Hi,
i am a student working on aluminum milling. i need help regarding optimizing machining time.
1. how to select optimum tool
2.how to select rpm,feeds,depth of cuts

i am using a VMC with 450x600mm table size and a 9kw spindle motor

There are many things to consider, starting with what processes you need to accomplish. what grade of material? How Ridged is your machine? Most of the cutting work all depends on how much material you can remove without chatter caused by the stiffness of the machine. Smaller machines can't handle heavy cuts. Tooling diameters mostly depend on needs of cut size. Carbide tooling allows faster heaveir cutting if the machine will allow it. Another aspect is how well you can hold the part. For some It takes years of practice to achieve a level of understanding. There are standard feeds and speeds for a reference in the machinery hand book that can give you some general guidlines for aluminum and other materials.