Thread Machining: Types, Methods & Applications

Threads are a critical part of the components that require assembling. Thread machining is the process that helps to create threads on these parts, and the method has various stages. If you want to learn how thread machining works and what its main parameters are, the guide below can help you. So, let's read.

What is Thread Machining?

Thread machining is a process that involves collaborating with CNC machines to create threads. The process involves removing material to create internal and external threads. These threads can be created in various sizes, and by the circular rotation of the machine tool, the threads of different depths can be attained.

There are different parts of the thread, which are composed of pitch, root, flank, and helix angle.

Main Parameters for Thread

The thread has various parameters, and some of these are discussed below:

Helix Angle: Helix angle is the angle between the helix and a thread axis in a straight thread. It is also the angle that is made by the conical helical area of the taper thread for the helical areas.

Root: It is at the lower part of the threads, which is located adjacent to the projected cylinder.

Flank: It is the threaded part that creates a connection between the crest and the root.

Crest: The top part of the threads is the crest, and the farthest area of the cylinder or cone is the crest.

Pitch: The pitch has a diameter similar to a cylinder. The distance of the pitch is measured on the threads that are adjacent.

Types of Machining Thread

There are two types of machining threads, which are discussed below.

Internal Threads

The internal thread has another name, which is called the female thread, and it passes through the machining with the help of a single-tip threading tool. Apart from this tool, a traditional threading cap is also used for cutting the CNC internal threads. Internal threads can be cut on concave surfaces only.

External Threads

External threads are such types of thread that are used in studs, bolts, and screws. These are created using lathes. Apart from using a lathe, the round die is also used for cutting these threads. Sometimes, hexagonal squares are also made, which help in interlocking components.

How to Cut a Machining Thread?

The components which have screwed connections are created using the thread machining process. The process of cutting threads is discussed below.

How is Internal Thread Cut?

In order to cut the internal threads, you will need the right tools, which include a box column drill, safety goggles, tap wrench, twist drill, and internal tap. Identify the hole diameter you want to have the thread placed in and then choose the right tap for cutting. Also, determine the core hole diameter, and for this, subtract the tap diameter and thread pitch.

When cutting the internal thread, first center it with a punch and then start drilling a core hole with the help of a twist drill. To make a chamfer in the core hole, use a countersink of 90 degrees and attach the tap wrench with the tap to turn the core hole.

How is External Thread Cut?

The tools required for cutting the external threads consist of a round die, vise, rod, file, die stock, and flat tip. The edges are at the round rod and then are chamfered at an angle of 45 degrees. Make sure that the chamfer is bigger than the thread depth.

Clamp the round die and firmly fix it so that the movement is avoided as the rod needs pressure for cutting the external thread. Also, use cutting sprays so that the quality of the surface of the component is improved.

Common Screw Thread Machining Methods in CNC Process

Some of the common screw thread machining methods in the CNC process are discussed below.

Tapping

When producing the internal threads, tapping is one of the common methods as it is efficient and cost-effective. The process helps to thread holes that have low accuracy of position and a small diameter. This method of screw thread machining is conducted in less time, and it is a high-speed machining process.

The tools used for such threading are cheaper, so they reduce machining costs; it is also suitable for many applications.

Thread Milling

Thread milling is a precision-oriented method that offers high versatility and creates threads by rotation. The process of thread milling uses a CNC machine that rotates a cutter along the component, which helps to cut the threads of the material. The process of thread milling cuts the external and internal threads, offering high-precision processes.

Thread Turning

Thread turning is an affordable and efficient process that helps create external threads. It is mainly opted for the more extended parts, the cutting tool is fixed in the helical path. The cutting tool in this process is controlled in a precise way, which ensures consistent and accurate threading.

Thread Grinding

It creates finished and precision-oriented threads. It uses a grinding wheel which can help shape the components for tooling, ball screws, and other components.

Thread Rolling

It creates threads without cutting and rolling the component between two dies. The process consists of creating a shape that is used for high-volume production.

Application of Threading

The process of threading has multiple applications, and some of these are as follows:

Automobile Industry

The automobile industry consists of threaded components that play an integral role in ensuring high performance. These threaded compensators are used for assembling transmission components, steering systems, and even engines.

Aerospace Industry

The aerospace industry requires tight fasteners to ensure that the components are assembled tightly. The parts, like engine components, cockpit parts, and airframe bolts, are used to mate with these threaded fasteners. The fasteners can also withstand the challenging conditions and offer high durability.

Manufacturing Industry

Threaded parts in the manufacturing industry are used in fixtures, assembly line operations, and robotic arms. They help to work like clamps and allow the manufacturing process to work with efficiency.

Electronic Industry

The electronics industry uses threaded components to assemble electronic gadgets and enclosures. They offer a compact assembly of the components, which makes them functional as well as durable.

Useful Tips for Machining Threads

When machining threads, some of the tips for the machining process are as follows:

• At the end of the internal threads, there should be a countersink.
• The preference is given to the low-height threads if there is no specific requirement.
• The start of the thread should have a flat surface with a consistent central axis.
• Standard forms and sizes of thread are cheaper.
• The need for a chamfer is essential in the external thread ends.
• The wall thickness of the tubular parts should be sufficient to handle the pressure of cutting.

Conclusion

The thread-making process is versatile and is a crucial part of almost every application, as the need for fasteners and screws is very important.

If you are looking for hands-on, high-quality thread machining services, we at DEK can provide them to you. Feel free to contact us and get the components manufactured, requiring thread machining.

FAQs

What is the purpose of threading?

Threading creates connections for the screws, which help components with assembly.

Can threads be machined on a mill?

Yes, threads can be milled using a CNC milling machine.

Is thread milling faster than tapping?

No, tapping is faster than thread milling.

What is the difference between rolling and machining threads?

The process of rolling consists of rolling the component between two dies, and there is no cutting involved, whereas, in machining threads, the process of cutting is involved.