Laser metal welding equipment and laser power measurement
Tuesday, December 03, 2019
Laser welding is quickly becoming the preferred welding method in many industrial projects. However, while this technique offers numerous benefits over conventional welding, its performance depends heavily on the power characteristics of the laser beam.
Unfortunately, laser beam power can fluctuate over time, resulting in inconsistent and potential dangerous welds. This is where regular maintenance and expert calibration comes in.
The quality and magnitude of your laser’s power have the greatest effect on the quality of your weld. Low power output can fail to generate enough heat to effectively join the metals together, leading to weak fusion and the development of cold cracks.
However, one of the most crucial factors that can affect weld quality is the amount of power delivered to the workpiece per unit area of the beam, also known as power density.
High power densities (high concentrations of power over a small area) give lasers the unique ability to maximize penetration while minimizing heat to the surrounding material. This attribute reduces the heat-affected zone and part distortion.
On the other hand, too much power delivered over a large beam area can increase the heat-affected zone, which can affect the microstructure of the area surrounding the weld and promote fracture and even corrosion failure.
Dirty optics is one of the leading causes of laser beam inefficiency. When welding in an industrial setting, it is almost inevitable that your optics will gather contaminants. Soot, vapor, oil, splatter, and other external contaminants will often accumulate on the nearest surface – the cover glass window.
This contamination increases the absorption of the glass surface, resulting in thermal distortion of the optics and changes to the window’s refraction index. This phenomenon causes the laser’s focal point to move closer to the optic and away from the workpiece, leading to loss of penetration and more contamination production.
Small alterations in your laser’s power can result in substantial changes to the weld. Therefore, another factor that can affect the quality of your laser welding process is the stability of your laser’s output power. This is especially crucial in sensitive and high-precision applications, such as micro-welding.
Laser welding involves the use of extremely high powered equipment. If the lasers are designed to melt and cut through metal, imagine what they can do to your measuring equipment. Therefore, one of the first things you need to do when measuring your laser is to ensure that you do not exceed the sensor’s damage threshold.
This threshold, which is typically defined in your measurement device’s manual, specifies the optical intensity or energy per unit area below which no damage will occur on the sensor. Several methods are available to reduce (or attenuate) the laser beam before applying it to the measuring equipment. Such methods include using additional optics to change the laser beam characteristics or positioning the detector away from the focal point.
Laser welding is known for its superior precision, speed, high power density, and relatively small heat-affected zones. However, routine calibration using reliable power detectors is essential to ensure that your laser welding equipment performs to its full potential. Avoid weld failures that can cost you money and your reputation; invest in the right power sensor for your business today!