I was machining a 3D surface up to 6mm deep in a block of alluminiun using a 4mm Square-end End-Mill (SQEM) for roughing and a 1.5mm Ball-nosed End-Mill (BNEM) for finishing. However, the 1.5mm BNEM broke and I don't know why (I'm still a novice).
1. One suggestion was that using a BNEM for roughing would make life easier for the finishing bit. Is this true?
2. Would it be preferable to use more than two bits (eg a second roughing stage using a smaller bit)?
3. As a good example, can anyone quote a set of tools and parameters for the case above?