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Chapter 7

Chapter 7. Manufacturing/Office Cells One Piece Flow and the Key to Employee Empowerment and Ownership. Cellular Layout. Comprises a group of equipment or desks dedicated to the complete production of a family of similar products, parts, or service Usually laid out in a “U” shape

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Chapter 7

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  1. Chapter 7 Manufacturing/Office Cells One Piece Flow and the Key to Employee Empowerment and Ownership

  2. Cellular Layout • Comprises a group of equipment or desks dedicated to the complete production of a family of similar products, parts, or service • Usually laid out in a “U” shape • Produce products one at a time by linking together a sequence of processes • Start with raw material and end with a finished product. • One Piece Flow Production

  3. 1 9 1 3 Henry FordFounder of One-Piece Flow -Assembly time per vehicle reduced from 13 hours to 2 hours 38 minutes within 3 months From “One Piece Flow” by Kenichi Sekine

  4. Current Process-Oriented Layout (Department Specialization) • Problems • Defects not detected until inspection process • Increase in defects due to material handling • Could take months to traverse the department • Raw and WIP inventory on the floor could occupy 25% of the available manufacturing space • These problems then created others • Identification of the root cause of defects difficult due to length of time • Scheduling the assembly department impossible – expediting not uncommon • Long lead times, missed delivery schedules, lost sales opportunities

  5. Benefits of Cells • Cells and One Piece Flow Production provide benefits that drastically reduce: • Product defects • Lead times • WIP & finished goods inventory • Required business space • Labor • Information/material handling • While improving: • Company-wide productivity & teamwork • Company capacity & flexibility

  6. Employee Empowerment • The greatest benefit to cellular design • The team will experience and develop • Improved communication and teamwork • An understanding of the entire process from raw material to the finished product • An opportunity to meet and discuss issues with customers • An environment of greater control in how the cell is run • Higher job satisfaction through increased job responsibility, ownership, and variety

  7. Cell Rules • Rule #1: • Cells will make the company more productive. Communicate with the team in advance what will happen to the extra people. • Rule#2: Jidoka – quality at the source • A thorough inspection process must be designed into each cell. • Each part will be made and verified one piece at a time. 100% inspection. • Automatic feedback should occur when a defect is detected.

  8. Cell Rules • Rule #3: • All shop floor issues; job classification, extra labor, etc. must be resolved before implementation begins. • Rule#4: • The design of the cell must consider • flow of the team working in the cell • flow of the material within and external to the cell • flow of information within and external to the cell • equipment maintenance access • 5S “U” shaped cells are not always the best design

  9. Cell Rules • Rule #5: • Minimize movement. It causes ergonomic issues and it is waste. • Rule #6: • Material is kept moving until it is finished. Product is not stored mid-stream. • Rule #7: • Create standard work – use pictures. No improvement can occur without standards in place.

  10. Cell Rules • Rule #8*: • If the takt time is very short, consider additional resources such as additional machines, shifts, etc. • Rule #9: • Cells operate best with an informal structure. Small team sizes of eight or less is best. *do not confuse cycle time with takt time

  11. Cell Prerequisites • Create product families • Parts that share the same set of manufacturing processes • Repetitive manufacturing/office processes • Dedicated cells are typically used for high volume parts • Small, dedicated, moveable equipment • Near zero setup for part changeovers • Flexible, cross-trainable employees • May need additional manufacturing/ equipment/ machine capacity if equipment is not fully burdened

  12. Cellular Manufacturing Characteristics • Production paced to takt time • Machines in order of processes steps • Small and inexpensive equipment • Multi-process-handling workers

  13. Summary • Manufacturing cells are powerful tools in improving: • Productivity • Team empowerment and business ownership • Customer deliveries and product lead times • Product quality • Available manufacturing space

  14. Lean Implementation • The five steps of Lean Implementation • Specify value • Map the value stream • Create flow • Pull • Pursue perfection

