Industrial machine frames and casings call for a LOT of chrome. More than what would be collectible without serious grinding.

Example for blast furnace with industrial machine casings:

• 34 industrial machine casing
• 34*6 chrome plates + 34 * 4 chrome plates (industrial machine frame) => 340 Chrome plates
• 9 ruby dust for 1 Chrome dust in Electrolyzer => 3060 Ruby dust
• 2,5 Rubies per Ruby Ore in Industrial Grinder => 1224 Ruby ore

That's... a lot of ruby ore.

Though there are other means of getting ruby dust (for example 3 for 32 redstone dust, Uvarovite dust, or UU-Matter) it still would take days of playing just for a few casings.