Faster production on a UV light curing conveyor starts with arithmetic, not experiments. If you can predict the dose a part receives at a given belt speed, you can set the line’s speed from the adhesive’s data sheet instead of guessing and scrapping parts.
Q: How do you calculate UV dose on a curing conveyor?
A: Dose (mJ/cm²) is irradiance (mW/cm²) multiplied by the time a point on the part spends under the lamp. On a conveyor, that time equals the lamp’s illuminated length in the direction of travel divided by belt speed. Double the belt speed and the dose halves; halve the speed and it doubles.
The Three Numbers You Need
Every dose estimate on a conveyor comes down to three inputs:
- Peak irradiance of the lamp head at the working distance, in mW/cm².
- Illuminated length along the belt, in inches.
- Belt speed, converted to inches per second.
Belt speed is usually quoted in feet per minute, so convert first. Multiply by 12 to get inches per minute, then divide by 60. On Incure’s CDM™ conveyor, which runs from 1.5 to 12.0 ft/min, that gives a range of 0.3 in/s at the slowest setting to 2.4 in/s at the fastest, with the nominal 6.0 ft/min setting at 1.2 in/s.
A Worked Calculation Using Published Head Data
Take the CDM™ + M51 focused-beam head. Its published peak is 6,150 mW/cm² at 365 nm across a 5-inch illuminated length. At 6 ft/min (1.2 in/s), a point on the part spends 5 ÷ 1.2 = 4.17 seconds under the beam. Multiply: 6,150 × 4.17 ≈ 25,630 mJ/cm², which matches the 25,630 mJ/cm² UVA figure Incure publishes for that configuration at 6 ft/min.
The same method checks out on a flood head. The CDM™ + L64 has a 6-inch length along the belt and 1,900 mW/cm² peak at 385/395/405 nm. At 12 ft/min (2.4 in/s), dwell is 6 ÷ 2.4 = 2.5 seconds, and 1,900 × 2.5 = 4,750 mJ/cm². At 1.5 ft/min (0.3 in/s), dwell is 20 seconds, and the result is 38,000 mJ/cm². Those are exactly the two ends of the L64’s published dose range.
Running the Calculation Backward
The more useful direction is usually the reverse: start from the dose your adhesive needs and solve for belt speed.
Required dwell (s) = required dose ÷ irradiance
Belt speed (in/s) = illuminated length ÷ required dwell
As a hypothetical, suppose an adhesive’s data sheet calls for 15,000 mJ/cm² and you plan to use the L64 at 1,900 mW/cm². Dwell = 15,000 ÷ 1,900 ≈ 7.9 seconds. Belt speed = 6 ÷ 7.9 ≈ 0.76 in/s, or about 3.8 ft/min. If that speed is too slow for the takt time of the upstream station, the calculation has already told you the lamp head, not the belt, is the constraint — before any parts have been run.
Email Us with your adhesive’s dose requirement and target line speed, and Incure can run the numbers against each CDM™ lamp head.
Arc Heads: Use the Published Dose Table Directly
For mercury-arc flood heads, Incure publishes dose at three reference speeds, and the inverse relationship holds across them. The F200x2AC, for example, delivers 9,000 mJ/cm² UVA at 1.5 ft/min, 2,250 at 6 ft/min, and 1,130 at 12 ft/min. Each doubling of speed roughly halves the dose. That makes interpolation straightforward: at 3 ft/min, expect roughly 4,500 mJ/cm² UVA from the same head, which is simply the 6 ft/min figure doubled.
The x2A dual-head versions double the dose at every speed rather than changing the relationship. The F200x2A reaches 4,500 mJ/cm² UVA at 6 ft/min, so a process that needs 4,500 mJ/cm² can run twice as fast on the dual-head configuration as on the single-assembly F200x2AC.
Why the Estimate and the Radiometer Can Disagree
These figures are calculated from a measured irradiance profile, illuminated length, and belt speed. Incure notes that delivered dose varies with working distance, part height, reflectivity, and measurement method. Three practical reasons a measured value lands below the calculation:
- Part height. A tall part sits closer to the lamp than the calibration plane, while a recessed bond line sits farther away. The irradiance figures above are quoted at a 2-inch working distance for the LED heads.
- Profile shape. Irradiance falls off toward the edges of the illuminated length, so a simple “peak × time” estimate is an upper bound.
- Lamp age. LED heads are rated past 20,000 hours with up to 20% intensity decay; arc heads are rated past 1,000 hours with up to 45% decay. Size your belt speed with that decay in mind, not just a new lamp’s output.
For that reason, treat the calculation as the starting speed and confirm with a radiometer pass at the chosen setting. The industrial overview of curing conveyors covers how dose fits alongside the other process variables on a line.
Where Calculation Stops Being Enough
Belt speed controls dose, not irradiance. If an adhesive has a minimum irradiance threshold, slowing the belt adds time but never raises mW/cm², so a low-intensity head can fail to cure regardless of the speed you set. That is the case for moving to a higher-intensity head instead. The CDM™ lamp-head guide lists irradiance for every configuration, and the lamp-head category guide explains how flood, focused-beam, and arc heads differ before you compare individual models.
A Short Checklist Before Setting Speed
- Confirm the adhesive’s required dose and any minimum irradiance from its technical data sheet.
- Use the irradiance figure for the wavelength your LED head is configured to, since 365 nm and 385–405 nm outputs differ.
- Convert ft/min to in/s before dividing.
- Allow margin for lamp decay over its rated life.
- Verify with a radiometer at the production working distance.
Contact Our Team for help translating a data-sheet dose into a belt-speed setting for your line.
Visit www.incurelab.com for more information.