Introduction:

After using the CNC laser cutting machine for several years, many friends found that the cutting effect is less than before. Both cutting accuracy and cutting speed will be reduced. Many parameters affect the cutting quality of fiber laser cutting machines, such as: cutting height, cutting nozzle model, focus position, cutting power, cutting frequency, cutting duty cycle, cutting air pressure, cutting speed, etc. In addition, the hardware conditions also include protective glasses, gas purity, quality of processing materials, focusing lens, collimating lens, etc. So, what causes the cutting effect of CNC laser cutting machines to decline?

10 Key Factors Affecting The Cutting Effect Of CNC Laser Cutting Machines

1. Laser power

The power of the laser source affects the cutting speed and ability to cut different materials. Higher laser power provides greater cutting force and faster processing speed.

• Higher laser powers generally allow for faster cutting speeds and the ability to cut thicker, tougher materials. The increased power provides more energy to vaporize or melt the material, resulting in a faster and more efficient cutting process.
• However, the optimal laser power for a particular material depends on its thickness and properties. Using too much laser power on thin materials may cause excessive melting, resulting in a wider kerf (cut width) and potentially affecting cut quality. On the other hand, insufficient laser power may result in incomplete or slow cutting.
• Finding the right balance between laser power and cutting speed is critical. It takes into account factors such as material type, thickness, desired cut quality, and production requirements.

In addition, different materials have different absorption characteristics of laser energy. For example, metals such as steel or aluminum have high absorption rates for fiber lasers, while non-metals such as wood or acrylic have low absorption rates. Adjusting the laser power to the material being cut is critical to achieving the best cutting results.

To sum up, laser power is the key parameter that affects the cutting effect of CNC fiber laser cutting machines. By selecting the appropriate laser power and optimizing cutting parameters, operators can achieve efficient and high-quality cutting of various materials.

2. Focus Position

The precise positioning of the laser beam’s focus point on the material surface is critical. The correct focus position ensures optimal energy concentration and a clean, accurate cut. The focus position refers to the exact location where the laser beam converges to its smallest spot size, known as the focal point. The focus position determines the intensity and distribution of the laser energy on the material being cut.

The three commonly used focus positions in fiber laser cutting are:

• Below the material surface

This focus position allows for deeper penetration of the laser beam into the material. It is suitable for cutting thicker materials, as the laser energy is concentrated deeper into the material’s cross-section. This position enables efficient cutting of materials with higher reflectivity or thickness variations.

• On the material surface

This focus position balances the cutting speed and quality. It is often used for cutting medium-thickness materials. The laser energy is focused precisely on the material surface, providing a good compromise between cutting speed and quality.

• Above the material surface

This focus position generates a wider and more dispersed laser beam. It is suitable for surface treatments or engraving applications where surface effects are desired. In this position, the laser energy is focused above the material, resulting in less material removal but greater surface interaction.

Choosing the correct focus position depends on several factors, including material type, thickness, desired cut quality, and specific application requirements. It is important to consider the focal length of the lens being used, as it determines the depth at which the laser energy is focused.

Finding the optimal focus position is a critical step in achieving the desired cutting effect. It involves adjusting the focus position based on the material’s characteristics to ensure a minimal heat-affected zone and high-quality cut.

In summary, the focus position plays a crucial role in the cutting effect of a fiber laser cutting machine. By selecting the appropriate focus position, operators can optimize the cutting process to achieve desired results for different materials and applications.

3. Cutting Speed

The speed at which the laser beam moves across the material affects the quality and efficiency of the cut. Adjusting the cutting speed appropriately for the material being processed is important to achieve desired results.

The cutting speed primarily affects two aspects of the cutting process:

• The amount of time the laser beam interacts with the material

If the cutting speed is too slow, the material will experience prolonged exposure to the laser energy, resulting in excessive heat accumulation. This can lead to increased heat-affected zone (HAZ), thermal damage to the material, and potential melting or deformation. On the other hand, if the cutting speed is too high, there might not be enough heat input to effectively melt and vaporize the material, resulting in incomplete cuts and poor edge quality.

• Cutting quality

The cutting speed also affects the overall quality of the cut. A well-optimized cutting speed ensures a smooth, clean, and precise cut with minimal burrs, dross, and distortions. It also influences the width of the cut, taper angles, and overall cutting efficiency. Finding the right cutting speed is crucial to achieving the desired balance between cutting speed and quality. The optimal cutting speed depends on various factors, including the material type, thickness, laser power, and specific application requirements. For different materials, there are recommended cutting speed ranges that provide the best cutting results. These ranges are typically determined through experimentation and process optimization.

