Assembly Line Balancing: Workstations

[@saDikus1]

Hello, the 9.6 mins is Takt time. Line cycle time is 8 mins. Thanks for the detailed analysis. It helps.

[@rodneyjav31]

The line cycle time is under takt time, is this the reason what te efficiency is calculate with 8 sec an not 9.6 seconds? Thanks for your answer

[@saDikus1]

@@rodneyjav31 yes. Takt is the expected production rate. 8 mins CT is the bottleneck which decides the line output. Hence, productivity uses it for calculation.

[@NusratJahan-mr5rb]

How to calculate line cycle time

[@camgere]

Very clear explanation. One worker could do tasks A & D in 9 minutes (under 9.6 minutes). Cellular manufacturing often has a U shaped path to allow workers easy access to more than one station.

[@carycountryman]

Remember the calculation on the minimum number of workstations is a theoretical minimum. To get the current process to 6 workstations as calculated, you would have to try a reduce the time associated with the tasks and re-arrange the process in order to maximize the cycle time in each workstation (no idle time).

[@yasarusta4410]

Sir you are very nice teacher.And you are teaching with Excel.It is so impressive.I can comfortly understand without my native language is not English.Thanks a lot.

[@benardictokositany4535]

Suppose that an assembly line contains the following task times in seconds: 40, 30, 15, 25, 20, 18, and 15. The line runs for 7 ½ hours per day and demand for output is 750 units per day. The workstation cycle time required to produce 750 units per day is 36 seconds. The problem is that one task in an assembly line takes 40 seconds. Discuss possibilities on dealing with such a task

[@carycountryman]

You have to figure out how to reduce that task time or break it into two different tasks.

[@carycountryman]

Given the present process and the amount of time for each task, you cannot get six workstations. If you could reduce the amount of time necessary for the task, it may be possible to combine tasks and stay under the cycle time of 9.6 minutes. For example, if you could reduce the time it takes to do task B from 7 minutes to 5 minutes, then tasks A & B could be combined into one workstation.

[@janardansubedi257]

Wow.It helped me out. Thanks a lot. Love from Nepal

[@carycountryman]

I am glad that you found it helpful. I keep thinking these videos are dated and no longer provide value. They really need to be redone but until I have some extra time, I will leave these videos up

[@carycountryman]

Recognize that the minimum number of workstations is just theoretical (if we can take the total amount of time associated with each task and divide it up into equal chunks of time then it would be possible to achieve this always). This is not always possible given the actual process and associated tasks. You simply try to make it as efficient as possible given the times of each task and the relationship between the tasks. You cannot exceed the cycle time.

[@gagzman1]

+Cary Countrym Hello sir Please i would love to know Could there be a situation where your min no of workstation is less than 1 If so what do you do in such a situation

[@carycountryman]

+Oghenevwogaga Izoma When calculate the theoretical minimum number of workstations, you should also round up. If you did get less than one, which would be very unusual, then theoretically all of the task could be grouped into one workstation.

[@andrekimble9239]

What if you have more workstations then needed?

[@carycountryman]

You try to group as many task together as you can while staying under the cycle time and looking at the order that tasks have to be done in (you cannot group a task at the end with one at the beginning). Due to these limitations, you may have to have extra workstations and therefore, the efficiency would go down. This is when you might want to analyze your process and determine if you can reduce the task times or rearrange the task to allow for more efficient grouping of the tasks into workstations.

[@euclides907]

Hello thank you for this video. I have one quick question. Why would we want to divide our total task time by 8 * #of stations, instead of dividing the "total task time" by ("Cycle Time" * Number of stations)

[@carycountryman]

+jasson toledo To calculate efficiency, you want to divide the Total Task Times by (the actual number of workstation (8) x the maximum cycle time in the actual workstations). This is to calculate the efficiency of the process as it currently is based on the grouping of tasks and the ability to maximize cycle time in the grouping of workstations (no idle time).

[@carycountryman]

+jasson toledo To calculate efficiency, you want to divide the Total Task Times by (the actual number of workstation (8) x the maximum cycle time in the actual workstations). This is to calculate the efficiency of the process as it currently is based on the grouping of tasks and the ability to maximize cycle time in the grouping of workstations (no idle time).

[@rodneyjav31]

Hello, because de line cycle time is under de takt time, is the reason to change de formula, the system flow rate is the minimum between system flow rate and demand.

[@benchpresser356]

How did you create the precedence diagram?

[@carycountryman]

You can draw or create this diagram in Excel using the Insert Shapes. It allows you to create the circles and label them. The arrows (lines) are also a part of the Insert Shapes. I show students how to create these diagrams in my videos about CPM (Critical Path Analysis) and PERT.

[@benchpresser356]

@@carycountryman Thank you sir! I did that in my assignment. Your video was very helpful as my professor barely talked about it.

[@ienasgafer1476]

hi , i thought that the # of stations you found was 6, shouldn't that match, if you have to draw your station to find your idle min ? and you should have total of 6 station circles ?

[@carycountryman]

+Ienas Gafer Remember that the calculation for workstations is the "theoretical" minimum number of workstations. Mathematically, one just take the total amount of task times and divides by cycle time. The mathematical problem doesn't account for the overall process and the way it is organized. The process as it is currently organized does not allow one to combine tasks and stay under the cycle time. This is why there is 8 workstations. One can not get less than the theoretical minimum number of workstations but often one has to have additional workstations because the tasks can not be grouped together because of the way the process was organized and the amount of time for each tasks.

[@nurulatikahlokman5875]

Sir may i know why the answer in the book for idle time is equal to 15 minutes.not same as to what you explain in the video.

[@carycountryman]

I probably need to go back and correct this video to reflect more of the practical approach to idle time. What I show in the video is the "theoretical" idle time. You will notice that the highest time for all of our workstations is 8 minutes. This means that in practical terms you do not have to wait until 9.6 minutes to cycle. You could cycle every 8 minutes. Instead of figuring out idle time for each workstation at 9.6 minutes, you would use 8 minutes. However, you will produce more than the daily demand of 50 (you will actually produce 60 units and cycle 60 times instead of 50). Therefore, your idle time would be 4+1+2+3+2+1+0+2=15 minutes instead of 27.8 minutes and it asks for the idle time for the entire day: since we are cycling every 8 minutes, we would cycle 60 times and that would give us (15 min X 60)/60 minutes = 15 hours per day. If we only wanted to produce 50 units and we used the cycle time of 9.6 minutes, this would give us (27.8 minutes X 50)/60 minutes = 23.17 hours per day.

[@nurulatikahlokman5875]

Thanks Sir for answering my doubt. I think now I do understand the different

[@steliosgallidis9778]

what if we are not given the demand ?

[@carycountryman]

You need to have demand in order to be able to calculate the cycle time. They might not use the term "demand" but instead use terms like forecast, quota, target amount, rate of production, etc. These are other ways of stating demand. How much do you need to produce?

[@ramdasmenon0908]

Which text book is this please?

[@carycountryman]

I am currently teaching an operations management course at BYU Hawaii and we have been using the textbook Principles of Operations Management (9th Edition) by Heizer and Render (published by Pearson). These videos were made some time ago to help my students and the question numbers do not match up with the current edition of the textbook.

[@ramdasmenon0908]

Thank you, sir

[@aaqibsultan6399]

Plz question 9.21 solve the problem

[@carycountryman]

You need to solve that one on your own. My purpose of creating these You Tube videos was to provide some simple examples to aid my students in learning the material but they still need to do their own homework and solve the other assigned problems on their own.