News&Events

Comprehensive Guide To Metal Laser Cutting Tips

Metal laser cutting is a process that may appear as simple as “setting the parameters and cutting,” but in reality, it involves a multitude of factors: laser power, focal position, nozzle, assist gas, gas pressure, cutting speed, material type, thickness, surface condition, optical path, lenses, cooling system, and machine motion accuracy.

This is particularly true for fiber laser cutting machines. As power levels have evolved from 3kW, 6kW, and 12kW to 20kW, 30kW, and beyond, simply increasing power does not guarantee cutting quality. Achieving truly high-quality, high-efficiency cutting requires establishing a comprehensive process system that integrates material, power, focal point, nozzle, gas, speed, pressure, and cutting path.

The following is a systematic summary of sheet metal laser cutting techniques from a practical production perspective.

1. Core Logic of Sheet Metal Laser Cutting

At its core, laser cutting utilizes a high-energy-density laser beam to rapidly melt, vaporize, or ignite the material locally, while simultaneously using assist gas to expel the molten material from the kerf (the cut gap).

A complete cutting process can be broken down as follows:

Laser generator → Beam transmission → Focusing → Material heating → Melting/Vaporization → Assist gas slag removal → Kerf formation

Consequently, cutting quality ultimately depends on several core variables:

Laser energy density + Focal state + Material response + Gas slag removal capability + Motion trajectory

Issues in any of these areas can lead to:

Burrs
Dross adhesion
Incomplete cutting
Excessive kerf width
Beveled edges
Edge burning
Over-burning
Hole deformation
Non-circular holes
Dimensional errors
Surface blackening
Reduced cutting speed
Lens contamination
Nozzle damage

2. Critical Preparations Before Cutting

Many cutting defects do not stem from parameter settings but rather from issues present before the actual cutting process begins.

1) Inspecting the Sheet Material

Before cutting, check the following:

Is the sheet thickness accurate?
Does the material type match the program specifications?
Is the sheet flat?
Is there severe surface rust?
Is there oil or grease contamination?
Is there mill scale?
Are there scratches?
Is there localized deformation?
Does the sheet contain internal stress?

This is particularly important for thin sheets. If the sheet itself is severely warped, achieving consistent cutting results is difficult, even with a laser head equipped with automatic focusing.

2) Recommendations

For high-precision parts:

Prioritize the use of sheets with good flatness.

For thick plates:

Pay special attention to internal stress and thermal deformation.

3. Cutting Techniques for Different Metal Materials

Different materials respond quite differently to laser energy and assist gases.

1) Carbon Steel

Carbon steel is one of the most common materials for laser cutting.

Common thicknesses:

0.5mm

1mm

1.5mm

2mm

3mm

4mm

5mm

6mm

8mm

10mm

12mm

16mm

20mm

25mm

30mm and above

Thin carbon steel: Thin sheets can generally be cut using air, oxygen, or nitrogen.

Advantages of oxygen cutting:

High cutting capacity
Good performance on thick plates
Relatively low cost

However, since oxygen participates in the oxidation reaction, an oxide layer forms on the cut edge.

2) Stainless Steel

Stainless steel is generally better suited for nitrogen cutting.

This is because nitrogen minimizes oxidation at the cut edge.

Advantages:

Better edge color
Brighter cut surface
Reduced oxidation
Suitable for subsequent welding
Suitable for processing parts where appearance matters

Advantages:

Better edge color
Brighter cut surface
Reduced oxidation
Suitable for subsequent welding
Suitable for processing parts where appearance matters

3) Aluminum Sheets

Aluminum is a material with high reflectivity and high thermal conductivity.

When cutting aluminum sheets, special attention must be paid to:

Laser reflection
Focal position
Piercing stability
Nozzle height
Assist gas
Material surface condition

Cutting difficulty increases significantly, especially with thick aluminum plates.

4) Brass and Copper

One of the biggest challenges with copper and brass is their high reflectivity.

Processing copper—especially with traditional-wavelength fiber laser systems—places higher demands on the laser source, cutting head, and process parameters.

In actual production, pay special attention to:

Whether the equipment supports highly reflective materials
Whether the laser source is suitable for copper
Piercing stability
Nozzle compatibility
Cleanliness of the protective lens

Do not simply apply standard parameters used for carbon steel.

