Mechanical Engineering - Workshop Technology - Discussion

Since ductility states the metal can be deformed. Particularly at thin thread structures it will definitely deform.

In SS 410 thread rolling is used but it is ductile.

What is mean by thread rolling?

Thread rolling is the preferred method for producing strong, smooth, precise, and uniform external thread forms. Thread rolling is different from other types of threading processes like cutting, grinding, and chasing.

Thread rolling is a cold forging process that can be performed on any ductile metal. The forming process can be used to produce other special forms, such as knurls. For the best quality threads, the process is performed on precision centerless ground blanks.

The blank diameter of a rolled thread is at the pitch diameter, a theoretical point between the major diameter and minor diameter.

Materials are limited to ductile materials because the threads are cold formed. However, this increases the thread's yield strength, surface finish, hardness, and wear resistance. Also, materials with good deformation characteristics are necessary for rolling; these materials include softer (more ductile) metals and exclude brittle materials, such as cast iron.

Tolerances are typically ±0.001 in. (±0.025 mm) , but tolerances as tight as ±0.0006 in (±0.015 mm) are achievable. Surface finishes range from 6 to 32 micro-inches.

Actually we cannot thread cut to hardmaterials. Because it resist the thread impression.

Thread rolling is restricted to use only ductile material because it posses good deformation properties.

Thread rolling is the process of making threads on fasteners by high pressure rolling dies.

The toughness of brittle materials is less so no ferrous and hard material the cracks will come in cold forming and thread rolling is cold working.