It’s important to note that the relationship between cutting speed and cutting quality is not linear. There is an optimal range within which the cutting speed should be set to achieve the best results. Operating outside this range can lead to compromised cutting quality, increased scrap rates, and reduced overall productivity.

In summary, the cutting speed significantly affects the cutting effect of a fiber laser cutting machine. By selecting the appropriate cutting speed, operators can control heat input, minimize thermal distortion, and achieve high-quality cuts with consistent results. Finding the optimal cutting speed requires considering material properties, laser parameters, and specific cutting requirements to optimize the balance between speed and cutting quality.

4. Assist Gas Selection

The choice of assist gas, such as oxygen, nitrogen, or compressed air, can greatly impact the cutting process. Different gases interact with the material being cut in various ways, affecting cut quality, speed, and the appearance of the cut edge.

Auxiliary gas is used in laser cutting to facilitate the cutting process and improve the overall cutting quality. The selection of the appropriate auxiliary gas depends on several factors, including the material being cut, the desired cutting speed, and the specific requirements of the application.

Here are some commonly used auxiliary gases and their effects on the cutting process:

• Oxygen (O2)

Oxygen is the most commonly used auxiliary gas in laser cutting. When used with a fiber laser, it provides a high exothermic reaction to assist in the cutting process. Oxygen reacts with the material being cut, typically metals, causing rapid oxidation and assisting in the expulsion of molten material.
This results in faster cutting speeds improved cutting efficiency, and the ability to cut thicker materials. However, the use of oxygen can also lead to increased oxidation or rusting on the cut edges, which may require additional post-processing.

• Nitrogen (N2)

Nitrogen is an inert gas commonly used when cutting non-ferrous metals like aluminum, stainless steel, or brass. It helps to prevent oxidation during the cutting process. Nitrogen is suitable when a clean, oxide-free cut edge is desired, as it eliminates the need for post-cutting surface treatment.
Nitrogen also provides a cooling effect, minimizing heat-affected zones and reducing the risk of thermal distortion. However, cutting with nitrogen typically requires higher laser power and slower cutting speeds compared to oxygen-assisted cutting.

• Air or Compressed air

In some cases, compressed air or ambient air can be used as auxiliary gases for certain applications. Air assists in blowing away the molten material from the cutting kerf, preventing re-melting and improving the overall cutting quality. However, the use of air may not be as effective as oxygen or nitrogen in achieving high-quality cuts, especially when cutting thicker materials.

• Other Gases

Such as argon, helium, or a mixture of gases, can be used as auxiliary gases in specific applications or for specialized cutting requirements. The choice of auxiliary gas depends on factors such as the material being cut, the desired cutting quality, the speed, and the equipment’s capabilities.

In summary, the choice of auxiliary gas significantly affects the cutting effect of a fiber laser cutting machine. Different gases have different effects on the cutting process, including cutting speed, cutting quality, oxidation, and heat-affected zones. By selecting the right auxiliary gas based on the material and application requirements, operators can achieve optimal cutting results and minimize post-processing needs.

5. Nozzle Design

The design and condition of the cutting nozzle play a crucial role in the cutting process. Proper nozzle alignment and cooling help to maintain stable and efficient cutting performance. The nozzle plays a crucial role in the laser cutting process by delivering the auxiliary gas to the cutting zone and helping to control the flow, direction, and interaction of the gas with the material being cut.

Here are some ways in which nozzle design affects the cutting effect of a fiber laser cutting machine:

• Gas Flow and Pressure

The design of the nozzle determines the flow rate and pressure of the auxiliary gas directed at the cutting area. Optimal gas flow and pressure are essential for efficient cutting. A properly designed nozzle ensures a consistent and uniform gas flow, which helps in maintaining a stable cutting process and achieving a clean and precise cut. It also helps in efficiently removing molten material and preventing excessive heat buildup.

• Gas Distribution and Alignment

The nozzle design determines how the gas is distributed around the laser beam and aligned with the cutting kerf. Proper gas distribution and alignment are crucial for effective material removal, preventing excessive splatter or spatter, and ensuring a smooth cutting process. The nozzle should be designed to deliver the gas evenly and precisely to the cutting zone, providing adequate protection to the laser beam and minimizing the risk of beam divergence.

• Nozzle Geometry and Cooling

The geometry of the nozzle, including its shape, size, and internal configuration, can impact the cutting performance. The nozzle design should be optimized to provide efficient cooling of the material and the nozzle itself, minimizing heat-affected zones and thermal distortion. Additionally, the nozzle geometry can also affect the focal length and focus quality of the laser beam, which further influences the cutting quality and accuracy.

