A straight lightguide cures what it points at. When the bond face is a vertical wall, the underside of a flange, or the floor of a recessed cavity, pointing straight at it may mean bending the guide too hard, twisting a robot wrist into an awkward pose, or simply not reaching it at all.
Q: How Do You Cure a Bond Face a Straight Lightguide Cannot Reach?
A: Redirect the Beam at the Tip With a Terminator Instead of Moving the Part
A lightguide terminator fits on the delivery end of the guide and turns the exiting UV beam to a new angle. Incure’s LGT-Series™ terminators redirect output at 90° or 60° to the guide axis in Ø5mm and Ø8mm apertures. That lets the guide keep a relaxed, straight approach while the light leaves at the angle the bond needs. The alternative approaches, re-fixturing the part or forcing the guide into a tight bend, both carry costs that a terminator avoids.
Why Not Just Bend the Guide?
Every lightguide has a minimum bend radius, and exceeding it breaks glass fibers or kinks liquid guides, both permanently. A guide forced into a hook shape to point sideways at a wall is either at that limit or past it, and it is flexed again every time the fixture opens. Re-fixturing the part so the bond faces upward is the other common workaround, but it adds a handling step and, on multi-face parts, several of them. Redirecting at the tip addresses the geometry where the problem actually is.
Choosing the Exit Angle
The two angles serve different geometries:
- 90° (LGT-90-5, LGT-90-8): bond faces genuinely perpendicular to the approach direction, such as vertical housing walls, PCB edge joints, and connector side walls.
- 60° (LGT-60-5, LGT-60-8): recessed bond lines and angled cavities where surrounding fixture geometry prevents a full right angle, including the base of deep channels and enclosed housings.
Sketch the approach axis and the bond face on the fixture drawing and measure the angle between them before choosing. If neither angle lines up with the face, the fixture design may need adjusting so one of them does.
Email Us with the bond face’s angle relative to your fixture’s approach axis and your lightguide model, and Incure can confirm which terminator reaches it.
Choosing the Aperture
Aperture is first a compatibility question and only then a spot-size question. The terminator’s aperture should match the core diameter of the guide feeding it; one wider than the guide’s core does not gain usable spot size and only adds a transition at the tip. Once matched, the general pattern is that Ø5mm suits precision spot delivery on small, tightly defined joints, while Ø8mm trades some positional precision for a wider spot and more total UV energy on larger bond areas. The LGT-Series™ is built around Incure’s LLG-1P-5 and LLG-1P-8 liquid lightguide cores, used with the S20™ UV arc spot lamp, and suits compatible fiber guide configurations on the L9000™ UV LED spot lamp.
Setting Up an Angled Cure
A short setup sequence keeps the first angled cure from becoming a trial-and-error exercise:
- Confirm the guide model and core diameter at the station.
- Select the exit angle from the fixture drawing and the matching aperture.
- Mount the terminator so its exit window sits at the qualified working distance from the bond face, measured along the redirected beam, not along the guide axis.
- Measure delivered output at the bond position with a radiometer before the first production part.
- Run a first-article cure and verify the bond at the qualified settings.
Step 3 is where angled setups most often go wrong. Spot-lamp irradiance falls steeply with distance, so a terminator that sits a few millimeters farther from a side wall than the straight guide sat from a flat face will deliver noticeably less dose.
Durability on Automated Lines
The LGT-Series™ uses a precision-machined aluminum body rated for continuous high-intensity UV exposure, built to stay on the guide tip through repeated cycles rather than being swapped per part. Dimensional stability at the tip matters because any drift there moves where the cure spot lands. On robotic cells, a terminator on the end-effector decouples cure direction from the robot’s approach axis, so several faces of one part can be cured without repositioning it. More on the hardware itself is in Incure’s LGT-Series™ terminator overview.
Keeping the Exit Window Clean
Redirected exit windows often sit closer to the part, and closer to wet adhesive, than a straight guide tip would. Contamination baked on under high-intensity light pits optical surfaces, so clean the terminator window with isopropyl alcohol and lint-free wipes on the same schedule as the guide tips, and cap it when the station is idle.
For the basics of how the guide feeding a terminator carries light, see Incure’s liquid light guide explainer.
Contact Our Team to set up angled UV delivery with lightguide terminators on your line.
Visit www.incurelab.com for more information.