ASDO Technical note - Threads

Many consider that the screw thread was invented in about 400BC by Archytas of Tarentum, a contemporary of Plato. They were then famously put to good use by Archimedes proving a ‘turning point’ in mechanics (apologies for the pun).

We don’t know much about ancient history at ASDO but we do know our threads, particularly large diameter Metric threads on steel tie rods. Threads are typically formed either by cutting (material is removed to form a thread) or by cold rolling (material is ‘moved’ to form a thread). ASDO are able to roll threads on bars up to 160mm in diameter & cut threads up to 460mm diameter and, depending on diameter, on bar lengths up to 27m!  
Metric threads are made in accordance with ISO 965 which gives precise data on the profile, form and tolerances required for male and female threads in order to provide a full strength connection. Male and female threads made to this standard should be fully interchangeable.

For static loads there is little difference between a thread that is formed by cutting or rolling, they will both have similar tensile capacities, however for dynamic loads rolled threads give much greater resistance to fatigue and should always be used for projects such as bridges but care should be taken after manufacture that the threads are not subjected to process (eg galvanising) that can introduce hydrogen as this can seriously affect the fatigue resistance.

For more information regarding threads and what types are suitable for your project contact our technical sales department.