Material Handling System

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Material Handling System

  1. 1. Automated Material Handling Systems (AMHS) Young Jae Jang (youngjae@mit.edu) MIT December 11, 2006 2.853/2.854
  2. 2. Contents <ul><li>Introduction to AMHS </li></ul><ul><li>AMHS in Semiconductor Industry </li></ul><ul><li>AMHS in LCD industry </li></ul><ul><li>Mathematical analysis in AMHS </li></ul>
  3. 3. Automated Material Handling Systems <ul><li>Automated material handling systems… </li></ul><ul><ul><li>Transfer parts from one place to another. </li></ul></ul><ul><ul><li>Include conveyor belts, automated guided vehicles, rail guided vehicles etc. </li></ul></ul><ul><ul><li>Used to be considered non-valued entities in manufacturing. </li></ul></ul><ul><ul><li>Play a critical role in productivity in some industries. </li></ul></ul><ul><ul><ul><li>Semiconductor industry </li></ul></ul></ul><ul><ul><ul><li>Liquid Crystal Display (LCD) industry </li></ul></ul></ul>M1 M2 B
  4. 4. AMHS Engineers <ul><li>Mechanical Engineering Disciplines. </li></ul><ul><ul><li>Control, Dynamics, and Robotics. </li></ul></ul><ul><li>Manufacturing Engineering Disciplines. </li></ul><ul><ul><li>Layout design, Track design, Optimizations, Scheduling, and so on. </li></ul></ul><ul><li>Example: Controller design and productivity </li></ul>Mechanical Engineering Manufacturing Engineering Material Handling System Engineering
  5. 5. Needs for AMHS Role of AMHS <ul><li>Supply chain Integration </li></ul><ul><li>Real time control of manufacturing </li></ul><ul><li>Low volume high product diversity </li></ul><ul><li>Flexible Manufacturing </li></ul><ul><li>Inventory WIP control </li></ul><ul><li>Pull system </li></ul><ul><li>High production rate </li></ul><ul><li>Push system </li></ul><ul><li>Low product diversity </li></ul><ul><li>Laboratory </li></ul><ul><li>No production strategy </li></ul>Production Strategy <ul><li>Real time communication with ERP system </li></ul>Advanced Production <ul><li>Advanced AMHS </li></ul><ul><li>Flexible AMHS </li></ul>Flexible Production <ul><li>Passive AMHS </li></ul>Mass Production <ul><li>No Automations </li></ul>Birth of Industry AMHS Strategy Stage
  6. 6. AMHS trends in Semiconductor and LCD industries Lab production Mass production Lean Production Lab production Mass Production Lean Production Semiconductor Chips <ul><li>Manual Delivery </li></ul><ul><li>Passive AMHS </li></ul><ul><li>Smart AMHS </li></ul>Critical Entity in Manufacturing 1970 1980 1990 2000 2010 LCD
  7. 7. Contents <ul><li>Introduction to AMHS </li></ul><ul><li>AMHS in Semiconductor Industry </li></ul><ul><li>AMHS in LCD industry </li></ul><ul><li>Mathematical analysis in AMHS </li></ul>
  8. 8. Semiconductor Manufacturing <ul><li>Front end – Wafer processing </li></ul><ul><li>Back end – Chip packaging </li></ul><ul><li>OHS – Overhead Shuttle System </li></ul><ul><li>Cassette base system </li></ul>
  9. 9. AMHS in Semiconductor Fab <ul><li>OHS </li></ul>
  10. 10. Fleet Size Analysis – Simulations Solution 1 Layout Solution 2 Layout Solution 3 Layout AMHSA Layout
  11. 11. Fleet Size Analysis – Simulations 2/3
  12. 12. Contents <ul><li>Introduction to AMHS </li></ul><ul><li>AMHS in Semiconductor Industry </li></ul><ul><li>AMHS in LCD industry </li></ul><ul><li>Mathematical analysis in AMHS </li></ul>
  13. 13. Main LCD Production Stages <ul><li>Similar to semiconductor device processes </li></ul><ul><li>More than 200 processing steps – Three stages </li></ul><ul><li>Array stage </li></ul><ul><ul><li>Transistors are fabricated on TFT glass </li></ul></ul><ul><ul><li>Color Filter Layers is processed on C/F glass </li></ul></ul><ul><li>Cell stage </li></ul><ul><ul><li>TFT glass and C/F glass are joined </li></ul></ul><ul><ul><li>The mother glass is cut into individual cells </li></ul></ul><ul><ul><li>Liquid crystal is injected between the two glasses </li></ul></ul><ul><li>Module assembly stage </li></ul><ul><ul><li>Additional components, such as driver integrated circuits and backlight units, are connected </li></ul></ul>Critical production Clean room environment TFT process C/F process Cell stage Module stage Array Stage C/F glass TFT glass Liquid Crystal
