In physical terms, light is a form of electromagnetic radiation. The range visible to the human eye extends from around 380 to 780 nm and borders on the ultraviolet (UV) and infrared (IR) spectrum. The emission wavelengths of typical UV light sources range from ultraviolet light (UV-C: 100-280 nm, UV-B: 280-315 nm, UV-A: 315-400 nm) through the visible range (400-700 nm) to the infrared range (700-3000 nm). UV wavelengths are measured in nanometres (nm), a unit that corresponds to one billionth of a metre. The energy contained in light can be utilised in a variety of ways. For example, radiation-curing systems use UV light (100-380 nm) to cure materials such as paints, varnishes, silicones and adhesives. LED UV technology offers high efficiency and emits light in a narrow spectrum centred on a specific wavelength, typically at 365 nm, 385 nm, 395 nm or 405 nm.
LED UV systems cover a wide range of applications and are used in a variety of curing processes - particularly in the curing of printing inks, coatings and adhesives. In addition to classic UV arc lamps, they are also increasingly being used in industrial curing processes.
For industrial applications, LEDs (short for light-emitting diodes) are arranged in several smaller units, depending on the required output. The resulting modules can contain 100 or more LEDs. These LEDs are controlled via an intelligent circuit, meaning they can also be controlled in zones. This zoned control makes it possible to adapt the LEDs to the working width and offers energy-saving potential.
It goes without saying that these compact units generate waste heat. As a general rule: The higher the efficiency of the individual LEDs, the less waste heat is generated. To extend the service life of the LEDs, this waste heat must be dissipated. If this is done with high efficiency, then the extended service life also yields high output. The development challenge is to ensure that the LED light emitted reaches the substrate with as little loss as possible. When doing so, optical decoupling is of critical importance. The issues of thermal and optical decoupling have been successfully implemented using XT8 technology. This results in a saving of 30%.
LED systems for curing inks or adhesives can be cascaded as a function of module width, and thus varied in length. The power supply cables present a challenge to cascading. If modules are now lined up with one another, parallel switching of these power supplies would be required. To get round this issue, this requirement was taken into account back at the layout design stage and solved by means of an internal power supply system.
LED technology is used in industrial drying and curing wherever its specific advantages are required. Advantages of light-emitting diodes, such as
are also valued in private, everyday use. They are a significant reason for the success of LEDs, e.g. in homes or in the automotive industry. Another common example of the use of LED technology is the polymerisation (curing) of plastics in dental Technology.
LED UV systems are used both in the printing industry and in numerous other industries on various substrates where coatings and adhesives play a role, such as
In principle, there is a variety of potential applications for LED curing technology in the industrial drying of inks, varnishes, silicones, seals or adhesives on different substrates. Retrofitting is also a possibility. If you are pursuing new approaches, talk to us! We will be pleased to help and promise to maintain confidentiality.
W/cm² has become the established unit of measurement in LED UV systems. This value indicates the maximum intensity per unit of area. However, since the intensity decreases with increasing distance, the value directly below the exit window is often cited. For comparable measurements, the location at which the power was measured is decisive. Values can vary depending on whether measurements are taken at the chip surface, at the exit window of the emission or at the substrate level. The spatial and temporal distribution in the measuring field must also be taken into account.
Furthermore, it is important to ensure that a suitable UV measuring system is used. This is characterised by a high and as uniform a sensitivity as possible in the wavelength range emitted by the LED.
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