machining gunmetal bronze

Hi Guys,

I am trying to design and make an improved end mill for machining (slotting) bronze. The exact material is C90500, composition 88%copper, 10% tin and 2% zinc.

Does anyone out there have experience of machining this material. If so, please advise any info you have on tool geometries, tool materials and coatings, feeds, speeds and coolants used.

There appears to be a huge difference in machinability depending on the alloying elements (for what I have read so far).

We are trying to improve tool life on a production milling operation cutting approx. 1/8" dia x 1/16" deep slot, cnc controlled, figure 8 type groove for an o-ring seal in a flange plate.