Chapter 14: JIT and Lean Operations History of TOYOTA Lean Production Goals and Building Blocks Lean Service History of Toyota Toyota switched from automated looms to military trucks just prior to WWII. Secondhand equipment and high unit costs forced Toyota to reduce waste and improve quality whenever possible. Toyota Production System was not invented overnight it is the outcome of a long evolution. 2 1
Lean Production 精實生產 Just in time: A highly coordinated production system in which materials are moved through the system with precise timing, just as they are needed. JIT (pull) MRP (push) JIT = lean production Lean operations for service systems. 3 The Toyota Approach Muda: waste and inefficiency ( 浪費 ) Heijunka: workload leveling ( 平準化 ) Kaizen: continuous improvement ( 改善 ) Jidoka:automatic detection ( 自働化 ) Poka yoke: fool proofing to reduce errors Team concept: small teams for improvement ( 品管圈 ) Kanban ( 看板 ) Pull system: supplying material based on demand 5 2
Goals and Building Blocks of JIT 6 Supporting Goals Eliminate Disruptions such as poor quality, equipment breakdowns, changes to the schedule, and late deliveries. A Flexible System: reduce setup and lead times in order to handle a mix of products and deal with some uncertainty. Eliminate Waste: Inventory, Overproduction, Waiting time, Unnecessary transportation, Processing waste, Inefficient work methods, Product defects Muda: 庫存過多 生產量過多 待工待料 搬運與包裝 產品設計過度 加工方法浪費或缺乏效率 不良品 7 3
Building Blocks: product design 1. Standard parts. 2. Modular design. 3. Highly capable production systems with quality built in. 4. Concurrent engineering. 8 Building Blocks: process design 1. Small lot sizes. 2. Setup time reduction. 3. Manufacturing cells. 4. Quality improvement. 5. Production flexibility. 6. A balanced system. 7. Little inventory storage. 8. Fail safe methods. 9 4
Single Minute Exchange of Dies 快速換模 faster set up smaller lot sizes smaller inventory F1 Pit Stops 1950 vs 2013_ Quick Changeover internal setup external setup 事先調整定位 簡易拆卸 預熱模具 10 Jidoka (autonomation) automatic detection of problems Kaizen: Continuous Improvement 降低庫存迫使生產線必須面對並解決各種問題 11 5
Building Blocks: personnel/organizational elements 1. Workers as assets. 2. Cross trained workers. 3. Continuous improvement. 4. Cost accounting. 5. Leadership/project management. 12 Building Blocks: manufacturing planning and control 1. Level loading. 2. Pull systems. 3. Visual systems. 4. Limited work in process (WIP). 5. Close vendor relationships. 6. Reduced transaction processing. 7. Preventive maintenance and housekeeping 整理 Seiri 整頓 Seiton 清掃 Seiso 清潔 Seikeetsu 素養 Shitsuke 13 6
Heijunka (level loading) 根據實際需求安排生產計劃, 使生產量與生產內容平準化 當月計劃生產 800A 600B 400C 每週生產 200A 150B 100C 每天生產 40A 30B 20C 實際現場排程 AAAABBBCC AAAABBBCC mixed model production 14 Kanban 由下游往上游拉 (pull) 的物料控制方式, 看板提供的相關資訊, 包括時間 規格 數量 運送地點等 15 7
Pull System with Kanban Control 上游 6 P 看板 4 2 P 看板 1 C 看板 7 A 5 前製程 B C 看板 3 A 2 後製程 B 市場 運送看板 (Conveyance): 各站完成加工的產品必須得到下游的運送看板才能前進 生產看版 (Production): 各站等待加工的產品必須得到該站的生產看板才能進行加工 16 Single-Kanban Systems Machine 1 (b) Machine 2 Demand Kanban 2 17 8
Machine 1 Machine 2 (c) Kanban 1 Machine 1 Machine 2 (d) Supply 18 Determining the Number of Kanbans Needed N = DT(1+X) C N = Total number of kanbans D = Planned usage rate of using work center T = Average waiting time for replenishment of parts plus average production time for a container of parts X = Policy variable set by management possible inefficiency in the system C = Capacity of a standard container 19 9
JIT Delivery and Focused Factory Networks 減少零組件庫存 直接配送至生產線使用地點 少量多次補貨 簡化訂貨與驗收 選擇鄰近供應商 發展成中衛體系 協助供應商改善品質 quality at the source 20 Lean Services Eliminate disruptions. 服務顧客時不中斷接聽電話 Make the system flexible. 訓練多能工以提高彈性 Reduce setup times and processing times. 備妥常用工具 資料庫查詢 Eliminate waste. 員工訓練, 減少錯誤與重工 Minimize work in process. 防止工作積壓 Simplify the process. MOD 電影 21 10
Conclusion Lean Production is suitable for assemble to stock, high volume and low variety production. The goal is to achieve a balanced, smooth flow of production. Key elements include quality at the source, elimination of waste, continuous improvement, setup time reduction, workload leveling, kanban control. There is more to a successful operational turnaround than the application of a set of tools. 是信仰, 不是技術 Mindsets of employees must be involved in the process. 22 11