38 FAQs for Fiber Laser Cutter Operation

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Laser Cutting Working Principle Drawing

What are the dangers when using various gases? What should I do in case of an emergency?

1) Prevent the appearance of inflammable and explosive materials near any cylinder.

2) Keep away from open flames. It is strictly forbidden to work at temperatures above 60 degrees and use gas from regular suppliers.

3) Dewar tank can’t be tilted more than 45 degrees to prevent frostbite. Eyeglasses and gloves must be worn during operation.

High gas concentrations during venting are strictly prohibited. After the Dewar cans fell to the ground, it should be righted up within two minutes.

4) Use a holder to fix the cylinder.

The main components of the laser cutting machine and their respective roles?

Laser source: generate the laser.

Laser cutting machine: for CNC machining.

Chiller: Cool the laser, cool the reflective lens and the cut head.

Air compressor: Provides air for laser cutting machine  and auxiliary machining gases.

Dryer: Filter water, oil, etc. in the air to keep the air dry.

Dust collector: Dust and waste gas exhaust.

Regulator: Keep the working voltage of the device stable.

The meaning of the following code

G00: Rapid positioning M00: Unconditional suspension
G01: Linear interpolation M36: Turn off followers
G02: Clockwise circular interpolation M31: Choose air
G03: Counterclockwise circular interpolation M35: Turn on followers
G04: Pause M10: Open mechanical shutter
G10: Empty stack M30: The program ends and returns to the program header
G50: Scale by M11: Shut down mechanical shutter
G09: Program read-ahead M06: Shut down electronic shutter
G51: Workpiece rotation M07: Turn on electronic shutter
G71: Metric programming M14: Turn off the auxiliary gas
G91: Incremental programming
G90: Absolute coordinates

Why recalibrate when changing different cutting materials and different types of nozzles? What should you do if the automatic calibration is not successful?

Because the height follows adopt the capacitive sensor, it is related to the material, contact area, and contact distance.

The nozzles have different contact areas, so replacing different types of nozzles requires recalibration.

If the automatic calibration is unsuccessful, execute M70 in MDI (manual) mode and then recalibrate or switch to manual calibration.

External light path and Z-axis coaxial adjustment method

The X axis is adjusted by adjusting the upper and lower left and right adjustment screws of the laser bracket; the Y and Z axes are adjusted by three adjusting nuts on the lens holder.

Generally, the red light is used for rough adjustment, and then the cross light fork is used for light adjustment, so that the front and rear spots are in the middle.

Method and precautions for finding focus

First prepare a flat board, placed at the near end of the laser cutting machine at a 30-45 degree angle.

Remove the nozzle, screw the scale to about -5, modify P199 (meaning: piercing delay, unit: ms) = 0, move the cutting head to the highest point of the board;

Bring up the program to pull the focus, manually open the air, execute the program and find the point where the burnt marks on the board are the thinnest, install the nozzle, and manually move the cutting head above the thinnest point.

Unscrew the scale until the nozzle is about 0.5 mm from the surface of the plate.

Record the scale value at this time. This scale value is what we call the zero focus scale.


Check if the direction of movement of the pull focus in the program matches the direction in which the board is placed to prevent reverse collision.

Air must be manually turned on before and after execution to prevent smoke from contaminating the lens.

After the program ends, the Z axis cannot be moved before the focus is found, and the board cannot be knocked.

Write a coaxial program and say the meaning of each sentence

 % Program header
P900002 Program name
N1010 Program annotation
N1020M10 Turn on mechanical shutter
N1030M21 Select laser pulse frequency
N1040M15 Select continuous wave mode
N1040G4F30 Pause 0.03 seconds
N1050G111V100 Laser power
N1060U1 Determine power
N1070M91 Cancel laser open limit
N1080M7 Open electronic shutter
N1090G4F10 Pause 0.01 seconds
N1100M6 Electronic shutter
N1110U0 Cancel set power
N1120M11 Turn off mechanical shutter
N1130M30 The program ends and returns to the program header

What are the factors that affect laser cutting?

