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1、第五章 流水生产组织,第一节 流水生产的基本概念 一、流水生产的概念 流水生产起源于福特汽车装配线。由于采用流水生产，汽车装配时间从12小时28分减少为2小时28分，生产成本由2800多美元，降为800多美元，使汽车成为大众化交通工具。,流水生产就是产品按预定的工艺顺序、统一的速度，连续不断地通过各个工作地，完成加工的一种生产组织形式。 二、流水生产的特征 1）工作地专业化程度高； 2）按统一节拍运行； 3）按产品专业化布置； 4）比例性程度高； 5）采用平行移动方式。,三、流水线的种类 1）按对象移动与否 固定式流水线 移动式流水线 2）按产品品种数 单一品种流水线 多品种流水线,6）按流水
2、线机械化程度 手工式流水线 机械化流水线 自动式流水线 四、组织流水生产的条件 1）产品市场需求量足够大； 2）产品结构和工艺合理； 3）产品标准化程度高。,第二节 单对象流水线组织设计 流水线包括硬件设计和软件设计。 硬件设计：技术设计:工艺设计、工艺装备设计、专用设备设计、运输装置设计等。 软件设计：节拍确定、设备数和工人数的确定、工序同期化、平面布置、标准计划。,一、单对象流水线组织设计 1、确定流水生产节拍(r） 节拍:流水线上连续出产相邻两件同种制品的时间间隔。 节拍是流水线硬件和软件设计的重要参数，决定了流水线的生产速度和生产能力。 公式计算：,Fe= 计划期有效工作时间； F0=
3、计划期制度工作时间； = 时间利用有效系数(0.90.96)； N= 计划期产量； 节奏(R )：连续出产相邻两个同种制品运输批的时间间隔。 当制品单件时间短、体积小、工序间距离较大时，按一定批量在工序间转移。,R= r n n= 转移批量。 2、流水线及各工序设备数和负荷率 i 工序需要的设备数Si (工作地数)，,工序和流水线设备负荷率：,Si 不为整数时 ： Sei = Si ， =取整号，取大于和接近于Si 的整数。 i工序设备负荷率：,流水线总负荷率：,k=0.851.05：组织连续流水线； 0.75-0.85：组织间断流水线。 负荷率与流水线连续性直接相关。 3、工序同期化 通过技
4、术组织措施, 调整各工序时间，使其与节拍相等或与节拍成整数倍。,工序同期化水平决定了流水线的负荷率和连续程度。 设备加工为主的同期化措施 1）改进设备、工装和加工工艺； 2）加大切削用量、减少加工工时； 3）改进工作地布置和操作方法，减少辅助时间。 4）提高工人操作水平和熟练程度。,手工操作为主的工序同期化措施 1）分解和组合工序； 2）合理调配工人； 3）采用高效工具；,Example of Line Balancing,Youve just been assigned the job a setting up an electric fan assembly line with the f
5、ollowing tasks:,Example of Line Balancing: Structuring the Precedence Diagram,Task Predecessors,ANone,A,BA,B,CNone,C,DA, C,D,Task Predecessors,ED,E,FE,F,GB,G,HE, G,H,Example of Line Balancing: Precedence Diagram,Question: Which process step defines the maximum rate of production?,Answer: Task C is t
6、he cycle time of the line and therefore, the maximum rate of production.,Example of Line Balancing: The Bottleneck,Example of Line Balancing: Determine Cycle Time,Question: Suppose we want to assemble 100 fans per day. What would our cycle time have to be?,Answer:,Example of Line Balancing: Determin
7、e Theoretical Minimum Number of Workstations,Question: What is the theoretical minimum number of workstations for this problem?,Answer:,Example of Line Balancing: Rules To Follow for Loading Workstations,Primary: Assign tasks in order of the largest number of following tasks. Secondary (tie-breaking
8、): Assign tasks in order of the longest operating time,C (4.2-3.25)=.95 Idle = .95,Which station is the bottleneck? What is the effective cycle time?,Example of Line Balancing: Determine the Efficiency of the Assembly Line,组织工序同期化的方法 例：某产品的生产节拍为10分钟，各工步的时间定额和工步顺序如下图示：,1,2,3,4,5,6,7,8,10,9,11,6,2,5,7
9、,1,2,6,3,5,4,5,Assembly Lines Balancing Concepts,Question: Suppose you load work into the three work stations below such that each will take the corresponding number of minutes as shown. What is the cycle time of this line?,Answer: The cycle time of the line is always determined by the work station
10、taking the longest time. In this problem, the cycle time of the line is 7 minutes. There is also going to be idle time at the other two work stations.,Example of Line Balancing,Youve just been assigned the job a setting up an electric fan assembly line with the following tasks:,Example of Line Balan
11、cing: Structuring the Precedence Diagram,Task Predecessors,ANone,A,BA,B,CNone,C,DA, C,D,Task Predecessors,ED,E,FE,F,GB,G,HE, G,H,Example of Line Balancing: Precedence Diagram,Question: Which process step defines the maximum rate of production?,Answer: Task C is the cycle time of the line and therefo
12、re, the maximum rate of production.,Example of Line Balancing: The Bottleneck,Example of Line Balancing: Determine Cycle Time,Question: Suppose we want to assemble 100 fans per day. What would our cycle time have to be?,Answer:,Example of Line Balancing: Determine Theoretical Minimum Number of Works
13、tations,Question: What is the theoretical minimum number of workstations for this problem?,Answer:,Example of Line Balancing: Rules To Follow for Loading Workstations,Primary: Assign tasks in order of the largest number of following tasks. Secondary (tie-breaking): Assign tasks in order of the longe
14、st operating time,C (4.2-3.25)=.95 Idle = .95,Which station is the bottleneck? What is the effective cycle time?,Example of Line Balancing: Determine the Efficiency of the Assembly Line,Group Technology:Benefits,1. Better human relations 2. Improved operator expertise 3. Less in-process inventory an
15、d material handling 4. Faster production setup,Group Technology:Transition from Process Layout,1. Grouping parts into families that follow a common sequence of steps. 2. Identifying dominant flow patterns of parts families as a basis for location or relocation of processes. 3. Physically grouping ma
16、chines and processes into cells.,重组工序原则： 1）组合工序工时不大于节拍； 2）组合工序符合工步顺序原则； 步骤：列出所有可能作为第i工序的工步组合方案； 求各编组方案后剩余时间可能组成的最少工作地数；,Ski = 第i工序，第K编组方案的可能最少工作地数；,全部工步,1、2、5,1、2、6,3、5,4、5,5、7,3、8,7,7,10,9、10,11,3、9,4,4、8,10、11,5,9,5,10,5,6,8,5,5,7,5,8,6,6,5,10,5,10,5,9,7,6,6,6,6,10,6,4,6,5,4、计算流水线所需配备的工人数 手工操作流水线 i 工序上所需的工人数： Pi =Sei Wi g 其中：Wi =i工序每一工作地上需同时工作的人
