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1、1 Operations Scheduling ?Scheduling and Control Functions ?Job-shop Scheduling & Priority Rules ?Shop-floor Control ?Waiting Line Management 2 MPS MRP 投日期 工單編號 工作內容 加工時間 交貨日期 201 201 202 202 202 203 15131 15143 15212 15340 15312 15293 轉軸 100 栓 300 栓 100 鋼棒 150 轉軸 60 鋼棒 120 11.4 10.6 4.3 8.6 6.5 7.5
2、212 220 218 214 220 222 Production Scheduling Shop Floor Execution Manufacturing Execution System Scheduling Process 2 3 1. 指派工單、設備、人員 (short-run capacity planning) 2. 安排工單處順序 (sequencing) 3. 根據現場況釋出工單 (dispatching) 4. 監控生產進與常況 (monitoring) 5. 跟催工單程 (expediting) Scheduling and Control Functions Shop
3、 Floor Control ?準時交貨meeting due dates ?低程時間minimize flow time (lead time) ?低重置成本minimize set up time or cost ?低在製品庫存minimize WIP inventory ?提高人員/設備的使用improve utilization Do not try to maximize this Processes are either machine-limited or labor-limited 4 Job Assignment Team/Machine A B C D E 05132I 2
4、 1 2 1 2130V 3205IV 3012III 4502II Team/Machine A B C D E 38465I 5 3 4 5 5463V 5427IV 5234III 8946II Team/Machine A B C D E 03132I 2 1 2 1 0130V 1205IV 1012III 2502II Team/Machine A B C D E 02031I 3 1 3 1 0140V 0104IV 1022III 1401II Team/Machine A B C D E 02031I 3 1 3 1 0140V 0104IV 1022III 1401II S
5、cheduling n jobs on m machines n=m What if nm or nm? 3 5 Forward and Backward Scheduling Infinite Loading MRP is an infinite loading, backward scheduling system. Gantt chart 6 Priority rules 工單處優先法則 FCFS 先先處 SPT (SOT) 小工作先處 有效低平均程時間與現場 庫存 EDD 交期早的先處 有效改善交貨延誤程 STR 寬放時間少的先處 寬放時間(slack) =距交期天-工作所需天 Cri
6、tical Ratio CR 值小的先處 CR =寬放天/距交期天 Random 隨意挑選 Sequencing and Priority Rules A good sequencing rule should be dynamic and based on slack. 延誤程Tardiness (lateness)、程時間Flow time 現場在製品庫存WIP、人員與設備使用Utilization 4 7 到達順序 A B C D E 加工時間 3 4 2 6 1 交貨天 4 7 8 10 3 slack 1 3 6 4 2 FCFS 順序 程時間 延誤天 SPT 順序 程時間 延誤天
7、A 3 0 E 1 0 B 3+4=7 0 C 1+2=3 0 C 7+2=9 1 A 3+3=6 2 D 9+6=15 5 B 6+4=10 3 E 15+1=16 13 D 10+6=16 6 Average 10 3.8 Average 7.2 2.2 EDD 順序 程時間 延誤天 STR 順序 程時間 延誤天 E 1 0 A 3 0 A 1+3=4 0 E 3+1=4 1 B 4+4=8 1 B 4+4=8 1 C 8+2=10 2 D 8+6=14 4 D 10+6=16 6 C 14+2=16 8 Average 7.8 1.9 Average 8.6 2.8 Forward Sc
8、heduling, Finite Loading 8 Operation 1 Operation 2 A 3 2* B 6 8 C 5 6 D 7 4 從尚未安排之工單中選擇單站作業時間最短者* 該站為第一站，安排該工單於最前的空位 該站為第二站，安排該工單於最後的空位 ? ? ? A 重複以上步驟直到所有工單均排入，總工作時間(makespan)最短 ? ? D A C ? D A Johnsons rule for n/2 flow shop Forward Scheduling, Finite Loading Exhibit 17.4 5 9 Shop Floor Control 1.
