Why does expected decline matter more than today?

Today's margin is the largest it will ever be. Output falls from the moment it is measured, so a margin can expire long before the next check.

Where do I get the decline figure?

From your own radiometer history. Published curves are nominal, and a dirty housing declines faster than any curve predicts.

My margin expires before the next check. What now?

Shorten the interval, usually. A monthly check costs a few measurements; slowing the belt pays for a scheduling gap forever.

Is a very large margin a problem?

Sometimes. Excess dose embrittles or yellows some coatings, and on a mercury line the infrared load scales with dwell. It may also be unclaimed speed.

UV Curing calculator

UV Dose Margin Calculator (Today and at the Next Check)

Check a UV process's dose margin today and at the next measurement. Enter the required dose, the measured dose, a minimum margin and the decline you expect.

What this calculator does

Check the dose margin a process has today and whether it survives the lamp decline before the next check.

Formula used

Margin today = (measured − required) ÷ required × 100
Headroom today = margin today − minimum margin
Dose after decline = measured × (1 − decline ÷ 100)
Margin at next check = (dose after decline − required) ÷ required × 100
Headroom at next check = margin at next check − minimum margin

Inputs explained

Required Cure Dose: The material's required cure dose, in a named band.
Measured Dose at Part Surface: Integrated puck reading through a real pass.
Minimum Acceptable Margin: The floor the process must stay above.
Expected Output Decline: Expected output loss before the next measurement.

How to use the result

Best suited to setting a radiometer check interval, checking a commissioning margin's shelf life, deciding between a shorter interval and more dose.
Models lamp decline only; reflector fouling can outpace it. One-sided; large margins are flagged as information, not as a limit. Assumes proportional decline, a planning approximation.

Common questions

Why does expected decline matter more than today? Today's margin is the largest it will ever be. Output falls from the moment it is measured, so a margin can expire long before the next check.
Where do I get the decline figure? From your own radiometer history. Published curves are nominal, and a dirty housing declines faster than any curve predicts.
My margin expires before the next check. What now? Shorten the interval, usually. A monthly check costs a few measurements; slowing the belt pays for a scheduling gap forever.
Is a very large margin a problem? Sometimes. Excess dose embrittles or yellows some coatings, and on a mercury line the infrared load scales with dwell. It may also be unclaimed speed.

Last reviewed 2026-10-01.