Hi,

Tool life depends most of all on deflection and tooth engagement. All else is just a way to achieve these 2 or a result of it is achieved properly or not .

Hence, rigidity of the machine, setup, speeds and so ...

Basically small tools/3-6mm/ at 16000rpm and 60 IPM is a good starting point at depth 1 diameter. Though i tend to go 18000 for hard woods and lower the feed if the bit is thinner than 3mm