  14. 14. Example of a Layout (TFT) <ul><li>Automated Material Handing System (AMHS) </li></ul><ul><li>Transport a part from one process machine to another machine </li></ul><ul><li>Example: Automated Guided Vehicles (AGV) based system </li></ul>Photo Depo Etch Clean Test
  15. 15. LCD panel production process
  16. 16. Automated Guided Vehicle (AGV) <ul><li>AGVs in a bay (3 rd -5 th generations) </li></ul><ul><ul><li>Transportation lot: a cassette </li></ul></ul><ul><ul><li>Bidirectional flexible system </li></ul></ul><ul><ul><li>Movie </li></ul></ul>Source: Shinsung ENG
  17. 17. Rail Guided Vehicle (RGV) <ul><li>Rail guided stocker robot (vertical and horizontal) </li></ul><ul><li>From 6 th generations </li></ul>Source: Shinsung ENG
  18. 18. Cassette – Transfer lot <ul><li>Fixed transfer lot size </li></ul><ul><li>AGV and RGV are cassette based transportation systems </li></ul><ul><li>No direct contact is required between glasses and AMHS </li></ul>
  19. 19. Loading System <ul><li>Load ports and Single Glass Loader (SGL) </li></ul><ul><li>Feeds glass between machines and cassettes </li></ul>Source: Shinsung ENG
  20. 20. Design Issues in AMHS <ul><li>Precision motion control </li></ul><ul><ul><li>Protect material (2.5m x 2m x 0.7mm glass) </li></ul></ul><ul><ul><li>Minimize vibration and impact </li></ul></ul><ul><ul><li>Not touch the upper surface </li></ul></ul><ul><li>Particle free environment </li></ul><ul><ul><li>Protect glass from a particle contamination </li></ul></ul><ul><ul><li>Not be a source of particles </li></ul></ul><ul><ul><li>Not generate turbulent flow </li></ul></ul><ul><li>Space constraint </li></ul><ul><li>Work-in-Process (WIP) Inventory </li></ul>
  21. 21. AMHS trends in Semiconductor and LCD industries Lab production Mass production Lean Production Lab production Mass Production Lean Production Semiconductor Chips <ul><li>Manual Delivery </li></ul><ul><li>Passive AMHS </li></ul><ul><li>Smart AMHS </li></ul>Critical Entity in Manufacturing 1970 1980 1990 2000 2010 LCD
  22. 22. Current Market Situation <ul><li>Inventory issue: </li></ul><ul><li>June 13, 2006 </li></ul><ul><li>Its inventory has risen to four weeks of goods, unusually high in an industry accustomed to a one- to two-week range. LG.Philips took the unusual step of declaring that it would reduce volume for the rest of the quarter. In addition, &quot;We are reviewing our total capacity plans for the year and beyond,&quot; Ron Wirahadiraksa, the company's president, said in a prepared statement. </li></ul><ul><li>June , 15 2006 </li></ul><ul><li>TAICHUNG, Taiwan -- AU Optronics Corp. has cut production of liquid-crystal displays because of bloated inventories , a move that could bring more stability to LCD prices by the third quarter if other companies follow suit, a company executive said. </li></ul>
  23. 23. Contents <ul><li>Introduction to AMHS </li></ul><ul><li>AMHS in Semiconductor Industry </li></ul><ul><li>AMHS in LCD industry </li></ul><ul><li>Mathematical analysis in AMHS </li></ul><ul><ul><li>Case 1 – Buffer Allocation </li></ul></ul><ul><ul><li>Case 2 – AMHS in LCD lines </li></ul></ul>
  24. 24. Case 1 - Buffer Allocations <ul><li>Which one has higher production rate? </li></ul><ul><li>9 Machine line with two buffer options: </li></ul><ul><li>This problem can be viewed as a bay structure with large stockers vs. unified structure with distributed I/O buffer in Fab </li></ul>
