Originally formulated to be cured with UVA/UVC light and then UVV visible light, the latest generation of Loctite light cure adhesives rely solely on the visible light spectrum to provide a safer, more efficient and immediate cure for a broad range of assembly applications. In tandem with the technical advancement of the adhesives themselves, Henkel has also continuously developed its range of UV light curing equipment and has now introduced a series of LED-based systems that offer significant performance benefits.
In the Henkel process, Loctite one-part adhesives remain liquid until exposed to light so parts can be precisely aligned before cure. Speed of cure then achieves high process speed and fast cycling to subsequent process steps. The method lends itself to quality assurance monitoring and the clear bond lines these adhesives provide enhance aesthetics and greatly expand design options.
These LED systems are claimed to be extremely efficient and cost-effective. The life expectancy of an LED is between 10,000 and 20,000 production hours; a traditional mercury vapour bulb by comparison lasts for around 1,000 hours, including warm-up and cool-down time. Typically the LED systems are built into solid-state housings making them extremely durable and portable.
Operating economies
Long-life, durability and easy maintenance translates into immediate and on-going cost savings, especially as LED systems consume less energy. They also take up less space than traditional UV cure equipment and are easy to automate. Safety is another significant benefit as LED light systems require no heat protective equipment or costly ventilation systems to protect against infrared and ozone.
As the LED systems emit highly focused UV light wavelengths in a significantly tighter output range than visible lamp technology, unnecessary heat/infrared energy is not released. This can be an important benefit when bonding thermally sensitive plastics. They also produce higher outputs that cure the adhesives more effectively whilst having lower power consumption therefore reducing operating costs.
Extensive range
The range of LED systems provided by Loctite spans a variety of application requirements and as Henkel is a single source supply of adhesives, dispensing and curing systems, the optimal choice and combination of each element can be assured.
The Loctite 7700 hand-held LED light source is used for light-curing products that respond to UVV cold light. It is available in two versions; the first for continuous use which can either be hand-held or mounted in a fixed position and the second, a rechargeable battery powered unit for intermittent use.
For adhesives curing in the UVA range Henkel has its Loctite UV spot cure LED. In its basic configuration the system is equipped with one LED head and one condenser lens but it can be extended with three additional LED heads. The unit is designed for manual work stations and also for integration into production lines and can also be equipped with a sensor head for measuring UV intensity.
Comprising a high-intensity flood array of 144 individual LEDs, connecting cable and controller, the Loctite LED flood cure system is specifically for curing UV adhesives using UVA or UVV light. The flood cure system provides a cure area of approximately 100mm x 100mm. The unit can be operated in a time mode via the built-in timer, in continuous mode via footswitch or via a customer-supplied PLC.
Customers can also choose a modular LED line array system whose controller can accept up to four LED heads, each containing 10 high power LEDs and a lens for creating a high intensity curing line over the length of the array. The design of the LED head makes it ideally suited to positioning above 'in-line' components on flow lines, providing a cure area of 5mm x 80mm. This system is also designed for curing UV-adhesives with UVA or UVV light.
