I'm having real problems with end mills breaking whilst milling 6082T6.

The details:
Machine: Emach router/miller
Speed: 21,000rpm
Feed rate:.25m/min
Cutter: 3mm carbide end mill for roughing, 2mm carbide two flute end mill to finish
Depth of cut: .3mm per pass
Coolant: oil based cutting fluid through mister system
Software: Vectric VCarve Pro 6.5

I'm using 6082 because several people more knowledgeable than me recommended this as the best grade for machining, but am breaking cutters at a rate. Feeds and speeds look about right according to GWizard. I'm cutting the word 'Bentley' in relief on badges to be fitted to engine rocker covers for vintage Bentley cars.

I don't need any structural strength from these items, so should I be using a different grade of ally?

Any help to reduce my increasing cutter bill and rising frustration would be appreciated.

Thanks a lot.