Broaching Operation; Process Parameters, Tools and Machines

There are various kinds of machining operations. One of these operations broaching process. Here we explain the general process parameters of broaching operation. Also, you can find additional information about the important term about broaching operation. So, you can find these kinds of information here;

• What are the broaching operations? The general summary and explanation of these processes.
• Types of broaching machines. Different orientations and shapes.
• Advantages and disadvantages of these processes. Also, you can make comparisons with other machining operations.
• Frequently Asked Questions. This section includes the most asked questions about broaching processes and machines.

What is Broaching Operation?

Firstly, in broaching processes, we are using multiple-teeth cutting tools. The tool makes the primary motion or cutting motion by moving parallel to the work part surface. We call the cutting tool a broach. 

There are various kinds of broaching operations that change according to the shapes of parts. In general, tooling orientations and methods change in these different types.

For example, internal and external broaching operations are changed according to the shape to be obtained. If you want to obtain external contours, you can use the external broaching machines.

So, there are different kinds of shapes that we can obtain with the broaching operations. We can produce these external and internal shapes in a serial production manner.

The serial production applicability of broaching machines makes them special from the other machining operations. Because other operations are not generally applicable to mass production. There is one exception which is the machining centers.

In the serial production of keyways, rectangular, hexagonal straight shapes, we use broaching machines generally.

Also, the cutters of the broaching machines are different. They have multiple-edge cutters and they are aligned in a special contour. In general, we require special cutter shapes for different contours.

If we think about all these facts such as operational costs, expensiveness of complexities of cutting tools, and limited shape capabilities, we can conclude that broaching operations are best for serial production.

Also, we can obtain very good surface tolerances. This is a very important parameter to obtain strict geometries.

What are the Types of Broaching Machines?

In the broaching process, we are using different types of machines. The first classification of these machines is the internal broaching machine and external broaching machine. This classification is about the type of shapes that we produce in these machines.

Internal and External Broaching Machines

In the internal broaching machine, we produce internal hole-like shapes on work parts. And in external broaching machines, we give different kinds of contours on the surface of the work part. There is a difference in the cutting tools in these two types of machines.

Vertical and Horizontal Broaching Machines

The other classification is the horizontal or vertical broaching machines. In the vertical broaching machines, the broach moves along a vertical path. Also in the horizontal broaching machines, the work part moves along the horizontal path.

Horizontal and vertical orientation may affect the sizes of the work parts to be machined. For example, we can machine the bigger parts in the horizontal machines than the vertical machines. Because the height of the machine in vertical orientation is limiting the work part size.

In general broaching operations, the broach is pulled by the machine to cut the work part. But there is an expectation.

Broaching Press

In the broaching press machine, the broach is pulled to create internal shapes. This is a very different working principle. Forces in broaching press machines can be high.

We stated that the broach or cutting tool moves to create chips from work parts. Also, work parts are stationary. So, there is another exception for that.

Continuous Broaching Machines

In the continuous broaching machine, we attach the work parts in a continuous endless belt. And they pass near the cutting tool. So, the cutting operation takes place like this. This is the general working principle of these machines.

Continuous working machines are the best type of broaching to apply to machining operations.

So, the work part makes the primary motion.

Surface Broaching Machines

This is the most classical configuration of the broaching machines. Furthermore, the cutting tool is moving along a straight line to obtain surface contours.

We can find vertical or horizontal broaching machines.

Turn Broaching Machines

This is a special type of broaching machine. They are using these machines to obtain circular or special contours. A crankshaft mechanism moves the cutting tool in these machines.

Rotary Broaching Machines

Rotary broaching machines are special for creating complex internal shapes. For example, we can create internal hexagonal, square, keyways, and other insertion shapes with the rotary broaching machine.

CNC Broaching

CNC or computer numerical control machines are very important technologies. They are used in all types of machining operations. Also, they are common in broaching machines.

One of the most important features of the CNC broaching machines is the tool holders. Turret-type tool holders are very useful to obtain very complex shapes.

Also, tolerances and surface finishes are very advanced in CNC broaching processes.

Which Kinds of Shapes We Can Create?

As we stated above, we can create internal and external shapes of work parts in broaching operations.

As you see above, there are different kinds of shapes that we can obtain with the broaching processes. For example, we can obtain symmetrical external broaching if you look at the first part.

Also, we can create the complete external contours of parts if you take a look at the second and the third part above.

We can make different kinds of surface contours also. Check the fourth and the fifth parts above the line.

If you check the parts in the second line, you can see that we can obtain different kinds of internal shapes. Also, we can create internal shapes that open to the outside from one or two sides. Check the fourth shape at the second line.

You can understand that we need to have very complex shapes of cutters. This proves the costs of cutters in broaching operations. So, if you are not producing these parts in a serial production manner, there is no meaning to using broaching operations.

Advantages and Disadvantages of Broaching Operations

Like other machining operations such as turning, drilling, milling, and shaping, broaching process also have its advantages and disadvantages. According to these advantages and disadvantages, you need to consider selecting broaching operation.

Advantages

• With the broaching operations, we can obtain very good surface finishes. So, we can obtain the final parts with the broaching operation. We generally do not need to use additional operations such as roughing or finishing.
• Close tolerance is another important advantage of broaching operations. We can obtain external and internal shapes with very strict tolerances. So, we can produce very critical parts which have close tolerances.
• Work shape variety is another important advantage of these operations. As we have shown above, you can see that we can obtain various kinds of shapes. So, this variety proves the versatility of the broaching operations.
• Production rates are very high in these processes. So, they apply to the serial production of certain parts. Maybe we can obtain these shapes in other machining operations. But, broaching operation is better at the application to serial production.
• There is no requirement for a skilled workforce. You can save money from the operations costs with broaching processes.
• The application of cutting fluid is better in these operations. Because the motion of the cutter makes the fluid movement between the work part and the tool.

Disadvantages

• Nearly for every type of shape, we need to produce tooling. So, tooling is very expensive in broaching operations. This is the main disadvantage of this operation.
• We can not obtain very complex shapes with these operations. We can only produce through shapes like the above. Maybe CNC broaching operations can help in the production of complex shapes.
• The cutting tool broach is prone to be damaged during the work.
• Broaching processes are economical only in the mass production of the parts. It is not sensible to use these machines for little production rates.
• There is a size constraint in these processes. The size of the work part is limited.
• The cutting forces in broaching operations are high. So, the work part must withstand these forces to obtain successful work.

Conclusion on Broaching Operations

As you see above, broaching operations are the best for the serial production of certain shapes. You can see these shapes above. Also, broaching cutting tools are different from the other kinds of machining tools.

With the different types of broaching machines, you can produce different kinds of shapes on a mass production basis.

Finally, you need to consider the advantages and disadvantages of broaching machines before setting them up.

Above all, do not forget to leave your comments and questions below about the broaching machines and broaching processes.

Your precious feedbacks are very important to us.

FAQs About Broaching Processes