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Takahashi's Scheduler Case Book: Chapter 3

The Case of the Semiconductor Plant

Production scheduling at a semiconductor plant...Speed essential for a production scheduler.

I visited a semiconductor fabrication plant. This company has put a lot of money and more than six months of time in developing their production scheduler and they have just started to put it into operation. Be that as it may, they would like to have a demonstration of our production schedulers. When I asked them why, I was told that whenever they run real data on their just-developed scheduler, schedule processing drops down to more than five hours. The semiconductor industry has to strictly observe promised delivery time even when changes are made in orders. If a change is made in the delivery time for the order, corrections have to be made in the production scheduler. Then what happens when processing takes five or more hours? That would lead to a delay in measures for countering delays in delivery time. If that happens, a human production scheduler would be faster, making determinations promptly and giving instructions to onside workers to ensure that delivery is on time. A slow production scheduler is fatal. We got the data from this plant's production scheduler and held a demonstration several days later. The semiconductor fabrication process features an exceedingly long 150 steps. Not only that it uses an enormous amount of data. We ran the production scheduling on real data with the customer in attendance. Then, what happened? We finished the entire process in five minutes! We were even questioned with "Did that really get all the calculations done just now?" Of course it's doing all the calculations. However, five hours had been turned into five minutes. In a situation like that any kind of change in order can occur, no matter whether that would be a change in delivery time or a change to an express order, and you can make changes in instructions with this production scheduler.

In the example that this company gives us, the scheduler they had developed was able to complete processing a schedule in a few minutes when data load was low, (all quite natural) but when real data was entered in large volumes there was a rapid drop off in production scheduling speed. If you're talking about the person who developed the program, they'll have an understanding of what the reason is. There are many difficulties in designing a production scheduler program that won't change speed no matter what the volume of data it handles. One thing that makes us proud about our Asprova production scheduler is that no matter how large the volume of data, its production scheduling speed remains the same. The production scheduling time for 10,000 jobs is ten times the production scheduling time for 1,000 jobs and one-tenth the production scheduling time for 100,000 jobs. This is the production scheduling logic that I came up with during a one-week sojourn in Hokkaido, traveling with the family in the summer of 2001. During that week I let the children play and I designed Asprova APS. What a wonderful memory.

After we got the system operating, I went back to check on it, and the manager told me, "We wouldn't be able to get our work done if we didn't have your production scheduler. From the schedule results we found out that leaving one semiconductor fabrication machine vacant causes a loss of 100 million yen. We would probably have bought this system even if it had cost 50 million yen. "

At any rate, the speed of a production scheduler is vital.


Case Closed. . .


Learn more about Production Scheduling at Production Scheduling System Asprova

Written by Kuniyoshi Takahashi: Production Scheduling Case Book

Takahashi's Scheduler Case Book: Chapter 9

The Suspicious Case of the Product Planning Scheduler

I installed a production scheduler at an auto parts manufacturing plant for Company I several years ago and had decided to pay them a visit to see how the scheduler was still operating. The first question I asked was why they weren't using KANBAN even though they were an auto parts factory. However, they replied that using KANBAN does not fit an auto parts factory that has many steps in the manufacturing process. This factory was using a production scheduler but it was not making full use of it. If you wonder in what way they were not using it to the fullest extent, it is that they did not use the results from scheduling to provide instructions for production. This would be startling to anyone who has ever used a production scheduler.

What does a production scheduler do for us by calculating a schedule?  It makes the preparations for production. In one of the books that describe the Toyota Production System, in order to use KANBAN they first have to prepare for production based on three months worth of unofficial order information.  The main work in preparing for production is firstly, calculate the quantity of parts needed from the unofficial order information and order any necessary raw materials from their suppliers and secondly, use the unofficial order information to check on the load conditions in the plant. At this plant those two jobs were performed using the schedule results obtained from the production scheduler. Because the requirements for the raw materials, the quantities of parts needed, and the equipment load conditions were already close to being satisfied when the actual production started, production can be performed by onsite discretion so that confirmed orders can be completed on time. (This way of using a production scheduler makes it more of an APS [Advanced Planning and Scheduling] or a product planning scheduler than it does a standard production scheduler.)

A production method like this is effective when used to manufacture a product with relatively stable demand such as auto parts. However, even for auto parts when it becomes difficult it becomes to predict fluctuations in demand, for example, with the production of special vehicles such as trucks, construction machines, fire engines and ambulances then there will be a greater need for the generation of work instructions by means of production schedulers. Even when fluctuations in demand are large, a production scheduler can calculate today what is needed in three months if it has received three-month's worth of unofficial order information.  However, it is impossible to forecast what will happen in three months by onsite discretion and provide a production schedule today for that forecast.

One of my beliefs as a businessman is that if you can read the future then you can predict the outcome in advance. Just how far can you read ahead?


Case Closed. . .


