What causes burrs to appear during cutting?

Burrs during cutting are usually caused by factors such as process parameters, equipment status, or material characteristics. Below are the specific causes, corresponding solutions, and practical suggestions:

I. Optical System Errors

1. Focus Position Deviation

Cause: Misalignment of the focus lens, failure of the laser head height sensor, or mechanical structure loosening after long-term use.

Solution:

Calibrate the focus using a special tool (the minimum spot position can be confirmed via marking method);

Check the verticality of the laser head lifting axis and adjust the lead screw or guide rail if necessary.

2. Lens Contamination or Damage

Cause: Dust, oil, or laser-induced cracks on the protective lens/focus lens, leading to beam divergence.

Solution:

Wipe the lens with a lint-free cloth dipped in alcohol; replace immediately if spots or cracks appear;

Verify the normal operation of the cutting head air-blowing device to prevent dust back-splash.

II. Mismatched Process Parameters

1. Imbalance Between Cutting Speed and Power

Cause:

Excessive speed: Incomplete material melting, leaving edge burrs;

Insufficient speed: Enlarged heat-affected zone, causing molten material accumulation and burrs.

Solution:

Adjust parameters based on material thickness (e.g., 10mm carbon steel requires ≥4000W power and 0.8-1.2m/min speed);

Use the equipment's built-in process database or optimize parameter combinations via trial cuts.

2. Improper Pulse Frequency and Duty Cycle Settings

Cause: High-frequency low-energy pulses may result in rough cuts; low-frequency high-energy pulses may cause over-burning.

Solution:

Thin plates (<2mm): Use high frequency (100-200Hz) and low duty cycle (30%-50%);

Thick plates (>5mm): Use low frequency (20-50Hz) and high duty cycle (60%-80%).

III. Assist Gas Issues

1. Insufficient Pressure or Low Purity

Cause: Low cylinder pressure, regulator failure, or use of industrial-grade (non-cutting-specific) gas, leading to incomplete molten material removal.

Solution:

For oxygen cutting of carbon steel, maintain pressure at 0.6-1.0MPa (adjust based on thickness);

For nitrogen cutting of stainless steel, ensure purity ≥99.99%; replace cylinders regularly and check gas line leaks.

2. Incorrect Gas Type Selection

Cause: For example, using oxygen to cut stainless steel may produce oxidized burrs; using air to cut aluminum may result in insufficient cooling.

Solution:

Carbon steel/low-carbon steel: Oxygen (supports combustion + removes slag);

Stainless steel/aluminum alloy: Nitrogen (prevents oxidation);

High-reflectivity materials (copper/aluminum): High-pressure air or nitrogen.

IV. Consumable Wear or Installation Problems

1. Nozzle Blockage or Wear

Cause: Molten material back-splash adhering to the nozzle hole during cutting, or nozzle diameter enlargement after long-term use, leading to turbulent gas flow.

Solution:

Check the nozzle inner hole before each cut and clean impurities with a fine needle;

Replace nozzles of the same specification if severely worn (enlarged diameter/edge burrs).

2. Ceramic Ring Damage

Cause: Cracks in the ceramic ring may cause coaxiality deviation of the laser head and beam offset.

Solution: Regularly inspect the integrity of the ceramic ring; replace immediately if cracks are found, and ensure coaxial installation with the nozzle.

V. Material and Equipment Factors

1. Uneven or Impure Material Surface

Cause: Warped plates changing the focus distance, or surface scale/oil affecting cutting quality.

Solution:

Flatten the plate before cutting and wipe the surface with alcohol;

For thick plates, perform edge pre-cutting to remove the oxide layer.

2. Reduced Mechanical Precision of Equipment

Cause: Wear of guide rails/lead screws, or abnormal servo motor drive, causing jitter in the cutting head movement.

Solution:

Check the lubrication of guide rails and replenish special lubricant;

Use a laser interferometer to detect machine tool positioning accuracy, and replace transmission components if necessary.

VI. Notes for Special Material Cutting

High-reflectivity materials (copper/aluminum): Burrs often result from insufficient local melting due to heat reflection. Increase power (≥6000W) and use high-pressure nitrogen (>1.5MPa).

Multi-layer plate cutting: Gaps between layers may accumulate slag; use a "stepped cutting" process (adjust focus for each layer).

Quick Troubleshooting Process

First check lens cleanliness and focus position (basic items);

Test the effects of different cutting speeds (±20%) and gas pressures (±0.1MPa);

Retry after replacing consumables like nozzles and ceramic rings;

If the issue persists, contact the equipment manufacturer to inspect laser head coaxiality and machine tool precision.

Through systematic troubleshooting, over 80% of burr issues can be resolved by optimizing parameters or replacing consumables. Complex mechanical failures require professional technical intervention.

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Ryder