What Is Cnc Gear Hobber?

What is a Gear Hobber?

Gear hobbing is the foundation of gear manufacturing and is a widely used gear production process. A gear hobber uses a cutting tool known as a hob, which reciprocates to cut teeth on cylindrical or shaft workpieces, progressively machining out the gear teeth. This hobbing process is characterized by high precision and low cost, making it highly favored by customers.

Types of Gear Hobbers

Gear hobbers come in vertical and horizontal configurations:

Horizontal Gear Hobbers: The gear blank is mounted horizontally on the work spindle, with the hob rolling to cut external gears. Suitable for longer workpieces, these machines are commonly used in mass production within automotive and heavy machinery industries.

Vertical Gear Hobbers: The gear blank is mounted on a vertical work spindle, ideal for hobbing annular gears and gear segments. The target is standard and precise, suitable for small-scale manufacturing of medium and small gears.

Long Shaft Spline Shaft Horizontal Gear Hobber: Specifically designed for processing long shaft spline teeth, this machine has an exceptionally large internal space capable of accommodating shafts up to 2 meters in length, meeting specific customer needs.

Gear hobber Wet Cutting vs. Dry Cutting

Gear hobber Wet Cutting

During the hobbing process, lubricants or coolants are used. Coolant effectively reduces the temperature in the cutting zone, slowing down tool wear and extending tool life. However, additional cleaning is required after hobbing when using lubricants. Wet cutting is the more common method in typical gear hobbing operations.

Gear hobber Dry Cutting

Without coolant to dissipate heat generated during hobbing, the machine design must ensure thermal stability, often achieved through special internal ribs. The absence of coolant can lead to faster tool wear and increased replacement frequency. Not all materials are suitable for dry cutting, particularly those prone to deformation at high temperatures like hard alloys.

The choice between dry and wet cutting depends on specific application requirements, material characteristics, and production environment factors.

Gear hobber Post-Hobbing Processing

Deburring and Cleaning: Removing burrs and cleaning machining residues such as metal chips and coolant from the gear.

Heat Treatment: Processes like quenching, tempering, or carburizing may be applied to enhance the hardness, wear resistance, and fatigue strength of the gear.

Grinding for Finishing: Gears typically undergo grinding to achieve higher precision grades and surface finish.

Coating: Applying a special coating material to improve corrosion resistance or reduce friction.

Inspection and Calibration: Comprehensive inspection of finished gears using professional measuring tools and technologies.

Assembly Preparation: Preparing for final assembly, which might include cleaning, lubrication, and marking.

Surface Treatment: Methods such as sandblasting or polishing to improve appearance or add certain physical properties, like corrosion resistance.

This detailed overview covers the essentials of gear hobbing and the considerations involved in choosing between different cutting methods and post-processing techniques.