4. Higher laser power not always better

Many users fall into a common misconception when selecting a laser cutting machine:

The higher the power, the better the cutting performance.

In reality, this is not the case.

For example, with 6kW, 12kW, or 20kW systems:

The advantages primarily lie in:

Ability to cut thicker materials
Higher cutting speeds
Greater production efficiency
A wider process window

However, when cutting:

Thin sheets (1mm, 2mm, 3mm)

High power does not necessarily translate directly into superior cutting quality.

For thin sheets, high power can even lead to issues such as:

Over-burning
Deformation of small holes
Edge melting
An enlarged heat-affected zone (HAZ)

Therefore, equipment selection should follow this principle:

Choose the power level based on the material type, thickness range, and production cycle requirements, rather than simply pursuing the highest possible power.

5. Focal position key to cutting quality

The focal position is one of the most critical parameters in the laser cutting process.

Simply put:

The focal position determines how laser energy is distributed across the thickness of the sheet.

If the focus is too high or too low, cutting performance will be affected.

1) Thin sheets

Thin sheets generally require a high concentration of energy.

If the focus deviates significantly, it can lead to:

Widened kerf (cut width)
Incomplete cutting (failure to cut through)
Increased burrs
Reduced cut quality

2) Thick plates

Cutting thick plates requires consideration of how laser energy is distributed within the material.

Adjustments to the focal position generally need to be made based on a combination of factors:

Material
Thickness
Laser power
Nozzle type
Gas pressure
Cutting speed

3) Do not rely blindly on a fixed focal position

The optimal focal position varies depending on the material, thickness, and gas used.

Therefore, actual production operations should establish a system linking:

Material + Thickness + Gas + Power → Corresponding focal parameters

This helps build the company’s own proprietary process database.

6. Nozzle selection is crucial

Although the nozzle is a small component, it has a significant impact on cutting quality.

Common nozzle types include:

Single-layer nozzles
Double-layer nozzles

Nozzles with various orifice diameters For example:

1.0mm

1.2mm

1.5mm

1.8mm

2.0mm

2.5mm

3.0mm

The actual selection cannot be based solely on material thickness.

Other factors must also be considered:

Laser power
Assist gas
Gas pressure
Cutting speed
Material
Nozzle structure

The nozzle must be accurately centered.

This is an issue that is often overlooked.

If the laser beam is not accurately centered within the nozzle:

It can result in:

Dross accumulation on one side
Slanted cut edges
Unstable cutting
Nozzle collisions
Piercing irregularities

Therefore, regularly checking:

Nozzle concentricityis crucial.

7. Tips for Selecting Assist Gas

Assist gas does more than just “blow away the molten slag.”

It actually plays a role in:

Slag removal
Cooling
Oxidation reactions
Cutting speed control
Cut quality control

Common gases:

Oxygen (O₂)

Primarily used for cutting carbon steel.

Advantages:

Strong cutting capability
Good performance on thick plates
Low cost

Disadvantages:

Oxidation layer forms on the cut edge

Nitrogen (N₂)

Primarily used for:

Stainless steel
Aluminum
Copper
High-quality aesthetic parts

Advantages:

Minimal oxidation on the cut edge
Better cut surface appearance
Suitable for subsequent welding and surface treatment

Disadvantages:

Higher gas cost
Thick plate cutting requires high gas pressure and equipment capability

Compressed Air

Air cutting has become increasingly popular in recent years.

Advantages:

Low cost
Easily accessible
Very economical for processing certain thin sheets

However, since air contains oxygen and moisture, attention must be paid to:

Air compressor + dryer + filtration system

Excessive moisture content in the air can compromise cutting stability and increase the risk of contaminating related components.

8. How to Adjust Cutting Speed?

Cutting speed is a critical parameter.

1) Speed is too fast

Potential issues:

Incomplete penetration
Dross adhesion at the bottom
Incomplete cut seam
Failure to cut through sharp corners
Reduced quality of small holes

2) Speed is too slow

Potential issues:

Over-burning
Increased heat-affected zone (HAZ)
Widened cut kerf
Plate deformation
Blackened edges
Increased dross adhesion

Therefore, the correct mindset is not “the faster, the better.”