  15. The Lean Enterprise Principles Lean Enterprise Workplace safety, order, cleanliness Flow and Pull Production Six Sigma Quality Empowered Teams Visual Management Pursuit of Perfection The workplace is safe, orderly, and very clean There is a relentless pursuit of perfection Products are built “Just In Time,” to customer rate based demand Member teams are empowered to make key decisions Visual Management to track performance and open the company to all people Six Sigma Quality is built into the product and the process

  16. What is Flow? • Parts moving through adjacent process steps with no delay and at the minimum possible quantities • Marbles through a hose • Make one, move one • Cellular manufacturing or office design

  17. Why do we produce more than we require? • The manufacturing steps are not all aligned on the takt time • Buffers are planned to provide for machine stoppages and rejects • Because we want a maximum margin of comfort (we want to work at our own pace) • Economic order quantities (EOQ) often promotes large batches because of our long setup times

  18. Lean Implementation Batch and Queue (Push) 30+ minutes for total order. First good piece in 21 minutes. Continuous Flow (Make one, move one) 12 minutes for total order. First Good Piece in 3 Minutes!

  19. Individual vs. System Efficiency

  20. Example: 5225-836 Match Grind Valve Total operations: 34 hours Mfg leadtime: 59 days 472 hours Difference: 438 hours 93% STORAGE, TRANSPORTATION, & WAITING TIME!! What are processes made of?

  21. The 5 Process Components Physical change of the material Transformation Inspection Comparison with a standard Transport Material movement Material storage before transformation Storage Delay before the part/batch is complete Delay / wait

  22. To Reduce Lead-times Transformation Inspection Transport Dedicated lines Storage One piece flow Delay / wait

  23. and are a major factor in long lead-times Potential gains 5 parts 2 h/part = 10 h 5 parts 2 h/part = 10 h 81.5 First good part A B 0.5 h 16 h 0.0 26.5 16 h 0.5 h 5 parts 2 h/part = 10 h 5 parts 2 h/part = 10 h C D 0.5 h 16 h 79.5 53.0

  24. Potential gains by eliminating and Eliminate transportation and storage times 5 parts 2 h/part = 10 h 5 parts 2 h/part = 10 h 81.5 First good part A B 16 h 0.5 h 81.5 0.0 26.5 16 h 0.5 h 16 h 0.5 h 5 parts 2 h/part = 10 h 5 parts 2 h/part = 10 h 16 h 0.5 h C D -49.5 16 h 0.5 h 53.0 79.5 16 h 0.5 h 5 parts 2 h/part = 10 h =32 = 10 h = 10 h = 10 h REMEMBER: The transformation of the parts has not changed! A B C D 0.0 10.0 20.0 30.0 32.0

  25. First good part 5 parts 2 h/part = 10 h = 10 h = 10 h = 10 h A B C D And what if we worked in one piece flow? 32.0 0.0 10.0 30.0 20.0 The dedicated line can reduce and eliminate transportation and storage. 1 part 2h/part = 2 h First good part Second good part = 2 h = 2 h = 2 h A B C D 0.0 2.0 2.0 4.0 4.0 6.0 6.0 8.0 10.0 8.0 One piece flow can reduce and eliminate delays and waiting time.

  26. TAKT time TIME A B C D E Operations 1 2 3 4 5 Operators Standard WorkWork Load Diagram - Analyze time of the Operator Excessive available time C B D A E human work time available time machine work time

  27. TAKT time TIME A B C D E Operations 1 2 2 2 1 Operators Workload Diagram New organization of human work and machine work C B D A E human work time available time machine work time

  28. Workload DiagramHuman work time separated from machine work time TAKT time Utilization of Available Time Maximize the available time by redistributing the work. C B D A E TIME Two workers: multiple operations human work time available time 1 2 3 4 5 machine work time Operators

  29. TAKT To reduce the available time, redistribute the work 3 Min A B E C D 1.8 2.7 2.1 1.2 2.4 DO NOT Hide the available time. TAKT Hidden 3 Min waste A B D C 2.55 2.55 2.55 2.55 TAKT Make the available time visible (make “ugly”) Visible waste 3 Min A C D B 3 3 3 1.2 Make the available time visible

