hi

>The machine body is properly earthed using 2.5 sq.mm wire.

2.5 sq.mm is certainly not enough ! triple it at least

the wire to be cut must be earthed and must be aequipotential with the machine body.

is there a way to keep the cutter isolated from the machine body ?

use antistatic devices (50 to 100 thousand volts of static voltage is not rare in plastic industry)

ed