UV Curing calculator

UV Conveyor Belt Speed Calculator

On a moving UV line, dose = irradiance × dwell, and dwell depends on how fast the belt is moving through the lamp's effective cure zone. This calculator combines the dose your chemistry needs, the irradiance you measured at the belt, and the lamp's cure-zone length to give a feet-per-minute setpoint you can dial straight into the conveyor controller.

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.
  • Solves for the belt feet-per-minute that gives your chemistry the dose it needs, given the lamp's effective cure zone and the irradiance you measured on the belt.

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 introducing a new SKU on a UV conveyor, after a lamp swap, after a focal-distance change, or when the radiometer profile shifts after a quartz cleaning.
  • Assumes uniform irradiance across the cure zone and parts that lay flat on the belt. For 3D parts add a shadowing margin, and for thick coatings or pigmented inks reduce speed further to compensate for absorbance — neither effect is in the formula.

Common questions

  • Where do I measure the lamp's cure-zone length? Run a profiling radiometer through the lamp at belt height and read the inches over which irradiance stays above ~80% of peak. That is the effective cure zone — usually noticeably shorter than the lamp housing length, especially on focused mercury lamps.
  • Why is irradiance measured at the belt and not the lamp face? UV intensity falls off rapidly with distance and varies with reflector condition. The number that matters for cure is what hits the part. A reading at the lamp face will overstate irradiance and the calculator will hand back a belt speed that under-cures.
  • Belt is already at max and the calculator wants more — what now? You have a capacity ceiling. Three real moves: increase irradiance (clean quartz, replace aged lamps, tighten focal distance), shorten the dose target with the chemistry vendor, or add a second lamp in series. Don't quietly run faster than this calculator says — you'll create a quiet undercure problem.
  • Does the calculator assume one pass under the lamp? Yes — single-pass dose. For a multi-lamp tunnel use the UV Multi-Lamp Dose calculator to sum the contributions, then come back here with the combined cure-zone length.

Last reviewed 2026-05-12.