This looks like heck of a problem... I don't think that grounding the machine will do a significant difference, considering that the extrusion is anodized, and anodizing is an insulator.
I'd probably concentrate on improving the "shoe" to catch more chips. And make some rails and lead screws protection, maybe attach some wipers to clean the debris...
Actually, I'm cutting plastics for some projects and that's the same problem I'm facing right now. I'm going to implement some protection solutions because otherwise those chips will ruin the mechanics one day.
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