Review of laser welding monitoring

The utility of a new laser interferometric technique, inline coherent imaging, for real time keyhole depth measurement during laser welding is demonstrated on five important engineering alloys. The keyhole depth was measured at 200 kHz with a spatial resolution of 22 mm using a probe beam, which enters the keyhole coaxially with the process beam. Keyhole fluctuations limited average weld depth determination to a resolution on the order of 100 mm. Real time keyhole depth data are compared with the weld depths measured from the corresponding metallographic crosssections. With the exception of an aluminium alloy, the technique accurately measured the average weld depth with differences of less than 5%. The keyhole depth growth rates at the start of welding are measured and compare well with order of magnitude calculations. The method described here is recommended for the real time measurement and control of keyhole depth in at least five different alloys.

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“…The theoretical growth rates show order of magnitude agreement with the measured rates, indicating the measured growth rates are realistic. 1 …”

Section: Introductionmentioning

confidence: 97%

Real time monitoring of laser beam welding keyhole depth by laser interferometry

Blecher

Galbraith

Vlack³

et al. 2014

Science and Technology of Welding and Joining

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“…Therefore, these benchmarks cannot be directly used to validate the results of a laser welding simulation. In this context, several experimental measurements were developed to study and to build a database (experimental benchmarks) of thermomechanical processes [27][28][29][30][31][32]. These experimental benchmarks can clearly be used to improve and validate numerical simulations.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study of Thermomechanical Processes: Laser Welding and Melting of a Powder Bed

et al. 2020

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In this study, an experimental approach was developed to analyze and better understand the laser welding and melting of a powder bed process. Different optical diagnostics tools (high-speed camera, infrared camera, pyrometer, etc.) were applied to measure different physical quantities (molten pool morphology, temperature field, residual stresses, and distortions). As a result, measurements during the laser welding process facilitated the building of a database of experimental results (experimental benchmarks). The study of the melting of a powder bed enabled a better understanding of the physics related to the formation and behavior of the molten pool. These results can be used by researchers to improve and validate numerical simulations of these processes.

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“…Various sensors are exploited for this purpose. [20][21][22] Radiation intensity detectors like photodiodes are a common choice, 23,24 they offer high temporal resolution and with appropriate filters can detect light at different wavelengths, 25 such as visible light, laser reflected radiation, or infrared. 26 Despite several efforts in the literature, the assessment of quality attributes along with the use of a noninvasive monitoring device able to detect such changes remains an open question.…”

Section: Introductionmentioning

confidence: 99%

Process development and coaxial sensing in fiber laser welding of 5754 Al-alloy

Garavaglia

Demir

Zarini³

et al. 2019

Journal of Laser Applications

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The use of Al-alloys is increasing in the automotive industry due to the pressing necessity to reduce weight and fuel consumption. Several parts concerning the car body are assembled through welding, where a high-quality seam is a key requirement. For this purpose, laser welding stands as an appealing option. On the other hand, laser welding of Al-alloys is a complex process due to the high reflectivity, reactivity, and crack susceptibility of these materials. In many cases, such issues limit the applicability of the autogeneous welding, which is an advantageous feature of laser welding. High-brilliance fiber lasers have been an enabling technology for improving the weldability of Al-alloys. However, laser welding of Al-alloys, especially in a lap-joint configuration, requires robust processing conditions able to maintain seam quality for each weld in high volumes even with part tolerances and tooling variability. Accordingly, this work discusses the process development and monitoring in laser welding of 5754 Al-alloy. In particular, the process was carried out in a double lap-joint configuration with 1 mm sheets, commonly used in automotive applications. A 3 kW fiber laser with in-source integrated monitoring capability was employed as the light source. The process feasibility zone was investigated as a function of laser power and welding speed, while the effect of focal position was investigated for the weld robustness. Weld seam types and defects were identified, as well as the monitoring signals associated light back-reflected from the process.

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Review of laser welding monitoring

Cited by 192 publications

References 103 publications

Real time monitoring of laser beam welding keyhole depth by laser interferometry

Real time monitoring of laser beam welding keyhole depth by laser interferometry

Experimental Study of Thermomechanical Processes: Laser Welding and Melting of a Powder Bed

Process development and coaxial sensing in fiber laser welding of 5754 Al-alloy

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