What is Gear Hobbing Machine Process?

 

 

Hobbing machines provide gear manufacturers a fast and accurate method for cutting parts. This is because of the generating nature of this particular cutting process. Gear hobbing is not a form cutting process, such as gashing or milling where the cutter is a conjugate form of the gear tooth. The hob generates a gear tooth profile by cutting several facets of each gear tooth profile through a synchronized rotation and feed of the work piece and cutter.

 

As the hob feeds across the face of the work piece at a fixed depth, gear teeth will gradually be generated by a series of cutting edges, each at a slightly different position. The number of cuts made to generate the gear tooth profile will correspond to the number of gashes of the hob. Simply put, more gashes produce a more accurate profile of the gear tooth.

 

The hobs several cutting edges will be working simultaneously, which provide significant potential for fast cutting speeds and/or short cycle times. With this realization, one can see the hobbing process’s advantage over other cutting processes.

 

All gear hobbing machines, whether mechanical or CNC, consist of five common elements.

1. A work spindle to rotate the work piece

2. A cutter spindle to rotate the cutting tool, the hob

3. A means to rotate the work spindle and cutter spindle with an exact ratio, depending on the number of teeth of the gear and the number of threads of the hob

4. A means to traverse the hob across the face of the work piece

5. A means to adjust the center distance between the hob and work piece for different size work pieces and hobs

 

 

While the hob and work piece are rotating, the hob normally feeds axially across the gear face at the gear’s tooth depth to cut and produce the gear. In conventional hobbing, the direction of feed matches the direction of the cutting motion. Alternatively, in climb feeding, the feed is opposite to the direction of the cutting motion. Generally, conventional hobbing produces a better finish, whereas climb hobbing yields better tool life. For either method, the cutting forces of the hob should be directed towards the work spindle and not the tailstock.

 

Gear Hobbing Basics

Gear hobbing is a diverse and wide-ranging process that can be used to create several different gear types: Helical, worm and spur gears are some of the most common, but others are possible as well. It's carried out using a special form milling machine, one that contains a tool known simply as a hob.

The hob is the tool that directly generates the teeth for both gears and splines, and it does so with relative simplicity compared to other gear manufacturing types. It allows for high-volume production of these gear types.

 

The final words

To cut a helical gear, a standard hob cutter can be used. Mechanical hobbing machines provide a differential motion through a series of change gears to generate a gear tooth helix. Today, CNC hobbing machines electronically provide this necessary differential to produce helical gears. Contact gear hobbing machine supplier for a quote!

Internal Spline Cutting vs. External Spline Cutting: Which is Right for Your Project?

Spline cutting is a machining process that involves creating ridges or teeth on a shaft or inside a bore to facilitate the efficient transfer of torque. When it comes to spline cutting, there are two primary approaches: internal spline cutting and external spline cutting. Both methods have their unique characteristics and applications. 

Internal Spline Cutting:

Internal spline cutting, as the name suggests, involves cutting grooves or teeth on the inside of a bore or hole. This process is commonly used when you need to mate two parts together within an enclosed space or when the spline is meant to engage with another component located inside the bore.

Advantages of Internal Spline Cutting:

Space Efficiency: Internal splines are ideal when space is limited, as they do not add external protrusions to the component.

Improved Torque Transmission: Internal splines can provide better torque transmission because they allow for larger and more robust teeth due to the confined space.

Reduced Wear and Tear: Internal splines are protected from external environmental factors, reducing the risk of wear and tear.

Applications of Internal Spline Cutting:

Gearboxes

Automotive transmissions

Hydraulic cylinders

Pump systems

Compressors

External Spline Cutting:

External spline cutting involves cutting teeth or grooves on the outside surface of a shaft or cylinder. This method is typically used when the spline needs to engage with an external component or when a sliding or rotating part requires grip and torque transmission.

Advantages of External Spline Cutting:

Ease of Assembly: External splines are easier to assemble and engage with other components, making them suitable for applications where disassembly and maintenance are required.

Enhanced Grip: External splines provide better grip and rotational control, making them suitable for components that need to be turned or operated manually.

Visible Inspection: External splines are readily visible and can be easily inspected for wear and damage.

Applications of External Spline Cutting:

Shafts for power transmission

Couplings

Gears

Shafts for industrial equipment

Axles for vehicles

Choosing the Right Option for Your Project:

Consider the Application: Determine whether your project requires internal or external spline cutting based on the specific functionality and engagement requirements.

Space Constraints: Evaluate the available space and clearance within your components. If space is limited, internal spline cutting may be the better choice.

Assembly and Maintenance: If your project involves frequent assembly and disassembly or maintenance, external spline cutting may be more practical.

Torque and Load Requirements: Assess the torque and load requirements of your application. Internal splines may provide better torque transmission in confined spaces.

Internal spline cutting and external spline cutting are two distinct methods, each with its advantages and ideal applications. To determine which is right for your project, consider factors such as space constraints, assembly needs, torque requirements, and the specific functionality of your components. Ultimately, the choice between internal and external spline cutting will depend on the unique demands of your project and your desired outcomes.