Laser welding is a high-efficiency and precise welding method that uses a high-energy-density laser beam as a heat source. It has the advantages of high efficiency, precision, and simplicity. Today, laser welding has been widely used in various industries, such as: electronic parts, automobile manufacturing, aerospace and other industrial manufacturing fields.
However, laser welding is not omnipotent. During the use of laser welding machines, sometimes errors may occur in processing due to reasons of operation or parameter setting. Of course, in order to make the laser welding machine work better, reduce the number of failures, and improve work efficiency, it is necessary to understand the working principle of the laser welding machine to avoid the same problems. Below, this article will introduce you to the common faults and treatment methods of laser welding machines.
Common faults and treatment methods of laser welding machine before starting
1. The device does not start (power supply)
Solution: Check whether the power cord switch supplies power
2. Pre-ignition failure (lamp does not light)
Solution: Check whether there is 220V voltage on the pre-combustion board, whether the lighting board is good or bad; whether the 3A fuse is good or not, and whether the xenon lamp is good or bad
3. The light is on, but the automatic state does not emit light, and the manual state emits light
Solution: Check whether the plug-in is loose; whether the internal control and external control modes are adjusted properly
4. Rotate (voltage adjustment) knob, the voltmeter has no indication
Solution: The intelligent thyristor rectifier module is damaged, the voltage regulating board is faulty, whether the feedback button is closed, and whether the connecting wire is loose.
Common faults and treatment methods of laser welding machine in welding
1. The welding seam is very black when the laser welding machine is welding
Solution:
1) The nitrogen is not turned on, just turn on the nitrogen to solve it.
2) The airflow direction of the shielding gas is wrong, and the airflow direction of the shielding gas should be opposite to the movement direction of the workpiece.
2. Laser welding machine welding penetration is not enough
Solution:
1) Lack of laser energy can improve pulse width and current.
2) The focus lens is not the correct amount, you need to adjust the focus amount close to the focus position.
3. The laser beam weakens when the laser welding machine is welding
Solution:
1) If the cooling water is polluted or has not been replaced for a long time, it can be solved by replacing the cooling water and cleaning the ultraviolet glass tube and xenon lamp.
2) If the focusing lens or resonator diaphragm of the laser is damaged or polluted, it should be replaced or cleaned in time.
3) Move the laser in the main optical path, adjust the total reflection and semi-reflection diaphragms of the main optical path, check and round the light spot with image paper.
4) The laser does not output from the center of the copper gas nozzle under the focusing head. Adjust the 45-degree reflective aperture so that the laser is output from the center of the gas nozzle.
5) The shutter is not fully open. Check and add lube to the shutter connector to make the connector mechanically smooth.
4. During use, the device suddenly does not emit laser light
Solution: Check whether the safety tube of the pre-combustion plate is damaged, check whether there is a power failure; whether the laser cavity leaks, etc.
5. During the working process, the buzzer sounds, and the power is cut off soon, and the cooling water temperature exceeds the upper limit setting temperature.
Solution: Check whether the external circulating water valve is open and whether the water path is unobstructed.
6. Welding spatter: After laser welding is completed, many metal particles appear on the surface of the material or workpiece, which adhere to the surface of the material or workpiece
Causes of splashing: the surface of the processed material or workpiece is not clean, there is oil or pollutants, and it may also be caused by the volatilization of the galvanized layer.
Solution:
1) Pay attention to cleaning materials or workpieces before laser welding;
2) Splash is directly related to power density. Appropriately reducing welding energy can reduce spatter.
7. Cracks: thermal cracks, such as crystal cracks, liquefaction cracks, etc.
Reasons for cracks: mainly due to excessive shrinkage before the weld is not completely solidified.
Solution: measures such as wire filling and preheating can reduce or eliminate cracks.
7. Porosity: There are pores on the surface of the weld
Causes of porosity:
1) The laser welding pool is deep and narrow, and the cooling speed is fast. The gas generated in the molten pool has no time to overflow, which easily leads to the formation of pores.
2) The surface of the weld seam is not cleaned, or the zinc vapor of the galvanized sheet volatilizes.
Solution: Clean the surface of the workpiece and the surface of the weld before welding to increase the volatilization of zinc when heated. In addition, the direction of blowing will also affect the generation of pores.
8. Undercut: The weld is not well bonded to the base metal, and there is a groove, the depth is greater than 0.5mm, and the total length is greater than 10% of the weld length, or greater than the length required by the acceptance standard.
Undercut reason:
1) If the welding speed is too fast, the liquid metal in the weld will not be redistributed on the back of the hole, and undercuts will form on both sides of the weld.
2) If the assembly gap of the joint is too large, the molten metal in the filling of the joint will be reduced, and undercutting will easily occur.
3) At the end of laser welding, if the energy drop time is too fast, the hole is easy to collapse, which will also cause local undercut.
Solution:
1) Control the matching of laser welding machine processing power and speed to avoid undercutting.
2) The undercut of the weld found in the inspection can be ground, cleaned and repaired to meet the requirements of the acceptance standard.
9. Weld seam accumulation: The weld seam is obviously overfilled, and the weld seam is too high when filling.
The reason for weld accumulation: the wire feeding speed is too fast or the welding speed is too slow during welding.
Solution: increase the welding speed or reduce the wire feeding speed or reduce the laser power.
10. Weld deviation: The weld metal will not solidify in the center of the joint structure.
Reason for deviation: inaccurate positioning during welding, or inaccurate alignment of filling welding time and welding wire.
Solution: Adjust the welding position, or repair welding time and welding wire position, as well as the position of lamp, welding wire and welding seam.
11. Weld sag: refers to the phenomenon of sag on the surface of the weld metal.
The cause of the depression: During brazing, the center of the solder joint is poor. The center of the light spot is close to the lower plate and deviates from the center of the weld seam, causing part of the base metal to melt.
Solution: adjust the light filament matching.
12. Poor weld formation: poor weld ripples, uneven welds, uneven transition between welds and base metals, poor welds, and uneven welds.
The reason for this situation: when the weld seam is brazed, the wire feeding is unstable, or the light is not continuous.
Solution: Adjust the stability of the device.
13. Weld bead: When the weld track changes greatly, it is easy to have weld bead or uneven forming at the corner.
Causes: The seam track changes greatly, and the teaching is uneven.
Solution: weld under the best parameters, adjust the angle of view to make the corners coherent.
14. Surface slag inclusions During the welding process, the surface slag inclusions that can be seen from the outside mainly appear between layers.
Reason analysis of surface slag inclusion:
1) During multi-layer multi-pass welding, the interlayer coating is not clean; or the surface of the previous weld is not smooth or the surface of the weldment does not meet the requirements.
2) Improper welding operation techniques, such as low welding input energy and too fast welding speed.
Solution:
1) Choose a reasonable welding current and welding speed, and the interlayer coating must be cleaned during multi-layer multi-pass welding.
2) Grinding and removing the weld seam with slag on the surface, repair welding if necessary.
The equipment has been used a lot, and there may be certain faults. In order to reduce the number of laser welding machine failures, reduce the number of failures, and improve work efficiency, we must understand the problems that need attention during its operation and the troubleshooting methods. Hope this article is helpful for the problem you are facing.