Internal thread by cold extrusion is a CNC machining procedure for metal and plastic that creates internal threads using extrusion taps. It features high material usage, precise CNC machining, smooth surfaces, high mechanical strength, and good fatigue resistance.Get more news about Precision Cold Extrusion,you can vist our website!

The cold extrusion CNC machining technique of the internal thread was investigated in order to increase the anti-fatigue service life of the thread. The plastic deformation law and surface integrity of the metal layer during cold extrusion are summarised to increase stability and economy.
Cold extrusion CNC Machining
Internal thread processing has slowly evolved into a trend that uses the cold extrusion method instead of chip processing. It has significant fatigue resistance because the internal thread, which was extruded using the metal-plastic forming method, has a superior surface quality, high hardness, and strength.

If the process parameters are not appropriately chosen, the internal thread extrusion formation will result in increased extrusion torque, excessive extrusion temperature, or even tap failure.The extrusion tap must endure a significant amount of extrusion torque during the cold extrusion of internal threads in order to overcome the resistance of metal plastic deformation.

The extrusion temperature will increase significantly as a result of the significant quantity of frictional heat produced in the area of contact between the workpiece and the extrusion tap.

Both have a significant impact on the thread formation quality and the service life of extrusion taps. The process parameters, the extrusion torque, and the resulting extrusion temperature are all variable while processing various types of threads.

It’s crucial to foresee the relationship between process parameters and extrusion quality in order to assure the extrusion quality and the efficient implementation of the extrusion process.
Mechanism of The Internal Thread Cold Extrusion
Extrusion of internal threads differs from conventional cutting and tapping. Cold-extruded threads have an identical lifespan of 4-30 times of cutting threads under identical conditions. Extrusion taps are used in this metal plastic processing technique to create a tooth profile.

A constrained area is used to carry out the plastic deformation of the metal when the tap extrudes the material. After multiple extrusion cycles, an internal thread is created by cyclically compressing the metal in the deformation zone. According to the size of the thread that will be extruded, a hole of a specific size is prepared on the workpiece, as seen in Figure 1a.The hole serves as a starting point and coordinates the axial feed and rotation of the tap. Intermittent contact between the workpiece and the tap’s teeth is observed. The metal accumulates and grows as it travels along the tap’s ridge.

The squeezed part is completely unloaded when the tap removes the workpiece, and the elastic deformation returns, the plastic deformation persists, and finally a thread profile is generated.