Turning cast iron.

[yota]

so I was cutting this cast iron backing plate, first time cutting cast iron, I think. have drilled plenty in the past. I was brushing oil on it as I usually do, then realized it didn't seem necessary at all. def figured out quickly to use a low rpm, was throwing nuggets everywhere at first LOL. started at 8" diameter and reduced it to 5.75. was running at 197 RPM's, carbide insert. did some googling about cutting cast iron with or without oil, saw a bunch of arguments online about the subject. quite a few guys say they cut everything dry with carbide, including steel. seems like heat would be an issue if you take big cuts. it sure is some messy stuff.

any opinions? thanks.

 

[DavidR8]

I've always understood that no cutting oil etc. is required for cast iron. And yes it makes one heck of a mess.
I recently had to re-cut the register on a backing plate for a new 4-jaw and used carbide. Was an easy job but generally I hate working with cast iron.

 

[tmenyc]

I recently did the same thing, turned down a backing plate for my new Shars 4jaw chuck. It was only a 40thou cut. My old Logan only has a 1/2HP motor, so I did it four 10thou passes, using a brazed carbide tool at 130rpm, and it was an easy job, just messy. The turnings were half dust/half small chips, but it did cut pretty well. Luckily I had cleaned up the lathe beforehand and minimized the oil around the base, so most of the mess vacuumed up.

 

[yota]

 

[Alexander McGilton]

Coolant on cast iron often makes for more mess than it's worth. Getting dust into ways is a sure fire way to shorten a machines usable life.

They do make cold air guns for this purpose to keep the cutting zone cool without liquids. But I would be hesitate to endorse it as the blowing of air is also be putting dust where you don't want it. Perhaps best just to lower cutting parameters so as not to over heat. But that comes at the cost of productivity.

 

[yota]

I was pretty happy with this casting. I'm sure it either came from china or india. it was very consistent and no air bubbles. cut like a dream
.

 

[benmychree]

The rule is to only cut cast iron dry, no oil, no coolant. Coolant is fine for grinding, Generally, turning iron, a deep roughing cut with heavy feed works best, makes the least dust, this also throws the most heat into the chips, not the workpiece

 

[yota]

I got a lot more nuggets than dust.

 

[stupoty]

Did you have a dust mask on or are your boggies going "donk" when they land ?



I've read old timers used to use water as flood just to keep the dust down.

Stu

 

[benmychree]

With correct HSS tool geometry it is possible to make semi continuous chips instead of "nuggets".