Mumbai University > Mechanical Engineering > Sem 3 > Production Process 1

Marks: 5M

Year: May 2016

• 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.
• Thread Rolling produces rolled threads on a wide variety of parts.
• Often, rolled threads are required by design because of their superior tensile, shear, and fatigue strength.
• Other processes remove material to produce the thread form, but thread rolling displaces the material with hardened steel dies.
• The result of moving the material grains (molecules) into the shape of the thread rather than weakening it by removing material, is that the grains become denser at the critical parts of the thread, especially in the root and on the flank below the pitch diameter.
• This effect improves the quality of the thread form.
• Additionally, the burnishing action of the steel dies produces an excellent (better than Ra32) micro-finish.
• The superior finish improves assembly between external and internal threads and reduces wear between mating components, thereby extending their life.
• A smooth finish is another advantage that roll threaded components have over other threaded components.