Gewinde

Gewinde, in English often called a thread, is a helical ridge that wraps around a cylinder or cone. It provides a continuous path to convert rotational movement into linear displacement or to join components by mating external and internal threads. Threads can be external (on bolts and screws) or internal (in nuts, bushings, or fittings). The majority are right-handed, though left-handed threads are used in some systems to resist loosening.

Key features of thread geometry include pitch (distance between adjacent crests), lead (axial advance per complete turn), crest and root, and flank angle. The ISO metric thread, the most common form worldwide, has a 60-degree flank angle. Metric threads are designated by diameter and pitch, for example M12 x 1.75. Fine-pitched and multi-start variants exist, affecting tightening torque and joint rigidity.

Standards and forms vary by region and application. ISO metric threads (M, including coarse and fine variants) are standard in many countries. Inch-series threads such as UNC and UNF are common in the United States. Historical Whitworth (BSC) threads use a 55-degree flank. For power transmission and travel screws, trapezoidal Acme and buttress threads are used for their strength. Pipe threads include tapered NPT (US) and parallel BSP/BSPT (UK), with sealing methods differing between systems.

Manufacture and tolerance: Threads are produced by cutting (taps, dies, thread milling, turning) or forming (rolling). Tolerances and fit classes (for example 6H/6g in metric, 2A/2B in imperial) specify permissible deviation and engagement. Surface finish and lubrication influence thread performance.

Applications include fasteners (bolts and nuts), pipe fittings, machine components, and linear actuators such as lead screws and actuators. Gewinde are fundamental to mechanical assembly and motion transmission.