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What is CNC Broaching

Table of Contents

CNC broaching is a highly precise and efficient machining process that utilizes computer numerical control (CNC) technology to create intricate surface features on various workpieces. It involves the linear reciprocating motion of a specialized cutting tool called a broach, which progressively removes material from the workpiece with each pass.

CNC boraching

What is CNC Broaching?

CNC broaching can be described as a metalworking process that involves using a computer-controlled cutting tool to lead or guide a multiple teethed broach through apiece of work, resulting in complex internal or external features such as keyways, splines or gear teeth. The reason why the method remains important is because it has been used to deliver high quality surface finishes within very close tolerances.

Types of CNC Broaching Machines

Different configurations in terms of size of parts to be machined, type of broaching required and volumes determine various forms available for CNC broaching machines. Common types are:

1. Horizontal CNC Broaching Machines

In line with this mode, the operation happens horizontally by working on the job done through spindles mounted on them. Internal parts like keyways, splines and gear teeth for shafts or cylindrical components are best produced using horizontal CNC machines.


2. Vertical CNC Broaching Machines

These systems have vertical motion while removing excess materials from their pieces with special cutter blades known as broaches. They can be used in producing outside characters together with flatness grooves and profiles for irregularly shaped objects such as flat plates made out metals.


3. CNC Broaching Centers

CNC broach centers are machine tools that combine several machining operations including milling and drilling with ram-type linear motion of the slide carrying the tooling fixture attached to it allowing complete part processing in single setup maximizing its efficiency and handling time reduction respectively.


4. Special-Purpose CNC Broaching Machines

For niche applications or industries there might exist specialized designs for specific industries requiring certain forms which include massive gear cutters among others yet using the broaching technology. Those could imply for instance, machining of large gears in gear making line or splines on spline shafts.


5. CNC Broaching Attachments

Existing milling, turning or multi-tasking machines can be retrofitted with broaching attachments or modules to give them broaching capability. Such attachments represent an economical solution for adding broaching capacities to already set up facilities while maintaining low cost of operations.

Characteristics of broaching

1) High productivity. Broaches operate with several teeth simultaneously, and after a stroke they can perform roughing and finishing.

(2)High durability of broach. The speed of broaching is modest, the thickness of each tooth cut is low; consequently, the cutting force applied also insignificantly decreases and reduces heat generated by cutting.

(3) High machining accuracy. A broaching size tolerance grade generally ranges from IT8 to IT6 and a roughness of Ra 0.8 ~ 0.1μm.

(4) Broaching only one main movement(linear motion), simple structure and easy to operate.

(5)Wide range of machining. Broaching can process round through holes, as well as any other complex shapes such as flat surfaces without obstacles for external surfaces, but cannot complete step holes, non-through holes or thin wall bores.

(6) Broaching high cost, sharpening complexity, in addition to standardization and specification of parts, in a single piece small batch production are rarely applied.

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CNC Machine Broaching Tools

Broaching Tools for CNC Machines

In CNC broaching operations, there are specialized broach tools that are designed to work with CNC machines. These tools comprise of a bar or a holder capable of holding firmly an insert or the broach. In addition, this cutting edge is made up of a series of teeth which grow progressively in size and take away material as it passes by.

Materials and Coatings for Tools

The hard and wear resistant materials used in manufacture of broaching tools include high-speed steel (HSS) and cemented carbides. HSS type are meant for machining relatively softer work pieces while the cemented carbide ones are suitable for harder materials e.g. abrasive applications. Moreover, such tools may be coated with advanced thin-film coatings like titanium nitride (TiN), aluminum titanium nitride (AlTiN) among others to enhance their performance, tool life as well as wear resistance.

Tool Life and Maintenance

Different factors determine the tool life of broaching tools such as work piece material, cutting parameters and even how well the tool is maintained. A constant performance guarantee is obtained through proper maintenance like regular inspection, sharpening and replacement of worn-out or damaged teeth ensuring maximum utilization of these tools over time.

Advantages of CNC Broaching

High Precision and Consistent Surface Finish

The ability to produce highly accurate and consistent internal or external surface finishes is one of the main advantages of CNC Broaching. In comparison with other machining processes, this method provides a better surface finish with close tolerances obviating any need for additional finishing operations.

High Material Removal Rates

With high material removal rates, CNC Broaching is an efficient process for large-volume production runs. This process is particularly useful in creating deep undercuts, intricate internal shapes, and complex profiles which would be impossible or too difficult to make using traditional machining techniques.

Versatility in Material Compatibility

On the other hand, another great advantage about CNC Broaching is that, it can accommodate almost all types of materials such as metals, plastics and composites. With such versatility firms can engage in various industries including automotive, aerospace as well as tooling sectors.

Cost-Effective Solution

CNC broaching offers a cost-effective solution for high volume production runs. Minimum set-up time is required before starting the operation; the parts manufactured are always of good quality thus reducing inspection requirements and reworks which eventually lower overall manufacturing costs.

Comparison of Broaching, Shaping, Boring, and Drilling Machining Processes

Machining Process

Cutting Action

Typical Applications




Linear reciprocating motion of a multi-tooth tool to create complex internal or external shapes

Internal keyways, splines, gear teeth, polygons

High surface finish, high material removal rates, complex shapes

Specialized tool required for each application, limited to straight/helical shapes


Reciprocating linear motion of a single-point tool to generate flat surfaces

Machining irregular surfaces, keyways, grooves

Versatile, can machine irregular shapes

Slower process, limited to flat surfaces


Rotary motion of a single-point or multi-point tool to enlarge or finish internal cylindrical surfaces

Enlarging or finishing cylinder bores, bearing surfaces

High precision, smooth surface finish

Limited to internal cylindrical surfaces


Rotary motion of a drill bit to create cylindrical holes

Drilling holes, deep hole drilling, gun drilling

Rapid hole production, various hole sizes

Limited to cylindrical holes, potential burr formation

Application of CNC broaching machines

CNC rotary broach machines are widely used in different manufacturing industries, especially for highly précised machining and mass production.

Some areas where they are commonly applied include:

1.Aerospace industry

High precision, high strength aerospace components like spacecraft shells, engine parts, turbine blades etc can be machined by the CNC broaching machines.


2.Automotive industry

Some of the automotive parts that can be processed by CNC broaching machines include axles, steering knuckles, gears and crankshafts among others.


3.Electronic industry

Electronic product casings, circuit boards and guide rails can all be manufactured on a CNC broaching machine.


4.Precision instrument manufacturing industry

These include microscopes such as electron microscopes and telescopes.


The present invention relates to improvements in a specialized machining process called CNC Broaching. It is a specialized machining process that combines multi-toothed broaches with computer numerical control (CNC) technology to produce complex internal or external features on a workpiece. Components with intricate internal or external features may be efficiently produced through this method by single–toothed cutting tools which are combined with the accuracy and automation of CNC systems.

EASIAHOME has focused on CNC machining for 17 years. We at EASIAHOME can assist you with your CNC machining project at an affordable cost within the shortest time possible because we have experts.

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