Cutting‑edge condition problems
Uneven edge honing, tiny built‑up edge, flank wear or micro‑chips on the threading insert will leave irregular scratches on the thread flank. Coating peeling also brings inconsistent surface quality.
Improper cutting‑parameter settings
Excessive feed rate, unsuitable spindle speed that triggers cutting chatter, or uneven depth‑of‑cut for each threading pass produce wavy, patchy thread surfaces. Low‑speed machining on ductile metals easily causes metal tearing.
Insufficient system rigidity
Over‑extended boring bars, loose tool holder clamping, poor lathe spindle stability and unsecured thin‑wall work‑pieces create tiny vibration during turning, generating uneven chatter marks.
Chip‑breaking and cooling issues
Unsuitable chip‑breaker geometry causes tangled chips to scratch the finished thread surface. Inadequate or mismatched cutting‑fluid fails to lower friction and prevent workpiece material adhesion onto the insert edge.
Work‑piece material property
Soft, ductile alloys such as aluminium, brass and low‑carbon steel are prone to material flow and tearing. Heterogeneous raw material structure from cast or forged blanks creates inconsistent machining performance.