• Nozzle Material and Durability

The choice of material for the nozzle can affect its durability and longevity. The nozzle should be resistant to high temperatures, wear, and chemical reactions with the auxiliary gas used. A durable and well-maintained nozzle ensures consistent performance over time, minimizing the need for frequent replacements and interruptions in the cutting process.

• Adaptive Nozzle Technologies

Advanced fiber laser cutting machines may feature adaptive nozzle technologies, such as programmable height control or automatic gas adjustments. These technologies optimize the nozzle’s performance during the cutting process, adapting to changes in material thickness, contours, and cutting speeds. Adaptive nozzle systems can help improve cutting consistency, reduce scrap, and enhance overall productivity.

In summary, the design of the nozzle used in a fiber laser cutting machine plays a crucial role in determining the cutting effect and overall performance. A well-designed nozzle ensures proper gas flow, distribution, and alignment, leading to efficient material removal, clean cuts, and minimized heat-affected zones.

6. Material Thickness

Different material thicknesses require specific cutting parameters to achieve optimal results. Adjusting the laser power, cutting speed, and focus position according to the material thickness is vital for a successful cut. The laser power, cutting speed, and focus position need to be adjusted according to the material thickness to achieve optimal results.

Here’s how material thickness impacts the cutting effect:

Laser Power

• The laser power required for cutting thicker materials is generally higher compared to thinner materials. Thicker materials require more laser energy to melt and vaporize the material, creating a cut.
• If the laser power is insufficient for the material thickness, the cutting process may be slow, incomplete, or result in a rough surface finish. Therefore, it is important to select a laser with sufficient power to handle the desired material thickness.

Cutting Speed

• The cutting speed for thicker materials is typically slower compared to thinner materials. This is because more laser energy is required to penetrate and cut through the material.
• Slower cutting speeds allow for better heat absorption and thermal dissipation to prevent overheating and ensure a clean, smooth cut. Adjusting the cutting speed also helps in maintaining a consistent cutting quality across different material thicknesses.

Focus Position

• The focal position of the laser beam is crucial for achieving optimal cutting results. For thicker materials, the focal point needs to be adjusted to ensure that the laser energy is concentrated at the right depth within the material.
• This adjustment helps to achieve a clean, precise cut by ensuring sufficient energy absorption and avoiding excessive energy loss at the material surface or over-penetration.

Assist Gas Pressure

• The gas pressure used as an auxiliary during laser cutting plays a vital role in material removal and effective cutting.
• For thicker materials, higher gas pressure may be required to enhance material ejection, remove molten material, and prevent the formation of dross or slag.
• Adequate gas pressure helps in maintaining a clear-cutting path and preventing the reattachment of molten material to the cut edge.

Kerf Width and Heat Affected Zone

• Thicker materials generally result in wider kerf widths, which is the width of the cut made by the laser. The laser beam’s energy disperses as it penetrates thicker materials, leading to wider kerf widths.
• Additionally, thicker materials may have a larger heat-affected zone due to the increased heat generated during the cutting process. This can impact the overall quality and precision of the cut, and it’s important to account for these factors when cutting thicker materials.

It’s crucial to optimize the cutting parameters, including laser power, cutting speed, focus position, and assist gas pressure, based on the specific material thickness to achieve desired cutting effects. Manufacturers typically provide guidelines and recommendations for cutting various material thicknesses using their CNC laser cutting machines, and experimentation may be necessary to fine-tune the parameters for specific applications.

7. Material Type

Various materials react differently to laser cutting, and their composition affects how the laser interacts with them. Different materials may require different cutting parameters and techniques.

Here’s how material type affects the cutting effect:

• Absorption and Reflectivity

Different materials have varying levels of absorption and reflectivity for the laser beam. Materials that have high absorption rates for the laser energy, such as metals, are generally well-suited for fiber laser cutting.

The high absorption allows for efficient energy transfer, resulting in effective cutting. On the other hand, materials with high reflectivity, such as aluminum or copper, are more challenging to cut because a considerable amount of laser energy is reflected instead of being absorbed. To overcome this, additional measures like using higher laser power or specialized cutting techniques may be required.

• Melting and Vaporization Point

Materials have different melting and vaporization points, which impact the cutting process. Laser cutting involves melting and vaporizing the material, so materials with lower melting points are typically easier to cut.