  25. 25. Decomposition Analysis – FAB design <ul><li>8 buffers vs. 2 buffers, r=0.19, p=0.01, t=1 </li></ul>
  26. 26. Results: <ul><li>Distributed buffer system in 300mm Fab </li></ul>
  27. 27. Contents <ul><li>Introduction to AMHS </li></ul><ul><li>AMHS in Semiconductor Industry </li></ul><ul><li>AMHS in LCD industry </li></ul><ul><li>Mathematical analysis in AMHS </li></ul><ul><ul><li>Case 1 – Buffer Allocation </li></ul></ul><ul><ul><li>Case 2 – AMHS in LCD lines </li></ul></ul>
  28. 28. LCD – OHS System Development <ul><li>Overhead shuttle layout design and track design </li></ul>
  29. 29. OHS System <ul><li>Pilot system using linear motors </li></ul>
  30. 30. OHS Track <ul><li>Layout </li></ul>
  31. 31. OHS Track <ul><li>Track configurations </li></ul>
  32. 32. Problem <ul><li>Identify the relationships between </li></ul><ul><ul><li>Number of vehicles </li></ul></ul><ul><ul><li>Loading/Unloading time </li></ul></ul><ul><ul><li>Vehicle utilization </li></ul></ul>
  33. 33. Approach – Analytical Model <ul><li>Developed an analytical model </li></ul>Analytical Model <ul><li>Number of vehicles </li></ul><ul><li>Vehicle speed </li></ul><ul><li>Track configuration </li></ul><ul><li>Loading/unloading time </li></ul><ul><li>Vehicle utilization rate </li></ul><ul><li>Service time </li></ul>Inputs Outputs
  34. 34. Approach – Queueing Model <ul><li>M/G/  /N queueing model with server selection rule </li></ul> : Arrival rate is given  : Service rate depends on arrival types
  35. 35. Modeling Assumptions <ul><li>Loop with by-pass line </li></ul><ul><ul><li>Enough space for idle vehicles </li></ul></ul><ul><ul><li>No blocking caused by loading/unloading vehicles </li></ul></ul><ul><li>Vehicle initiation delivery policy </li></ul><ul><ul><li>(Busy vehicle case) </li></ul></ul><ul><ul><li>FCFS rule </li></ul></ul><ul><li>Load port initiation policy </li></ul><ul><ul><li>(Idle vehicle case) </li></ul></ul><ul><ul><li>Closest vehicle rule </li></ul></ul><ul><li>Idle vehicle policy </li></ul><ul><ul><li>Idle vehicle staying at the last delivery point </li></ul></ul><ul><li>Delivery request rate </li></ul><ul><ul><li>Poisson random arrival </li></ul></ul>
  36. 36. Time Definitions <ul><li>Dispatching Time ( T p ) </li></ul><ul><li>Transport Time ( T v ) </li></ul><ul><li>Loading/unloading Time ( T l ) </li></ul><ul><li>Queue Waiting Time ( T q ) </li></ul>
  37. 37. Time Definitions <ul><li>Dispatching time ( Tp ) </li></ul><ul><li>Transport time ( Tv ) </li></ul><ul><li>Loading/unloading time ( Tl ) </li></ul><ul><li>Queue waiting time ( Tq ) </li></ul><ul><li>Vehicle service time ( Ts ) </li></ul><ul><ul><li>Ts = Tp + Tv + 2Tl </li></ul></ul><ul><li>Vehicle delivery time ( Td ) </li></ul><ul><ul><li>Td = Ts + Tq </li></ul></ul>
  38. 38. Modeling Input-Output <ul><li>Inputs: </li></ul><ul><ul><li>From-To time matrix, T(i,j) </li></ul></ul><ul><ul><li>Total request ratio,  </li></ul></ul><ul><ul><li>Request frequency, f(i.j) </li></ul></ul><ul><ul><li>Number of vehicles, V </li></ul></ul><ul><ul><li>Loading/Unloading Time , Tl </li></ul></ul><ul><li>Outputs: </li></ul><ul><ul><li>Average transport time, Tv </li></ul></ul><ul><ul><li>Average dispatching time, Tp </li></ul></ul><ul><ul><li>Average waiting time, Tq </li></ul></ul><ul><ul><li>Average delivery time, Td </li></ul></ul><ul><ul><li>Vehicle utilization, u </li></ul></ul>
  39. 39. Transport time <ul><li>Given Values </li></ul><ul><ul><li>From-To time matrix, T(i,j) </li></ul></ul><ul><ul><li>Total request ratio,  </li></ul></ul><ul><ul><li>Request frequency, f(i.j) </li></ul></ul><ul><ul><li>Number of vehicles, V </li></ul></ul><ul><ul><li>Loading/Unloading Time , Tl </li></ul></ul><ul><li>Transport time, Tv, is easily computed using spatial distribution </li></ul>
