(See related pages)
Assembly line | Equipment or work processes are arranged according to the progressive steps by which the product is made. |
Assembly-line balancing | The problem of assigning all the tasks to a series of workstations so that each workstation has no more than can be done in the workstation cycle time, and so that idle time across all workstations is minimized. |
Manufacturing cell | Groups dissimilar machines to work on products that have similar shapes and processing requirements. |
Precedence relationship | The order in which tasks must be performed in the assembly process. |
Project layout | The product remains at one location, and equipment is moved to the product. |
Systematic layout planning (SLP) | A technique for solving process layout problems when the use of numerical flow data between departments is not practical. The technique uses an activity relationship diagram that is adjusted by trial and error until a satisfactory adjacency pattern is obtained. |
Workcenter | Also called a job-shop or functional layout; a format in which similar equipment or functions are grouped together. |
Workstation cycle time | The time between successive units coming off the end of an assembly line. |
Nội dung chính
- What is the time between successive units coming off the line?
- What is the cycle time for the assembly line in?
- What are the steps in line balancing an assembly line start at the beginning?
- What specifies the order in which a firm will make product components?
Assembly line balancing
An assembly line consists of a series of workstations each with a uniform time interval that is referred to as a takt time (which is also the time between successive units coming off the end of the line) At each workstation work is performed on a product by adding parts and/or by completing an assembly operation. The work performed at each station is made up of many tasks (also referred to as elements, or work units). Such tasks are described by in option-time analysis. Generally, they are groupings that cannot be subdivided on the assembly line without paying a high penalty in extra motions. The total work to be performed at a workstation is equal to the sum of the tasks assigned to that workstation. The assembly line balancing problem is one of assigning all of the tasks required to a series of workstations so that the time required to do the work at each station does not exceed the takt time, and at the same time. the unassigned (i.e., idle) time across all workstations is minimized. An additional consideration in designing the line is to assign the tasks as equitably as possible to the stations.
The problem is further complicated by the relationships among tasks imposed by product design and process technologies. This is called the precedence relationship which specifies the order in which the tasks must be performed in the assembly process.
Steps in assembling line balancing.
The sequence of steps required to balance an assembly line is
straightforward:
I. Specify the sequential relationship among tasks using a precedence diagram. The diagram consists of circles and arrows. Circles represent individual tasks; arrows indicate the order of task performance.
2. Determine the required takt time (T). using the following formula: Production time per day T = Output per day (in units)
3. Determine the theoretical minimum number of workstations (NI) required to satisfy the takt time constraint using
the following formula:
Sum of task times (S)
N =--------
I Takt time (T)
4. Select a primary rule by which task are to he assigned to workstations, and a secondary rule to break ties.
5. Assign tasks. one at a time. to the fir~t workstation until the ~UI11of the task times is equal to the takt time, or no other tasks are feasible because of time or sequence restrictions.
1.Repeat the process for Workstation
2. Work-ration
3. and so on. until all tasks are assigned.
6. Evaluate the efficiency of the resulting assembly line using the following formula:
Sum of ta-k times (S) Efficiency = ~-~--:---=---:----:----------
Actual number of workstations (N,,) '< Takt time (T)
7. If efficiency is unsatisfactory, rebalance the hue using a Jltkrent decision rule.
A toy company produces a Model J Wagon that is to be assembled on a conveyor belt. Five hundred wagons are required per day. The company is currently operating on a one-shift, eight-hour-a-day schedule, with one hour off for lunch (i.e., net production time per day is seven hours). The assembly steps and times for the wagon are given in Exhibit 8.10. Assignment: Find the balance that minimizes the number of workstations subject to takt time and precedence constraints..
What is the time between successive units coming off the line?
Workstation cycle time is the time between successive units coming off the end of the assembly line.
What is the cycle time for the assembly line in?
Cycle time of Assembly Line is the maximum time of individual work stations. Balance delay indicates the ideal time on the assembly line. Assuming Production happens 24 Hrs in 3 shifts each of 8 hrs.
What are the steps in line balancing an assembly line start at the beginning?
Steps in Assembly Line Balancing.
Outline your workstation sequence and draw a precedence diagram. ... .
Estimate the needed cycle time for each workstation. ... .
Calculate the hypothetical number of workstations you will need. ... .
Start assigning tasks to the workstations until the process times are equal..
What specifies the order in which a firm will make product components?
This is called the precedence relationship, which specifies the order in which tasks must be performed in the assembly process. In assembly-line balancing the theoretical minimum number of workstations is found by a ratio of the sum of all task times divided by the cycle time.