So the aluminum on the piece rubs against the aluminum on the wheel, producing more heat, which produces more melting, and so on.
(the aluminum on the piece; rubs; against the aluminum on the wheel) (the aluminum on the wheel; producing; more heat, which produces more melting, and so on) (more heat; produces; more melting)
the aluminum on the piece the aluminum on the wheel more heat
rubs producing produces
against the aluminum on the wheel
more heat, which produces more melting, and so on
more melting