When manufacturers produce threaded products, they must take particular care with the thread design. Numerous standards exist around the design and manufacture of threads. Thread design should depend on the intended application. The two most widely used options for thread production are rolling and cutting.
Production method chosen will depend on a variety of factors including: custom versus standard, thread profile, overall part design, material selection and of course expected use for the threaded product. This blog post will discuss the differences between the two methods to help readers make informed decisions.
What are Rolled Threads?
Thread rolling is a cold-forming process that shapes threads by applying pressure. The blanks, which are slightly smaller than the maximum thread diameter, get compressed between flat plates or round dies with thread pitch machined onto them. The components are then rolled across the dies under extreme pressure to press the thread shapes into the shaft. This results in a change in the material grain structure.
When to Use Thread Rolling
Thread rolling processes can be faster than thread cutting. This process is often used for fasteners and larger components made from lower grade materials which tend to have properties that will make the forming process more efficient. Additionally thread rolling may be preferred for parts that are threaded the entire length. The thread rolling process is recommended for standard thread forms where dies are already made and readily available. A set of thread rolling dies can be very expensive and cost prohibitive for special and one off part manufacturing.
What are Cut Threads?
For smaller part designs cut threads are made using machine tools, such as CNC lathes. For larger cut threads Jerpbak Bayless uses specialty thread milling machines. The blank component has a shaft size the same as the outermost diameter of the threads, and the excess material is cut away to create threads in accordance with the specified design. Cut threads are primarily made through one of these methods:
- A single point tool that cuts away the material around the threads as the component itself rotates.
- A multi point cutter that rotates and cuts material as the component itself rotates.
- For smaller parts a threading die that rotates around the component shaft may be used. It cuts away material with each rotation as it moves further down the shaft.
When to Use Thread Cutting
Machined threads are best for higher grade, stronger, and harder metals that feature higher tensiles and yields. Many of these metals respond poorly to rolling, which relies on the metal’s ability to flow without cracking or breaking. For these higher grade metals thread cutting is the prefered method for producing components with properly formed threads. Thread cutting is also preferred for part configurations that have shoulders and steps.
Rolled vs. Cut Threads: Which Type is Better?
Thread rolling isn’t universally superior or inferior to thread cutting. Each process has its unique advantages depending on the grade of material selected and the part configuration. When you’re choosing between rolled or cut threads, carefully consider the material grade, the intended application, and your required order timeline.
Choose Jerpbak-Bayless for Custom Machined Thread Services
At Jerpbak-Bayless, we specialize in threading processes that create high-quality, high value components. Since 1945, our company has been creating standard and custom threaded components for industrial clients across the United States, including clients in heavy industry and the military. Contact us or request a quote to see how we can support your project.