Excerpt from TPiCS report No. 68.
Since I had issued the previous report (No.67,) I tried my very best to think about “how I can manage to solve this problem.” I finally found out my own answer and immediately incorporated the function into TPiCS-X Version 3.0.
I have been involved in the job of TPiCS for nearly 20 years, but I think that the functional addition this time is another epoch-making job in the history of TPiCS.
I am going to briefly explain the problem itself first that I was trying to solve.
Suppose you are going to use a new production control system instead of TPiCS. To use a production control system means you make purchases for parts and materials, and make production according to the instructions from the system.
In the case of making production according to the instructions from the system, you normally assume the situation where the workload by day shown in the instructions (schedule) coming from it is not leveled. For example, if somebody told you to make 10,000 pieces for today and 100 pieces for tomorrow, you would be working all night today but would have to take a half day off for the afternoon tomorrow. This sounds horrible for those who actually make production in the factory. They would ask you, “What are we going to do?”
In order to solve this problem, to “make the schedule that is leveled” or to “make the schedule where allocation of the resources such as manpower and equipment capacity is considered” will be needed.
But it is a very difficult job.
① Since there’s the Automatic Leveling Option in TPiCS-X, you can make the schedule that is leveled to some extent. But it is not something perfect.
② There’s a function that coordinates with the scheduler in TPiCS-X. But the operation of the scheduler seems quite difficult in reality.
③ As the most basic solution, it is the manual labor that makes the production schedule leveled. Since TPiCS-X allows you to move a day to schedule on forward and backward with the drag-and-drop also on the scheduling screen, operability is considerably good. Yet, when the process gets deeper and there are common processes involved, it’s going to be a tremendous work.
④ Next solution I can think of is “leave it to the factory” in my previous report. The system is operated with the order issue period a little longer to “have them adjust it at the discretion of the factory,” but harmful influence by it was a great deal.
⑤ The last solution of “make production with the schedule that is different from the system’s” is also found in my previous report. The system is only used for arrangements for parts, and the instructions to the factory are made according to another schedule. The case of my previous report was an example of weird results, which were derived from the misuse of the functions of the actual results corresponding to the plan and the actual results corresponding to inventory in TPiCS-X.
At any rate, that was difficult to solve and a down-to-earth bottleneck for running the production control systems.
Are there any ways to solve it? Is there a practical way with a simple logic? Is there a simple solution that doesn’t have to score 100 points but that scores 80? As no answers come out by the way anybody can think of, it has to be a completely different idea. When trying my very best to think about it, a hint suddenly springs to my mind.
To begin with, let me explain the points of my solution.
The factory floor is living. It is very difficult to bring momentarily changing situations in the system, and to calculate in a real-time manner and give instructions of the schedule, which is leveled in each process and consistent, despite those situations.
On the contrary, all that’ required is that people at the factory floor know, “What and how many should we make today?” at any rate. They don’t mean to tell you to decide “every single movement of chopsticks.” They just want to know, “What and how many should we make today? What can we make now? If there’s anything we can’t make in today’s production, why can’t we make it? When can we possibly make it, then? What is it we have to make in a hurry?” If you have only to provide the information they want, they make a judgmental decision for themselves as for the rest according to the situations they are in.
Organizing the thoughts this far, the rest is easy.
There’s the Shop Floor Control Option in TPiCS-X.
To begin with, the Shop Floor Control is to clarify the information of “What should we make today? What can we make now? If there’s anything we can’t make in today’s production, why can’t we make it? When can we possibly make it, then? What is it we have to make in a hurry?” The only thing the current Shop Floor Control doesn’t have is the “function to clarify the production level (quota) to be achieved today.”
Now, let me move on to the explanation on how to calculate and display the production level.
When the production schedule, which had not been leveled, has been leveled, it must show work hours of average value. If there’s any order to follow in the production, it is desirable that the scheduled days should just be shifted in that order once it’s been leveled. Considering this average value to be the production level, if you only select the work that reaches the production level and is possible to start in the priority order, they are going to a quota. If you can give the factory these instructions in a real-time fashion, it means you have accomplished the objective.
The average value of how many coming days to take varies depending on the user. Though I find it suitable to be a week cycle in the modern age, there may be some users who say, “We want a month to be leveled due to the relationship with our union.”
So, we have made the setting of the leveling period available in the “Production Level Calculation Period by Work Center” of [System Configuration Settings]-[Operation Method]-[Shop Floor Control.]
And now, I’m going to continue with my explanation based on the operation of determining the production level in a week cycle from here on.
① Placing the personal computers at pivotal points of the factory, you learn to be able to use the traffic controller of TPiCS-X.
The screen of the traffic controller shows the Manufacturing Order data that have been released for each floor.
② You execute the calculation for the average value of the workload for the next week from the current production schedule at the office every Friday.
③ As much production quantity as the production level is written in the mantissa field of the Work Order data upon click of the [Mantissa] button on the screen of the traffic controller at each floor.
④ When the previous process is only finished in the middle, or when all necessary parts are not prepared, the quantity possible to produce is written in the mantissa field.
⑤ In addition, when you finished your work for the morning and start working in the afternoon to click the [Mantissa] button once again, only the production quantity corresponding to the remaining of the production level is written in the mantissa field, the quantity of the work finished in the morning being subtracted.
⑥ The order to fill in the mantissa field follows that of the displays, but you can freely determine it. And the traffic controller also allows you to manipulate the values of the sort keys from the following process － the function to send a message from the following process to the unfinished previous process.
⑦ If there’s anything left unfinished among the work prior to today, it is displayed in red and the work after today is displayed in blue.
⑧ Besides, since this function works with the function of “Issue Management” added in Version 3.0, the quantities possible to start can be calculated based on the quantities of parts issued to the factory floor.
I’m going to add some more explanation regarding the calculation method of the production level.
① The production level is calculated from the current production schedule.
It is not calculated from the workforce enrolled but from the production schedule to be required.
If the manpower of your section is not sufficient, you ask another for the backup. If that’s not possible, you make changes to the production schedule. That is, you shift the schedule for next week to that for the week after next week. If you can’t shift forward any further, the only way is to work overtime or overnight.
② On the contrary, if you have a little work, the modern thinking is that “since there’re no orders, it's a waste of money to make many useless things. ” Then, you could go to other sections for backup or do maintenance on machine and equipment. But if you don’t think you can in reality, you could make adjustments to the calculated production level to raise it. This is a job somebody must do with positive intent.
③ The case where the production for this week is already behind schedule.
For example, if there’s delay that cannot be recovered within today as of Friday, you have to prepare a margin to recover next week in the production level.
The calculated working hours for next week are written to the Work Center master, but right next to them are displayed the working hours for this week and the remaining of those for today.
The greater the remaining of working hours is, the little greater you have to make the working hours for next week. If you understand this mechanism, you can consequently tell whether behind or ahead of schedule to occur against the original production schedule that is not leveled. You can’t make errors in the leveling or delay and progress zero.
The point is, it’s the balance between the permissible limit of delay and progress, and the degree of the leveling. In addition to that, if you use the Shop Floor Control, you can get answers in completely different directions like never before to such problems as, for example, “we want to make production in a mass if we use the same mold,” and “since it is more efficient if it changes from red to white than if it changes from red to yellow…” There are so much more functions in the Shop Floor Control, but I must stop here at the explanation of “Instructions to the factory floor and the leveling” as my explanation defocuses.
Above are the answers, which have been achieved by the Shop Floor Control in TPiCS-X Version 3.0, to the “problems of the instructions to the factory floor and the leveling.”