How to Save on Wire Threading Costs
Cut threading is a process that removes steel from a round bar or rod to form threads.
Roll threading is a process where steel is pressed or extruded to form the thread, instead of being removed, as in cut threading.
When comparing roll thread and cut thread steel wire, many people believe that rolled thread products are weaker because the wire diameter is smaller. This is in fact NOT true. Since the thread dimensions of a cut thread and rolled thread fastener are identical, there is no difference in strength. However, the work that has been done on the weakest point of the root will affect the strength of the finished product. A cut thread requires no work on the base material since the thread is formed by simply removing the metal. A roll thread, however, is formed by metal displacement (cold work), so the work hardening, which occurs during the roll threading process, is what gives a rolled thread a stronger tensile strength.
Additionally, cut threading interrupts the natural grain structure of the round bar. Roll threading reforms it. Most agree that cuttng into the grain of a round bar when cut threading will product threads that have less structural integrity than a part that has been roll threaded.
Advantages of Cut Threading
- Few limitations with regard to diameter and thread length
- All specifications can be manufactured with cut threads
Disadvantages of Cut Threading
- Significantly longer labor times means higher costs
- Since the molecules of the metal are interrupted and removed (cut away) the final threads are not as strong
Advantages of Roll Threading
- Significantly shorter labor times means lower costs (3-5 times faster)
- Because a roll threaded wire has a smaller base diameter, it weighs less than its full bodied counterpart. This weight reduction reduces the cost of the steel, galvanizing, heat-treating, plating, freight, and any other costs associated with the fastener that are based on weight.
- Cold working makes threads more resistant to damage during handling
- Rolled threads are often smoother due to the burnishing effect of the rolling operation
- Dies do not require sharpening. There is much less maintenance for sharpening or resetting
- Rolling can be performed on the collet end behind a part's shoulder, often saving a secondary threading operation
Disadvantages of Roll Threading
- High cost of rolling dies makes it uneconomic to roll a limited number of pieces
- If the depth of the thread is over 15% of the diameter, the roll is very difficult because the pieces after rolling are distorted.