Innovative Laser Techniques applications have been playing one of the major role in the Automotive Industry for many years which bought transformation in automotive designs. Laser technology has many advantages compared to traditional material processing methods for welding, cutting component parts and identification processes. Lasers technology in automotive industry have various applications that may vary from cutting component parts or labeling many automotive parts to welding of spark plugs and batteries & including back-lit laser marking technology on body.
The use of lasers technique by automobile manufacturers has increased since years to the position where about 15% of all mostly industrial processing lasers machines are installed in production plants. Although these manufactures OR laser marker are mainly dedicated to cutting applications & significant and growing proportion of lasers is being applied to laser welding technique.
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.
Industrial laser are of two types, that too depends on structural fabrications; Nd:YAG lasers & CO 2 lasers. These lasers have different characteristics.
Laser Welding technique in the Automotive Industry an Overview:
Laser Techniques in Automotive Components
The applications of lasers in automobile component manufacturing cover alternators, solenoids, fuel injectors, fuel filters, engine parts, transmission parts, air conditioning equipment and air bags which enables weight savings to be made through the use of thin walled assemblies and optimisation of the compactness of the component.
Laser marker companies have production advantages of the laser welding process which have been established compared to alternatives such as electron beam welding. This is due mainly to the high productivity and small amount of down-time compared to vacuum based systems and the subsequent reduced manufacturing costs  . However, there is a need to spend a high amount of effort on component preparation and high precision of component handling and beam transmission is required
Welding in Automotive Body Assembly
Extensive work has been performed worldwide to realise 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 utilised 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. [5,6] 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 vaporisation 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.
Tailored blank welding
In the manufacture of tailored blanks, the two main points of debate centre on the preparation of the edges for welding and the choice of laser type. For the edge preparation, there is a desire to use standard blanked edges but this normally requires special clamping or welding systems to ensure that the blanks can be welded consistently. The clamping systems developed include using side pressure on the fixtures or using a roller system to deform the sheet adjacent to the weld to bring the sheet edges into intimate contact (<0.1mm gap).
The welding systems employed where the gaps between the sheets are >0.1mm include beam weaving or twin spot welding, but this generally reduces the maximum welding speeds that can be achieved. The use of precision re-shearing of the edge prior to welding within a blank welding system is claimed to improve weld consistency as the cross-sectional area of the joint is guaranteed and the welding speed can be maximised. 
There is a growing interest of businesses in the exploitation of aluminium alloys for tailored blank application,  but the laser welding is more critical as the weld line is a zone of weakness, see Fig. 5. Developments have focused on the application of wire feed and twin spot welding to improve weld quality and consistency.
Lasers are capital intensive tools and, in order to ameliorate the costs, systems should be utilised to maximise 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.
Laser welding has “come of age” for automotive manufacture, where it is an established technique for automotive components, tailored blanks and body assembly. The main advantages to be gained through the use of laser welding include low distortion, single sided access, high torsional stiffness of components, and cost savings through elimination of other manufacturing operations. Most of the applications to date have focused on welding of steels but there is a growth in confidence in laser welding of aluminium alloys.
The advent of high average power Nd:YAG lasers, delivering over 3kW power to the workpiece, will make an increasing impact on the type of laser welding systems installed in production, but there will be considerable pressure to reduce capital costs and improve efficiencies of the laser source. Competition will also be fierce from CO 2 laser manufacturers and non-laser processes in this significant market.