Do doses from separate lamps really add?

For a dose-limited cure, yes. The photoinitiator does not care whether the energy arrived in one pass or four, so total dose is what governs through-cure. The exception matters: where the cure is limited by peak irradiance, as with oxygen inhibition at the surface, the sum is meaningless and only the strongest station's intensity counts.

What happens when one lamp fails on a four-station line?

Production continues at reduced dose, which is the problem. Nothing stops, no alarm is guaranteed, and the parts look identical. They are simply undercured by whatever fraction that station contributed. On matched stations that is around a quarter. Per-station monitoring or a lamp-out interlock is the only reliable way to catch it, and knowing the reduced total in advance is what makes the decision easy when it happens.

How much station-to-station variation is acceptable?

It is not really a specification question. What matters is whether the total clears the requirement and whether the line still clears it after a failure. That said, a spread beyond about half the mean is a diagnostic in itself: it points at mismatched lamp ages, a fouled reflector, a dirty quartz sleeve or a station running at a different power setting, and every one of those is worth finding.

Should I replace all the lamps at once?

Usually yes on a multi-station line. A set replaced together decays together, so the stations stay matched and the total falls predictably; replacing them one at a time as each fails produces a permanently mismatched set where the dose profile shifts every few weeks. Set against that, a full set costs more per event. The lamp replacement page prices both patterns in cost per operating hour.

My part rotates between stations. Does this still work?

Not for any single point on the part. If different stations illuminate different faces, their doses do not add at a given location, and what you have is several partial exposures rather than one cumulative one. Measure at the surface you care about, with a probe that travels the way the part travels, and treat the result as that surface's dose rather than the machine's.

Why is the strongest station reported separately?

Because it is the number that matters where the sum does not apply. For an oxygen-inhibited surface cure the governing quantity is peak irradiance, so a line's ability to cure the surface is closer to a function of its best station than of its total. Printing both makes it obvious when a line has plenty of cumulative dose and no single station strong enough to beat inhibition.

UV Curing calculator

UV Multi-Lamp Dose Calculator: Total, Spread, and What a Failure Costs

Add up what four lamp stations contribute and see two things a total on its own hides. Enter each station's dose measured alone, in the same band with the same probe. The calculator returns the cumulative dose, the strongest and weakest stations, the spread between them, and the total that would remain if the strongest station failed. That last figure is the one worth knowing in advance: a multi-station line does not stop when a lamp goes out, it quietly delivers less dose while producing parts that look exactly the same.

What this calculator does

Add the dose contributions of four lamp stations, and report the spread between them and the total that remains if the strongest fails.
Use it for confirming a multi-station line still meets its dose requirement, planning for a single lamp failure before it happens, finding a station that has drifted or fouled, deciding whether to replace a lamp set together or individually, checking whether a line has enough redundancy to run on three stations.
Add the dose contributions of four lamp stations, and report the spread between them and the total that remains if the strongest fails.

Formula used

Total cumulative dose = station 1 + station 2 + station 3 + station 4
Strongest single station = MAX of the four
Weakest single station = MIN of the four
Total if the strongest fails = total − strongest
Station spread (%) = (strongest − weakest) ÷ mean × 100

Inputs explained

Lamp station 1 dose contribution: Dose from station 1 alone, measured with the other stations off, in one consistent band.
Lamp station 2 dose contribution: Dose from station 2 alone, same probe, same band, same pass speed.
Lamp station 3 dose contribution: Dose from station 3 alone.
Lamp station 4 dose contribution: Dose from station 4 alone. Enter zero for an unused station.

How to use the result

Best suited to confirming a multi-station line still meets its dose requirement, planning for a single lamp failure before it happens, finding a station that has drifted or fouled, deciding whether to replace a lamp set together or individually, checking whether a line has enough redundancy to run on three stations.
Adding doses is invalid where cure is limited by PEAK IRRADIANCE rather than accumulated dose. Oxygen inhibition is the common case: four weak stations do not replace one strong one. Assumes the part presents the same face to each station. On a rotating or indexing line, different stations may illuminate different surfaces, and their doses do not add for any single point. Ignores dark cure and thermal effects between stations, which matter for cationic chemistry where the reaction continues after the light stops. Says nothing about uniformity across the width of any individual station. Treats a station's contribution as constant, when lamp output decays continuously between measurements.

Common questions

Do doses from separate lamps really add? For a dose-limited cure, yes. The photoinitiator does not care whether the energy arrived in one pass or four, so total dose is what governs through-cure. The exception matters: where the cure is limited by peak irradiance, as with oxygen inhibition at the surface, the sum is meaningless and only the strongest station's intensity counts.
What happens when one lamp fails on a four-station line? Production continues at reduced dose, which is the problem. Nothing stops, no alarm is guaranteed, and the parts look identical. They are simply undercured by whatever fraction that station contributed. On matched stations that is around a quarter. Per-station monitoring or a lamp-out interlock is the only reliable way to catch it, and knowing the reduced total in advance is what makes the decision easy when it happens.
How much station-to-station variation is acceptable? It is not really a specification question. What matters is whether the total clears the requirement and whether the line still clears it after a failure. That said, a spread beyond about half the mean is a diagnostic in itself: it points at mismatched lamp ages, a fouled reflector, a dirty quartz sleeve or a station running at a different power setting, and every one of those is worth finding.
Should I replace all the lamps at once? Usually yes on a multi-station line. A set replaced together decays together, so the stations stay matched and the total falls predictably; replacing them one at a time as each fails produces a permanently mismatched set where the dose profile shifts every few weeks. Set against that, a full set costs more per event. The lamp replacement page prices both patterns in cost per operating hour.
My part rotates between stations. Does this still work? Not for any single point on the part. If different stations illuminate different faces, their doses do not add at a given location, and what you have is several partial exposures rather than one cumulative one. Measure at the surface you care about, with a probe that travels the way the part travels, and treat the result as that surface's dose rather than the machine's.

Last reviewed 2026-08-25.