Up until 5 or 6 years ago there was an old duplex where I work. We rough machined 8" cubes of cast iron on it. Hogging cast iron off the OD, with no coolant, was a dirty job. That machine sure removed alot of material, very quickly. It took me over two years to move that product and the machine out of the facility. I offered the duplex mill to the vendor that took over that product line but they went to an enclosed horizontal mill.