Instead, the goal is to maximize stable cutting speed while ensuring full penetration and high cut quality.

9. How do you determine if the cutting speed is appropriate?

You can observe the cutting sparks.

1) Normal state

Sparks:

Discharged smoothly
Stable direction
No significant upward back-spray
Continuous cut line

2) Speed too fast

Typically observed:

Sparks trail significantly backward
Difficulty discharging slag from the bottom
Incomplete cutting in some areas

3) Speed too slow

May result in:

Expanded molten zone
Abnormally concentrated sparks
Overheating of the plate edge

This is a very practical method for on-site assessment.

10. Piercing techniques

Piercing is often one of the stages in laser cutting most prone to issues.

Especially with:

Thick plates, highly reflective materials, and special materials

Piercing is more difficult.

1) Do not use standard cutting parameters for piercing

Piercing conditions differ from continuous cutting conditions.

Separate settings are usually required for:

Piercing power
Piercing time
Piercing gas pressure
Piercing focal position
Number of piercing pulses
Piercing height

2) Multi-stage piercing is recommended for thick plates

For thick plates, you can use:

Low-energy pre-piercing → High-energy penetration

Or multi-stage piercing.

This helps reduce:

Spatter
Lens contamination
Nozzle damage
Piercing failure

11. Small-hole cutting techniques

This is a crucial technique in actual production.

Example: 6mm plate thickness, 6mm hole diameter

Cutting such small holes is significantly more difficult than cutting standard contours.

Generally speaking:

The closer the hole diameter is to the plate thickness, the more difficult the cut.

For small-hole processing, focus on adjusting:

Laser power
Speed
Focal position
Gas pressure
Piercing parameters
Lead-in line
Cornering speed

Do not simply copy parameters used for outer contours.

12. Why do small holes often turn out elliptical?

Common causes include:

1) Cutting speed too fast

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut elit tellus, luctus nec ullamcorper mattis, pulvinar dapibus leo.

2) Acceleration too high

The mechanical system changes direction frequently within the small circle.

3) Laser power too high

Can easily cause localized heat accumulation.

4) Inappropriate gas pressure

Insufficient slag removal capability. 5) Inaccurate focus

This results in uneven energy distribution on both sides of the kerf.

5) Insufficient machine motion accuracy

Specifically regarding:

Racks
Gears
Guide rails
Servo systems

Errors in these components will affect the roundness of small holes.

13. Sharp Corner Cutting Techniques

Straight-line cutting is relatively easy.

The true test of equipment and process capabilities lies in:

Sharp corners, acute angles, narrow slots, small holes, and intricate patterns.

If the laser head maintains high speed while navigating a sharp corner, the following issues may occur:

Rounding of the sharp corner
Over-burning
Dimensional deviation
Enlargement due to melting
Therefore, it is usually necessary to:
Reduce speed at the corner + Adjust laser power output

This ensures a more appropriate heat input in the sharp corner area.

14. Importance of Lead-in Lines

A well-designed lead-in line prevents noticeable defects at the starting point of the workpiece.

Common methods:

Straight-line lead-in
Arc lead-in
Tangential lead-in

For parts with high aesthetic requirements, it is advisable to avoid starting the cut directly on a critical edge of the product.

The piercing point can be placed in:

The scrap area or the lead-in area.

This significantly improves the edge quality of the product.

15. Techniques to Avoid Thermal Deformation

Laser cutting of thin sheets is particularly prone to thermal deformation.

This is caused by the localized high temperatures generated by the laser.

Common manifestations:

Sheet warping
Workpiece deformation
Edge curling
Dimensional changes

Solutions:

Method 1: Optimize nesting

Avoid concentrating a large number of small parts in a single area.

Method 2: Use skip cutting

Alter the cutting sequence to reduce localized heat accumulation.

Method 3: Sectional cutting

Divide the entire sheet into multiple zones.

Method 4: Properly set the cutting sequence

Usually, cut internal features before external ones.

This prevents the outer contour from severing the sheet’s support for the workpiece prematurely.

16. Nesting Techniques

Effective nesting can directly increase material utilization.

Factors to consider:

Part spacing
Sheet edge margins
Kerf width
Heat-affected zone (HAZ)
Part orientation
Rolling direction
Subsequent bending direction

For mass production of parts, common-line cutting can be employed.

