I’m not sure your information is correct. Take a look at the link below.
I see you are in Michigan like I am and Lincoln Electric in Euclid, Ohio also does plant tours and that facility is absolutely huge.
I had as nice advantage years ago as the company I worked for was contracted to Lincoln for strip steel and I used to go there at least a couple times a month and their steel storage facility was also where they first article tested engine drives so I got to see them running them at maximum output day in and day out until they puked and then they took them apart to see what failed and what needed to be improved.
Was always warm in there as the resistor banks that were eating up the amperage were also giving off heat and the big banks were outside and water cooled.
I also got to wander around the plant with no guides (so long as I was wearing PPE) so I got to not only mingle with the employees but got to watch the manufacturing processes too.
I believe they do plant tours 2 times a week. The Lincoln facility in Euclid, Ohio is bigger than the Miller facility in Appelton if I'm not mistaken. Even if I am, it's quite an educational tour and if you want a Lincoln machine, you can buy it there too, which is how I bought my TIG machine. Right from the factory.
I got to deliver to a lot of interesting places in my employment, even the oil filter factory in Cleveland, Ohio where the only thing that changed on the filters was the color of the can....
Delivered to a lot of automotive plants and second tier automotive suppliers as well. The outfit I worked for was the preferred supplier for Fiat Chrysler so I did a ton of their plants too. Went to Fords and GM as well and the one thing that always was the same was the poor attitude of the union employees. Maybe that has changed to day, but back then, they acted like you owed them plus they were lazy.
Back then Lincoln was not union. Not sure about today. I know back then, Lincoln treated their employees like gold.