1) Beam quality:

  • Beam wavelength
  • Power
  • Energy
  • Mode
  • Beam angle
  • Polarization state
  • Beam position
  • Stability
  • Pulse width and peak power
  • Repeat frequency
  • Average output power

2) Process parameters:

  • Speed
  • Power
  • Air pressure
  • Cutting height
  • Focus position
  • Nozzle size and roundness

3) External light path:

  • How good is the focusing mirror?
  • Degree of contamination of circular polarizers and reflector

4) External conditions:

  • Gas purity
  • Sheet quality

What kinds of gases that is needed for the laser to work? What is the purity of each? What is the external minimum pressure?

laser cutting auxiliary-gas

ROFIN: High purity nitrogen 99.999% 5bar

Mixed gas (carbon dioxide, helium, nitrogen, carbon monoxide, oxygen, helium), designated supplier

PRC High purity nitrogen 99.999% 5bar

High purity carbon dioxide 99.999% 5bar

High purity helium 99.999% 5bar

Pure nitrogen 99.995% 5bar

 TK High purity nitrogen 99.999% 5bar

High purity carbon dioxide 99.999% 5bar

High purity helium 99.999% 5bar

Note: The gas blown by the TK laser is shunted by high-purity nitrogen inside the laser.

Precautions before executing the program? And what should you pay attention to during processing?

Whether the selection procedure is correct, whether the process parameters are called correctly, whether the external auxiliary gas is ready, and whether the plate position is correct;

Prevent sheet deformation during machining to avoid collisions. When the machine is running, the operator cannot leave the machine and pay attention to personal safety.

What are the several types of lenses that are used on the machine?

Focusing mirror, circular polarizer, round reflect mirror.

Stainless steel hanging slag, why can’t it be cut through and how to solve it?

The burr on the bottom is similar to the slag

There are two types of slag on the lower surface:

Hanging hard dregs can generally be solved by lowering the focus or increasing the air pressure;

Hanging soft slag can generally be solved by speeding up the cutting speed, reducing the power and increasing the focus position.

When can not cut through, it can generally be solved by reducing the speed, increasing the power and adjusting the focus position.

What is the relationship between the diameter of the cutting hole and the thickness of the plate? If it is out of range, what should be done?

Carbon steel:

The hole diameter below 8mm is not less than the plate thickness, and the hole diameter above 10MM is not less than 1.2 times the thickness of the plate.

Stainless steel:
The hole diameter below 4mm is not less than the thickness of the plate, and the hole diameter above 5mm is not less than 1.5 times the thickness of the plate.

Holes beyond the above requirements can adopt marking positioning or pulse slow cutting.

Sudden power outage during processing, how should we continue laser processing?

If the machine is powered off during the machining process, after restarting the machine, the operation steps are as follows:

  1. The machine returns to the reference point again to establish the machine coordinate system;
  2. Open the NC program that is being executed before the power is turned off, and check whether the Q999997 (calling the workpiece coordinate system memory subroutine) subroutine is called in front of the program. (If the Q999997 subroutine is not called, then we can’t find the workpiece zeropoint, we can only manually locate.).
  3. If Q999997 is called, then we can execute G54 (workpiece coordinate system selection);
  4. Then G00X0Y0, so you can find the workpiece zero point;
  5. Open the loop parameter and check the value of parameter P8 (the program line number being executed before power off) and P12 (the last line number of G00 fast positioning before power off); open FASTPLOT to check the program to ensure the program number is correct.
  6. Call the NC program, and modify the program, add M00 (unconditional pause) after G09 (read ahead of time, pre-stage function), increase the skip command GO**** (value for P12 memory), and at P12 after the memory G00 command line is added, the cutting layer process subroutine is added, such as: Q990051 (first layer cutting parameter call);
  7. Execute the program, the auxiliary function and laser power call will be turned on, and the automatic positioning will resume the cutting.

