Jetting System and Spray Valves Work in Harmony to Prevent LED Headlights from Icing

Application Success Story

Advances in automotive lighting technology over the last decade have led to new and interesting challenges for manufacturers. Today, most new vehicles have switched from halogen headlights to LED for better energy and lighting efficiency. Plus, LED bulbs last significantly longer than traditional halogen bulbs.

However, one issue with LED lighting is that it produces very little heat. In many warmer climates this is of little consequence. However, in colder northern climates, LED bulbs are unable to melt accumulated snow and ice. This can be dangerous when snow and ice stick to headlights, making it difficult to see when driving at night and potentially leading to accidents.

Nordson EFD recently helped an automotive lighting manufacturer looking for a solution to apply two critical materials to prevent snow and ice from decreasing drivers’ visibility in hazardous winter conditions.
Here is some information about this application:

Fluids Used

• Silver conductive ink
• Conformal coating

Application Requirements

• Accurately dispense silver conductive ink on an uneven surface within tight spaces
• Dispense the conductive ink fast and efficiently to keep up with high production rates
• Accurately spray conformal coating to completely cover the conductive ink

Solution

• PICO Pµlse jetting system
• 781Mini spray valve
• GV Series automated dispensing system

Results

Jetting Conductive Ink

Several Nordson EFD dispensing solutions were considered and evaluated. But after careful testing and validation, we recommended the PICO Pµlse jetting system. With the curved geometry of the headlight lens covers, the complex continuous line pattern, and changing Z-axis heights of the lines of conductive ink, jetting was determined to be the best solution. Jetting valves dispense a few millimeters above the substrate surface, eliminating the need for time consuming Z-axis calibrations that can slow down productivity and reduce unit-per-hour output.

The PICO Pµlse also features a heater block, which can be set up to 100° C depending on the type of fluid to be jetted. Heat on the fluid helps to lower and stabilize the viscosity of the conductive ink to enhance the jetting process. In addition, the original conductive ink formulation presented some challenges for jetting. We teamed up with the local fluid formulator to tweak the formulation (without affecting its critical properties) to get consistent and repeatable jetting results.

In addition to the benefits from the non-contact dispensing, jet valves provide excellent dot-to-dot repeatability that stich together to make the continuous line pattern. Repeatable micro-deposits at speeds of up to 1000Hz continuous (with bursts up to 1500Hz) make faster line patterns to increase throughput and productivity not achievable with contact dispensing.

One accessory that proved beneficial was the protruding nozzle fluid assembly. The protruding fluid assembly extends the nozzle orifice on the PICO Pµlse valve. This extra length was needed to provide clearance of the PICO Pµlse valve and mounting fixture from the edges of the curved lens assembly as the outer areas of the line patterns were applied. The protruding nozzle offered a solution to dispense closer to the part without the jetting system getting in the way of the equipment around it.

Once the complex pattern of conductive ink was applied to the headlight lens, the pattern needed to be sealed. It was determined the best way to efficiently apply a very thin protective coating onto the line pattern was by micro spray. The Nordson EFD 781Mini spray valve was considered and tested. The 781Mini proved to be the perfect solution for applying a thin “micro coating” over the jetted conductive ink. A seamless coating was sprayed over the entire pattern thus protecting the conductive ink from inclement weather conditions.

The small form factor and footprint of the 781Mini spray valve enabled easy mounting for access into the tight space of the curved headlight lens and robot end-of-arm tooling. The LVLP (low volume, low pressure) function of the 781Mini also provided precision spray control to eliminate overspray on parts. This reduced rejects and saved time and cost with less wasted fluid while providing accurate coverage onto the substrates.

Since the headlights were large and production rates were very high, a large working envelope was required for the substrate size and larger fixture plate that would accommodate multiple lenses for increased unit-per-hour output. The 800 mm gantry robot provided an adequate working platform and fixture area to produce more parts at once. The GV Series includes proprietary DispenseMotion™ software with an integrated CCD smart vision camera, making both set up and programming quick and easy.

The Future Looks Bright

Given the success of the PICO Pµlse jet and 781Mini spray systems, this automotive lighting manufacturer is looking toward an even brighter future. We will recommend our new PICO XP jetting system to provide even greater repeatability for longer periods, regardless of environmental factors such as temperatures rising or falling. PICO XP jet technology offers additional enhanced features and functionality to ensure superior process control and performance during application and after jet valve fluid body maintenance.

If you would like to discuss your next dispensing project with an experienced fluid dispensing expert, don't hesitate to email us at [email protected].

About Claude Bergeron

Claude Bergeron is the Senior Global Product Line Manager of Jetting Systems at Nordson EFD. He uses his extensive application and product knowledge to lead the development of some of the most innovative dispensing valves on the market. Claude has more than 40 years of fluid dispensing experience. He joined Nordson EFD in 1981.