Answer:
Some possible causes of over-production are:
Produce as much as possible in the process, regardless of the appropriate speed at which the following process can operate (stage, line, ...)
Excessive freedom to produce and internal performance metrics that incite to produce more
Excess capacity that causes more manufacturing than necessary without taking into account the customer's real demand
Over-production is considered as the "mother" of all waste as it causes all others. Indeed, more production, more inventory (need for more space), more transport (with its associated costs), more waiting, more risk of defects, etc ...
We will find wasteful consumption of labor and public services and we will consider investing in new machines or systems despite not being necessary. In addition, over-production makes the problems are not so visible.
Eliminating overproduction means taking care of planning but also not necessarily seeking to use resources full time. We cannot continue thinking about these myths: "The machine cannot be neglected" or "We have to use our resources to the fullest", without having carefully analyzed the situation.
The key lies in proposing a range of products and services but producing according to customer demand. We have to forget about the Push system in which the production works are programmed according to the capacity of the process and work according to a Pull system where the start of a job is “triggered” by the completion of another strictly following the customer's demand. The use of Kanban cards can help us organize the work in a simple and efficient way. It will also be necessary to carry out plans for monitoring planned production based on demand and leveling operations.