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Loctite® 7700 LED Light Source Consistently Cures
Medical Light Cure Adhesive in 10 Seconds

Challenge

US Endoscopy, a manufacturer of endo-scope accessories used for exploration and/or biopsy of organs and tissue, approached Henkel to get support in meeting its specific requirements for the new biopsy inlet valve production:

The blue thermoplastic valve needed to be assembled using clear PVC tubing with an adequate pull strength. In order to meet their production target, a 15 to 20-second cure time was required.

An optimal amount of adhesive that should be used for the joint:

Too little adhesive and the bond strength or seal could be compromised.
Too much adhesive would cause excess material to drip down the side of the valve, creating an aesthetic reject.

Initially, a UV adhesive and two competitive UV wands were rejected. The first UV wand was a 50 Watt wand that required a 100 seconds cure time to achieve consistent cure because much of the light was absorbed by the blue inlet assembly.

A 200 Watt UV wand was able to reduce the cure time, however, the heat generated by the wand deformed the inlet valve.

Finally, US Endoscopy wanted the equipment and the adhesive to come from one supplier, thus ensuring a well-designed process and post sales support.

Curing the Assembly of Medical Devices in 10 Seconds: IIllustration of the bonded inlet valve assembly.

Figure1 Illustration of the bonded inlet valve assembly.

Curing the Assembly of Medical Devices in 10 Seconds: Illustration of one work cell.

Figure2 Illustration of one work cell.

Curing the Assembly of Medical Devices in 10 Seconds: Close up of cure station

Figure3 Close up of cure station

Solution

By using the Loctite® 7700 Hand Held LED Light Source with Loctite® 3922™ Medical Device Light Cure Adhesive, US Endoscopy was able to consistently cure the assembly in 10 seconds, while nearly doubling the pull strength:

The spectral output of the Loctite® 7700 LED Light Source is very high intensity visible light (as opposed to UV light).
The wavelength of the visible light exactly matches that absorbed by Loctite® brand visible light cure adhesives.
The light source is inexpensive, small in size, portable, generates minimal heat and minimal ultraviolet energy, making it safer to work with than traditional UV light sources.

Results

US Endoscopy set up a two operator work cell to manufacture the devices:

A dispense station consisting of a Loctite® Integrated Semi-Automatic Controller Dispenser (97020) with a Loctite® Light Cure Dispense Valve (98009) was set up in between the two work cells so that both operators could access it (see Figure2).
Each of the work cells had its own cure station consisting of a 7700 Light Source, timer, foot switch and a custom made fixture to hold the assembly during curing (see Figure 3).