Wrench grinding machine

Grinders patterned like Blanchard's rotate parts on a table under a rotating segmented wheel. Much like a face mill, the axes being parallel, can remove tremendous amount of material and excellent flatness. Surface exhibits a finish, cross hatched like cylinder honing.
Arter design use a rotating table under a perpendicular wheel, periphery does the work. Also flat results, though smaller work envelope, but high surface finish.
Both machines handle full size plates or multiple parts, securely blocked in place, on a magnetic chuck. Non magnetic items can be fixtured too.

The wrenches are in a purpose built machine, oscillating essentially Arter-like. That ensures good cosmetic flatness over long production runs, by distributing wear over entire abrasive. Unsure of it's exact nature, could be ceramic wheel, abrasive brush, inflated drum sander; it's hidden by flood coolant.

Wrench grinding machine - GIF