Learn more about Production Scheduling at Production Scheduling System Asprova

Written by Kuniyoshi Takahashi: Production Scheduling Case Book

Takahashi's Scheduler Case Book: Chapter 10

The Strange Case of the Ever Increasing Inventory

I recently visited a clothing manufacturing plant in China. Company J had already installed a production scheduler in their Japanese plant and it was producing good results. This time I was off to China to install a production scheduler in their Chinese plant.

Before the installation of the production scheduler in their Japanese factory, all of the processes in the factory had their own WIP (Work In Progress) inventory and this was being stored in different rooms. Because of this a large amount of inventory was being built up between each process and it was resulting in long production lead-times. The person in charge of installing the production scheduler thought that this WIP inventory between processes was the source of all their problems and believed that it was necessary to connect the production processes together one after another in order to improve the flow of production. Thus it was, that a production scheduler had been chosen as the tool to do that job.

By installing a production scheduler Company J could clearly see the necessary amount of raw materials that they would need and also the exact timing of when these materials would be needed for each process. As a result of this they were able to vastly reduce the mountain of inventory that had been building up between each process and as a consequence they freed up 50 percent of the factory floor area.

The important point here is that they clearly recognized that the WIP being built up between the processes was the source of their problems and that they made the bold decision to remove it.


Case Closed. . .


Learn more about Production Scheduling at Production Scheduling System Asprova

Written by Kuniyoshi Takahashi: Production Scheduling Case Book

Takahashi's Scheduler Case Book: Chapter 11

The Uncanny Case of the Fragmented Production Control

Company K had a food processing plant that I was called upon to visit. A certain Software Integrator had developed the production control system for the plant and there were a number of points about it that the president did not care for. I had agreed to demonstrate our production scheduler and whilst the demonstration was going on, the president came over and interrupted me. He told me that this was just what he needed. He wanted to be able to manage the entire manufacturing process as one interconnected line.

 In certain cases, the production control system can be divided up to control each process individually. However, this kind of system places a limit on how much you can reduce the lead-time. This is why our production scheduler came to be incorporated into this production control system.

It's fine for the managers of each department to think about only their own manufacturing processes but not surprisingly it's the president who has to think about the entire company. No matter whether it's the company's overall supply chain or the flow of processes in the factory, it's important to look at it as one-line throughput in an attempt to optimize the entire overall system.

One of the many advantages of a production scheduler is that it allows you see the big picture of what's happening in your factory, even if your production control system doesn't.


Case Closed. . .


Learn more about Production Scheduling at Production Scheduling System Asprova

Written by Kuniyoshi Takahashi: Production Scheduling Case Book

Takahashi's Scheduler Case Book: Chapter 12

The Perplexing Case of the Imperfect Production Fortune Teller

I visited a plant belonging to Company L that had completed the installation of a production scheduler, which was now up and running successfully. The factory produced tools and dies. The first thing I did was to take a tour of the plant. The results of the production scheduler operation had been printed out and posted on the plant's bulletin board. Typically, the basic function of a production scheduler is to provide detailed work instructions but at this plant the work instructions were not output. Instead, there was a graph displaying the load of each machine and the allocation of operations for all the machines. After this was calculated the actual work would be performed according to what the conditions on site were.

Tool and die manufacturing involves the processing and assembling of several hundred different parts. Just to produce one tool and die can involve an enormous number of processes totaling several hundred. Furthermore, the manufacture of many different types of tool and die has to flow together simultaneously and in parallel. Thus it is extremely difficult for a human being to calculate the total load placed on every machine in a factory. However, through the use of a production scheduler it is possible to produce detailed instructions for each machine by considering their total load even for the most complex manufacturing processes.

However, there is a lot of processing time for the processing steps of the tool and die production that cannot be fully determined at the design stage. This means that you won't be able to know what the final processing time will be until the work actually starts. If this occurs a lot then the work instructions calculated precisely by the production scheduler and the load values calculated from those instructions will be of use only as reference values. That is why the processing work is carried out through decisions made on site at the time of the actual production using the load values and work allocation for each machine generated by the production scheduler as only reference values.

It is because of this kind of situation that there is a tendency for people to think that a production scheduler cannot be used when there are a large number of inaccuracies in the BOM resulting in processing time that is not completely accurate. However, even if there is a certain degree of error in the BOM, as long as the production scheduler can make the calculations then the required load of the machines and the necessary quantity of raw materials can be understood. With this information displayed as graphs the production scheduler allows you to realize the "visualization" of your manufacturing and it is by making full use of this information that is of the most benefit.

In all instances in life, not just in business, there's no way to tell what the future will bring. What's important is to get all the information we can obtain right now, forecast the future to the best of our ability and then make the first move.


Case Closed. . .


Learn more about Production Scheduling at Production Scheduling System Asprova

Written by Kuniyoshi Takahashi: Production Scheduling Case Book
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