Analysis of Modern Thread Machining Technology: From Traditional Cutting to High-Efficiency Forming Technology

Thread machining is a crucial part of mechanical manufacturing, its core being the creation of internal and external threads on the surface of a workpiece using specific tools. Thread machining is mainly divided into two categories: one is thread cutting, which removes material using forming tools or abrasives, and the other is thread forming, which uses molds to induce plastic deformation in the material. In the modern fastener and automated assembly fields, the widespread application of products such as self-drilling screws places extremely high demands on the precision and efficiency of thread machining.

In traditional thread cutting processes, turning is the most basic and widely used method. Using a form tool or thread comb on a lathe, the tool moves precisely one lead axially for each workpiece revolution. Form tools have a simple structure, making them ideal for single-piece, small-batch production; while thread combs, although complex in structure, offer extremely high production efficiency and are suitable for mass production of fine-pitch, short threads. This high-precision turning process provides a high-quality blank foundation for self-tapping thread-forming screws, ensuring the stability of subsequent forming processes.

Milling threads is another highly efficient cutting method, typically performed on a thread milling machine using disc or comb-shaped end mills. Disc end mills are mainly used for machining trapezoidal external threads such as lead screws and worm gears, while multi-edged comb-shaped end mills require only 1.25 to 1.5 revolutions of workpiece rotation to machine ordinary internal and external threads, resulting in extremely high productivity. This efficient milling process allows for precise control of pitch and thread profile, providing reliable technical support for manufacturing various high-standard self-tapping fasteners.

For high-precision workpieces that have undergone heat treatment and hardening, thread grinding is an essential finishing process. Using single- or multi-thread grinding wheels, grinding can achieve extremely high pitch accuracy (grade 5-6) and excellent surface roughness. Single-thread grinding is suitable for precision lead screws and thread gauges, while plunge grinding offers higher productivity. This precision grinding technology ensures the fitting accuracy and wear resistance of high-end drilling screws under harsh operating conditions.

Besides cutting, tapping and threading are also common machining methods. Tapping involves screwing a tap into a pre-drilled hole to machine internal threads, while threading uses a die to cut external threads into the bar stock. The machining accuracy of these two methods directly depends on the precision of the cutting tools. In the production and assembly of various self-tapping fastening nails, tapping is often used to machine matching nuts or internal threaded holes; it is simple to operate and can be done manually or mechanically.

Thread rolling is a chipless machining method that uses a forming die to plastically deform the surface of a workpiece to create threads. This method not only boasts high material utilization but also significantly improves thread strength and hardness due to work hardening, while maintaining a surface roughness superior to machining. Thread rolling is particularly suitable for mass production of standard fasteners and is the preferred high-efficiency process for manufacturing self-drilling self-threading screws.

Depending on the die used, thread rolling can be divided into two categories: thread rolling and thread tapping. Thread rolling uses two staggered thread rolling plates to reciprocate linearly press the workpiece; thread tapping uses rotating thread tapping wheels to radially or tangentially press the workpiece. Tangential thread tapping (planetary thread tapping) allows for continuous workpiece feeding, resulting in extremely high productivity and making it ideal for automated production of large quantities of standard parts, such as auto-drilling and self-tapping screws.

In precision manufacturing, thread grinding is often used to correct machined threads. Using grinding tools made of softer materials such as cast iron, the workpiece is ground in both forward and reverse directions, effectively eliminating pitch errors. For hardened internal threads, grinding can also eliminate deformation. This ultra-precision machining method ensures the ultimate fit performance of the Self-Drilling Thread-Forming Screw in high-end mechanical equipment.