Catalogue range comparison
The verified data lists ER32 at 2.0-20.0 mm and ER40 at 3.0-26.0 mm.
Application fit
ER32 suits many milling, drilling, boring, reaming and tapping jobs. ER40 can support larger tools but requires a compatible holder and work envelope.
Selection caution
Do not choose ER40 only for range. Consider holder size, spindle clearance, nut access and tool projection.