I cut tons of urethane & aluminum. But I have a question. We are looking at a very large production job machining cast iron wheel blanks. I have cut it maybe once or twice here. We are looking at thousands of castings for wheels and some have thru bores for sleeve bearings and some have stepped I.D. for sealed bearings. I think we will need to hold +/-.0005 on the bores. Diameters will range from about 4 inches by 2 inches wide to 14 inch diameter 6 inches wide. The bearing bores are around 1.5 diameter we will be machining. How is this stuff on tool life? Is coolant needed? We need to paint them after and no coolant will help with the painting.
Cast iron parts are a good opportunity because a lot of shops don't want to touch it. That's how you make money - doing the stuff that nobody else wants to do, as long as you quote appropriately.
You mentioned cutting a lot of aluminum and plastics. How much steel have you machined in the past? It's close enough to 1018 or annealed 4140 that you can use steel cutting parameters as a starting point. Cut dry and use steel-specific cutting tools for facing, profiling, etc. Stay away from iron-specific inserts in the beginning, because IME they're designed for high production environments and are more brittle than steel cutting inserts. We machine cast iron daily and no longer use any iron-specific tooling.
Once your machines are making good parts, your attention will be directed toward dealing with the dust. Cast iron dust is no joke, as it will make your machine dirty in a heartbeat. While bulk material removal is done dry, we use coolant for all drilling, tapping, threadmilling, brush finishing, and washdown. No part comes out of our machines dry. The benefit of this is that parts are free of dust. The drawback is that all that dust ends up in the coolant. Most of our machines (DMG MORI) have drum-filter chip conveyors, which handles the dust very efficiently. The one machine we have that doesn't have a drum filter has flooding problems if we don't clean out the mesh filters every 1-2 months. This requires lifting up the entire conveyor with a chain hoist in order to get to the filters, which is as much of a PITA as it sounds.
Some dust gets through the filters and ends up at the bottom of the tank. Every few months, we drain each tank, scoop out the sediment, and then pump the coolant back in. Not a fun task, as it's very dirty and requires wearing a painter's suit, but at least we don't go home with the "coal miner" / "black boogers" problem.