人工装配线课件

1、Chapter 17: Manual Assembly Lines 人工裝配線Instructor：劉天倫 老師Chapter 17: Manual Assembly LiIntroductionClassification分類Type III MFavoring factors (characteristics) 採用的因素(特性) Demand is high or medium.需求是高或中等的Products are identical or similar.產品相同或相似The process can be divided into small work elements.過程可能被

2、分成小的工作項目Technologically impossible or economically infeasible.技術上不可能或在經濟上不可行IntroductionClassification分類IntroductionWhy is it productive?為什麼它是有生產力的？ Specialization of labor勞工的專業化 Learning curve學習曲線Interchangeable parts可互換零件 Work principle工作原則Applied to make smooth material handling可應用來達到平順的物料處理 Line

3、 pacing生產線步調Maintain production rate by a mechanized conveyor.透過機械化的輸送裝置保持生產率IntroductionWhy is it producti17.1 Fundamentals of Manual Assembly Lines人工裝配線的基礎Figure 17.1 (圖17.1) Assembly workstations 組裝工作站Workers stand or sit. 工人站或坐Average manning level 平均人工化水準 wu: number of utility workerswi : numbe

4、r of workers assigned to station iUtility workersHelping workersRelieving workersMaintenance17.1 Fundamentals of Manual 17.1.2 Work Transport Systems 工件運輸系統 Manual methods of work transport 人工方法的工件運輸Starving and blocking buffers 缺料和阻擋現象 緩衝區 Mechanized work transport 機械化的工作運輸 Continuous transport 連續的

5、運輸 Work units may be fixed or removable工件可能是固定的或可移動的例如輸送帶 (汽車或電子產品)Synchronous transport 同步運輸 Move simultaneously 同時移動(例如轉盤)Asynchronous transport非同步運輸Move independently、Small queues 獨立移動、小量等候17.1.2 Work Transport Systems17.1.2 Work Transport Systems 工件運輸系統Mechanized work transport 機械化的工作運輸17.1.2 Wo

6、rk Transport Systems17.1.3 Line Pacing 生產線步調Rigid pacing 硬性步調固定時間完成工作Pacing with margin 有範圍的步調Allowing queues 允許等候線Designing the station to be longer length 設計工作站有較長的輸送帶長度 For fixed work unit with continuous moving.Allowing to move beyond the boundaries 允許在邊界以外移動 No pacing 無步調No time limit 沒有時間限制 Ma

7、nual transport, removable work unit or asynchronous conveyor. 人工運輸、可移動的工件或非同步輸送帶Motivating workers to achieve a certain pace.激勵工人達到一定步調17.1.3 Line Pacing 生產線步調Rigid 17.1.4 Coping with Product Variety 對應於產品種類 Single model 單一模型 No varietyBatch model 批量模型 Hard varietyMixed model 混合模型 Soft varietyVs. ba

8、tch modelNo production time lost 沒有生產時間浪費 Lower inventories 較低的存貨Adjustable production rate 可調整的生產率 Line balancing problem 生產線平衡問題 difficult scheduling and logistics困難的排程和運籌 17.1.4 Coping with Product Var17.3 Design for Assembly (DFA) 為方便組裝的設計 During product design:在產品設計階段Fewer parts 更少的零件Easy to as

9、sembly. 容易組裝General principles 一般通則Use the fewest number of parts possible儘可能的使用最少的零件數量 Combine functions 結合功能 Reduce the number of threaded fasteners減少螺紋緊固件的數量 Standardize fasteners 使緊固件標準化 Less inventory and distinguish 較少存貨和辨識工作 Reduce parts orientation difficulties降低零件定向困難 Symmetrical features 對

10、稱的特徵 Avoid parts that tangle 避開纏結的零件Less hooks, holes, etc. 較少鉤，洞等等17.3 Design for Assembly (DFA)17.4 Analysis of Single Model Assembly Lines單一模型裝配線的分析 Required production rate (unit/hr) 所需生產率(單位/小時) Da: Annual demand 每年需求 plant operates 50 wk/yr 工廠一年運作50週 S:每週班次 H:每班次工作時數Cycle time週期時間(min/cycle) a

11、nd cycle rate週期率(cycles/hr 對於生產線而言) (E=0.90.98)E: line efficiency (uptime proportion) 生產線效率(正常運作時間比例)Work content time (Twc) 工作內容時間The total time of all work elements to make one product.製造一種產品的全部工作項目的總時間17.4 Analysis of Single Model 17.4 Analysis of Single Model Assembly Lines(Hourly) Workload (每小時

12、)工作量 Minimum number of workers 至少工人的數量 Theoretical formula because of:此乃理論公式因為Repositioning losses: 重新定位之損失E.g. workers walk from the ending position to the starting position.The line balancing problem 生產線平衡問題 Task time variability 工作時間變化性 Quality problem品質問題 17.4 Analysis of Single Model 17.4.1 Rep

13、ositioning losses . 重新定位的損失 Maximum allowable service time (Ts) 最大的可允許的服務時間Tr: repositioning timeFigure 17.4Repositioning efficiency 重新定位效率17.4.1 Repositioning losses .17.4.2 The Line Balancing Problem 生產線平衡問題 Assigning the individual work elements to workstations so that all workers have an equal a

14、mount of work. 把個別的工作項目分發到工作站，以便全部工人有相等的工作量。Concepts概念Minimum rational work elements 最小合理的工作項目 Precedence constraints先後順序限制條件 17.4.2 The Line Balancing Prob17.4.2 The Line Balancing ProblemMinimum rational work elements 最小合理的工作項目 A small amount of work having a specific limited objective (required t

