Which of the four lead time elements discussed on page 279 might cause the most difficulty? Why? Why might other lead time elements be less important?
Queue time frequently accounts for 80 percent or more of total lead time; it’s the element most capable of being managed. Reducing queue time means shorter lead time and, therefore, reduced work-in-process inventory. This reduction requires better scheduling. Queue time can be compressed with good PAC design and practice.
Out of the four elements queue would cause the most difficult of all. Since queue time is the period of time during which the product awaits transfer to a workstation, undergoes further inspection and subsequent manufacturing processes. It is the single largest element in the overall lead time and its elimination is critical for successful drive toward manufacturing process. The reason why other lead time elements be less important than queue time is because queue is the amount of time a lot must wait at a work center before the operation is set up and production begins.
What does the textbook say about queue time that may not make it the most difficult to manage? And since it may not be the most difficult, which of the remaining three elements is the most difficult to manage? And why?
I think run time would be the hardest to manage, because how ever long it takes to run the lot size is how long it takes(5 seconds per lot or 5 hours per lot), the run time is pretty much set . Managers can not make the machines go faster . Run time is typically the most difficult to manage because you have a plethora of factors that impact how effective the “run” or the “process” is. Some of these include employee skill sets, employee experience, machine/equipment slippage, process slippage, documented procedures vs. tacit knowledge, time of day, time of week, status of customer satisfaction, etc.
I think that all four elements have their own individual challenges and obstacles that will need to be overcome. The Run time does seem to me to be the most difficult to alter or speed up. You can only run a machine as fast as it is designed to handle. There is always the option of upgrading equipment when available to get faster results from them. The likely hood of being able to purchase upgraded equipment is not good so therefore keeping your equipment well maintained and running at optimal speed is the best that can be expected to keep things running smoothly.
With most of the process parameters being fixed, the run time is the most difficult to manage. This is followed by the setup time. These are pretty much technology/process dependent and there is a little room for change/improvement. Mostly, the change would come with the upgrade in the equipment or chane in the process which is a costly affair. Probably the move time and queue time is easy to manange as there is a lot of room for process improvement here and Textbook also mentions that Queue time frequently accounts for 80 percent or more of total lead time; it’s the element most capable of being managed.
If queue time and move time are easy to manage, what does it do to the overall lead time?
Move and queue time can be compressed with good PAC design and practice. Reducing queue time means shorter lead time and, therefore, reduced work-in-process inventory. Queue time represents slack that permits the choice of alternative schedules. This slack can be removed by good SFC practice. With the ability to manage queue time and move time it will allow you to tighten these areas if you need to make up time to meet deadlines. So having areas that can be altered easily or contained will allow you to make up in areas that are not so easily maintained.
However, move time would be the next easiest. Queue time and Move time are the two elements most capable of being compressed. Does this make sense?
Of the four elements of lead time, which element might cause the most difficulty, and why? Also, why might other lead time elements be less important?
What would cause the delays with move time? Also, isn’t the actual delay considered queue time?
I think there is a fine line between queue time and move time because they seem to be ralated to each other in a way. If there is less queue, move time will be minimal. On the other hand, if there is a long queue, the delay cause by the queue will mean that it will take a longer time to transition from one work center to another.
A delay in move time could be caused by an issue that has happened in the next work center such as a machine breaking down or resources not being available to further the production. Move time differs from queue time in that move time is the delay of waiting to be moved plus the time spent moving from one work center to another where as the queue time is the time spent waiting to be processed at the work center. Queue time is the most critical because it usually counts for 80% or more of the total lead time in production. In order to reduce lead time you must reduce queue time or work-in process which requires good scheduling
Jacobs, Berry, Whybark and Vollmann. Manufacturing Planning and Control for Supply Chain Management, 6th Edition. McGraw-Hill Learning Solutions, 2011.
Queue, move, and setup time are dependent on run time. Additionally, with queue time…, it is the only element that does not directly relate to the product being produced. It can be the cause of any of the other 3 elements. Remember, queue time is wait time for something to occur; and that can be caused by delays, lengthier than normal run times, backlogs, etc.
Run time is typically the most difficult to manage because you have a plethora of factors that impact how effective the “run” or the “process” is. Some of these include employee skill sets, employee experience, machine/equipment slippage, process slippage, documented procedures vs. tacit knowledge, time of day, time of week, status of customer satisfaction, etc.