Collection: Milling Inserts

APMT has a positive rake (10°+ rake) for low cutting forces, used in shoulder mills and slot mills. APKT has a more neutral geometry with a stronger edge, used in face mills and heavier roughing. Both have similar nominal dimensions but are not interchangeable — check your cutter body.

Yes, if the ISO code matches exactly including the chipbreaker letter (e.g. APMT1604PDER-MM). Physical dimensions are identical; the grade and coating differ, which changes performance and cost per edge.

Round inserts give the strongest edge (any point on the circle shares load evenly). Used for profiling, slotting tough steels, and rough copy milling. Lower peak force per tooth but cannot reach into square corners.

High-feed geometry uses a very small lead angle (around 10-12°) so most cutting force points axially (into the spindle, which is rigid) instead of radially. Allows 3-5× normal feed rate at shallow depth of cut. Ideal for large-volume material removal on strong machines.

Most common cause: too light cut (insert rubs instead of cutting) or too heavy interrupted cut without proper grade. Use a tougher grade (lower hardness, higher toughness) for interrupted milling; ensure depth of cut is at least 0.7× nose radius.