15、ime: Tek)ne：number of work elements 工作項目的數量 The task time at station I 在工作站i 的工作時間 17.4.2 The Line Balancing Prob17.4.2 The Line Balancing ProblemPrecedence constraints先後順序限制條件 Restrictions on the order of the work elements.對工作項目順序上的限制E.g. drilling a hole before fastening a screw 例如固定一個螺絲之前需先鑽一個孔Pre

16、cedence diagram (先行圖)17.4.2 The Line Balancing Prob17.4.2 The Line Balancing ProblemExample 17.117.4.2 The Line Balancing ProbExample 17.1Example 17.117.4.2 The Line Balancing ProblemMeasures of line balance efficiency 生產線平衡效率的測量 where Ts = max Tsi Eb = 0.9 0.95Balance delay 平衡延遲Labor efficiency (勞工

17、效率) = E Er EbRevised number of workers 修正工人的數量 17.4.2 The Line Balancing Prob17.5 Line Balancing Algorithms 生產線平衡算法 To distribute the total workload as evenly as possible. 儘可能平均分發總工作量Heuristic methodsLargest candidate ruleKilbridge and Wester methodRanked positional weights method17.5 Line Balancing

18、 Algorithms17.5.1 Largest Candidate Rule(最大需時法則)依據 Tek 大小來決定步驟步驟 1：將Te值依遞減順序由上而下列出步驟 2：由上而下指派適合工作單元給第一個工作站先行關係Tek 總和小於Ts步驟 3：重複步驟 2 ，直到沒有適合的工作單元可加入步驟 4：重複步驟 2、3 建立其他工作站直到工作單元指派完畢17.5.1 Largest Candidate Rule17.5.1 Largest Candidate Rule(最大需時法則)Example 17.2Work ElementTekPreceded by30.7180.63, 4110.5

19、9, 1020.4-100.385, 870.32350.3290.276, 7, 810.2-120.121160.11340.11, 217.5.1 Largest Candidate RuleExample 17.2Example 17.217.5.2 Kilbridge 與 Wester 法(K-W 法)依據先行圖位置來指派工作單元，前端者先選入步驟步驟 1：建立先行圖，並將工作單元排列成行步驟 2：以步驟一所排之先行圖上的行數，列出工作單元步驟 3：按照行序從第一行開始，進行工作單元指派，直達到Ts值為止步驟 4：重複步驟 3 建立其他工作站直到工作單元完畢Example 17.31

20、7.5.2 Kilbridge 與 Wester 法(K-Example 17.3Example 17.317.5.3 Ranked Positional Weights Method (RPW, 相對位置加權順位法)依據工作單元的RPW值，再考慮先行圖位置與Ts值限制來指派步驟步驟 1：按先行圖箭頭之路徑計算每一工作單元的RPW值，即累加路徑上之Tek值步驟 2：依照RPW值之大小，由上而下表列工作單元步驟 3：按照RPW順序，且考慮先行關係與Ts值限制指派工作單元Example 17.4Which method is better?17.5.3 Ranked Positional Weig

21、hExample 17.4Example 17.417.6 Mixed Model Assembly LinesTypically used to accomplish the final assembly such as automobiles.Issues Number of workersLine balancing Model launching17.6 Mixed Model Assembly Line17.6.1 Determining Number of WorkersNumber of workersWorkload (min/hr)P: number of modelsThe

22、oretical minimum number of workersi.e. Er=100%, Eb=100%Realistically, Example 17.517.6.1 Determining Number of W17.6.2 Mixed Model Line Balancing TTsi:total service time at station ITotal time per element for all productsTotal service times at each stationMeasures of balance efficiency17.6.2 Mixed M

23、odel Line BalancExample 17.6 Example 17.6 Example 17.6 Example 17.6 17.6.3 Model Launching in Mixed Model LinesLaunching of base parts onto the beginning of the lineSingle model: the time interval = Tc (constant)Mixed model: different Twc different Ts launches are interdependentHigh Twc launching at

24、 short time intervals congestedLow Twc launching at long time intervals starved(idle)The model sequence in launching must consist of the same model mix used to solve the line balancing problem.Launching disciplineVariable rate launchingFixed rate launching17.6.3 Model Launching in MixeVariable rate

25、launchingThe time interval between the launching of the current base and the next is set equal to the cycle time of the current unit.Time interval before the next launchTwcj: work content time for the product model j just launchedExample 17.7AdvantageWithout causing idle time or congestion Problems

26、Work carriers are usually at constant intervalsSupplying the correct components. Variable rate launchingThe timFixed rate launching for two modelsThe time interval depends on the product mix and production rate.The models must be launched in a specific sequence to avoid congesting or starving.Fixed

27、rate launching for two mFixed rate launching for two models m: launch sequenceThe cycle time associated with model j in launch position hCongestion: positive differenceIdle time: negative differenceThe criteria to select model for launchingExample 17.8Fixed rate launching for two mFixed rate launchi

28、ng for more modelsThe previous equation does not provide the desired part mixModels whose Tcjh are close to Tcf over-producedModels whose Tcjh much differ from Tcf under-producedRevised formulationQjm: quantity of model j units remaining to be launchedThe additional term(Rpj/Qjm) is to reduce the ch

29、ances that a unit of model j will be selected as the number of that model j already launched increases.All Rpj could be divided by the largest common denominator, e.g. 4 A and 6 B 2 A and 3 BExample 17.9Fixed rate launching for more 17.7 Other Considerations in Assembly Line Design 其他組裝線設計的考慮Methods analysis方法分析 Improve hand and body motions, better workplace layout, etc.改進手和人體運動，更好的工作場所佈局Subdividing work elements再細分工作項目 E.g. drilling operation of thick cross-section hole.例如鑽厚的橫截面的孔Sharing work elements between