| Résumé : |
Spot curing lamps have been around for about 15 years. The first systems were built by adhesive manufacturers who needed small portable curing systems to process and evaluate their adhesives and coatings. They started out as what would kindly be considered prototyping or demonstration tools that were barely able to cure the adhesives in a reasonable time. At best, the intensity was about 300 mW/[cm.sup.2] from the end of the light guide, and the power quickly dropped off to a fraction of the initial intensity. This meant that if an engineer specified a process with the lamp when new, the process very quickly fell below the minimum requirement, and the potential for producing bonds that were incomplete was very high.
At this point, the adhesive manufacturer was not as concerned with perceived process variables that lay with the equipment, but rather with the adhesive variables, as this was where the engineer had the least amount of experience and therefore the greatest amount of anxiety as to how the process was to be verified. To be fair, there were times when the adhesive was the culprit due to improper formulation or lack of care taken in how the adhesives were stored in the customer's facility, but usually the problem lay with the poor performance of the existing spot cure equipment.
The difficulty was diagnosing and correcting this equipment problem while still maintaining a working process. One method presented itself when equipment manufacturers began to offer radiometers to determine what intensities were being generated by the low power lamps and to allow the engineer the ability to make a time adjustment to compensate for the unpredictable loss in generated intensity. |
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UV spot curing facilitates bonding in critical areas in ADHESIVES AGE, Vol. 40, N° 4 (04/1997)