9、Assigning priority of each shop order 2. Maintaining work-in-process information 3. Conveying information to the office 4. Providing actual output data for capacity control purposes 5. Providing quantity by location by shop order for WIP inventory and accounting purposes 6. Providing measurement of
10、efficiency, utilization, and productivity 7. Data Integrity = Shop Discipline 10 Dispatching 確認工單之相關 資訊，檢查工單所需各項資 源已經完備，根據現場 況，控制訂單釋出的時機 Anticipated Delay Report 預期會延誤之訂單，查明原 因並訂出因應措施 Input/Output Control Report 各單位實際生產進與預定 生產進之差距 Tools of Shop Floor Control 6 11 Principles of Work Center Scheduling
11、 ?work flow=cash flow ?現場管制的效能取決於 work flow的速 ?work flow的速取決 於瓶頸機台的改善 ?減少插單，避免中斷進 中的工作 ?儘低現場的確定 性與突發況 ?排程配合各機台的每日 實際進每日重新排程 Exhibit 17.9 12 Scheduling Service Systems (1) Scheduling customers 以顧客為依據 Appointment systems control the timing of customer arrivals. Reservation systems estimate demand for
12、a given time period. How to deal with process delay, emergency, late arrivals, no shows? (2) Scheduling workforce and equipment 以資源為依據 (3) Waiting Line Management 等候線管 7 13 Personnel Scheduling 1. Forecasting Demand 2. Convert into Workforce Requirements 3. Convert into Daily or Weekly Work Schedule
13、s 4. Assign Workers to Work Schedules Receive Preprocess MicrofilmVerify volume rate hours rate hours rate hours rate hours checks 2000 10002.0 6003.3 2408.3 6403.1 statements 10006001.7 2504.0 1506.7 notes 200306.715 13.3 investments 400 1004.0508.0 2002.0 1502.7 collections 500 3001.73001.7608.4 t
14、otal hours 14.426.316.020.9 adjusted 18.032.920.026.1 staff required 2.34.12.53.3 Exhibit 17.10 14 Scheduling Hourly Work Times: First Hour Principle 10 11 12 1 2 3 4 5 6 7 8 9 Requirement 4 6 8 8 6 4 4 6 8 10 10 6 Assigned 4 On Duty 4 將人員需求反映至值班表將人員需求反映至值班表 2 6 2 8 0 0 0 0 0 8 8 8 8 8 4 8 4 10 2 10
15、 0 10 2132434A 2132434forecast SunSatFriThuWedTueMon 2121323B 1120212C 1110101D Scheduling Consecutive Days OffExample 17.4 8 15 Waiting Line Management(TN 7 p.289) 服務完成 Queue discipline Arrival process 排隊方式 Service process Reneging Balking 潛在顧客 16 Service Capacity vs. Waiting Line Trade-Off EX. TN7
16、.1 Cost of Waiting Cost Cost of Capacity Service Capacity Large Small Total Cost minimum 9 17 Perceived Wait TimePerceived Wait Time ?顧客認知的等候時間長 等於實際等候時間 ?對顧客滿意較有影響 t* 0 0.2 0.4 0.6 0.8 1 perceived wait 容忍界值 敏感 Satisfaction Actual Wait Time vs. Perceived Wait Time 18 等候的型等候的型 公平與公平的等待 舒適與舒適的等待 可解與可解
17、的等待 有同伴與無同伴的等待 等待高價值或低價值服務 建設性與無建設性的等待 主動與被動的等待 Suggestions for Managing Queues 1. 評估顧客願意接受的等侯時間長 2. 轉移顧客的注意 3. 提前告知顧客可能的況 4. 讓顧客誤認服務人員怠職 5. 將顧客分進服務 6. 訓服務人員表現友善與關懷 7. 鼓顧客使用峰時段 8. Take a long term perspective. 10 19 Multiple Queue Take a Number 34 8 2 610 12 11 5 7 9 多對多：應該排那邊？ 一對多：號碼牌制 多對一：應該服務誰？(t
18、raffic control) Enter Single queue Queue Structure(number of lines) ? 20 Queue Capacity (Limit)等候隊伍容 影響顧客是否能夠加入排隊以及排隊情緒 degree of patience 到達後觀察即去arrive, view, and leave (balking) 排隊至中途才去arrive, wait awhile, and leave (reneging) Queue Discipline 排隊規則 First Come, First Served (FCFS, FIFO)先先服務 Shortes
19、t Processing Time (SPT)小工作先服務 Earliest Due Date (EDD)先交件先服務 Priority預約或視潤高低 Emergencies first依緊急程而定 11 21 ?finite or infinite population 潛在顧客人多寡 ?stationary or unstationary 尖峰與峰時段 ?exponential interarrival times = Poisson process 顧客隨機到達 ! )( )( )( n eT nTPetf Tn t = 0.00 0.05 0.10 0.15 0.20 0.25 012
20、345678910 0.00 0.10 0.20 0.30 0.40 0.50 05101520 Customer Arrival Process 22 Service Process: single server, single phase Poisson到達速； 服務速 服務變性 2 System load = / 1 model 1 (exponential service 2=(1/)2) model 2 (constant service 2=0) + = 12 W TimeWait 2 22 q Queue LengthLq=Wq System TimeWs=Wq+1/ Numbe
21、r in systemLs=W n n P = 1 model 1 only 12 23 Service Process: Multiple servers, single phase Number in systemLs=Lq+ / Wait TimeWq=Lq/ System TimeW=Wq+1/ Poisson到達速； 服務速 服務人員目S (S) Model 3 (exponential service) Use = /and S to find Lqfrom exhibit TN7.11 =1LP(wait) q S 24 Conclusion ?Workflow equals c
22、ash flow. Scheduling lies at the heart of this process. ?Software packages are available to schedule jobs to determine bottlenecks and adjust job priorities. ?In services, the focus is on employee scheduling to meet expected customer demand. ?Waiting line management must balance the cost of waiting with the cost of adding more resources