《Nd YAG Laser Welding Guide》.pdf

UNITEK MIYACHI CORPORATION Nd:YAG Laser Welding Guide Copyright  2003, Unitek Miyachi Corporation The material contained herein cannot be reproduced or used in any other way without the express written permission of Unitek Miyachi Corporation Contact: Unitek Miyachi Corporation 1820 S Myrtle Avenue Monrovia, CA, 91017-7133 Tel.: 626 303 5676 Fax: 626 599 9636 2 Table of Contents 1. Laser basics 4 1.1 Introduction 4 1.2 Principle of Laser Generation 4 1.3 Nd:YAG laser medium 6 1.5 The Pump Source 6 1.6 Resonator 6 1.7 Laser safety 7 2. Fundamentals of Laser Welding 8 2.1 Pulsed Welding Lasers 8 2.1.1 Real Time Power Feedback 9 2.1.2 Power Ramping 9 2.1.3 Pulse Shaping 9 2.1.4 Time Share 10 2.1.5 Energy Share 10 2.1.6 Beam Delivery 10 2.1.7 Focus Head 10 2.2 How a laser welds 10 2.3 Key Welding Parameters 11 2.3.1 Joint Design and Fit-up 11 2.3.2 Part Alignment 12 2.3.3 Material Selection and Plating 12 2.4 Laser Parameters 13 2.4.1 Glossary of Terminology 13 2.4.2 Fiber Optic Cable 14 2.4.3 Focus Optics 15 3.4.4 Peak Power and Pulse Width 16 2.4.5 Seam Welding 17 2.4.6 Cover Gas 18 2.5 Examples of Welds 18 3 1. Laser basics 1.1 Introduction The word “LASER” is an acronym for Light Amplification by Stimulated Emission of Radiation. The elements of a laser are – 1. L