For example, two rectangular parts share a single edge.

This allows for:

Reduced cutting length
Fewer piercing operations
Increased production efficiency
Lower gas consumption
Higher material utilization

However, common-line cutting requires special attention to:

Cutting sequence and thermal deformation.

17. Lens Protection Techniques

The protective lens of a fiber laser cutting machine is a high-frequency consumable part. Contamination of the protective lens can lead to:

Reduced laser power
Abnormal beam spot
Failure to cut through the material
Reduced cutting speed
Poor cut quality
Lens overheating or even damage

Therefore, inspections should not be limited to times when cutting issues arise.

It is recommended to establish:

A routine inspection schedule for the protective lens.

18. How do I determine if the protective lens is contaminated?

Check for the following:

Dust on the lens surface
Yellow spots
Black ablation points
Oil stains
Cracks

If any abnormalities are found, inspect and replace the lens according to the equipment manufacturer’s guidelines.

Do not wipe optical surfaces directly with ordinary paper towels or fingers.

19. Cutting head height control

The distance between the laser head and the sheet metal is critical.

If the height is too high:

Gas flow disperses
Slag removal capability decreases
Cutting becomes unstable

If the height is too low:

Risk of collision increases
Nozzle is prone to damage
Slag can easily contaminate the nozzle

Therefore, maintaining a stable nozzle-to-sheet distance is essential.

Modern equipment typically employs:

Capacitive height tracking systems

To automatically control the laser head height.

20. What should be done if the sheet metal is uneven?

If the sheet metal shows significant warping, it is recommended to:

Use automatic height adjustment
Reduce cutting risks
Prevent laser head collisions
Pre-treat severely deformed sheets

For ultra-thin sheets, flatness is particularly important for processing quality.

21. How can dross (slag) formation be reduced?

Dross formation is one of the most common laser cutting defects.

Adjustments can be made in the following areas:

1) Increase or decrease cutting speed

Determine the adjustment based on the shape of the dross.

2) Adjust assist gas pressure

Pressure too low:

Insufficient slag removal capability.

Pressure too high:

May cause abnormal behavior of the molten material.

3) Adjust the focal point

An incorrect focal point makes it difficult to expel molten material from the bottom of the cut.

4) Check the nozzle

Nozzle issues such as:

Deformation
Contamination
Misalignment (eccentricity)

…can all affect gas flow.

5) Check the lenses

Contamination of the protective lens can also lead to a drop in actual output power.

22. Common Laser Cutting Defects and Solutions

Cutting Issues	Common Causes	Priority Checks
Incomplete cut	Excessive speed / insufficient power / abnormal focus	Power, speed, focus
Dross at the bottom	Improper gas pressure, speed, or focus	Gas pressure, speed
Blackening at the top	Excessive heat input	Power, speed
Rough cut edge	Parameter mismatch	Focus, speed, gas
Widened kerf	Excessive energy / abnormal focus	Focus, power
Circular holes becoming elliptical	Speed, acceleration, or mechanical precision	Parameters, servo, mechanics
Sharp corners rounded off	Excessive heat at corners	Speed, power
Dross on one side	Nozzle misalignment	Coaxiality
Piercing failure	Improper piercing parameters	Piercing power/time
Sudden deterioration in cut quality	Lens contamination	Protective lens
Unstable cutting	Gas supply or nozzle issues	Gas pressure, nozzle
Plate deformation	Heat concentration	Nesting, sequence

23. Cutting parameters involve more than just a single figure

Many operators focus solely on speed when adjusting parameters. This is insufficient.

A complete set of process parameters should include, at a minimum:

Power + Speed + Focus + Nozzle + Gas + Gas Pressure + Height + Piercing Parameters

Therefore, establishing an in-house laser cutting process database is crucial.

For example:

Material	Thickness	Gas	Power	Nozzle	Speed	Focus	Air pressure
Q235	3mm	O₂	6kW	1.5mm	Process Test	Process Test	Process Test
Q235	6mm	O₂	6kW	1.5/2.0mm	Process Test	Process Test	Process Test
304	3mm	N₂	6kW	1.5mm	Process Test	Process Test	Process Test
304	6mm	N₂	6kW	2.0mm	Process Test	Process Test	Process Test
Aluminum	3mm	N₂/ Air	6kW	1.5mm	Process Test	Process Test	Process Test

Note: The parameters in the table should be based on the specific laser source, cutting head, nozzle, material batch, and process validation results; they should not be used directly as universal settings.

