The Expert: Kyle Rhodes of Dymax Corp.

Question: Our tube set application uses a nylon tube bonded to a clear urethane tube, with a bond gap overlap of 0.010 inch x 0.004 inch thick bond gap. We have been looking at a DYMAX medical grade light-curable adhesive to bond the tube sets and get good adhesion, but we found that during our manufacturing run, some of the adhesive gets pushed inside the opaque nylon tube, and does not cure. Will this material cure by itself over time?

Answer: Unfortunately, most light-curable adhesives cure line-of-sight from the curing lamp to the adhesive in the bond line. If there is a shadow area, in your case inside the opaque tube, the adhesive will remain uncured. A few options to overcome this issue would be to limit the amount of adhesive in the bond line: use an adhesive dispensing technique to place smaller drops in multiple locations rather than large drops in a few locations, assemble and then backfill the adhesive into the bond line with a timed air/pressure dispense unit, or use a lightguide at an angle to cure down the axis of the nylon tube.

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