  40. 40. Dispatching time <ul><li>Transport time is evaluated using the spatial distribution of vehicles and utilization ratio </li></ul><ul><ul><li>Vehicle utilization u </li></ul></ul><ul><ul><li>Prob( idle vehicle is j | there is V number of vehicles ) </li></ul></ul><ul><ul><li>Spatial distribution of idle vehicle </li></ul></ul><ul><ul><li>Prob( idle vehicle is in the loading zone k | there is only one idle vehicle ) = Prob( destination is k ) </li></ul></ul>
  41. 41. Dispatching time <ul><li>Spatial quantity D(i) and time quantity u are independent each other. </li></ul><ul><li>Prob( two idle vehicles are in loading point 1 and 2 | one vehicle is dispatched ) = Prob( two idle vehicles | at least one idle vehicle) * Prob( vehicle are in loading point 1 and 2) = </li></ul>
  42. 42. Dispatching time – Nearest Dispatching Rule <ul><li> (i) : Set of combinations of loading points at which idle vehicles are located. </li></ul><ul><ul><li>Example: Three loading points L1, L2, L3 and two vehicles. </li></ul></ul><ul><li> (v,i,j) : Set of combinations of loading points at which idle vehicles are located given that there are v number of idle vehicles and there is request from Li and the closest loading point is Lj. </li></ul><ul><ul><li>Example: V=2 </li></ul></ul>
  43. 43. Dispatching time example <ul><li>V=2 case </li></ul>
  44. 44. Dispatching time <ul><li>Expected dispatching time and its variance </li></ul>
  45. 45. Queue waiting time - Tq <ul><li>Service time = dispatching time + transport time + 2*loading time </li></ul><ul><ul><li>=> Ts = Tp + Tv + 2Tl </li></ul></ul><ul><li>Delivery request rate is given :  </li></ul><ul><li>Apply M/G/  /N queue system for Tq </li></ul>
  46. 46. Iterative Method <ul><li>u : vehicle utilization </li></ul><ul><li>Ts : Service time of a vehicle </li></ul><ul><li>Ts = F(u) </li></ul><ul><li>u=F(Ts) </li></ul><ul><li>Solve the problem iteratively </li></ul>
  47. 47. Solution Algorithm <ul><li>Iterative algorithm </li></ul>
  48. 48. Model Verification <ul><li>Case 1: 4 loading points 2 Vehicles </li></ul>1.23% 1.19% 2.99% 0.0 Error AGV utilization Total Travel Dispatch Transport 0.3128 0.2599 0.2567 3 2.494 2.4643 1.5 0.994 0.9643 1.5 1.500 1.5 Heuristics Simulation Analytical 0 0 20 0 4 20 0 0 0 3 10 0 0 20 2 0 20 10 0 1 4 3 2 1   480min Part flow rate 0 1 2 3 4 1 0 1 2 3 2 1 0 1 2 3 2 1 0 1 4 3 2 1   Travel Time
  49. 49. Model Verification <ul><li>Case 2: 9 loading points, 5 Vehicle </li></ul>14.09 -2.53% 13.319 13.6566 Total Travel -2.06% - -4.99% 0.042% Error AGV utilization Waiting time Dispatch Transport 0.919 0.870 0.889 18.05 12.365 7.045 6.271 6.584 7.045 7.048 7.045 Heuristics Simulation Analytical 0 0 0 44 0 22 0 25 75 9 0 0 0 0 15 37 12 38 0 8 63 41 0 0 0 0 48 0 39 7 54 0 32 0 52 12 0 65 0 6 22 0 18 27 0 54 25 0 0 5 0 0 16 74 30 0 72 0 65 4 0 0 72 52 25 0 0 52 0 3 0 37 0 26 0 30 20 0 0 2 0 65 0 28 50 0 18 15 0 1 9 8 7 6 5 4 3 2 1   4800min Part flow rate 0 8 10 10 14 12 10 6 2 9 4 0 6 6 6 8 6 6 6 8 2 10 0 12 16 14 12 8 4 7 6 6 4 0 4 6 8 8 8 6 10 6 12 8 0 2 8 8 12 5 8 4 10 6 6 0 6 6 10 4 10 6 12 8 8 2 0 8 10 3 6 6 8 8 8 6 4 0 8 2 6 6 8 8 12 10 8 4 0 1 9 8 7 6 5 4 3 2 1   Travel time
  50. 50. Analysis <ul><li>Utilization </li></ul>
  51. 51. Optimization <ul><li>Optimal number of vehicles and loading/unloading time. </li></ul><ul><li>Fixed utilization rate (u=0.6). </li></ul>
  52. 52. Conclusions <ul><li>AMHS becomes an important part in manufacturing systems. </li></ul><ul><li>In semiconductor and LCD industries, AMHS plays a critical role in the productivity. </li></ul><ul><li>Analysis for AMHS is often performed with simulations. </li></ul><ul><li>Analytical models can provide AMHS engineers with intuition and understanding of the dynamic behavior of the system. </li></ul>

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