UV Curing calculator

UV Cure Defect Rate Calculator

PPM is the language of customer scorecards and SPC trending. This calculator converts the cure-related defects you found this month against the total cured parts produced into a clean PPM number, with a side-by-side gap to your target so the verdict is unambiguous in a quality review.

What this calculator does

  • Convert cure-related defects per shift into a parts-per-million rate, with a verdict against your customer or internal PPM target.
  • Use it for monthly quality reports, customer scorecards, and SPC reviews when the question is whether the UV cure step is on or off-target.
  • Returns cure-related defect rate in PPM and the gap to your published PPM target.

Formula used

  • PPM = defects ÷ total parts × 1,000,000
  • Gap to target = PPM − PPM target (positive = over)

Inputs explained

  • Cure-related defects this period: Defects directly tied to UV cure: tacky surface, undercure, embrittlement, surface haze. Exclude unrelated defects.
  • Total cured parts this period: All parts that passed through the UV cure station, including both good and cure-defective.
  • PPM target: Customer or internal goal — typical 50–500 PPM for general manufacturing, <100 PPM for premium customers.

How to use the result

  • Use it monthly in quality reviews, on customer scorecards, in SPC trending of cure performance, and when investigating a defect spike to confirm the spike is real (not a counting artifact).
  • Reports the rate, not the cause. A high PPM with stable lamps and stable dose usually points to chemistry batch variation, substrate change, or a fixture / shadowing issue. Pair this with UV Dose Margin trending and a defect Pareto to find the cause.

Common questions

  • What's a 'good' UV cure PPM? 100–500 PPM on general industrial UV lines (printing, coating, light assembly). 10–100 PPM on tightly controlled lines (medical adhesives, optical bonding, premium automotive). Above 1,000 PPM (0.1%) on a mature line usually means a process control issue, not bad luck.
  • PPM is up but lamp checks are fine — where do I look? Common in this order: chemistry batch change (new lot, new viscosity, new pigment loading), substrate batch change (different surface energy, different UV transmission), fixture issue (new operator loading parts off-position into shadowed area), or a quartz / reflector fouling that didn't show in the radiometer pass.
  • Should I count rework as a defect? Yes for a true PPM (any escape from the process is a defect). Some scorecards use a 'first-pass yield' definition that excludes reworked parts; check the customer's definition. Either way, log rework separately in UV Rework Cost so the financial impact is captured.
  • How do I make PPM trends actionable? Pair the PPM number with the dominant defect mode (tacky / under-cure / embrittlement / haze) and the time of day. Tacky-surface spikes that show up after lamp warm-up point to oxygen inhibition; embrittlement spikes after lamp swap point to over-dose; haze on an older lamp points to focal-distance drift.

Last reviewed 2026-05-12.