CNC stands for Computer numeric control, and is usually associated with a lathe or milling operation that requires device position feedback for proper end effector control. This type of device generally is used to perform sequential operations by a preset program.
A PLC or Programmable logic controller ( a.k.a Programmable Controller, PC ) performs a job based on ladder logic. This means when a input condition is met for a given line a output condition is set. These are usually found in applications with conveyor systems, or repetitive tasks that follow one another. Most often the PLC is interfaced to external drive controls or higher power relays to control the process.
Batch/Recipe control in food, plastic, or metal casting processing are common place for PLCs .
Hopper puts one ingredient in, next hopper puts next ingredient in after first, then mixer starts , next burner, then dumped out.
CNC machines can use PLC's within them for things like conveyors, machine doors, part loading, etc..
Both devices are used in a host of applications with PLCs being used almost in every industry known to man.
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· 1 decade ago