What are the specific reasons for focusing lens contamination?

Air or auxiliary gas (O2, N2) is not clean containing moisture, particles, soot, oil, etc.;

The outer light path skin tiger is unclean; the slag is reversed during the cutting process and the perforation process.

Which materials cannot be processed with a laser?

Gold, silver, copper, pure aluminum, hard alloy steel, marble, cast iron, glass, etc.

How many perforate methods are there? Under what circumstances is each method used? What is the cause of burst holes when using ordinary perforation method? How to deal with it?

There are three ways to perforate:

  • Common perforation
  • Progressive perforation
  • Burst hole

Generally, carbon steel plates of 10 mm or less use ordinary perforations, and carbon steel plates of 10 mm or more use progressive perforation.

Burst holes are not commonly used.

(Note: Aluminum alloys cannot use progressive perforations, but should be perforated at the focal point)

The reason for the blast hole:

  1. The piercing time is not enough;
  2. The perforation pressure is too large;
  3. The perforation focus is too high.

What are the reasons for the inconsistent cutting end faces?

  • Coaxial misalignment
  • Incorrect light path
  • No nozzle
  • Bad quality plate
  • Focusing mirror pollution
  • The start cutting surface is not good
  • Light opening delay

What are the types and sizes of nozzles? How should nozzles be selected for different thicknesses of materials?

Nozzle Types

There are two types of nozzles: double-layer high nozzles (1.4, 2, 2.5, 3.0) and single-layer straight bottom low nozzles (1.5, 2.0, 2.5, 3.0).

Carbon steel generally uses double-layer high nozzles. Generally, 1.4 is used within 8mm; 2.0 is generally used for 10-12mm; 2.5 is generally used for 14-18mm; 3.0 is generally used for 20-25mm.

Stainless steel and aluminum alloys generally use a single-layer straight bottom low nozzle.

Detailed processing parameters of oxygen cutting 10mm-16mm carbon steel and nitrogen cutting 8mm stainless steel

Laser Generator Type Sheet Power Speed Focus Nozzle Dia. Cutting Height Cutting Gas Air Pressure Lens
mm W mm/min mm mm mm Bar inch
TK2000 MS 10 1800 1000-1200 1 2 1.2 O2 0.8~1.0 7.5
PRC4000 MS 16 2450 800-1000 2 2.5 1.2 O2 0.6~0.7 7.5
ROFIN DC030 SUS 8 2950 800-1100 -8 2.5 0.65 O2 20 7.5

What are the advantages of 21.5-inch and 7.5-inch lenses when cutting sheets?

5-inch lens

Cutting thin plates is fast and in good quality

7.5 inch lens

With small taper and good quality for cutting thick plate, good for protecting the lens

What is the difference between the far end and the near end of the optical path in the focus, why is there such a difference? How to solve the impact of its cutting?

The focus of the distal end of the optical path is relatively lower than the focus of the proximal end. This is because the non-absolute parallel light of the laser has a divergence angle.

During the cutting process, the height of the operation panel can be adjusted by adjusting the adjustment knob or adjusting the cutting speed override to solve the effect of different focus.

What should you pay attention to when cutting non-metal?

Cancel the follow-up; cut with nitrogen or air, it is strictly prohibited to cut with oxygen;

Increase the nozzle distance to prevent collisions and leave the micro-connection to prevent dust from contaminating the lens.

How to prevent the workpiece from deforming and turning during the cutting process? What are the causes of the dimensional deviation of the cut workpiece?

Misalignment cutting, micro-connection, and changing of the position of the cutting point can be used to prevent deformation and turning during cutting;

The deviation of the workpiece size is too large due to the deformation displacement.

Why cut a small round when cutting stainless steel over 4mm, or start with a slow cutting?

