level packages in each facility. Finally, we now come to the computation of the power density: 1. At the focal point of the laser beam: Area of the focused spot is A = /4) × d2 o Power density (for CW laser) is I = P/A Power density (for pulsed laser) is I = (E)/(t × A) 2. At the material’s surface, which is the preferred location: Measure the width of the weld nugget at its metallographic cross section. Use 80% of this measurement for Class II metal (see the Laser Welding Q&A, September 2016 Welding Journal) as the diameter of the focused beam (db). Substitute db for do. Complete the computations as presented above. The importance of measuring the symmetry and uniformity of the spatial profile of the laser beam and how it affects the power density of the focused laser beam will be discussed at a later date. Reference 1. Fuerschbach, P. W., et al. 2004. Development and evaluation of an insitu beam measurement for spot welding lasers. Welding Journal 83(5): 154-s to 159-s. 26 WELDING JOURNAL / NOVEMBER 2016 WJ SIMON L. ENGEL is president of HDE Technologies, Inc., Elk Grove, Calif. He serves as vice chair of the AWS C7C Subcommittee on Laser Beam Welding and Cutting and is a member of the US TAG for ISO/TC44/ SC10/WG9 on Hybrid Welding. He is also a senior member of the Laser Institute of America and a life member of the Society of Manufacturing Engineers. He is considered a specialist in industrial laser applications and has been in the business for forty years. Questions may be sent to Simon Engel, c/o Welding Journal, 8669 NW 36 St., #130, Miami, FL 33166, or via email at simon_of_hde@yahoo.com. For info, go to aws.org/adindex For info, go to aws.org/adindex See us at FABTECH booth N5115
Welding Journal | November 2016
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