CNC Vertical Machining Center

How to Operate CNC Machine

Oct 11, 2023

CNC machines hold imagination and innovation, which allow them to master robotic accuracy while applying cutting-edge technologies. CNC machines are revolutionizing production by providing unique toolpaths so that ideas can come alive. Jewelry-making to aerospace—you decide what’s possible.  In this guide, we will learn how to work a CNC machine in a pro way of doing things.

What is CNC Machine?

The name CNC stands for computer numerical control, and CNC machining is a subtractive manufacturing method that often makes use of computerized controls and machine tools to chip away layers of material from a stock component, also known as the "blank" or "workpiece," to create a custom-designed item.

This method can be used for a variety of materials, including metals, plastics, wood, glass, foam, and composites. It is also useful for large CNC machining, producing prototypes and parts for the telecommunications industry, and CNC machining aerospace parts, which have tighter tolerance requirements than other parts of the economy.


Understand the Working Principle of CNC Software

As the go-between for the user and the CNC machine, CNC (Computer Numerical Control) software translates design instructions into machine commands. The procedure starts out with the design phase, during which CAD software is used to conceptualize the final product. Toolpaths are created, and the CAD file is translated into machine-readable G-code using CAD software. In a CNC machine, the G-code is sent to the controller, which is in charge of executing the program. CNC software may gather data, track the machine's progress, and run simulations to help visualize and catch mistakes as they happen. CNC software improves the effectiveness and precision of production by enabling accurate and automated machining processes.

CNC Machining Tables

Table 1: Linear Tolerances in CNC Machining

In CNC machining, the term "linear tolerances" refers to the allowable deviation or variation in the dimensions of a machined object along a linear axis. This can be either positive or negative. It guarantees precision and accuracy within the parameters that have been set.

Linear dimension range(mm) Tolerance class
f (fine) m(medium) c(coarse) v(very coarse)
0.5-3 ±0.05 ±0.1 ±0.2 -
3-6 ±0.05 ±0.1 ±0.3 ±0.5
6-30 ±0.1 ±0.2 ±0.5 ±1
30-120 ±0.15 ±0.3 ±0.8 ±1.5
120-400 ±0.2 ±0.5 ±1.2 ±2.5
400-1000 ±0.3 ±0.8 ±2.0 ±4.0
1000-2000 ±0.5 ±1.2 ±3.0 ±6.0
2000-4000 - ±2.0 ±4.0 ±8.0

Table 2: Angle Tolerances in CNC Machining

When discussing CNC machining, the term "angle tolerances" refers to the allowable variation or departure from a defined angle for items that are being machined. It guarantees the necessary angular precision and accuracy within the parameters that have been established.

Dimension range (mm) f (fine) m(medium) c(coarse) v(very coarse)
0-10 1°30‘ 1°30’
10-50 0°30‘ 0°30‘
50-120 0°20‘ 0°20‘ 0°30‘
120-400 0°10‘ 0°10‘ 0°15‘ 0°30‘
400 0°5‘ 0°5‘ 0°10‘ 0°20‘

Table 3: Radius and Chamfer Tolerances in CNC Machining

In CNC machining, "radius and chamfer tolerances" relate to the permissible deviation or variation in the dimensions of curved or beveled edges of machined objects. These dimensions might be chamfered or rounded off. They guarantee the quality and accuracy of the feature within the parameters that are established for it.

Dimension range (mm) f (fine) m(medium) c(coarse) v(very coarse)
0.5-3 0.2 0.2 0.4 0.4
3-6 0.5 0.5 1 1
6 1 1 2 2


Step-by-Step Guide on How to Operate CNC Machine 

1. Prioritize Safety

Firstly, operating the CNC machine should be safe. operation using Personal protective equipment like safety glasses, gloves, and ear protection is acceptable. The most important thing is to read and know about precautions against potential risks while wearing Personal protective equipment. After that, working in a tidy environment without any accident happens.


2. Understand the CNC Machine

The parts of the CNC machine must be understood, controls figured out, and how it operates underlined. Consider studying those products from the instruction manual for accurate operations of this equipment. Identify where the control panel, and emergency stop button, among other vital apparatus, are placed by looking at their interface. For example, look closely at this part and understand the instructions given on making its use effective.