For example, metals like steel and stainless steel have higher melting points, requiring higher laser power to achieve successful cutting. Conversely, materials like acrylics or plastics have lower melting points, making them easier to cut with lower laser power.

• Thermal Conductivity

The thermal conductivity of a material affects the dissipation of heat during laser cutting. Materials with high thermal conductivity, such as copper or aluminum, tend to conduct heat away from the cutting area more rapidly.

This can make it more challenging to achieve efficient cutting since the heat dissipates quickly, requiring higher laser power or slower cutting speeds to maintain a consistent cutting effect. Materials with lower thermal conductivity, like wood or some plastics, are generally easier to cut as they retain heat better in the cutting zone.

• Material Thickness

Material thickness interacts with the cutting effect in conjunction with material type. Thicker materials require higher laser power to cut through, regardless of the material type.

However, different materials may exhibit distinct behaviors in terms of edge quality, kerf width, and cutting speed when varying material thicknesses are involved. Thus, it’s important to consider the material type along with its thickness when optimizing cutting parameters.

• Material Toxicity and Safety

The material being cut may have safety considerations due to its toxicity or ability to release harmful fumes when subjected to the high heat of the laser cutting process. Materials like certain plastics or composites may emit toxic fumes, requiring appropriate ventilation or specialized laser-cutting systems designed for such materials.

To achieve optimal cutting results, it’s crucial to understand the specific characteristics of the material being cut and adjust the laser cutting parameters accordingly. This may involve adapting the laser power, cutting speed, focus position, and assist gas settings to suit the material type and its properties. Manufacturers often provide guidelines and recommendations for cutting different materials using their CNC fiber laser cutting machines, assisting users in achieving desired cutting effects.

8. Beam Quality

The beam quality of the laser—such as its focusability, stability, and shape—directly affects the cutting precision and quality. A high-quality beam ensures better-cutting results. The beam quality refers to the spatial distribution of the laser beam’s intensity and its ability to focus on a small spot.

Here’s how beam quality affects the cutting process:

• Focusability

A laser beam with good beam quality can be focused to a smaller spot size, resulting in a higher power density at the focal point. This concentrated energy facilitates effective cutting by enabling precise and localized material removal. Improved focusability allows for sharper cuts and finer details, especially in materials with high precision requirements like thin metals or intricate patterns.

• Beam Divergence

Beam quality also affects beam divergence, which is the spreading of the laser beam as it travels away from the laser source. A laser with low beam divergence maintains a tighter beam over longer distances, providing better cutting performance. Lower beam divergence ensures that the laser energy is concentrated on the workpiece, resulting in cleaner, more accurate cuts, especially for thicker materials or when cutting at greater depths.

• Beam Stability

Beam quality influences the stability of the laser beam during the cutting process. A stable beam produces consistent and predictable cutting results, ensuring uniformity across the entire workpiece. Unstable beams can cause fluctuations in power, resulting in uneven cuts or variations in the cutting speed. Excellent beam quality contributes to stable laser operation, minimizing cutting defects and enhancing overall cutting performance.

• Cutting Speed

The beam quality of a fiber laser cutting machine can impact the cutting speed. A laser beam with good beam quality facilitates efficient energy transfer to the material, allowing for faster cutting speeds without compromising the quality of the cut. Higher cutting speeds are particularly advantageous for industrial applications where productivity and throughput are essential.

• Material Compatibility

Different materials have varying sensitivities to the laser beam’s quality. Some materials, such as reflective metals, are particularly sensitive to beam quality variations.

With better beam quality, the laser can achieve higher absorption rates, resulting in improved cutting performance and reduced reliance on complex techniques to overcome material challenges. CNC Fiber laser cutting machines are designed to provide high beam quality, ensuring precise cutting capabilities across various materials. However, it’s still important to consider the specific requirements of the material being cut and adjust the cutting parameters accordingly for optimal results.

9. Assist Gas Pressure

The pressure of the assist gas used during cutting impacts the removal of molten material and debris from the cutting area. It helps to ensure a smooth and efficient cutting process. The choice of auxiliary gas and its pressure can have a significant impact on the quality, speed, and efficiency of the cutting process.

Here’s how the auxiliary gas pressure affects the cutting effect:

• Assist Gas Flow

The primary purpose of the auxiliary gas is to remove molten material from the kerf (the cut path) during laser cutting. The gas, such as oxygen, nitrogen, or compressed air, is directed onto the material surface through the nozzle to blow away the molten material and create a clean cutting edge. The pressure of the auxiliary gas determines the flow rate and the force exerted on the molten material. Higher pressure can enhance the removal of molten material and facilitate better cutting performance.

