Hi all, I'm a first year mech eng student starting a mid-term assignment which is a report into the durability, machinability and cost of 3 different materials. First off, I'm looking for a durability index for different materials; brass, aluminium and plastic (ABS) What is the procedure for checking durability of a material and how does the grading work? And where would I check machinability of these materials? Speaking to the lecturer and researching from different sources give different answers (unsure if they're stating opinion rather than fact) Can anyone point me in the right direction?! Thanks!