What were the episodes that didn't feature any cartoon characters?

For years I've been searching online for my fav episodes. I would wait and hope for the episodes that featured factory lines and machinery, cogs and wheels going. They would often feature Raymond Scott's "Powerhouse" song and Rube Goldberg like contraptions. I remember the post office with a sorter, sorting a stack of mail into their various slots, while on the other side, we see all the mail falling into a single container.

I was a kid that loves legos and building things after taking them apart which is why I loved the Roadrunner cartoon with the coyote.

Is their a way to describe these episodes? Is their a label or something the animators called them? I remember one was the American Defefense Factory and of course they would have a bomb testor hitting the shells with a hammer... And a food processing plant, or canning factory.

[edit] I found this video by searching for Looney Toons Factory Episodes

"Swooner Crooner" (1944) with Porky Pig - Flockheed Eggcraft Factory