Thread rolling is a type of threading process which involves deforming a metal stock by rolling it through dies to form external threads along its surface. Internal threads can be formed using the same principle, specifically termed thread forming.
The processes of generating threads are generally classified into three methods: subtractive, deformative, and additive. These differ on how the thread is shaped or formed.
The main advantage of thread rolling is the stronger surface and dimensional accuracy of the product. However, the process is limited to soft metals and requires more expensive tooling.
There are different types of thread rolling machines that vary according to the type of die used. Thread rolling machines can be a flat-die, planetary, or cylindrical-die type.