Underfile Performance Curve Chart

Impellers – why underfile?

Underfiling is the removal of material from the underside (also back side, “non-working” side, or suction side) of an impeller vane at the inlet or the exit.  In this article, underfiling will refer to the exit.  The terms “underfiling”, “back-filing”, “S2 cutting”, and “Sv cutting” are equivalent.