24. Process strategies for different thicknesses

0.5-2 mm thin sheets

Key focus:

High speed
Low heat input
Small-hole quality
Prevention of over-burning
Prevention of sheet deformation

3-6 mm medium-thin sheets

This is a very common thickness range in laser cutting production.

Key focus:

Speed
Assist gas
Focal position
Small-hole quality
Common-line cutting

8-12 mm medium-thick sheets

Focus shifts to:

Piercing
Gas-based slag removal
Nozzle
Focal position
Gas pressure
Cut-face perpendicularity

16-30 mm thick sheets

Key focus:

Laser power
Piercing capability
Gas pressure
Focal position
Cutting speed
Material quality
Cutting head capability

When cutting thick sheets, one should not simply pursue speed; instead, prioritize:

Stability + Cut-face quality + Continuous processing capability.

25. Core methods for improving cutting efficiency

If the goal is to increase production capacity, consider the following approaches:

1) Increase laser power

Suitable for high-volume thick sheet processing.

2) Optimize cutting parameters

Avoid relying on conservative parameters for extended periods.

3) Reduce the number of piercings

Achieved through optimized nesting and common-line cutting.

4) Optimize cutting paths

Reduce non-cutting (air-cut) movement.

5) Increase acceleration

Enhance dynamic performance within the machine tool’s limits.

6) Automated loading/unloading

Reduce manual handling.

7) Automatic nesting

Improve material utilization.

8) Establish a parameter database

Reduce machine setup/testing time.

26. Integrating robotics/automated loading and unloading with laser cutting

For mass production, further integration can be achieved using:

Intelligent sheet storage + Laser cutting machine + Automated loading/unloading + Finished part sorting

…to form an automated production cell.

Typical workflow:

Smart material storage → Automatic material retrieval → Laser cutting → Finished part sorting → Scrap handling → Finished part buffering

This reduces:

Manual handling
Waiting time
Time spent locating materials
Loading and unloading time
Production errors

At the same time, it improves:

Equipment utilization
Personnel safety
Production continuity
Material utilization

For high-volume sheet metal production, this represents a key direction in the evolution of laser cutting from “standalone processing” to “smart manufacturing cells.”

27. Tips for Daily Maintenance of Laser Cutting Machines

Daily Checks

Key items to check:

Nozzle
Protective lens
Gas pressure
Chiller
Laser head
Sheet metal platform
Dust removal system

Weekly Checks

Recommended checks:

Guide rails
Gear racks
Transmission components
Cables
Gas lines
Cooling system
Nozzle coaxiality
Periodic Checks

Includes:

Laser output status
Optical system
Motion accuracy
Servo system
Automatic height adjustment system
Coolant
Compressed air system

Maintenance should be performed according to the equipment manufacturer’s requirements.

28. Tips for Improving Laser Cutting Precision

If high dimensional accuracy is required, considerations must be made across three areas: mechanical, software, and process.

Mechanical Aspects

Check:

Guide rail accuracy
Rack and pinion
Lead screw
Machine frame rigidity
Crossbeam deformation
Servo motors

Software Aspects

Check:

CAD drawings
CAM parameters
Kerf compensation
Lead-in lines
Path planning
Acceleration/deceleration

Process Aspects

Check:

Sheet thickness
Thermal deformation
Cutting sequence
Focal point
Cutting speed

29. How to Improve Cut Surface Perpendicularity?

This is particularly important when cutting thick plates.

If the cut profile is wider at the top and narrower at the bottom (or vice versa), there may be an issue with the laser beam’s energy distribution along the material’s thickness.

Key areas to check:

Focal point position
Laser beam quality
Nozzle coaxiality
Assist gas
Cutting speed
Protective lens
Material condition

If the problem persists, further inspection of the laser beam and the cutting head’s optical system is required.

30. Most Practical Troubleshooting Sequence for the Production Floor

When laser cutting quality suddenly drops, do not immediately make drastic changes to all parameters.

Recommended approach:

Step 1: Check the sheet material

Verify: Material type, thickness, and flatness.

