chapter 9
DESCRIPTION
Chapter 9. In-process Inventory, Just- In- Time, and Theory of Constraints. In-Process Inventory. 在製品存貨是完成成品所經過的每個階段情況下,所產生的項目構成,在製品可能是經過 一個或多個加工程序 所形成,所以在製品常是製造業面臨的問題。 對於在製品的投資評估,包括直接材料費用、直接人工、製造加班的成本所累計而成。. Production Processes. 1. Continuous Processes & Flow Shop. - PowerPoint PPT PresentationTRANSCRIPT
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Chapter 9
In-process Inventory, Just- In- Time,and Theory of Constraints .
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In-Process Inventory
在製品存貨是完成成品所經過在製品存貨是完成成品所經過的每個階段情況下,所產生的項目構成,的每個階段情況下,所產生的項目構成,在製品可能是經過在製品可能是經過一個或多個加工程序一個或多個加工程序所所形成,所以在製品常是製造業面臨的問題。形成,所以在製品常是製造業面臨的問題。 對於在製品的投資評估,包括對於在製品的投資評估,包括直接材料費用、直接人工、製造加班的成直接材料費用、直接人工、製造加班的成本所累計而成。本所累計而成。
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Production Processes
1. Continuous Processes & Flow Shop
2. Intermittent Processes & Job Shop
3. Special Project
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Scheduling
1. Forward Scheduling
2. Backward Scheduling
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過多的在製品存貨會引起1. a long manufacturing cycle time.2. a complex and costly control system.3. high materials movement cost.4. high floor space requirement.
In-Processes InventoryIn-Processes Inventory在製品存貨能防止工作站作業的停止,並可調節瓶頸站及各工作站間的通路。在製品有何用途 ?過多在製品又將會如何 ?
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LEAD TIMELEAD TIME
Setup
time
Process
time
Wait
time
Move
time
Queue
time
Manufacturing Cycle Time
生產循環時間 (Production Cycle Time)是由採購原物料到成品完成並包裝所需時間製造循環時間 (Manufacturing Cycle Time)是所有製造所需作業的時間
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Time Cycle Charts
Critical items line
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Bottleneck Work Centers瓶頸工作站明顯是限制產能的地方,如果想要增加全部產能,就必須擴充瓶頸工作站的產能。
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Input / Output Control
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Input / Output Control
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減少在製品存貨1. 購買物料的交貨排程,要在第一個作 業開始日期到達2. 在作業需要時,才由倉庫中領出物料3. 平衡投入和產出4. 在人員、物料、工具和供給服務齊全 下才開始作業5. 在實際需求下才考慮使用時間的增加
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Critical Ratio TechniqueCritical Ratio Technique
決定一些會使用相同設備下,訂單之先後順序critical =
完成工作所需時間當天日期需求日期
完成工作所需時間剩餘時間
供給時間需求時間
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Just - In - TimeJust - In - Time
JIT 是意味著對必要的東西在必要的時間裡只生產必要的數量。如果及時生產能在公司整體性達成,工廠裡多餘的庫存都會完全被排除,使貯藏室或倉庫變成不必要的設施。存貨費用也將減少,資本週轉率也將可隨之提高。
JIT 有何目的 ?用途 ?( 請你列出 !)
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breakdownsbreakdowns
defectsdefects
JIT
queuesqueuesWork-in-process
lead timelead timelot excesseslot excesses
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breakdownsbreakdowns
defectsdefects
JIT
queuesqueuesWork-in-process
lead timelead timelot excesseslot excesses
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breakdownsbreakdowns
JIT
queuesqueues
Work-in-processlead timelead time
lot excesseslot excesses
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breakdownsbreakdowns
JIT
queuesqueues
Work-in-process
lead timelead timelot excesseslot excesses
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breakdownsbreakdowns
JIT
Work-in-processWork-in-processlead timelead time
lot excesseslot excesses
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Just-In-Time GoalsJust-In-Time Goals
Zero defectsZero defectsZero setup timeZero setup timeZero lot excessesZero lot excessesZero handingZero handingZero queuesZero queuesZero breakdownsZero breakdownsZero lead timeZero lead time
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傳統傳統 JITJIT些許缺點是可接受的 零缺點多量少樣 少量多樣快速生產是有效率的 均衡生產是有效率的
預留安全存量 安全存量是一種浪費存貨是一種資產 存貨是一種負擔線狀排列是必須的 線狀排列是可忽視的供應商是敵對 供應商是工作夥伴 供應來源多才安全 供應來源少較易控制 故障時才維修 預防保養等候時間愈長愈好 等候時間愈短愈好設置時間是必須的 設置時間愈短愈好命令式管理 互動式管理 工作權限受限制 工作權限依職務分配
ConventionalConventional vs. JIT
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KanbanKanban
Enhance quality assurance
Waste prevention
Small lot production
Waste reduction
Expose quality problems
Improved JIT performance
Fast detection
Fast correctionQuality problem
elimination
Further lot
size reductions
Start
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KanbanKanban
看板數量的決定公式如下:DL(1.0 + a)
Q a= safety stock policy variable D= demand per day in units L= lead time Q= quantity of parts held in a container
N≧
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Theory Of ConstrainsTheory Of Constrains
限制理論認為任何系統至少存在著一個限制理論認為任何系統至少存在著一個限制,否則就有可能有無限的產出。限制,否則就有可能有無限的產出。想要提高一個系統的效能,必須要打破想要提高一個系統的效能,必須要打破系統的限制。系統的限制。
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Bottleneck & non-bottleneckBottleneck & non-bottleneck
任何系統都可以看做是一連串的環節,任何系統都可以看做是一連串的環節,而這個系統的強度則是取決於其最弱的而這個系統的強度則是取決於其最弱的一環,而不是最強的一環。一環,而不是最強的一環。因此,若我們從因此,若我們從瓶頸瓶頸下手改善,會有比下手改善,會有比較顯著的效果。較顯著的效果。
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TOC TOC & & BottleneckBottleneck
如果我們強化了系統中最弱的一環,另一個次弱的環就會成為最弱的環。也就是說一個系統的限制會隨著改善四處移動。限制理論便是利用不斷地強化瓶頸,來達到全體提升的目的。
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Drum-Buffer-RopeDrum-Buffer-Rope
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VAT PlantsVAT Plants
End items End items End items
V-Plant A-Plant T-Plant
Input Input Input
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Continual ImprovementContinual ImprovementIdentify constrains
Optimize constraint output
Subordinate all decisions to constraint optimization
Expand the constraint
Is
constraint
still active?
Yes No