CNC Grooving: Define, Tools, Types And Process

CNC grooving, like other forms of CNC machining, has had extensive impact in different industries. This unique technique has been part of different CNC manufacturing methods for many years. When done correctly, CNC grooving brings precision, cost-effectiveness, and versatility to projects.

What Is Grooving?

What is CNC Grooving

CNC grooving, also called recessing, is a popular machining process that machinists perform on the CNC lathe machine. The process creates a groove or recess in the material, usually a metal. Grooving is essential where there is a need to fit seals, O-rings, and related components.

In brief, the machinists feeds the special grooving tool to the workpiece axis of rotation in a perpendicular direction. To perform this process precisely and effectively, the cutting tool is sharp and thin.

Types Of Grooving Tools

Several designs of grooving tools are available, but they are all usually cemented carbide or high-speed steel (HSS) types. Below is a brief coverage of these types of groove cutting tool:

Face Grooving Tools

Face Grooving tool

If the groove aligns to the workpiece axis, we call it a face groove. The cutting tool that produces this type of groove is the face grooving tool. This tool comes in handy in creating grooves at a part’s face. The capability of this tool to reach seemingly unreachable parts of the workpiece is the biggest advantage.

Outer Diameter Grooving Tools

CNC Grooving

In an external groove, the idea is to create an external feature or even a gear that serves in different applications. The outer grooving tool can have different geometry and dimensions to achieve the groove parameters that the machinist desires.

Inner Diameter Grooving Tools

innter Diameter Grooving Tools

For creating a groove inside a pipe, tube, or any other hollow component, you need an outer diameter grooving tool. The resulting internal groove holds in place seals that enhance the functionality in a wide range of items.

How To Grooving with CNC Machines?

There are several stages to a successful grooving operation on the CNC machine. Here is an outline of the process in five steps:

Step 1: Plan and Design the Groove

At the start of the grooving operation with a CNC machine, one needs to specify the parameters and characteristics of the groove. These include the location and size of the groove on the workpiece. This is where the machinists uses CAD (Computer-Aided Design) software to produce a model.

Step 2: Save the Groove Designs

Armed with the model, the next step to save it in a compatible file format. Most CNC machines use the IGES or STEP file format. Most experts would recommend the STEP file format for its higher neutrality.

Step 3: Set Up the CNC Machine

With the groove model ready and saved, it is time to set up the CNC machine. At this stage, the operator needs to choose the most appropriate tool for the v grooving process. Fixing the tool to the CNC machine is also part of this stage. To finalize this setup step, fix the workpiece securely and correctly on the machine.

Step 4: Perform the Grooving Operation

It’s now time for the grooving operation. Since every detail of the process is in the CNC program, the operator does not have much to do for the workpiece to be grooved. The v grooving process proceeds as planned, with the set feed rate and rotation speed. If the planning and design stage was correct, the grooves should have accuracy.

Step 5: Undertake Quality Checks

After every machining process, it is important to perform quality checks. Therefore, the groove making process completes with an inspection for accuracy and cut quality on the metal. Its good for the metal to attain the desired surface quality, so there are different checks to perform.

Types of Grooving Methods

Straight Turning

Straight Turning

Also referred to as cylindrical turning, straight turning reduces the diameter of the workpiece to a specified measurement. The grooves in this case are open. Here, the operation involves a straight-turning tool.

Face Grooving

In this type of grooving method, the grooves align to the axial direction of the workpiece. A face grooving tool does this type of machining.

Contour Grooving

When you want to create specific geometries for the groove, you use the method called contour grooving. Contour grooves suit situations where the path is non-circular or non-linear. While there is more freedom in groove design in this case, the programming part can be challenging.

Internal Grooving

Internal Grooving

As mentioned above, internal grooving creates grooves in a hollow surface, for example, a pipe.

External Grooving

External grooving

External grooving entails the production of grooves on the external surface of the material or workpiece. You can use this process to produce three types of external grooving:

  • Single-cut Grooving – As the name suggests, this grooving variety entails a single cut on the outer surface of the workpiece.

  • Multiple Grooving – The CNC machine creates several deep grooves on the outer diameter of the material.

  • Ramping – In this type of grooving, the radial and axial movements are sequential during the machining process.

Considerations When Choosing A Grooving Tool

There are several factors to consider when choosing the best grooving tool. Here is an overview of some of them:

Types of Groove

Cutting tools are designed for different cutting operation and setups. There are specific grooving tools for particular types of grooves. A cutting tool for internal grooving may not work for external grooving.

Materials Property

Every grooving tool has qualities that suit properties of a particular material or set of materials. Types of materials that you can groove are plastic, metal, wood, and so on. The grooving tool should be compatible with the material.

Groove Geometry

Depth and width are the key geometries of a groove. Every grooving tool has design capacity to produce particular groove geometry. The cutting tool that you select for grooving should be capable of producing the desired depth and width of the groove.

Cutting Parameters

The machine parameters such as feed rate and rotation speed are equally important when choosing a grooving tool. Choose a tool that can operate optimally within the limits of the machine.

Machine Setup

The setup of the machine, particularly regarding the toolholder, is essential when choosing the perfect grooving tool. That’s because the safety and functionality of the cutting tool depends on how well it is secured to the CNC machine.

Common Problems and Solutions in Grooving Machining

Grooving machining is good, but it can present some challenges:

Poor Surface Finish

Poor surface finish is a common challenge in groove machining. This mostly happens when the cutting speed and feed rate are not optimal. For better results, you want to adhere to the approved cutting speed. Starting with a slower feed rate and gradually increasing it also works.

Cutting Tool Breakage:

Tool breakage may also occur, usually due to no or inadequate cooling of the workpiece and cutting tool. Machinists are encouraged to use cooling fluid whenever performing grooving operations. The fluid lowers the surface temperature and safeguards the tool – prevents tool breakage.

Dimensional Accuracy Issues:

It is not always easy to achieve the accuracy and precision requirements in grooves. Operators have all forms of measuring tools at their disposal. Some of these tools lack the necessary dimensional accuracy.

It is therefore important to know which measuring equipment to use for any situation. For instance, steel rulers suit low-accuracy measurements while Vernier calipers are ideal for higher-accuracy requirements.

Tool Chatter or Vibration:

V grooving and other forms of grooving machining are prone to tool chatter and vibration. This problem is not only dangerous but it could also affect work quality. To minimize it, use the most sturdy tool holders and cutting tools. Avoid tool overhangs as much as possible.


We have looked at the definition of CNC grooving and discussed several aspects of the process – types of grooves, types of grooving tools, choosing a grooving tool, and much more.

When it comes to groove machining, you may need the support of an experienced CNC machining company. That’s where we come in. We have modern CNC machines and expertise in different axes of CNC machines.

Grooving is only part of what we are capable of. Our forte also entails CNC milling, boring, turning, and others. Contact us for more insights into all types of CNC machining processes.


Gavin Leo is a technical writer at Aria with 8 years of experience in Engineering, He proficient in machining characteristics and surface finish process of various materials. and participated in the development of more than 100complex injection molding and CNC machining projects. He is passionate about sharing his knowledge and experience.