  30. OPERATION SEQUENCE SHEET SUMMARY Actual Proposed Date: Process Team: Process Observed: Minutes Number Minutes Number SET-UP TIME MACHINE TIME HUMAN WORK INSPECTION TRANSPORTATION STORAGE DELAY TOTALS TRANS. DISTANCE TRANSPORTATION MACHINE TIME HUMAN WORK INSPECTION SET-UP TIME STORAGE DELAY # OPERATION

  31. Barriers to Flow • Long lead times • Large batch sizes • Long setup times • Quality problems • High WIP levels • Poor layout • Wrong sized machinery • Unreliable machinery

  32. Ways to Implement Flow • Move processes closer together in cellular flows • Spaghetti diagram • Modify work sequences to be in line with customer requirements • Takt Time • Reduce setup time and then lot sizes • SMED • Balance the workload to prevent overproduction • Work load diagrahm • Reducing/eliminating machine breakdowns • Preventative maintenance and total productive maintenance (TPM) • Reducing/eliminating defects and rejects • Process control and poka-yokes • Reducing/eliminate information flows • Making expedites of no use • Shorter lead-times

  33. Five Step Cell Design Process • Group products • Establish takt time • Review work sequence • Combine work to balance process • Design the layout

  34. Establishing Takt Time • Net available time includes planned downtime: • Breaks, lunch, clean-up time, team meetings, TPM • It does not include: • Material outages, breakdowns, tardiness, changeovers • Takt time is used to synchronize pace of production with pace of sales

  35. Takt Time • Can only be changed if the available time or customer demand changes • Must be re-calculated on a regular basis • Drives staffing decisions for cell layout • Should not be adjusted to accommodate system problems • Pace the process to a planned cycle time to accommodate system problems

  36. Planned Cycle Time • Cycle time calculated with factors that affect overall production • Do not plan for waste Remember: (see slide 42) # of people needed = cycle time takt time

  37. Review Work Sequence • Current layout and material flow • Observe work sequence of tasks each worker performs • Collect current cycle times • Identify value-added versus non-value-added elements • Eliminate non-value-added elements

  38. Review Material Flow

  39. Review Current Work Sequence

  40. Time Observation Form • Three types of Cycle Time • Machine Cycle Time • Time it takes for a machine to produce one unit, including the time taken to load and unload • Machine Time • The time it takes for a machine to produce one unit, exclusive of loading and unloading • Operator Cycle Time • The time it takes for a person to complete a predetermined sequence of operations, inclusive of loading and unloading; exclusive of time spent waiting

  41. Time Observation Form

  42. Determine Labor Requirements

  43. Create Work Load Diagram

  44. Identifying Non Value-Add Waste Do a waste walk to identify the 8 types of waste seen

  45. Waste Walk Tips • Start with training • Select “big hitter” process to observe • Use teams to perform waste walk: • A skilled facilitator • Management from the area • “Subject matter experts” on the process • Members from other areas • Use a standardized form to collect data • Carefully record the waste seen • Combine like ideas together • Use multi-voting or weighting to prioritize • Decide on the forum for action

  46. Spaghetti Diagram Tips • Start with training • Select “big hitter” process to observe • Be the “thing” – record all touches and distance traveled between them • Secure a to-scale layout of the workspace • Draw your spaghetti diagram as you walk the process – USE PENCIL • Engage in brainstorming and prioritization of ideas • Decide on the forum for action

  47. Spaghetti diagram CELL 1 INTERNAL: 3380 FEET EXTERNAL: 26,400 FEET (SPIDER) EDM GANG DRILL TUMBLE CLEAN-AIR BENCH ENSHU LAPMASTER HONE OVEN CLEAN-AIR BENCH PRESSURE WASH MAZAK V-10 HELICOIL BENCH P/C

  48. Design Cell Layout • Physical location of machines should correspond to work sequence • U-shaped designs are most efficient • Movement should flow counterclockwise • Benefits: • Improves flow • Reduces inventory build-up

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