Step 2: Check the nozzle

Verify: Check for deformation, clogging, or contamination.

Step 3: Check the protective lens

Verify: Check for contamination or damage.

Step 4: Check gas

Verify: gas type, pressure, purity, and flow rate.

Step 5: Check focus

Verify: correct focus position.

Step 6: Check speed

Make minor adjustments.

Step 7: Check power

Verify: normal laser output.

Step 8: Check mechanical system

If the following issues persist:

Dimensional errors
Deformation of circular holes
Straight lines not straight
Abnormal repeatability

Then further inspect:

Guide rails, gear racks, servo systems, the machine frame, and the motion control system.

31. "Golden Rules" for Laser Cutting Process Optimization

In actual production, the following principles can serve as quick diagnostic criteria:

Failure to cut through: Check speed, focus, and gas first.

Dross accumulation: Check speed, gas pressure, focus, and nozzle first.

Dross on one side: Focus on nozzle concentricity.

Non-round small holes: Check speed, acceleration, focus, and mechanical precision.

Sharp corners burning: Reduce heat input at corners.

Sheet deformation: Optimize nesting and cutting sequence.

Sudden drop in cutting quality: Check the protective lens and nozzle first.

Inability to cut thick plates: Focus on power, piercing, gas pressure, and focus.

Thin sheets prone to burning: Reduce heat input and optimize speed, power, and piercing.

32. Advanced Optimization Strategies for Sheet Metal Laser Cutting

If a company can already consistently perform standard laser cutting, the next stage is to move beyond merely “getting the cut done” to:

① Cut faster

Increase:

Cutting speed (m/min)

② Cut better

Improve:

Roughness
Perpendicularity
Burrs
Heat-affected zone (HAZ)
Round hole precision

③ Cut more economically

Reduce:

Oxygen consumption
Nitrogen consumption
Electricity consumption
Nozzle consumption
Lens consumption

④ Cut more reliably

Increase:

Continuous processing time
Piercing success rate
Parameter repeatability
Batch consistency

⑤ Cut intelligently

Further introduce:

Auto-focusing + Automatic nozzle changing + Automatic loading/unloading + Intelligent nesting + Intelligent warehousing + Process database + MES production management

Ultimately establishing:

Intelligent warehousing → Automatic loading → Laser cutting → Automatic sorting → Finished product buffering → Data management

…a complete intelligent sheet metal production workflow.

33. Quick Checklist for Sheet Metal Laser Cutting

Production personnel can perform checks directly in the following order:

1) Before Cutting

□ Correct sheet material

□ Correct sheet thickness

□ Sheet is flat

□ Laser unit status normal

□ Chiller functioning normally

□ Gas supply normal

□ Nozzle in good condition

□ Protective lens clean

□ Focus calibrated

□ Nozzle coaxiality normal

2) During Mtela Laser Cutting

□ Stable piercing

□ Normal spark direction

□ Stable cutting sound

□ No significant dross/slag

□ No significant edge burning

□ Stable laser head height

□ Stable gas pressure

□ No severe thermal deformation of the sheet

3) After Cutting

□ Inspect cut surface

□ Check for burrs

□ Check dimensions

□ Check hole diameters

□ Check roundness

□ Check perpendicularity

□ Record optimal parameters

□ Update process database

34. Summary: What Defines Truly High-Level Laser Cutting?

High-level sheet metal laser cutting is not simply a matter of owning a high-power laser cutting machine.

A truly excellent laser cutting process requires getting everything right across these areas:

Equipment, materials, parameters, gas, nozzles, focus, piercing, cutting paths, nesting, maintenance, and automation.

This can be summarized in a comprehensive formula:

High-quality laser cutting = Appropriate laser power + Stable beam quality + Accurate focus + Suitable nozzle + Appropriate assist gas + Precise gas pressure + Reasonable cutting speed + Excellent machine motion accuracy + Correct cutting path + Good maintenance

For modern sheet metal factories, the direction of future development is:

High-power laser cutting → High-speed cutting → Automatic loading/unloading → Intelligent nesting → Automatic sorting → Intelligent warehousing → MES/ERP data integration

This represents the core trajectory for the evolution of sheet metal laser cutting—moving from standalone machines toward intelligent, automated, and unmanned production lines.