How do you calculate UV conveyor belt speed?

Divide the required dose by the measured irradiance to get dwell time in seconds, then divide cure-zone length (in feet) by that dwell and multiply by 60. With an 800 mJ/cm² dose, a 10-inch zone, and 1200 mW/cm² irradiance, dwell is 0.667 sec and belt speed is 75 ft/min.

What happens if I run the belt too fast?

The part spends less time under the lamp, so it receives less than the required dose and under-cures — leaving tacky surfaces, weak adhesion, and poor chemical or scratch resistance. The calculated speed (75 ft/min in the example) is the ceiling; running faster sacrifices cure.

Why does dose equal irradiance times time?

Dose is energy per area and irradiance is power per area; energy equals power multiplied by time. So dose (mJ/cm²) equals irradiance (mW/cm²) times dwell (seconds). The calculator inverts this to solve for the dwell, then converts dwell and cure-zone length into belt speed.

Should I use peak irradiance or the radiometer's measured value?

Use the radiometer's measured irradiance at belt height in the same UV band the chemistry needs. Peak irradiance from a spec sheet assumes ideal focus and a new lamp; a real puck reading at the belt captures lamp aging, reflector condition, and dirty quartz.

How does an aging lamp change my belt speed?

As a UV lamp ages its irradiance falls, so to keep the same dose you must slow the belt. If irradiance dropped from 1200 to 900 mW/cm², dwell would rise and the 75 ft/min speed would have to come down proportionally to still deliver 800 mJ/cm².

What dose should I enter?

Use the dose from the chemistry's technical data sheet for the correct UV band, confirmed with cure testing (solvent rub, adhesion, hardness). The example's 800 mJ/cm² is typical for many coatings, but inks, adhesives, and gel coats vary widely — always verify against the TDS.

UV Curing calculator

UV Conveyor Belt Speed Calculator

UV conveyor belt speed is the line speed at which a part passes under a UV curing lamp and still receives the full energy dose (in mJ/cm²) the coating, ink, or adhesive needs to cure. It is the practical link between a radiometer reading at the belt, the physical cure-zone length of the lamp head, and the dose spec on the chemistry's technical data sheet. Coating engineers, UV press operators, and finishing line supervisors use it to set a defensible belt speed instead of guessing — run too fast and you under-cure (tacky, poor adhesion, solvent resistance failures); run too slow and you waste throughput and risk overcure or substrate heat damage. Get this number right and the line runs at the fastest speed that still hits full cure.

What this calculator does

Set conveyor belt speed (fpm) so parts spend long enough under the UV lamp to hit a target dose at a known irradiance.
Use it when commissioning a new product on a UV conveyor or recovering after a lamp swap and you need a setpoint that hits the dose target without slowing the line more than necessary.
It computes the conveyor belt speed in ft/min that delivers the required UV dose, by finding the dwell time the part needs under the lamp and converting cure-zone length over that dwell into line speed.

Formula used

Required dwell (sec) = required dose ÷ measured irradiance
Belt speed (ft/min) = (cure-zone length ÷ 12) ÷ required dwell × 60

Inputs explained

Required dose: Target from the chemistry data sheet at the relevant UV band.
Lamp cure-zone length: Effective UV-emitting length along the belt direction (not lamp housing length).
Measured irradiance at belt: Calibrated radiometer pass on the belt at the same height as the parts.

How to use the result

Use it when commissioning a UV line, after a radiometer reading, when switching chemistries with a different dose spec, or when a lamp ages and irradiance drops.
It assumes a single uniform irradiance value across the cure zone and a flat part at belt height; it ignores spectral match (UVA/UVB/UVC weighting), reflector focus, part topography, and lamp warm-up, all of which change the real dose a 3D part receives.

Common questions

How do you calculate UV conveyor belt speed? Divide the required dose by the measured irradiance to get dwell time in seconds, then divide cure-zone length (in feet) by that dwell and multiply by 60. With an 800 mJ/cm² dose, a 10-inch zone, and 1200 mW/cm² irradiance, dwell is 0.667 sec and belt speed is 75 ft/min.
What happens if I run the belt too fast? The part spends less time under the lamp, so it receives less than the required dose and under-cures — leaving tacky surfaces, weak adhesion, and poor chemical or scratch resistance. The calculated speed (75 ft/min in the example) is the ceiling; running faster sacrifices cure.
Why does dose equal irradiance times time? Dose is energy per area and irradiance is power per area; energy equals power multiplied by time. So dose (mJ/cm²) equals irradiance (mW/cm²) times dwell (seconds). The calculator inverts this to solve for the dwell, then converts dwell and cure-zone length into belt speed.
Should I use peak irradiance or the radiometer's measured value? Use the radiometer's measured irradiance at belt height in the same UV band the chemistry needs. Peak irradiance from a spec sheet assumes ideal focus and a new lamp; a real puck reading at the belt captures lamp aging, reflector condition, and dirty quartz.
How does an aging lamp change my belt speed? As a UV lamp ages its irradiance falls, so to keep the same dose you must slow the belt. If irradiance dropped from 1200 to 900 mW/cm², dwell would rise and the 75 ft/min speed would have to come down proportionally to still deliver 800 mJ/cm².

Last reviewed 2026-05-12.