• Cutting Speed and Efficiency

The auxiliary gas pressure affects the cutting speed and efficiency. Adequate gas pressure ensures sufficient force to blow away the molten material efficiently. With higher gas pressure, the speed at which the molten material is expelled from the kerf increases. This allows for faster cutting speeds and higher productivity, as the laser can move more swiftly across the workpiece without compromising cut quality.

• Kerf Width and Heat Affected Zone (HAZ)

The auxiliary gas pressure influences the width of the kerf and the size of the heat-affected zone. The kerf width refers to the width of the cut itself. Higher gas pressure can result in a narrower kerf, as it aids in rapidly removing the molten material from the cutting zone. A narrower kerf allows for more precise cuts, especially when intricate details or tight tolerances are required. Additionally, higher gas pressure can help reduce the heat-affected zone, the area around the cut that is thermally affected. Minimizing the heat-affected zone is crucial in applications where heat distortion or damage to the surrounding material is a concern.

• Material Compatibility

Different materials require different gas pressures for optimal cutting results. The gas pressure should be chosen based on the material type and thickness being cut. Thicker materials may require higher gas pressures to blow through the molten material effectively, while lighter materials may require lower pressures to prevent excessive material displacement or deformation.

It’s important to note that the choice of auxiliary gas, in addition to pressure, also influences the cutting effect. Different gases have varying effects on the cutting process, such as oxygen facilitating exothermic reactions and enhancing the cutting speed for certain materials.

10. Machine Maintenance

Regular maintenance and calibration of the CNC fiber laser cutting machines are essential for consistent and accurate cutting performance. Ensuring proper alignment, cleanliness, and condition of optical components and cutting accessories is crucial.

Machine maintenance plays a crucial role in ensuring the optimal cutting effect of a fiber laser cutting machine. Regular maintenance helps to preserve the machine’s performance, accuracy, and reliability.

Here are some ways in which machine maintenance can impact the cutting effect:

• Beam Alignment

Proper beam alignment is essential for achieving accurate cuts. Over time, vibrations, wear, or mechanical stress can cause the beam alignment to shift. Regular maintenance checks and adjustments ensure that the laser beam remains accurately aligned with the cutting head and the workpiece. This alignment directly impacts the precision and quality of the cuts.

• Optics Cleaning

The optical components of a fiber laser cutting machine, such as lenses and mirrors, can accumulate debris, dust, or residue from the cutting process. Dirty optics can scatter or absorb the laser beam, reducing its cutting power and accuracy. Regular cleaning of these optics helps maintain their transparency and ensures optimal beam quality for effective cutting.

• Cooling System Maintenance

CNC Fiber laser cutting machines generate a significant amount of heat during operation, and a properly functioning cooling system is crucial for maintaining stable cutting performance. Regular maintenance of the cooling system, including checking coolant levels, cleaning filters, and inspecting water flow and temperature, helps prevent overheating and ensures consistent cutting efficiency.

• Gas Supply and Pressure

As mentioned earlier, auxiliary gases and their pressures are important factors in the cutting process. Regular maintenance should include checking and maintaining the gas supply system, ensuring proper gas pressure, and monitoring any leaks or blockages. Inadequate gas supply or incorrect pressure can compromise the cutting quality, speed, and overall effectiveness.

• Servicing of Mechanical Components

CNC Fiber laser cutting machines have various mechanical components, such as motors, bearings, belts, and guides, which require regular inspection, lubrication, and adjustment. Proper servicing of these mechanical components helps to maintain the machine’s accuracy, stability, and smooth operation, which directly affects the cutting quality.

• Software Updates and Calibration

Laser-cutting machines often rely on advanced software for control and operation. Regular software updates ensure that the machine benefits from the latest advancements and improvements, which can enhance cutting performance. Additionally, calibration of the machine at regular intervals helps to maintain accuracy, compensate for any mechanical wear, and optimize the cutting parameters.

By following a comprehensive maintenance program, operators can minimize downtime, extend the machine’s lifespan, and ensure optimal cutting results.

Conclusion:

To achieve optimal cutting effects with CNC fiber laser cutting machines, careful consideration of various factors is essential. Factors such as laser power, focus distance, cutting speed, material type and thickness, gas type and pressure, nozzle diameter, beam mode, assist gas alignment, and beam quality must be meticulously adjusted to ensure precise and efficient laser cutting operations. By understanding these ten factors and their impacts, operators can maximize the performance of CNC fiber laser cutting machines in their respective industries.