Bengali
Project at a Glance
| Customer | Optical lens and prism assembly plant (name withheld under NDA) |
| Location | Baden-Wurttemberg, Germany |
| Industry | Optical component manufacturing and optical bonding |
| Application | UV adhesive bonding of lens elements and prism stacks |
| Equipment supplied | CG-GHL-W400-360x27-A/C water cooled LED UV curing conveyor, 1500W, 365nm, 18W/cm2 |
| Commissioned | Single unit retrofit into an existing assembly cell |
The Challenge
The plant assembled lens elements with UV-curable optical adhesive on a manual bench under a 2kW mercury lamp. The process worked, but it was difficult to control. Mercury lamps needed a long warm-up before the shift started, output drifted as the lamp aged, and the radiant heat deformed thin lens blanks and shifted focus. Operators also had to keep a fixed distance by hand, so cure depth varied from part to part.
Twelve months of quality data showed the cost of that variability: roughly 6% of bonded assemblies were reworked or scrapped, and the slow cycle limited the cell to about 120 units per hour. The engineering team wanted three things from a replacement: a stable high intensity UV source, a fixed single wavelength that matched their adhesive photoinitiator, and a conveyor that let them set dose by belt speed instead of by operator judgment.
The Solution
After a sample trial on the customer's own adhesive, we specified the CG-GHL-W400-360x27-A/C: a water cooled LED UV curing conveyor, 1500W, delivering 18W/cm2 through a 360x27mm quartz window, built for a single fixed 365nm wavelength. The configuration was chosen for four reasons:
- Wavelength matched to the adhesive: the photoinitiator in the optical adhesive peaks at 365nm, so the LED array was binned to 365nm and calibrated rather than running a broad spectrum lamp.
- Intensity and speed instead of dwell time: at 18W/cm2 the adhesive reached full cure in a single pass, so dose moved from operator technique to conveyor belt speed.
- Low heat load on thin optics: the 360x27mm narrow window concentrates the dose on the bond line, and water cooling holds the head at a stable temperature, so lens blanks no longer pick up radiant heat. Intensity is dimmable from 0 to 100%, which the team uses for low-dose trial runs.
- Stable output over a shift: the matched chiller and flow alarm keep peak intensity flat through continuous production, removing the warm-up and lamp-age drift of the mercury source.
Technical Configuration
| Model | CG-GHL-W400-360x27-A/C |
| Lamp power | 1500W |
| UV intensity | 18W/cm2 at 100% output, 0-100% adjustable |
| Wavelength | 365nm fixed per unit (385nm / 395nm / 405nm available at order) |
| Emitting window | 360x27mm |
| Cooling | Water cooling with matched chiller |
| Conveyor | Integrated belt conveyor, adjustable speed |
| Working distance | 30-50mm |
Implementation
The unit arrived as a complete package with head, driver, chiller and belt frame, and it was retrofitted into the existing assembly cell without changing the fixture layout. Commissioning took two days:
- Day one: mechanical installation and chiller connection, then a dose mapping run with a radiometer across the 360x27mm window or the whole belt width.
- Day one: belt speed was set so that the adhesive received the same dose the laboratory trial had validated, and the dimming range was locked to two recipes: production and low-dose trial.
- Day two: an 8 hour continuous run with tack and peel checks every 30 minutes to confirm stability and cure depth.
Results After Three Months
| Metric | Before (mercury lamp) | After (LED conveyor) |
|---|---|---|
| Cure cycle per assembly | 90 seconds | 20 seconds |
| Throughput | 120 units/hour | 215 units/hour |
| Rework and scrap rate | 6.0% | 1.2% |
| Warm-up time | 10-15 minutes | None, instant on and off |
| Cell power draw for curing | 2kW lamp plus extraction | 1500W LED plus chiller |
| Heat on thin lens blanks | Visible distortion during long runs | No distortion observed |
Because dose is now controlled by belt speed and dimming, the plant can hand the same machine to the laboratory for low dose trials and then run full production without a changeover.
Customer Feedback
"The mercury lamp was the last part of the cell we could not control. With the LED conveyor the operator sets a belt speed, the radiometer reading matches the recipe, and it stays there all shift. Cure time dropped, rejects dropped, and the optics no longer warm up on the belt." - Process Engineering Manager, optical assembly plant, Germany
Why This Configuration Works
Optical bonding failures usually trace to the wrong wavelength for the photoinitiator, unstable intensity, or heat. A binned single wavelength 365nm head addresses the first, a water cooled closed loop addresses the second, and a narrow window with matched chiller addresses the third. The adjustable speed conveyor turns all three into repeatable process parameters.
Discuss a Similar Project
If your line cures optical adhesive, UV ink, coating or potting compound, send us your substrate, required dose and throughput. Our engineers will confirm the matching emitting window, wavelength option, conveyor speed range and chiller size within 24 hours.