The importance of threading pipes without voids

Pipe threading is the process of cutting a screw thread into a pipe. It is a vital step to join two pipe ends mechanically. Pipe threads are not only used to make mechanical joints but also to leak-proof gas or liquid seal. The threading quality becomes essential as it directly influences the quality of joining two pipes. Precise machining of the thread form with no voids between the two threaded pipes is indispensable to achieve leak-proof quality.

Key components to achieving perfectly threaded pipes

There are various components involved in threading a pipe with top quality. This article covers insert types, infeed methods, steps to follow during threading, and what Copier Machinery offers to ensure optimum pipe threading.

Threading inserts

When selecting a threading insert, one must be aware of whether to choose partial, full, or semi-full form. The partial form can be used for a series of samples, but it has a shorter lifespan because the nose radius is smaller than that of the full form, and finishing with another operation is necessary.

When a full form is used, there is no deburring needed after threading, but it requires different threading inserts. While using a semi-full form, no deburring is needed after threading but it requires different threading inserts, and finishing with another operation is also necessary.

Infeed methods

Infeed methods dictate how the insert is applied to the pipe to create the required thread form. There are four-thread turning infeed methods; radial, flank, modified, and incremental infeed.

• Radial infeed is the standard programming for wire cutting and is the most convenient to use. It has a broad application as the cutting conditions can be easily changed. It has uniform wear on both the right and left sides of the cutting edges. However, it is difficult to control the chip during the later cutting stages since it is subject to vibration. It is ineffective for high-pitch threading and when the nose radius is heavily loaded, it will be damaged.
  
• Flank infeed is a semi-standard wire feed program and is also convenient to use. It has reduced cutting force and is suitable for large pitch threads or easily peelable materials. It has a good chip discharge. However, a large flank wears on the right side of the cutting edge, and re-programming is needed to change the cutting depth.
  
• Modified flank infeed prevents flank wear on the right side of the cutting edge and has reduced cutting force. It is also suitable for large pitch threads and easily peelable materials. It has a good chip discharge but involves complex machining programming.
  
• Incremental infeed has uniform flank wear on the right and left side of the cutting edge and reduced cutting force. It is suitable for large pitch threads or materials that peel easily. It has complex machining programming as it is difficult in changing cutting depth and chip control.

Increase efficiency in pipe threading with the following steps:

1. Different Infeed methods have their highlights and can be chosen according to production needs. Preventing damage to the nose radius increases the tool life and nose radius damage can be avoided by using Modified flank Infeed. Crater wear can be prevented by flank Infeed and having uniform wear on both sides of the cutting-edge radial infeed method is ideal. Both Flank and Modified Infeed prevent chip problems and prevent vibration.
2. When using radial Infeed cutting, an inverted holder should be used while changing the coolant supply to a downward direction. Reduce the cutting speed in the latter half of the passes and decrease the cutting speed.
3. Increase machine efficiency by increasing cutting speed. It depends on the maximum revolution and rigidity of the machine. Reducing the number of passes up to 30-40% can improve the chip discharge since the thicker chips are produced. Performing the final whip pass at the same depth of cut as the regular pass improves surface efficiency, if a flank infeed method is used change to Radial Infeed only during the final pass.

What we offer

Copier Machinery's specialized pipe threading machine has radial and axial feeding, enabling the user to adjust tool holder positions. As per the operator’s requirement standards, dimensions and tolerances can be set to get the contour of the thread. Customized CNC control has data storage options, which allow subsequent operators to pull pre-set shapes.

Our beaver CNC and RTL ZX machines perform most of the standardized threading like NPT (National Pipe Thread) and NPS (National Pipe Straight). These have the same thread, angle, and pitch (threads per inch). The difference is that NPT threads are tapered and NPS threads are straight.

In addition, our machines have options to program different infeed, and they are compatible with various insert types. Copier’s inbuilt programs and customization at your fingertips mean that you don’t have to be concerned about complex entry programs and they help you thread pipes without any voids for industrial uses.