UV Curing calculator

UV Dose Margin Calculator

UV lamps lose output over hours; quartz fouls; reflectors age. The number that matters is whether the dose hitting the part is still above the chemistry's cure threshold. This calculator turns a radiometer reading into a clean margin (% over the required dose) so a process engineer can decide whether to keep producing, schedule a quartz wipe, or replace the lamp before the next shift.

What this calculator does

  • Compare a measured UV dose against the chemistry's required dose and see how much headroom (or shortfall) you have before lamp drift puts you under-cure.
  • Use it after a radiometer pass to decide whether a line can keep running until the next scheduled lamp service or whether a setpoint change is needed now.
  • Returns the percent that the measured dose exceeds (or falls short of) the chemistry's required dose, plus the gap to your minimum-margin process rule.

Formula used

  • Margin (%) = (measured dose ÷ required dose) − 100%
  • Verdict = ✅ if margin ≥ minimum acceptable margin, ⚠ otherwise

Inputs explained

  • Required dose: From the chemistry data sheet at the matching UV band.
  • Measured dose at part: From a profiling radiometer pass at the part surface, current setpoint and speed.
  • Minimum acceptable margin: Process target — typically 20% over the required dose.

How to use the result

  • Use it after every scheduled radiometer pass, after lamp swaps, and any time you suspect quartz fouling, reflector burn, or focal-distance drift has eaten your dose headroom.
  • Treats the radiometer reading as ground truth. Calibration drift, wrong UV band, or measurement off the cure plane will silently bias the margin in either direction. The calc does not care about uniformity — a healthy average can hide cold spots; pair with the UV Dose Mapping calculator for spatial coverage.

Common questions

  • What dose margin is healthy in production? Most UV process specs aim for 20–50% over the chemistry minimum. 20% is tight and means you must radiometer often; 50% wastes lamp life on a mature line. New lines start higher and trend down as the cure window is characterized.
  • Margin is positive but I am still seeing tacky parts — why? Average dose can be fine while a portion of the part sits in a cold spot. Run UV Dose Mapping with multiple readings across the work surface, and check for shadowing or oxygen inhibition on exposed surfaces (those have dedicated calcs in the related list).
  • I am at 0% margin — do I have to stop? Treat 0% margin as a hard stop. Required dose is the chemistry's minimum to cure; running at the floor leaves no buffer for the next lamp-aging hour. Slow the line, swap the lamp, or clean the quartz before continuing.
  • How often should I be checking margin? Tie it to lamp hours, not calendar time. Mercury lamps lose output measurably every 100–300 hours; LED arrays drift more slowly but still drift. A weekly profiling radiometer pass is a defensible baseline; daily on safety-critical or high-mix lines.

Last reviewed 2026-05-12.