OPC/U2 Topic 11 PPC: Job, Batch, Mass (Assembly) and continuous
Batch process refers to a process that consists of a sequence of one or more steps that should be performed in a defined order. A finite quantity of the product is produced at the end of the sequence, which is repeated in order to produce another product batch.
Generally, batch is a process that results in the production of limited quantities of material through subjecting quantities of raw materials to a set of processing activities over a significant period of time with the use of one of more piece of equipment. Processing of successive batches must wait until the completion of the current batch.
A flexible assembly system is appropriate when:
- A wide variety of products and/or parts is to be manufactured on the same equipment
- Products have a short life cycle.
- Environmental uncertainties are taken into account in order for a firm to accommodate internal changes and external influences.
- Offshore competition can produce products at much lower costs than can traditional manufacturing methods.
- Parts can be easily damaged by over-handling through manual cells.
- A high degree of accuracy and repeatability is required.
- Parts are too intricate to be assembled efficiently with considerable human intervention.
- Volumes are moderate to high, i.e., cycle time rates are not dependent on the slowest worker.
- Ergonomics is a significant factor.
- The assembly task requires less than roughly 10 seconds.
A continuous process, on the other hand, refers to a processing that involves moving a single work unit at a time between every step of the process without any breaks in time, substance, sequence or extend. As the name suggests, the flow of product or material is continuous. Every machine operates in a steady state and performs a certain processing function.
For majority of applications, continuous flow saves costs, energy and time. When this process is properly implemented, it can reduce waste, improve quality by making it easier to identify and correct errors, increase productivity and adapt to the needs of customers more efficiently than batch processing.