Surfacing speed

I make a 3.5 in. bevel gear out of C954 AL BRZ on a regular basis. I surface the gear teeth on a 4 axis VMC. I can cut them all week long with the same end mills @ 6K rpm and 35 ipm. My customer wants some out of 1040 CRS. Roughing the stock is no problem, however finishing is a different matter. I'm using an ALTIN coated 1/8 ball mill @ 6K rpm and 7.5 ipm. My semi-finish pass is taking approx. .005 stock off. I can only do about 5 of the 15 teeth before the end mill goes away. Any advise for speed and feed? Thanks