Why does the page ask for irradiance?

Because dwell on its own is a units conversion. Dose is irradiance times time, and dose is what cures, so the requirement can only be compared once irradiance is known. Without it the margin has nothing to sit against.

Can I run at the fastest speed shown?

No. That speed meets the dose exactly, with zero margin for lamp decline. Run below it by enough to survive the interval between radiometer checks. A line commissioned at the ceiling is undercured before the next measurement.

Why are parts tacky when the margin is fine?

That is usually oxygen inhibition, not dose. Air quenches radicals in the top few microns, leaving an uncured skin over a cured bulk. Peak irradiance beats it; more time at the same irradiance often does not.

Does belt width change the answer?

Not the arithmetic, but the applicability. Irradiance falls toward the edges of the illuminated width, so a centerline reading overstates what a wide part's edges receive. Check the coldest point when the spread is significant.

UV Curing calculator

UV Dwell Time Calculator

Find the dwell and dose your line delivers, and whether they clear the requirement. You need the useful zone length, belt speed, required dose and irradiance at belt height.

What this calculator does

Seconds a part spends under the lamp, the dose that delivers, and the margin against the requirement.

Formula used

Belt speed in in/s = belt speed × 12 ÷ 60
Dwell = cure-zone length ÷ belt speed in in/s
Dose delivered = irradiance × dwell
Margin = (dose delivered − required dose) ÷ required dose × 100
Fastest speed = cure zone ÷ (required dose ÷ irradiance) ÷ 12 × 60

Inputs explained

Lamp Cure-Zone Length: Useful illuminated length along travel; measure where irradiance matters, not the housing.
Conveyor Belt Speed: The speed the line runs at today.
Required Cure Dose: The material's cure-dose requirement, in a named spectral band.
Measured Irradiance at Belt: Radiometer reading at belt height in the same band.

How to use the result

Best suited to checking an existing line against a new material, diagnosing undercure from the line's settings, finding speed a comfortable margin is hiding.
Single station and surface dose only. Multi-lamp tunnels and through-cure are separate pages. Does not model oxygen inhibition or substrate heating. Assumes a flat part facing the lamp; shaped parts shadow themselves.

Common questions

Why does the page ask for irradiance? Because dwell on its own is a units conversion. Dose is irradiance times time, and dose is what cures, so the requirement can only be compared once irradiance is known. Without it the margin has nothing to sit against.
Can I run at the fastest speed shown? No. That speed meets the dose exactly, with zero margin for lamp decline. Run below it by enough to survive the interval between radiometer checks. A line commissioned at the ceiling is undercured before the next measurement.
Why are parts tacky when the margin is fine? That is usually oxygen inhibition, not dose. Air quenches radicals in the top few microns, leaving an uncured skin over a cured bulk. Peak irradiance beats it; more time at the same irradiance often does not.
Does belt width change the answer? Not the arithmetic, but the applicability. Irradiance falls toward the edges of the illuminated width, so a centerline reading overstates what a wide part's edges receive. Check the coldest point when the spread is significant.

Last reviewed 2026-10-01.