This is one of the problems that arise in these discussions and I'm glad you clarified what you were thinking of.

"Industrial" spans a wide range. The problem I run into is that when I mention using Arduino or pi in industrial applications, people immediately jump to thoughts of extremely harsh environments and safety-critical applications. There are plenty of existing solutions to those problems.

Where the Pi shines is in "light industrial" tasks that a standard PC would be unsuited for (cost, size, I/O, power consumption, etc), but the environmental requirements aren't stressful. Those can be anything from counting rebar loaded onto a rack or providing help to truckers at a loading dock.

Even so, I have lots of small devices (arduino clones, Raspberry Pi) in machine control applications and they've been working very well.