Chris

The formula is 200 X (Micro Steps ?) = steps per rev

The amount the screw turns 1 rev (5mm i think in your case)

In my machines i use 10 microsteps so the formula is 200 x 10 = 2000 / 5 = 400 steps per rev

The velocity in the Mach setup tab is the fastest you are allowing the machine to run in your case you have set it to 600mm per minute which is on the slow side

So if you divulge you micro step setting your figures can be confirmed but 640 (Your Setting) steps per equates to 16 microsteps and the generally accepted maximum is 10

Phil