Introduction:

The digital age has ushered in a comprehensive transformation of machine tools, and in recent decades, machining processes have undergone revolutionary changes thanks to widespread digitalization.

Gear processing equipment has also been fully updated with digital technology, significantly altering processing techniques. Even complex gear products are now easier to process, and the variety of techniques has expanded. It is estimated that there are now over 20 different gear manufacturing processes, summarized as follows:

1. Gear Milling (distinguishing between standard milling cutters and form milling cutters)

2. Gear Hobbing (form hobbing cutters, mainly completed by CNC hobbing machines and five-axis turn-mill composite machines)

3. Gear Shaping (using CNC shaping machines and form shaping cutters)

 

4. Gear Shaving (using shaving machines and shaving cutters)

5. Gear Turning (using five-axis machine tools and specialized turning tools)

6. Gear Grinding (using CNC grinding machines and form grinding wheels)

7. Gear Honing (using honing machines and honing tools for super-precision machining)

8. Wire EDM Processing (wire EDM processing for spur gears)

9. Powder Metallurgy (mold pressing, heating sintering, heat treatment, and post-treatment)

10. Waterjet Cutting (CNC waterjet cutting for spur gears)

11. Laser Cutting (CNC laser cutting for spur gears)

12. Gear Broaching (using CNC broaching machines and internal spline processing)

13. Gear Planing (using planers and form planing tools)

 

14. Electrochemical Machining (using EDM and chemical electrolytic machining)

15. Stamping Processing (CNC punch press molds for stamping spur gears)

16. Spin Forming (a type of cold extrusion, including both hot and cold spinning)

17. Gear Rolling (using gear rolling machines and rolling tools)

18. Gear Scraping (using CNC gear scraping machines and scraping tools), suitable for mass production.

19. Casting Processes (including silica sol precision casting and sand casting)

Gear Manufacturing Processes

II. Introduction to Gear Processing Stages

1. Gear Blank Processing

After heat treatment, the raw blanks undergo machining. This stage mainly prepares the gear blank for subsequent gear tooth processing, ensuring the internal hole and end face meet the specified technical requirements.

2. Gear Tooth Processing

This stage focuses on the fine machining of the gear's shape, resulting in gears that fully meet the blueprint specifications. The gear tooth precision achieved in this stage must meet the requirements for final precision machining.

3. Heat Treatment

If no hardening is required, gear tooth processing completes the gear manufacturing. For gears that need hardening, the process ensures the gear surface meets the specified hardness requirements.

4. Gear Tooth Finishing

Gears that have been hardened typically need finishing to correct any deformation caused by hardening and to further improve tooth accuracy and surface roughness to meet final precision requirements.

5. Gear End Processing (Post-Processing)

Gear end processing includes treatments like rounding, chamfering, and deburring. These processes facilitate easier meshing when the gear slides axially and remove sharp edges to prevent chipping during transmission.

Involute tooth forms are the most common. The main processing methods for involute tooth forms fall into two categories: forming and generating methods. Below are various gear manufacturing processes sourced from the web.

1. Gear Milling

Using disc-type or finger-type milling cutters, gear milling belongs to the forming method, where the cutter's tooth profile corresponds to the gear's tooth space. This method is less efficient and precise, suitable for small batch production.

2. Form Grinding

Also a forming method, but less common due to the difficulty of dressing grinding wheels.

3. Gear Hobbing

A generating method, gear hobbing works on the principle of a pair of helical gears meshing. The hob's prototype is a helical gear with a large helix angle, typically with few teeth (usually z=1) and long teeth forming a worm with a small helix angle. After slotting and flanking, it becomes a hob with cutting edges and clearance angles.

4. Gear Shaving

Common in mass production for non-hardened gears, gear shaving uses a shaving cutter and the workpiece in a free meshing motion. The relative sliding between them shaves fine chips off the tooth surface, improving precision. Shaving can also create crowning to improve the contact area.

5. Gear Shaping

Another generating method, gear shaping involves the shaping cutter and the workpiece meshing like a pair of cylindrical gears. The shaping cutter's reciprocating motion is the primary movement, while its rotational motion with the workpiece is the feed motion.

6. Generating Method Grinding

Similar to gear hobbing, generating method grinding is a precision finishing method, especially for hardened gears. It can use worm grinding wheels, conical grinding wheels, or disc grinding wheels.

7. Gear Honing

Similar to gear shaving, gear honing uses a honing wheel and the workpiece meshing without backlash. The relative sliding with applied pressure hones the gear teeth.

8. Wire EDM

Short for electrical discharge machining, wire EDM develops from EDM drilling and forming, expanding its applications and partially replacing traditional EDM methods.

Gear manufacturing is a highly complex process requiring the correct techniques to enable efficient production. Every stage must achieve precise dimensions.

The gear manufacturing cycle typically includes turning, gear hobbing, gear shaping, gear shaving, hard turning, gear grinding, gear honing, drilling, inner bore grinding, welding, and measurement. Proper clamping systems are crucial for these processes, which will be introduced alongside the gear processing tools and techniques.

Comprehensive Overview of Gear Processing Tools and Techniques