HDPE dosen't fray in my experience. UHMW does...it's easy to confuse them since virgin UHMW looks alot like HDPE.
You could probably take the entire .2" on a single pass with an 1/8" end mill unless it puts too much lifting stress on the work piece.
I usually leave between .01 and .02" for a finishing pass. 100ipm@4000rpm. Leaves a nice smooth surface.
Paul |