3. Prepare the Workpiece and Tools

Appropriate tool and workpiece preparation before starting a project is vital for successful CNC machining. Follow these steps to properly set up the working tool, as well as your project's tools:

Material Selection

Selecting the appropriate material for your project is crucial. Take into account the project specifications, the material's attributes, and the desired end result. Wood, polymers (such acrylic or ABS), and metals (like titanium, steel, or aluminum) are frequently used materials in CNC machining.

Workpiece Specifications

Determine the necessary dimensions and parameters for your project after selecting the material. To precisely measure and label the dimensions of the material, use precise measuring equipment like calipers or micrometers.

Cutting the Material

Use the proper cutting equipment, such as saws, shears, or CNC laser cutters, if the material needs to be cut to size. Make that the cutting procedure is accurate and adheres to the prescribed dimensions. Use good cutting techniques and take the necessary safety precautions while cutting, such as wearing safety goggles.

Work Holding

The workpiece must be carefully positioned during the machining process after being prepared. The material, shape, and dimensions of the workpiece influence the choice of work-holding technique. Typical work-holding techniques:


The workpiece should be clamped to the worktable. Choose clamps that are suitable for the material and offer a tight grip without doing any harm.


The best tool for gripping objects with straight edges is a vice. They provide stability during machining by securely clamping the workpiece between two jaws.

Vacuum Tables

Suction is produced by vacuum tables, which hold the workpiece in place. They provide homogeneous and dependable gripping for flat and thin workpieces.

Tool Selection and Installation

Based on the material and the required machining method (such as milling, drilling, or turning), choose the right cutting tools for your machining operation. Make sure the tools you choose can efficiently cut the material you've chosen and are compatible with the tool holders on the machine. To prevent any slippage during machining, install the tools firmly, adhere to the manufacturer's instructions, and tighten them appropriately.

Tool Presetting and Calibration

Tool presetting and calibration should be done before the machining operation begins. Setting the tool lengths, diameters, and offsets in the CNC machine's control software is necessary for this. Precision machining is ensured by accurate tool presetting, which also reduces mistakes.


4. Set Up the CNC Machine

The next stage is to set up the CNC machine for the machining operation after the workpiece and tools have been prepared. To ensure a proper setup, adhere to the following steps:

Power on the Machine

Start by turning on the CNC machine and performing the power-up procedures as directed by the manufacturer. It's critical to stick to the suggested startup order to guarantee proper machine initialization.

Homing the Machine

The homing procedure used by most CNC machines creates a reference point for the machine's axes. Before beginning the machining operation, this procedure ensures the machine is in the correct position. To start the homing procedure, which will move the axes to specified places, follow the machine's instructions.

Workpiece Dimensions and Tooling Details

Fill out the control panel on the CNC machine with the necessary data. This usually comprises the workpiece's measurements, such as its length, width, and height. To achieve perfect machining, it is crucial to enter precise measurements. Include information about the cutting tools being used, including tool numbers, offsets, and any other pertinent characteristics. The machine can do calculations and appropriately carry out machining operations thanks to this information.

Work Coordinate System (WCS) Setup

The origin and orientation of the workpiece with respect to the machine's axes are determined by the work coordinate system. Set up the WCS in accordance with the particular specifications of your project. This phase makes sure that using the set reference point, the machine accurately interprets the programmed tool movements.

Tool Length Compensation

To account for differences in tool length, CNC machines frequently use tool length compensation. In accordance with the programmed tool trajectories, this guarantees that the machine positions the cutting tool precisely. Enter the relevant offsets to set up tool length compensation, or, if one is available, use a tool measuring probe.

Machine Warm-Up

Give the machine time to warm up before beginning the actual machining process. As a result, the machine's temperature is stabilized, resulting in constant and precise milling throughout the process. For information on the suggested warm-up period, consult the machine's handbook or manufacturer recommendations.


Load the CNC Program

One of the most important steps in efficiently using a CNC machine is loading the CNC program. Ensure the program is ready and compatible with your particular CNC machine before loading it. Check the program again for any mistakes or problems, such as improper tool paths or missing commands. To comprehend the intended machining operations, familiarize yourself with the program's G-code or machine-specific instructions.

Access the machine's software interface via the control panel or computer terminal to load the CNC program. Transfer the program file to the computer's memory or the selected program storage location from a compatible storage device, such as a USB drive or network connection. Locate the relevant program file by using the menu options or prompts on the software interface. By checking the program name and related instructions, ensure the right program has been loaded. You can now move forward with the machining process, ensuring accuracy and precision in the operations carried out by the CNC machine after the CNC program has been properly loaded.


