Industrial Lasers and Applications in Automotive Welding (Unit 4)

This paper was presented at a Workshop entitled Lasers in the Automotive Industry, held at Nissan Motor Manufacturing (UK) Ltd, Sunderland.

Introduction

The use of lasers in automotive manufacture has increased dramatically over recent years to a position where about 15% of all industrial processing lasers are installed in production. Although the lasers are devoted mainly to cutting applications, a significant and growing proportion of lasers is being applied to welding. In a survey in 1992, about 20% of the lasers installed in the automotive industry were used in welding applications. Since that time, there has been an explosion of growth in welding applications, particularly involving steel manufacturers, for tailored blank manufacture and in body-in-white welding applications.

This paper will review the industrial laser types which are available for welding applications, then describe the range of current applications used in the automotive industry and highlight areas where developments in processing techniques and equipment are poised to make an impact for laser welding in the future.

Industrial Laser Types

There are two main types of industrial laser of interest to structural fabrication; CO ₂ and Nd:YAG lasers. The lasers have different characteristics that are summarized in Table 1.

Table 1. Summary of characteristics of CO ₂ and Nd:YAG lasers

Property	CO 2 laser	Nd:YAG laser
Lasing medium	CO 2 +N 2 +He	Neodymium doped yttrium aluminium garnet crystal rod
Radiation wavelength	10.6µm	1.06µm
Excitation method	Electric discharge	Flashlamps
Efficiency	5-10%	2.5-5%
Output powers	Up to 60kW	Up to 4kW
Beam transmission	Polished mirrors	Fibre optic cable

Начало формы

High power CO ₂ lasers are predominantly used for the welding of automotive components, such as gears and transmission components, which require circular and annular welds and in tailored blank applications. The majority of lasers have a power of 6kW or less.

High power Nd:YAG lasers are now available at workpiece powers of 4kW, which have fibre-optic beam delivery. The welding applications are concentrated in body-in-white assembly. Higher power equipment is likely to be developed in the next 2-3 years and there are likely to be improvements in the efficiency of Nd:YAG lasers with the arrival of diode pumped Nd:YAG lasers.

Within the laser industry, one of the main advances in the past two years has been in diode lasers (wavelength 0.8-0.9µm), where 2kW systems are now commercially available. However, at the current status of development, the power densities required for welding of sheet materials used in the automotive industry (about 1x10 ⁶ W/cm ²) have not been achieved. Research work is underway in Germany to develop diode lasers and their applications and this situation may change in the next 3 years.