Fusion UV Systems is a leading supplier of UV-based curing processes. In this article we look at the applications of UV technology, its advantages over other techniques and the resulting environmental benefits.

UV curing is a technologically advanced photochemical process in which intense ultraviolet (UV) light is used to instantly cure or "dry" inks, coatings, adhesives and other materials in a wide range of industries. Since it was originally introduced in the 1960s, UV curing has been widely adopted in many industries including automotive, telecommunications, electronics, graphic arts, converting and metal, glass and plastic decorating. Much more versatile and cost-effective than conventional curing methods, it has become the system of choice for many applications, replacing the energy-intensive heat treatment of traditional materials which are either toxic or emit solvent vapour.

UV curing uses the energy from UV light to initiate polymerisation of a liquid, resulting in a fully cured substrate which can be further processed immediately afterwards. The technology was introduced into the graphic arts industry, however, replacing large ovens with small, compact UV lamps together with fast curing times and immediate in-line processing had obvious advantages and other uses of the technology quickly became apparent. UV curing was used for wood finishing, for coatings to vinyl flooring and, subsequently, for the printing and decorating of cups, tubes and bottles where durable, bright images can be produced at high speed on plastic, styrofoam and other heat-sensitive materials without damaging the container.

Screen printing is used to apply highly-designed multi-colour graphics on intricate, designer-shaped bottles. These often have to be spun or tilted while printing to ensure that the often-delicate graphics are perfectly registered. With speeds of up to 60 bottles per minute, the benefit of UV curing is that the inks are instantly cured as they are applied. Curing ink with conventional heat requires very long production lines, up to 60 feet, whereas it is possible to lay down 3 and 4 colours with UV in less than 10 feet. In addition to reducing the space required for manufacturing, by using UV customers can reduce the thickness of the containers, leading to further savings.

Other applications for UV curing include protective coatings for optical fibres, printing onto cable and wire and numerous adhesive, encapsulation and marking applications in the electronics industry. The UV curing process is used to form a polymer layer that is applied to provide protection, flexibility and strength to optical fibres. UV curing has also been making in-roads into the high performance, industrial coatings market, which, in the majority of cases, involves working on complex three-dimensional shapes.

Automotive parts such as headlamp lenses and reflectors, wheel trims and motorcycle helmets are now being commercially produced using UV curing to produce hard, scratch resistant coatings. Now the challenge is to develop UV exterior coatings which offer superior weather resistance, hardness and clarity under years of sunlight and acid rain, yet must radically reduce overall manufacturing costs. Fusion is currently working with some of the coating industry's leading companies to produce a race car coated with the latest paint and coatings technology and has helped to install a facility for handling large-scale automotive parts.

UV curing has also recently been introduced in the coating and printing processes for CD and DVD manufacture. DVDs have introduced another exciting application of UV curing where an adhesive layer is "sandwiched" between two polycarbonate half-thickness disks and UV cured to form a durable bond.

As UV curing is virtually instantaneous (less than one second), productivity is increased compared with thermally cured coating. On headlamp lenses, for example, the coating and curing process may take several hours with several hundred parts in the process, whereas UV curing significantly reduces the number of parts. This provides a production environment which is more responsive to "just in time" parts supply as well as reducing the reject rate. The faster cure time also reduces the chances of contamination during processing. As UV curing delivers the energy directly to the point where it is needed, a UV curing station will typically occupy around one tenth of the floor space of a gas-fired oven, leading to significant energy savings. UV curing also eliminates the harmful emissions and waste products caused by the evaporation of solvents produced by earlier technologies.

UV curable coatings have come a long way since their introduction into the graphics industry to provide high gloss, decorative finishes. UV curing technology is now being used to provide sophisticated, high performance coatings to a range of materials and parts in some of the world's largest industries.

For more information on the environmental benefits of UV curing and other Spectris technologies, see our environmental report.

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