Test and Simulate the Program

Before executing the CNC program on the machine, test and simulate it to ensure smooth machining. Use the machine's software or control panel to simulate tool movements and operations. Program flaws and collisions can be detected.

The CNC program's interface shows toolpaths, cutting operations, and feed rates. Start the simulation to see how the tool interacts with the computer-generated workpiece. Check the toolpaths for collisions and needless material removal. Before continuing, correct any program mistakes.

Testing and modeling the CNC program reduces mistakes and collisions during milling. It optimizes toolpaths, verifies program accuracy, and fixes issues. Proactively managing the machining process ensures precise, high-quality output.


Run the CNC Program

After the CNC program has been checked and simulated, the machining process can begin. Here's how to get the machine's CNC program up and running:

The CNC program can be activated by selecting the appropriate command from the machine's user interface or control panel. Be sure to take all essential safety measures, such as donning protective gear, before beginning the program.

Pay close attention to how the machine is being utilized once the program has begun. Keep an ear out for strange noises and watch for any shaky or jerky motion that could indicate trouble. Maintaining a high level of attentiveness while machining is essential for achieving both precision and safety.

If something strange or unexpected happens, you should be ready to shut down the machine instantly. If something goes wrong, you should be able to instantly halt the procedure by pushing an easily accessible emergency stop button on the machine. Prioritize safety at all times and address any issues right away.

Closely monitoring the machine's actions while the CNC program runs will guarantee accurate and secure manufacturing. If you want your CNC machining job to go smoothly and fast, you need to keep an eye out for problems and be ready to fix them right away.


Monitor and Make Adjustments

It is essential to constantly supervise the operation while using a CNC machine. Regularly check the workpiece for correctness and quality, paying special attention to specifics like its size and polish. Before continuing, pause the program and make the required modifications.

Maintain constant vigilance over the machine's operations, and correct any problems you find. Watch the motion of the cutting tool, how it contacts the workpiece and the overall development of the machining process. Periodically comparing the workpiece to the intended specifications and quality standards will ensure it meets the necessary criteria.

Respond quickly to any discrepancies or issues discovered throughout the monitoring process. Put the brakes on and give some thought to the situation at hand. Determine whether modifications are needed to the machine's machining parameters, tools, or software. Make the necessary modifications to fix the issue or enhance the machining process so that the final product meets all criteria.

By keeping a close eye on the machining process and making adjustments as needed, you can ensure the accuracy and quality of the finished item. Routine inspections and timely adjustments are crucial to the successful completion of the CNC machining process, which in turn produces accurate and better final products.


Complete the Machining Process

After the CNC program has been successfully executed and the machining process has concluded, the completed workpiece must be gently removed from the machine's worktable. Be very careful while handling the object to keep it undamaged. Carefully compare the product to the criteria and requirements set out by the project. Don't lose track of process deviations or opportunities for improvement. The information gleaned from these analyses will be used in future CNC machining process enhancements and optimizations.


Clean and Maintain the CNC Machine

For the CNC machine to last a long time and operate at its best, proper maintenance is necessary. Allocate time to fully clean the machine, removing any debris, chips, or coolant after finishing a project. For basic maintenance chores like lubrication, tool calibration, and replacing worn-out parts, adhere to the manufacturer's instructions. To prevent operational problems, routinely check the machine for wear or damage signs and take immediate action if necessary.


Documentation and Continuous Improvement

Maintain thorough documentation to improve your CNC machining abilities and guarantee consistency in upcoming projects. Record the CNC programs that were utilized, along with any alterations or corrections that were made while the machine was being used. This documentation is a useful resource and makes it possible to replicate comparable projects successfully. Note any additional takeaways or opportunities for development, such as ways to improve tooling techniques or fine-tune machining parameters.



Professional CNC machine operation calls for a deliberate approach that prioritizes safety, painstaking preparation, and a thorough understanding of the machine's capabilities. You can ensure accurate and efficient machining, which will result in high-quality results, by adhering to the step-by-step technique described in this detailed guide. You may become a proficient CNC machine operator with the correct education, experience, and dedication to lifelong learning, helping to progress various industries by producing accurate and complex components. Take advantage of the possibilities provided by CNC machining, and allow your commitment to fine workmanship and accuracy to influence the direction of production.

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