Ensuring Optimal UV Curing: Controlling the Variables

Posted on 6/30/2020 12:06:31 PM By ASC

There are variables that have to be taken into account when curing. These include the quantity of adhesive being used and its location; the length of time the adhesive will be exposed to the UV light, and level of light intensity; and the distance between the source and the bondline. These process variables should be fixed to ensure consistency of process repeatably in the future.

The distance between the lamp and the adhesive: Light intensity drops considerably as the distance increases. According to the formula outlining the rate of fall, if the distance is doubled, only one quarter of the energy will remain. Shortening the distance as much as possible will result in the fastest cure, improve performance and shorten the process period.

Using lower power UV light for a longer time period to try and make up for the loss of intensity could result in less optimal or incomplete curing, especially when using adhesives that have minimum levels for energy activation.

The length of exposure to UV light is what both kick starts, and stops, the curing process of most adhesives. As soon as the adhesive is exposed to light, curing starts and then stops as soon as the light goes off. Keeping the light on throughout the delivery of the correct dose lessens the chance of the bond being affected, as it often is when multiple exposures are used.

Exposure can also be affected at the bondline if neither substrate is able to transmit the necessary amount of light to the adhesive.

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