Exploring the Different Types of Grinding Machines

Not to be confused with a milling machine, a grinding machine is a heavy-duty machine that's used to remove material from the surface of a workpiece. While milling machines feature a rotating cutting tool that's placed against a stationary workpiece, a grinding machine features a rotating grinding wheel, which is also placed against a stationary workpiece. There are several different types of grinding machines, however, each of which works in a different way.

 

Bench Grinding Machine

Bench grinding machines are characterized by their bench-like shape. They usually feature two different grinding wheels: one for the removal of material and another for finishing processes. They are called "bench grinding machines" because their grinding wheels are secured to the top of a workbench. As a result, bench grinding machines are easy and convenient for manufacturing workers to use.

 

 

Belt Grinding Machine

Belt grinding machines are characterized by the use of a belt sander. Like other grinding machines, they are designed to remove material from workpieces, thereby making workpieces smaller and with a smoother and more desirable surface. With belt grinding, the belt is coated in an abrasive material, after which it's run against the surface of a workpiece until the desired results are achieved. Belt grinding is most commonly performed on metal workpieces, though it supports workpieces made of other materials as well.

 

Surface Grinding Machine

A third type of grinding machine is a surface grinding machine. Surface grinding machines are unique because they feature an adjustable head. The head on a surface grinding machine can be lowered down to the workpiece. Once lowered, the head can then rotate back and forth under the machine's grinding wheel.

While belt grinding machines are typically used for finishing processes, surface grinding machines are most commonly used for material removal. When compared to other grinding machines, surface grinding machines are able to remove significant amounts of material, making them desirable for such applications.

 

Gear Grinding Machine

 

 

Gear grinding machines are designed specifically for the removal of material from shafts. Using grinding wheels, they can grind the center of a shaft with extreme precision.

 

Die Grinding Machine

A smaller and more basic type of grinding machine is a die grinding machine. Unlike the other machines listed here, die grinding machines are handheld. They are connected to an air compressor, which works to power the machine's grinding wheel. If an air compressor isn't used, the die grinding machine will likely receive power from an electric motor.

 

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Difference Between Gear Milling and Gear Hobbing

Gear is a vital component for rotating machines, with teeth mesh with another toothed part to transmit torque. How gears are made? Other than casting, forging, CNC machining can be applied to achieve the final shapes, dimensions, and surface finish of a gear. Here we introduce and compare two gear manufacturing methods – gear milling vs gear hobbing, what are the differences between them?

 

CNC Gear Hobbing Machine

 

What is Gear Milling?

 

Gear milling is a common CNC milling operation and gear-cutting process of creating a gear. It can be operated either after or instead of forming processes including casting, forging, and extruding. Gears are usually made from metal, plastic, and wood. Many metal and plastic gears made by die-casting, injection molding, or additive manufacturing may not require cutting. For coarse-pitch gears, the generative gear milling technology can improve efficiency, expand the pitch capacity of the machine, reduce cutter cost, and may decrease the machining times.

 

What Cutter Used in Gear Milling?

 

The gear can be cut on a milling machine or jig grinder utilizing a gear cutter and indexing head or rotary table, the quantity of gear cutter is determined by tooth count of the gear required. Various types of cutters can be used for producing gears, for example, the rack shaper, with six to twelve teeth, straight and move in a direction tangent to the gear. The cutter has to move back to the beginning position for the new round cut.

 

What is Gear Hobbing?

 

Gear hobbing is also a gear manufacturing method to cut teeth into the blank with a hob like an index hob and master hob on CNC gear hobbing machines. The hob and gear blank rotate at the same time in a mesh and cut the teeth by continuous cut, the rotating hob is fed inward until achieving proper depth, then work for the entire gear. Gear hobbing is a great choice for medium to high volume production runs. The hobbing features for gears including straight, helical, straight bevel, face, crowned, worm, and chamfering.

 

How to differentiate gear hobbing and gear milling?

 

1. The way gear teeth are produced

 

In gear milling, a single tooth spacing or gap between gear teeth will be created by a rotating multi-edge cutter at a time, the cross-section of generated teeth is similar to that of the cutter. In gear hobbing, the gear teeth are progressively produced by a series of cuts with a hob. So the hob cuts several gaps simultaneously.

 

Hobbing Machine

 

2. Cutter

 

Gear milling uses a rotating form cutter, when each tooth space is cut, the cutter will return to the starting point and gear blanks are indexed for next cutting process; gear hobbing uses a helical hob cutter, the hob and the workpiece are both rotating constantly when the hob is fed across the face width of the blank.

 

3. The number of teeth cut in one time

 

Each cutter in gear milling is designed to cut a range of tooth numbers, while in gear hobbing, both the hob and gear blank rotate continuously as in two gears meshing until all teeth are cut.

 

4. Price of tool

 

Generally, the gear milling cutting tool is cheaper than that of hobbing, but the productivity of gear hobbing may be higher.

 

5. Application

 

Gear hobbing is more often used for high production runs, and gear milling is a low production process.

 

6. Others

 

– Gear milling requires deburring

– Gear milling is often used when other generating processes are unavailable.

 

If you’re eager to learn more about the gear hobbing machine, or if you have an order you’re ready to place, contact GEEPRO today! We’ll have a quote back to you in less than 24 hours.