What Are The Main Differences Between Cut Thread And Rolled Thread Bolts?
Rolled Vs Cut Thread Bolts Irrespective of whether we’re talking about headed bolts, bent bolts, or rods, threads constitute a mechanical fastener that is produced by rolling or cutting. As its name suggests, roll threading implies introducing a hardened steel die between the diameters of the finished thread. The dies penetrate the blank space, leading […]
Rolled Vs Cut Thread Bolts
Irrespective of whether we're talking about headed bolts, bent bolts, or rods, threads constitute a mechanical fastener that is produced by rolling or cutting. As its name suggests, roll threading implies introducing a hardened steel die between the diameters of the finished thread. The dies penetrate the blank space, leading the newly formed thread roots outwards to create the crests.
Photo credits: www.learneasy.info
On the other hand, cut threading entails removing the material from a round bar of steel to form the threads. While technically both processes yield the same results, the main distinctions between the cut threads and rolled threads bolts reside mostly in the manufacturing process. Let's elaborate.
Rolled Thread Bolts Have Smaller Bodies
Find the hardware solutions you're looking for here.
With the cut threading process, manufacturers can obtain a bolt with a full one diameter body and one diameter threading, whereas the rolled threading reduces the fastener's body to only .912 inches, while maintaining the threading to one inch diameter. This is why some engineers argue that a bolt with a reduced body is weaker than its full sized counterpart.
However, it is necessary to mention that the strength of the fasteners lies in the threading and not its body size. Because the weakest area of any mechanical fastener resides in the minor differences of the threads and both processes can provide identical threads, you can understand why this belief is nothing more than a misconception.
Cut Threading Leaves Behind Tiny Tears
If you were to put two bolts obtained via roll threading and respectively cut threading side by side and analyzed with a magnifying glass, you will notice that the latter presents tiny tear marks. Cut threading tends to tear the material, leaving a set of marks that run perpendicular to the direction of the thread and that travel into the fastener's body. Unfortunately, the minor fractures made by the tool cutting the thread can, and in most cases will, grow over time threatening the bolt's stability.
Opposite to the cut threading process, roll threading deforms and cold works the material, thus adding to its innate endurance. Not only does the hardened steel die add to the bolt's resilience and strength, but the process doesn't leave any tears that can later on transform into cracks.
Rolled Thread Bolts Cost Less
The main advantage of the cut threaded bolts is that they can be manufactured to all specifications, as there are few limitations with regards to diameter and thread length. Without denying that cut threading could be invaluable for manufacturing special fasteners for sensitive pieces of equipments, let's not forget that the process implies significantly longer labor times and the implicit higher costs.
Opting for rolled thread bolts means shorter labor times and substantially lower costs. The lower cost of roll threaded bolts also comes from the smaller body diameter; a smaller body means less weight and consequentially, less materials and resources used for heat-treating, galvanizing, plating, so on and so forth. Moreover, the burnishing effect of the rolling makes the bolts smoother, while the cold working makes them overall more resilient to damage.
