I would think that a powered cross feed is a disadvantage during parting because it can't change the rate at which the tool advances as the diameter decreases. I have never seen one that does anyways. I have little experience, but I have always done this manually to control the rate of tool advance in proportion to the deminishing diameter.
I'm no expert, my previous lathe had no power cross feed. 11 years ago, I got a new Gearhead Lathe that does. Do I'm still learning too. Prolly will till my bride throws the dirt in over me.
That said, that's not my understanding. Depth of cut and speed are related but not that strongly. You can do the same depth of cut from beginning to end, but you have to keep the surface speed within the acceptable range for the tool and the material. That means speeding up the lathe as you cut deeper. On the other hand, the feed depth of cut can stay constant.
Some materials do require negative rake angles, but they need custom ground tools - not inverted ones.
The tool inversion is just a way to stop the tool from digging in and twisting the tool holder in a dangerous inward path. Which will break something. It has nothing to do with exotic materials.
That said, exotic materials do require special methods. Typically a unique insert as well as feeds and speeds. Fortunately, most of us don't use these materials because..... we can't afford them!
Typically they are materials that deform plastically instead of elastically and are generally difficult to machine. Not steel, aluminum, brass etc. but certain lead alloys, some types of plastic, and other exotic metals used in the nuclear industry.
Yup!
Today I managed to break another carbide point on an aluminum blank. Building up practical knowledge will take time
WD40 will work on aluminium but it isn't even really necessary. Steels are another matter and cutting oil is much more important.
Big question. Are you using aluminium cutting inserts? This is important. Most insert tooling comes with inserts for steel. They will work on aluminium but not very well. Since you know materials better than most, it helps to visualize the cutting process from a granular perspective. Steel grains prefer to be torn out. So a duller harder tool is required. Aluminium prefers to be peeled by a much sharper tool. Try to find the aluminium version of the insert, follow its cutting recommendations, and I'll bet you have better success.
