DIFFERENCE BETWEEN ROLLING THREAD AND CUT THREAD PIPES

First comes, the differences in their processes. Cut threading simply removes material from the round bar of steel to form threads while roll threading takes place with the help of a hardened steel die between the diameters of the finished thread. This causes the formed thread roots outwards to create the crests.

One of the most important things is the cost of the thread pipe nipples as well. The way steel is processed during cut threading, takes longer labor times which adds to its costs. Cut threaded bolts are not suitable for manufacturers of sensitive equipment as there are quite a few limitation with regards to diameter and thread length with cut threaded bolts.

On the other hand, rolling thread pipe nipples and bolts require much shorter labor times, which means that they are a slightly more affordable option. The rolling thread process also strengthens the bolts in three ways. This includes tension, fatigue and shear resistance.

Rolled thread bolts also have smaller bodies that cut thread bolts. This of course, adds to the lower cost of rolled thread pipes. However, some engineers believe that the smaller bodies of the rolled thread bolts causes them to be weaker. But you can say that this belief is clearly a misconception as the strength of the bolt lies in the way it was manufactured and threaded, not in the size of its body.

Cut threading severs the grain structure in the steel, whereas roll threading reforms it in a line along the thread form. Rolling thread also provides a smooth and consistent surface finish to the bolt which helps it from not becoming the starting point of fatigue failure.

Rolling thread pipes are my first choice, for sure. They are economical to produce, increase tensile strength, low cost, longer lifespan, shorter manufacturing time, etc. It is just easier to produce rolling thread pipes at a higher rate than cut threading them.

Rolling threads are so much more resistant to damage during handling as well than cut threads.

However, the only downside I see to using roll threading is that the pitch diameter round bar is only available limitedly for certain material grades.

Both cut threads and rolling threads have their downsides when it comes to diameter and thread length.

To say the last for cutting thread bolts, well, they have tiny tear marks in them. This can be observed with the help of a magnifying glass. Cut threading tears the material, and leaves marks perpendicular to the direction of the thread. This, although, does not seem like a huge problem at first, it can greatly affect the stability of the bolt.

Since roll threading deforms and cold works the steel or other material, and preserves its integrity, it does not have any tears that could turn into cracks after a while. Instead, its smooth surface is quite appealing.

If it were me, I’d choose rolling thread pipes over cutting thread on any day! They are efficient, long lasting, and cost less.