Any here have some real experience machining bronze castings? I have to do a job with a 4"deep bore 1.750 dia. and a 32 finish. Can I do it with a long carbide end mill? I use 4" LOC hanita vari-mills in cast iron and they leave a really sweet looking finish when they are new. (when they get dull the start to chatter).
Or is this boring head territory? I have a tooling guy quoting me some boring heads.
Remove 333 to reply. Randy
I have only slight experience with manganese bronze turning and boring, but be aware that just "bronze" isn't much help in figuring out how to machine it. Different grades of cast bronze range from 8% to 90% of the machinability ratings of free-machining brass. If you know what you have, I can give you its machinabilty rating.
Some of them are exceedingly tough and gummy. Others cut like yellow brass.
I would say the 32 finish and the tolerance on the hole would delegate how you want to machine it. If it was one part, I would drill and bore it. But I have alot of boring bars at my disposal here.
Tom
As Ed said, a lot depends on the alloy. I used to be in the marine hardware business and have machined a lot (1) of 85-5-5-5 and manganese bronze castings. We used round inserts for most of the work on the 85-5-5-5 castings -- stuffing boxes, stern bearings, etc., and though we had no specific finish requirement, I'm going to guess it was in the 32 neighborhood.
The manganese bronze was tougher, and less tolerant of large tool radii on a long tool.
(1) Enough that after a day of running stuffing boxes on the J&L turret lathe I'd have what felt like a pound of bronze chips my pants pockets.
Bronze per ASTM CA836 ( 85-5-5-5) Remove 333 to reply
Aha. Ounce metal, formerly known as "leaded red brass."
Machinabilty, 84% of free-machining leaded yellow brass. 'Piece of cake.
I have some Si-Bronze that I turned in nice long curls. It was so pretty that I put paper down to collect the gold. I thought that some day I might want to use them as hair curls in a figure.
I was making a tool for the lathe - these were the nuts and double nuts for End mill and Morse tapers that then are locked into the spindle. One end screws into the lathe nose gear and the other end locks down on the far end of spindle. Common on lathes and mills.
Mart> >
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