Competitiveness, Optimization, and Compliance in Industrial Laser Applications
By Simon L. Engel, President, HDE Technologies, Inc., and Technical Director, Laser Welding Certification Program, University of Wisconsin, Madison
The business objectives in the title of this article are standard in all types of manufacturing, and laser-assisted fabrication is no exception. A set of tools has become available in the past few years that allows end users of industrial lasers to optimize the laser process while complying with current ISO and AWS technical standards. This helps manufacturers remain competitive in the US and in the global markets.
In my work as an independent technical consultant and in the past as owner of a laser contracting and system building company, I found the following tools to be quite useful in meeting goals related to competitiveness, optimization, and compliance.
| The Ophir-Spiricon (https://www.ophiropt.com/photonics) BA-500 Integrated Beam Analyzer is to be used with collimated laser beams generated by Nd:YAG and solid state lasers. With one setup, you can measure the spatial and temporal characteristics and behavior of the laser beam. This includes pulse shape, energy per pulse, spatial profile, pulse rate, and changes in these parameters. A real time display facilitates the accurate alignment of the laser and optics. Once the equipment is aligned, changes (temporal behavior) can be observed and recorded. The data can then be examined for compliance with ISO standards. Days of effort to characterize the laser beam are reduced to a few hours (the first time, even less time after that). |
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Ophir-Spiricon’s Beam Cube does all the above but with the focused laser beam. This is the most critical information as the laser beam has passed through all of the beam steering and beam shaping optics by the time it gets to the focus point. Remember, in material processing with lasers, the size and the quality of the focused beam are the critical parameters. Although Beam Cube is rated at 150 watts average power, some of HDE’s clients (end users) have used it with lasers up to 5,000 watts by adding the appropriate beam splitter and beam dump. Further, one of our clients actually integrated Beam Cube into their system to allow for periodic inspection of the focused beam.
Figure 1. Laser Spot welds made on a consumer product. Each weld nugget is made with a single pulse.
Figure 2. The Resultant Pulse Shape that was used to make the welds shown in Figure 1. Please observe the differences between the Programmed Pulse Shape and the Resultant Pulse Shape. The Ophir BA-500 (that incorporates the PR-series Energy Meter) was used to program the laser to achieve the desired pulse shape.
One example of process optimization is the laser welding of thin gage carbon steel in the lap weld configuration where there is excessive gap between the pieces. See Figure 1.
By using a special pulse shape, "spike welding" can be achieved, where the gap between the pieces is overcome by controlling the flow of the metal with the special pulse shape. The practical way to set the pulse shape is with the use of one of the Ophir devices discussed above, or by using one of the RP-Series Ophir-Spiricon energy detectors. With this approach, welded assembly rejection rate was reduced from 600 parts per million (ppm, 0.06%) to under 100 ppm (0.01%). Now that is an achievement!
Now is the time to stop and look at your current laser welding operation. Is your process optimized? Is your process compliant with current ISO and AWS standards? Are you the leader and are you competitive in your industry with your existing laser process? If not, perhaps it is the time to put some of the new tools to work for you.
Industrial Laser Courses
The laser material processing courses from the University of Wisconsin–Madison cover a wide range of topics, including laser welding, weld inspection, weld defects, laser cutting, laser drilling, beam analysis, beam diagnostics, and process validation. Ophir- Spiricon is working with instructor Simon Engel to ensure students have access to the latest beam measurement equipment, including the BA-500 Integrated Beam Analyzer, , Beam Cube, and the PR-Series of energy detectors. Find out more at
http://epdweb.engr.wisc.edu/laser-processing-welding-courses.lasso
References
- Dijken, D. and Hoving, Willem: ‘Laser Spike Welding’, Industrial Laser Solutions, October 2004
- Engel, Simon L.: ‘Laser Welding 201’, Practical Welding Today, January/February 2008
Simon L. Engel
Simon is currently the Technical Director of the Laser Welding Certification Program in the EPD Department of the University of Wisconsin, Madison, WI. He has been presenting laser applications courses at U of W on a regular basis since 1978. He is an active member of the C7.4 and C7.2 Laser Standards Sub-Committees at AWS. The material for his courses, publications, and patents comes from his consulting assignments, and his 40 years of experience in this field, during which time he owned and operated a successful contract shop and laser systems company for 22 years. Simon can be reached at simonlaser@yahoo.com