Application in automotive
The automotive industry relies on revolutionary fiber lasers as the ideal laser tool for common cutting, welding, marking, engraving and brazing processes, and as an enabling technology for value-added remote welding and seam welding and tube and profile welding processes. As new lightweight vehicle designs come to the forefront, fiber lasers are increasingly critical in today’s highly automated, flexible production lines. Fiber lasers are simple to integrate, flexible and easy to use and are highly reliable, while requiring next to no maintenance or consumable parts. Automakers enjoy shortened ROI due to the low operating costs of compact and highly efficient fiber lasers, which can even be shared over multiple process stations using beam switch technology.
Welding of Automotive Components
The applications of laser in the manufacture of components cover engine parts, transmission parts, alternators, solenoids, fuel injectors, fuel filters, air conditioning equipment and air bags. The attractions of laser welding for these applications are the ability to weld pre-machined precision components with restricted heat input and minimal distortion. This enables weight savings to be made through the use of thin walled assemblies and optimization of the compactness of the component.
Most automotive manufacturers have invested heavily in CO 2 laser technology for these types of applications and most of the issues relating to the production of millions of components have been resolved. Developments have focused on expanding the range of material combinations which can be welded using lasers, including joining of cast irons to steels through the use of wire feed techniques and optimization of the procedures to harden components whilst avoiding problems with cracking due to high carbon levels in the weld zone.
Welding in Automotive Body Assembly
The potential benefits of implementing laser welding technology are numerous – advantages may be gained in respect of single sided access, reduced flange widths, increased torsional stiffness (thus leading to improved vehicle structural performance and/or down gauging of material thickness), smaller heat affected zones and less thermal distortion, high speed automated processing and design flexibility (e.g. in multi-layer joints).
Extensive work has been performed worldwide to realize the potential of laser welding for automotive body manufacture. As the turn of the century approaches, the number of systems installed in production is increasing, where two main types of laser welding are being employed. The first is a direct replacement for resistance spot welding or adhesive bonding, where lap joints or hem flange joints are utilized on pressed components for body-in-white assembly. The second is the laser butt welding of flat sheets (which may be dissimilar thickness or material grade), which are subsequently formed into pressings. The pressings are called “tailored blanks” and the widespread acceptance of this technology has spawned a number of companies and enterprises associated with steel producers to meet the demands of the automotive industry in addition to in-house manufacture.
The implementation of laser welding of sheet assemblies as a replacement for resistance spot welding is growing, where welding of the roof to side panel is one of the most common applications. This component is normally a two-layer lap joint in zinc coated steel, with periodic three-layer thicknesses to be welded, over lengths of 2.5-3m. One of the main challenges for laser welding of these types of joints is the presence of the zinc coating at the interface between the sheets, where the low vaporization temperature of the zinc (906°C), can cause problems with weld consistency due to the formation of blowholes and porosity, if the sheets are tightly clamped together. Various approaches have been adopted to overcome this problem including:
Roller clamping systems which create a gap at the interface
Stamping of dimples in the steel pressings of consistent depth
There are both CO 2 and Nd:YAG lasers in production for this kind of application, and it is forecast that Nd:YAG laser applications will grow due to the flexibility of the fiber optic beam delivery as higher powers become available
In fact, lasers are capital intensive tools and, in order to ameliorate the costs, systems should be utilized to maximize their production capacity. One method of achieving this is to use one laser source for cutting and welding. This principle has been demonstrated industrially in the manufacture of a C column, where two zinc coated steel sheets are overlaid in the clamping system and then laser cut. The cut edges are then re-positioned and welded together in a butt joint configuration using filler wire additions. For this application, the main advantage is the achievement of a high-quality weld which requires minimum finishing to produce a Class A surface.
Application of laser in Automotive:
Whilst it is predicted that the above automotive laser welding applications will grow, in some cases, at a substantial rate, there are other components and materials that will benefit from the advantages of laser welding. Listed below are some of the topics where laser welding is poised to make an industrial impact: (Metal Welding, Marking, Cutting, Brazing, Polymer Welding, Coating Removal, Drilling, Soldering)
Pressed components to hydroformed tubes or extrusions
Production of tailored hydroformed tubes or other stiffened structures consisting of welded sheet
Production of node structures in aluminum alloy castings/extrusions or extrusions/extrusions
Welding of magnesium alloy components