys Well balanced stages  easier pick up problems faster Require   strict operating conditions & higher flow linearity Nguyễn Như Phong 11 April 2003 CONWIP  Use both K&C  CONWIP   control the main flow Kanban  11 April 2003 control part delivery the line Nguyễn Như Phong 53 8/13/2018 MATERIAL HANDLING ROUTE  Regular set route a MH –     a powerful regularity concept Pacemaker – the heart beat MH – circulation sys lifeblood Material handling   Waste, spread out among many operators Group up – single MH, vital part of flow Nguyễn Như Phong 11 April 2003 Material handling route  MH  follow a route,   collect Ks, pick & deliver parts  start & end at the pacemaker / H box initiate the next round as the H card issued working w the PM  look out the problems      11 April 2003 essentially levels the production rate shortage / stoppage notify problems supervisor Nguyễn Như Phong 54 8/13/2018 Material handling route  The route   Carefully workout the standard time Just a little less than the pitch increment 11 April 2003 Nguyễn Như Phong HEIJUNKA   Capacity management The ultimate tools for    stability, quality, productivity 11 April 2003 Nguyễn Như Phong 55 8/13/2018 Heijunka  The classical method in L scheduling in a repetitive envi  Level schedule/pacing,     visibility of schedule, early problem highlighting Used at PM proc., control & pace the whole plant Schedule developed & controlled by sup at the Gemba 11 April 2003 Nguyễn Như Phong Heijunka  A post-box sys K cards     Authorize production in pitch increment-sized time slots Loaded at the cell level by sup / team leaders Manual finite schedule Always visible & up2date 11 April 2003 Nguyễn Như Phong 56 8/13/2018 Heijunka  H box    Columns each pitch increment Rows each prod / family H card placed in one prod row authorize production of PI’s amount of work  a PI fills a part container 11 April 2003 Nguyễn Như Phong Heijunka [A, B, C, D, E] = [300, 200, 150, 100, 50] (sp/ng) Q = 25: N [A, B, C, D, E] = [12, 8, 6, 4, 2] (thẻ/ng) TAT = 48000 gy/ng, TDD = 800 sp/ng: TT = 48000/800 = 60 gy PT = 60  25/60 = 25 ph [A, B, C, D, E] = [6, 4, 3, 2, 1] (K) AAAAAABBBBCCCDDE 11 April 2003 Nguyễn Như Phong 57 8/13/2018 Heijunka AAAAAABBBBCCCDDE PT A 1 1 1 B 10 1 1 11 12 13 1 C D 14 15 16 1 E Nguyễn Như Phong 11 April 2003 Heijunka ABCDEABCDABABACA PT A B C 1 D 12 13 1 1 11 1 10 14 15 16 1 1 1 E 11 April 2003 Nguyễn Như Phong 58 8/13/2018 Heijunka  MH authorized   to collect only that specific quantity at that time Loading up the H box levels the schedule  Withdrawing the cards paces production  during the shift 11 April 2003 Nguyễn Như Phong Heijunka  Immediately apparent    Item fails be ready collection Cell unable start work The worst case of undetected cell failure – PI 11 April 2003 Nguyễn Như Phong 59 8/13/2018 Heijunka    The pacemaker of MHS Heijunka used w FG store Demand not met at the H schedule   MH draws on BS but raise a flag BS replaced at the end of the shift 11 April 2003 Nguyễn Như Phong Heijunka  Mixed model scheduling inherent in H   H box loaded MM fashion H not a tool for   the job shop / highly variation production 11 April 2003 Nguyễn Như Phong 60 8/13/2018 Heijunka  TT changes  Maintain constant PI, derive the pitch quantity      No PI change meet the demand End the shift w idle/over time Most popular Stability of MH route & rate of work Maintain the standard container quantity, derive PI   Rebalance required MH routes may change 11 April 2003 Nguyễn Như Phong Heijunka  Very long work cycle / TT     Large item – pulse line PI made a fraction of the pitch time, eg 30m/1h H built around PI standard block of work The great advantage of leveling & pacing remain 11 April 2003 Nguyeãn 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