Push or pull principle
These two production control system principles differ in terms of the direction in which the information required for production is passed on.
The push principle for long-term availability
Controlled by a central production plan or logistics plan, the push principle drives products, parts and materials forward through the entire logistics production chain form one production cell to the next. The parts are processed at one workstation then passed on to the next workstation.
The advantage of the push principle is that storing products in between production stages and at the end of the process guarantees good supply availability. Both personnel and machinery can also be used to their full capacity.
The disadvantage to the push principle is two-fold – firstly, intermediate storage leads to waste and, secondly, short-term changes requested by the customer lead to undesirable and expensive capital tie-up in the product warehouse or problematic bottlenecks in supply.
The pull principle for less waste
The pull principle is a demand-driven production system and a theoretical element of just-in-time production. In the pull principle, it is not the sequence of the production steps that dictates the process but rather a flow of information that runs against the production flow. In other words, the downstream cells in the production process pull production forward. In practical terms, this means that the customer – the primary order-placer – tells the production system what is required. Each production cell then tells the next cell upstream what it needs in order to meet the set requirements. The upstream cell then produces what has been ordered in line with requirements.
The result is that each cell within the logistics chain receives only the volume of materials that it actually needs for production purposes. Ultimately, production becomes highly flexible and delivers the right quantities and quality while largely eliminating the waste associated with stockkeeping.
The disadvantage of this principle is the dependency on suppliers inside and outside the company. Goods have to be supplied on time and in the required quantity and quality, otherwise production stoppages can occur.