Calculate the Value of Thread Rolling for Yourself

Thread rolling strengthens the thread profile by cold working (work hardening) and wrapping the material’s microstructure string along the tooth form profile. This results in stronger threads compared to cut threading, yielding important engineering and performance benefits.

Production costs can be reduced, too, by more efficient material use (rolling stock has a smaller diameter than cutting stock, minimizing material waste), higher productivity (more threads are produced per roll, reducing tooling costs per thread) and faster production (rolled threads are created as much as 10 times faster than cut threads).

That said, I’ve often been asked by machine shop owners and managers how to justify thread rolling versus cutting. As a technical and analytical person, I wanted to be able demonstrate with real, practical data how to determine which process makes more sense depending on the material, thread type and other job specifications.

Thread rolling generally proves more economical than thread cutting when producing 4,000 parts or more.

Therefore, I set out to establish the variables that govern an OD threading process. Several key factors came to mind. These include hardware costs (attachments and insert tool holders), tooling costs (thread rolls and inserts), tool life (the number of parts produced with one thread roll or insert), process setup time (how long it takes to install attachments or toolholders), cycle time (how long it takes to produce a thread) and shop rate (the cost of running an operation per hour).

Based on these variables, CJWinter developed a thread rolling calculator to determine the cost performance of thread rolling (both axial and radial style) versus a single-point cutting process. With the assistance of some of its engineers, the company analyzed several common use cases to demonstrate the applicability of the calculator to a range of applications. CJWinter considered:

• Material – 1018 steel, 360 brass, 303 stainless steel
• Thread size – ¼ -20, ¼- 10, M10-1.5, and 9/16-18 and various thread lengths
• Hardware – Radial and axial thread rolling attachments
• Hardware – Three-edged laydown-style indexable threading insert holder
• Tooling – Three-edged indexable inserts, thread rolls
• Shop rate – An average rate of $130 per hour

Table 1 below shows the results of the studies for a ¼ -20 thread. The testing found that the economics of thread rolling followed these basic economic principles:

• Axial thread rolling has a quicker pay off than radial by almost 2:1  compared to single point threading.
• The volumes of parts and shop rates are key factors to determining the cost effectiveness (and profitability) of the decision to roll or not to roll.
• The coarser the thread, the fewer parts needed to justify rolling versus cutting.
• The harder the material, the fewer parts needed to justify rolling versus cutting.
• The higher the shop rate, the fewer parts needed to justify rolling versus cutting.

CJWinter’s process to verify its calculator has shown that thread rolling generally proves more economical than thread cutting when producing approximately 4,000 parts or more, depending on the specific application variables.

The thread rolling calculator accessible at cjwinter.com/calculators is designed to provide valuable insights into your true cost of threading rather than going by opinions or gut feelings, giving you higher certainty regarding the economics of your threading process. Other calculators on the CJWinter website help determine thread rolling penetration rate, thread load, material thread rollability and pitch and blank diameter.