Common gear machining methods

Historically, gear machining methods have been classified into three main categories: shaping, blanking, and die machining. So let's learn in detail about these popular groups of gear machining methods through VISC's article below:

1. Shaping processing

Forming uses cutting tools of the desired gear shape to create gears using rack cutting, gear shaping and gear grinding methods. This is often the first step in the production of machined gears.

Shaping processing

Below are some of the most popular shaping methods:

1.1. Milling

This method uses shaped milling cutters such as modular disc milling cutters or modular end milling cutters whose profile is similar to the profile of the tooth groove.

The milling method is performed on universal milling machines equipped with grading tools. The workpiece will be mounted into the indexing head, the milling cutter is mounted so that the outer diameter of the disc milling cutter or the end face of the end milling cutter coincides with the highest generating line of the part. Then, adjust the knife to the height so that the tooth groove has the required depth (depending on the machined tooth module). Proceed with machining by finishing machining a groove, then use the grading head to rotate the workpiece 360o/z and then continue machining the next groove until completed.

The milling method has some disadvantages such as low accuracy, errors in groove boundaries and graduations. In mass and bulk production of large modules, this method is only used for destructive machining.

1.2. Shaping

The shaping process is performed on toothed planing machines with shaping knives with profiles similar to tooth groove profiles or regular knives with templates. Similar to profile milling, leveling heads for each tooth are also used.

The shaping method is mainly used for rough machining of external and internal mesh gears with large modules.

1.3. Broaching

The broaching method uses a broaching knife with a gear profile. During the machining process, one groove or many grooves can be broached at the same time. After each stroke of the tool, one or several tooth grooves are machined. To machine other grooves, the part is turned at an angle thanks to the grading mechanism. It is also possible to sharpen all grooves at the same time, but due to the complex knife structure, poor chip evacuation ability and high cutting force required, this method is rarely used.

The cutting tool is a set of shaped knives with each step installed into the broaching head. The amount of lift of each cutting edge depends on the thickness of the chip layer being cut Sz, the type of gear material and cutting speed..., this amount of lift is chosen as with a conventional broaching knife.

The layer of material to be cut is divided according to the total number of cutting edges of the tool, so the life and durability of the sharpening knife are often large. However, the investment cost for tools is high, so this method is only used for mass production of large quantities, gears with large modules and gears without heat processing and grinding. The advantage of the shaping broaching method is its high productivity and accuracy.

2. Gear machining

Gear machining is gear cutting that includes tools used to create gear profiles, using gear milling, shaping, slotting, planing and EDM methods. Blanking machining is one of the essential methods in gear machining. It involves shaping gears by removing excess material from the workpiece using a variety of machines. Gear machining processing includes the following methods:

2.1. Gear hobbing
Gear hobbing is one of the most popular types of gear cutting. In tooth milling, a complex machine removes material by rotating at high speed while in contact with gears. During the tooth milling process, the rotation of the milling cutter and the rotation of the part must be within the drive chain of the blank. Milling cutters used in this method have a quite complex structure, so the price is quite high.

The gear hobbing method is used on specialized milling machines, rotating milling cutters that cut continuously, can be milled forward or reverse milled. CNC machines are preferred by gear manufacturers for milling due to their high efficiency and ease of operation

2.2. Gear shaping
Gear shaping uses up and down movements of the tool head to machine the full tooth width, radial feed movement to machine the tooth height and tool yield movement.

Planing and slotting are also common forms of blanking and slotting processing. Planers use linear reciprocating motion to move their tools along the workpiece, creating flat surfaces or grooves on them as needed. Slotting machines, on the other hand, create slots by removing material along specific lines. The combination of planing and slotting creates industrial-grade gears.

 2.3. EDM electric discharge machining method
Another commonly used gear cutting method is electrical discharge machining (EDM). This process uses an electrode to remove material from a conductive surface placed near it. This results in extremely precise cuts, making EDM perfect for manufacturing complex gears.

3. Machining gears without using cutting tools

Machining gears without using cutting tools: gear shaping produces gears without using cutting tools using rolling, casting, powder metallurgy, and 3D printing methods.

There are three essential methods that manufacturers can use to make gears without the use of cutting tools: rolling, casting and powder metallurgy. Each method has its own advantages and disadvantages depending on the specific requirements of the project.

• Rolling is a popular choice for producing large quantities of gears with high precision at low cost. This process involves pressing the metal between two rollers until it takes the desired shape. The resulting gears have excellent strength and durability, making them ideal for heavy-duty applications.
• Casting is a method of shaping gears in which molten metal is poured into a mold and allowed to cool before being removed from the mold. This technique produces gears with complex shapes that are difficult or impossible to produce using other methods. However, cast gears may have lower dimensional accuracy than gears made using other techniques.
• Powder metallurgy involves compressing metal powder in molds under high pressure to form complex shapes such as gears. This process also allows manufacturers to create parts with different properties by adding alloying elements to the mix during compression.

4. Other gear processing methods: 3D printing

3D printing, additive manufacturing builds a three-dimensional object, layer by layer, from a 3D CAD model. Due to the nature of the process, additive machines can form complex designs with modeled lattice structures to achieve mass reductions not easily achieved with conventional methods. This type of geometry is typically created using 3D topology optimization and generative computer design.

Regular and non-circular gears can be made using additive manufacturing processes and high-quality 3D printers are relatively affordable and widely available. Because of this availability, it becomes the choice for repair and mechanical projects such as educational toys or other devices that need fully functional gears. You can also include additional features and even combine geometry with gear shapes to add custom shafts, pins, or tracks to the same block.

If you are looking for a reputable supplier of gear processing machines, VISC is a reliable address for you
The above article has summarized the most common gear machining methods today. Hope it will help readers in learning about gear manufacturing technology.

If you are looking for a gear processing machine supplier, please contact us immediately. VISC specializes in distributing outstanding gear processing machines for many applications. With more than 13 years of experience as an industrial processing solution consultant in combination with leading machine manufacturing experts in the world. VISC ensures we provide advice that effectively meets your unique needs.

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