Keermestamine

Keermestamine, or threading, is a metalworking process that produces screw threads on cylindrical parts. It creates external threads on fasteners and shafts, or internal threads in holes. Threads may be formed by removing material (cutting), deforming it (forming), or both. The process follows standard thread forms such as ISO metric or Unified standards.

The main methods are thread cutting, thread forming, and thread milling or tapping. Thread cutting uses a single-point tool on a lathe to cut the thread profile in multiple passes. Thread forming (rolling) shapes the workpiece between dies to form threads without material removal, yielding stronger threads but requiring ductile stock and appropriate equipment. Tapping and thread milling are used for internal threads; taps cut internal threads, while thread milling employs a milling cutter to generate the thread.

External threads can be produced with dies or on a lathe by thread-cutting; internal threads with taps or thread milling. Finishing operations may include deburring, chamfering, and lubrication. Tolerances and class designations (for example metric M, UNC/UNF) specify allowable deviations and fit.

Quality control uses gauges such as go/no-go gauges, plug gauges for internal threads, and ring gauges for external threads, along with optical or coordinate measuring methods to verify pitch, diameter, and length.

Uses include fasteners, joints in machinery, automotive components, and pipework. Knowledge of material properties, thread standards, and machining parameters is essential for reliable assembly and long service life.