Ensure that the auxiliary airflow is quickly blown down at the beginning of the cutting, effectively preventing the reverse slag.

What kind of gas is used to cut carbon, what effect does gas purity have on cutting?

Generally, oxygen is used, and its purity is generally 99.5% or more;

The higher the purity, the better the cutting edge.

What kind of gas is used to cut stainless steel, and what effect does gas purity have on cutting?

Generally, nitrogen is used, and its purity is generally 99.6% or more. With low purity, the cutting section will have yellow edge; with high purity, the cutting section is brighter.

Besides, it can also reduce the drosss at the bottom edge.

When cutting stainless steel with film, face up or down? Why do this? What should you pay attention to with film cutting?

With the film facing down, it is not conducive to slag discharge, therefore the film should face up.

When cutting with a film, pay attention to the film peeling off and snag the cutting head. Generally, the method of first marking and then cutting can be used.

What should you pay attention to when installing FASTCAM?

After the installation is complete, overwrite the correct configuration files PA8000.com and SETUP.DAT under the FASTCAM installation directory.

What are the requirements for the incoming line for the stainless steel/carbon steel with different thicknesses?

Straight leads can be used for stainless steel below 3mm; 4mm or more are generally use straight line plus small arc;

Carbon steel is generally use a circular arc.

What should be done if there is a sudden occurrence of a bad phenomenon during normal processing?

First pause, then analyze the cause of the undesirable phenomenon and deal with it accordingly.

What are the advantages and disadvantages of using bottled gas, dewar tank, and storage tanks?

Use bottled gas:

The pressure can be well guaranteed, but the high cost and short use time require frequent gas change;

Use Dewar tank:

Easy ventilation, long service life, suitable for long-term processing, and low cost;

(It is recommended to use high pressure Dewar tank. Gasification gas is generally not less than 80 cubic meters)

Use the storage tank:

Very gas-saving, in very low cost, long-lasting use time, usually charge liquid nitrogen in half a month, is a one-time investment, recommended for use when two machines are used at the same time and a large amount of nitrogen is used as auxiliary processing gas.

What are the steps in programming in FASTCAM and FASTNEST?

The FASTCAM programming steps are as follows:

Import DXF\DWG file, do CAD clear compression processing, set processing process and process settings, add tool compensation.

Output the program, specify the origin, and verify the program.

The programming steps in FASTNEST are as follows:

Set the plate size, modify the machine parameters, set the file type, and set the FASTPATH.

Then, the processed workpiece pattern is added into the discharge table, the number of workpieces is set, the automatic nesting is clicked, and the manual adjustment can be performed to perform fine adjustment, and the output program is simultaneously verified.

The meaning of CUTTING HEAD NOZZLE LOSE , the reason and solution for this alarm?

  • The cutting head sensor nozzle loses alarm;
  • Check if the nozzle is off;
  • Whether the ceramic ring is intact;
  • Whether the calibration is correct.

What is the meaning of EX CHANGE TABLE ALARM and how to solve this alarm?

Exchange workbench failure; check whether the cutting head is raised to the highest point.

What is the meaning and solution of AXIS Z MINUS LIMIT ALARM?

Z-axis negative hardware limit fault; press the emergency stop, screw the cutting head off the hard limit switch, and then return to zero to eliminate.

How to protect the ceramic ring from damage?

Effect of ceramic ring and sealing ring on cutting quality

Ensure that the cooling ceramic ring gas is normal;

The operator must not leave the machine while the machine is running, pay attention to the sudden release of the plate release stress and the workpiece flipping, and timely processing after the pause; prevent damage to ceramic rings and cutting heads.

It is strictly forbidden to use double-layer high nozzles when cutting stainless steel and aluminum alloy with high-pressure nitrogen.

What are the reasons for the slag on the lower surface of the carbon steel plate?

  • Incorrect focus position
  • Small air pressure
  • The surface of the sheethas foreign bodies such as rust, oil and glue.

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