Few automobiles are made today without the use of lasers. Multikilowatt CO2 and Nd:YAG laser systems are now common on production lines, where they weld bodywork, power train assemblies and accessories. Continuous seam welds in sheet materials not only improve the stiffness, handling, road noise and crashworthiness of an automobile, but they also enable new joint designs to be used, leading to cost reductions through savings in materials. In addition, light materials and novel designs are becoming more popular, notably the aluminium alloy space frame.
Multikilowatt laser are now common on automobiles lines
A hybrid system comprising a multikilowatt Nd:YAG laser beam and a metal–inert gas head is used for welding the spaceframe components combining the high penetration and productivity of laser welding with the tolerance for joint fitup and gap-filling ability of arc fusion welding.
The first commercial airbags appeared in automobiles in the 1980s. Airbags are constructed from tightly woven cloth of nylon or polyester. They are inflated with a gas produced from a contained chemical reaction that is triggered when a sensor detects a sharp deceleration. Airbag materials must be tough but flexible, which causes difficulties for mechanical cutters. A sealed 240 W CO2 laser is an excellent means of cutting airbag material, since the beam does not physically contact the material, and can be programmed to follow intricate contours easily. Nitrogen is used to assist the cutting process.
The edge is simultaneously sealed. Materials can be cut quickly in single or multiple layers. Heat treatment has been used for centuries to improve the mechanical properties of materials. Manufacturers are now able to choose from a wide range of techniques to meet performance requirements. Laser hardening is a relative newcomer to manufacturing industry, offering precision, productivity, high quality, and opportunities for new design.
Powdered metallic alloys can be melted by a laser beam to create prearranged deposited patterns on surfaces. Laser cladding involves the production of surface layers with properties that are different from the substrate – they are tailored to the application. The technique has been extended to build up three-dimensional objects, and is one of a family of rapid manufacturing processes.
These are novel techniques of fabricating components that are difficult to make by conventional means because of the material characteristics or the component geometry. Parts are constructed layer by layer from a CAD mode. The process is readily scaleable and easily integrated into a production line. Composite layers comprising different materials can also be produced. Thus mechanical properties can be customized in particular locations by varying the processing parameters or the material type.
Laser-based near-net manufacturing processes can save 20% to 30% of the cost of the part by eliminating material waste and minimizing the use of expensive consumable cutting tools. Additional savings are possible because inventories can be reduced and manufacturing times shortened. The method can also be used to make moulds: conditions are created such that the deposit is easily removed from the substrate surface, thus creating an impression of the topography in a solid form suitable for the casting process.
Next time you step into an aircraft, consider the contributions that laser processing could have made: laser-welded aluminium fuselage skin stiffeners; laser-drilled nickel superalloy jet engine components; laser-marked polymer cabling insulation; and laser-cut titanium ducting. Ships, railway carriages, satellites, bicycles and Formula 1 racing cars also benefit from cost savings, new designs and reduced environmental impact that laser-based fabrication provides. Industries have grown up around the short wavelength and rapid pulsing capabilities of laser light. A beam of short wavelength has a high energy, which is capable of vaporizing material.
Vapour can be condensed to form thin films on materials; an ideal method of manufacturing sensitive electronic devices. An exciting development in nanotechnology is the ability to grow carbon nanotubes and other structures using a similar technique. Nanostructures have outstanding mechanical properties and can be used as the basis for atomic-scale electronic devices. Output from the Ti:sapphire laser can be obtained in pulses on the order of femtoseconds (10−15 s) in length.
This is shorter than kinetic events in atoms and molecules, and provides means for high precision athermal micromachining of electronic components.
