While we often extol the various attributes of cold formed (rolled) threads, the materials that can be rolled are seldom outlined in broad terms.
Steels are virtually all roll-able. Included in the steel family are Structural, Case Hardening, Nitriding, Free Cutting, Heat Treatable, Tempered, Tool Steel, High Speed, Stainless, Cast Steel, Malleable Iron and Cast Iron with an elongation factor greater than 8%.
Rollability is also practical in Copper, Copper Alloys, Zinc Alloys, Aluminum Alloys and Titanium Alloys. In addition, Nickel, Monel, Hastelloy, Inconel, Waspaloy and Titanium are also good candidates for rolling.
The principle deciding factor in the ability of any material to cold form (roll) is an elongation factor greater than 8 percent. As can be seen by the listing many of these same materials are difficult to machine and tough on tooling. Roll life varies throughout the variety of material applications but cost per thread is always an advantage rolling has over cutting.
The tensile strength of a rolled thread will increase from about 40% to as much as 300% in some materials. The tensile strength improvement makes rolling highly desirable in military, aviation and automotive applications. Marine applications using Nitronix 50 and 60 are especially suited to rolling. This is a material with notorious work hardening ability.
We can predict with relative accuracy if your material is a good candidate for thread rolling. Does it conform to the materials we’ve outlined and is the hardness less than 40 on the Rockwell C scale? If you’re processing one or more of these materials daily and not rolling but cutting your threads you’re adding cost and lowering the quality of your finished product.