How to use the production scheduler to prepare for production 【Partial optimization and global optimization】

Outline of this article

The original purpose of the production scheduler is to prepare a detailed production plan and issue work instructions at the field level. In plants where demand fluctuation is small and stable, daily work instructions are issued by site judgment. However the fluctuation in demand becomes hard to predict, work instruction by the production scheduler is going to be effective.

What is production preparation?

The purpose of the scheduler is “to create a production plan” from the viewpoint of small schedule planning, but from the viewpoint of the large schedule and medium schedule planning, it can be effectively used as a production preparation.

It was a problem how to combine production scheduler with the Kanban system, which had become a big hindrance by the implementation of the production scheduler so far, I also had experience getting difficuluties because of this problem.

Since the work instruction is done by the kanban kanban, the choice is to either stop the kanban system and switch to the scheduler, or use the scheduler by using the scheduler except the work instruction.

In the Kanban system, it is usual to carry out “preparation for production from three months forecast”, but in this case production preparation refers mainly to the following work.

  1. Arrange raw materials and subcontract by calculating requirement amount from forecast information.
  2. Make capacity plan of plant resources based on forecast information.
  3. Visualization of whole process (gloval optimization)
  4. The forecast is managed with due date based on backward, fixed order is based on forward.
  5. Simulation for maximizing throughput
  6. Relocation of resources in factory

Even if you follow the work instructions with the kanban, if you can carry out the production preparation with the result of the production scheduler, you can realize the combined use of the kanban system and the production scheduler.

However, at factories where demand fluctuation is small and stable production is carried out, daily work instructions can be sufficiently made at site judgment. As it becomes more difficult to predict the fluctuation of demand, it is necessary to reschedule the change as much as possible to create a more accurate plan, so work instruction by the production scheduler is required.

Partial optimization and global optimization

The production scheduler makes it possible to visualize the process flow in the plant at a glance, so it helps to think about overall optimization instead of process units.

In many cases, the production control system separates management for each process, but with this, there is a limit to shortening the lead time. If each process has a partition or separate buildings for each process in the factory, the stock between processes becomes stacked and the production lead time becomes longer.

The wall that separates the processes is the factor that stagnates the flow of the goods and the flow of the information and causes the lead time to become loose and the work in stock increase. It can be understood the importance of connecting the production process to the skewer shape and making the flow in the production.

Inventory is reduced between each process by clarifying the required quantity of materials and the timing of input to the process by the production scheduler.

Delivery due date control

After coming orders, reschedule as soon as possible from the delivery date in backward, to check the raw material stock and fix the production schedule to create with Just in Time.

By rescheduling the express orders in forward, you can quickly check the delivery date as soon as you can confirm when the production will be completed.

Confirm whether the order of the latest delivery date is in time for the delivery due by forward assignment, when the order of the delivery date in the long term should start with backward assignment to arrange the materials until when.

Scheduling direction during booming times and recession

Increasing throughput is the biggest issue when booming like in Indonesia in the middle of economic growth than inventory reduction and lead time reduction.

If the line is empty, you just want to place a short lead time order, but you can use the production scheduler to simulate capacity maximization with existing resources.

On the other hand, when demand for Indonesian domestic manufacturing industry declines due to the Lehman shock and slowing demand in the Chinese economy, operators pretend to busy and it is easy to make useless movements.

If there is a production scheduler, it is logically understood how busy actually is, and it is judged that it is better to ask another job without producing extra things if they have free time.

In 2013, in Indonesia labor-management negotiations became intense and labor demonstrations began to occur frequently. If a demonstration occurs, production will be stopped and the delivery date will be delayed, causing damage to business partners.

By preparing a business continuity plan (BCP) from the viewpoint of business continuity assuming unforeseen circumstances, at the same time, by reflecting the events that happened to the scheduler and rescheduling, we can think about specific countermeasures.

Delivery delay occurring immediately after implementation of production scheduler

If you say “Please manufacture based on the production order generated by production scheduler” to the site which was working based on the manufacturing instruction generated by ERP’s MRP, the manufacturing site will throw a big boo.

As an example in Indonesia, we introduced a production plan generated by the production scheduler based on the final process delivery date to the manufacturing site that issued three production orders from SAP, First process → Second process → Final process, I inputted the manufacturing results, turned red with a delay in delivery.

At the beginning of the implementation of the scheduler, it will be a genuine red Gantt chart with a delay in delivery, but we think that this is a process of shortening the lead time to the last, and it is necessary to ignore. It is also possible to tuning the parameters of this production scheduler to shorten the manufacturing lead time step by step.