Why a Laser Fails to Cut Through Metal
Laser cutting is a complex process. During cutting, the kerf is often uneven, or the cut does not go all the way through.
There are many reasons for a failed cut. The most common one is a drop in laser power or aging of the lamp/tube, which makes the beam energy insufficient and leads to a failed cut on the sample.
If the cutting speed is too high, the focusing lens is damaged, the focusing effect is poor, the beam path is misaligned, and the voltage is unstable — all of this can be the reason the laser does not cut all the way through.
Of course, there are also many other factors that prevent a clean or full-depth cut: the material itself, insufficient assist gas pressure, cloudy water in the cooling system, poor heat dissipation, and so on.
Laser cutting problems must be taken seriously and a solution must be found — this is essential for higher production efficiency and high cutting quality.
Below is a detailed list of six reasons why laser cutting may fail to cut through metal.
Reason 1: Drop in laser power
After long-term use, the power of a fiber laser cutting machine gradually decreases, which reduces cutting capability and leads to situations where the cut does not go all the way through.
Reason 2: Contamination of optical elements
Optical elements include the focusing lens, the reflector (mirror), and so on. Because they operate in harsh conditions for long periods, soot/film builds up on their surfaces, which reduces the laser output and leads to incomplete cutting.
Reason 3: Beam spot alignment is out of spec
The beam spot of a fiber laser cutting machine is an important factor affecting cut quality. When the beam spot alignment cannot meet the standard, you cannot get a clean, through-cut.
Reason 4: Cutting speed is too high
If the cutting speed is too high, the metal will inevitably not be cut all the way through.
Reason 5: Insufficient assist gas pressure
The assist gas is used to remove the melt from the cutting zone. When the gas pressure is not high enough, the melt is difficult to evacuate, which leads to the metal not being cut through.
Reason 6: Sheet thickness exceeds the machine's cutting range
Fiber laser cutting machines have a cutting thickness range. If the sheet thickness exceeds the range recommended for that specific machine, the cutting performance will not be ideal and, for this reason, the metal will not be cut through.
How to solve the "laser doesn't cut through" problem
To solve the issue of a power drop and low current, replace the laser tube in time and use a more powerful voltage regulator to increase the laser's output current and improve the output power.
You should reduce the cutting speed appropriately, clean contaminated mirrors promptly and properly, and replace focusing lenses.
If the beam path is misaligned, adjust it and tune the focal distance until the laser leaves a round mark on a piece of paper.
When cutting copper and aluminum, it is better to polish the surface in advance or apply a light-absorbing coating to solve the high-reflectivity problem.
Regularly clean the nozzle from foreign particles, raise the assist gas pressure to the required level, and replace the distilled water in the cooling system on time.
Maintenance of the fiber laser cutting machine
Use a vacuum cleaner to remove dust and dirt from the machine once a week; all electrical cabinets must be kept closed to protect them from dust.
Always check the steel belt of the fiber laser machine and make sure it is tensioned. Otherwise, problems during operation can injure people and even lead to fatalities. The steel belt looks like a small thing, but if something goes wrong it causes a lot of problems.
Every six months, check the straightness of the beam path and the squareness of the axes of the fiber laser machine; perform timely maintenance and alignment if there is any deviation. If you skip this, cutting performance will degrade, errors will accumulate, and cut quality will suffer. This is the most important task.
A dual-focal-length laser cutting head is a wear part on a laser cutting machine and gets damaged through prolonged use.
The guideways of the fiber laser cutting machine should be regularly cleaned of dust and debris to keep the equipment running properly. The carriage should be wiped frequently and lubricated with oil. The rack and motor must also be cleaned and lubricated regularly so the machine can operate without issues, cut more accurately, and produce higher-quality parts.