Process Types

In designing automated systems the first task that needs to be accomplished is to determine what type of process will be taking place. Often when making this decision we go with what we know: if building an assembly machine I’m going to build it where it performs discrete assembly tasks, right? Kind of an assembly line like the classic Henry Ford example…but Lean Manufacturing advises against work in process, batches are bad, so what other options are there?

From the Primer:

2.6.2 Processes are said to be asynchronous when they do not rely on a master timing signal. An example of this might be an operation which takes place when a product arrives at an operator station from a previous process on a conveyor. The component may then be operated on when its arrival has been detected by a sensor rather than at the index completion signal from the conveyor.

2.6.3 Synchronous processes rely on a master clock or timing signal. This may be an electrically or mechanically based system; cam driven devices on a line shaft are examples of a synchronous process. Assembly line operations may be synchronous, asynchronous or a combination of both depending on the source of the initiating trigger.

2.6.1 Chemical, food and beverage production often operates in a continuous fashion. Chemicals or ingredients are mixed together continuously to produce a “batch” of product. Plastics are often extruded continuously and then segmented into individual pieces for further operations.

So when making a decision on what kind of equipment to specify when designing an automated system these kinds of things need to be taken into account. Is it cost effective to use a synchronous system such as an indexing chassis? How much WIP or Work In Process is present in the system at a given time? Should some of the assembly steps be performed manually, i.e. human labor? As I begin a new phase in my career I am hoping to leverage some of my experience to start to think a bit more outside of the box on some of these decisions. Just because things have always been done a certain way doesn’t make that the best way.

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