1.Background and Objectives
In the R&D of UV-curable resins and customer technical support, inquiries regarding equipment power and curing effects are frequently encountered. This article clarifies the differences and correlations among four core concepts: equipment power consumption, radiant power, radiant intensity and curing energy value. It helps practitioners accurately interpret equipment parameters and provide scientific guidance for customers on equipment selection and process parameter setting.
2.Definition of Core Concepts
2.1 Power Consumption
Definition: The electric energy consumed by UV equipment (mercury lamp or UV LED) from the power grid per unit time.
Unit: Watt (W) or Kilowatt (kW).
Physical significance: It reflects the electricity cost and heat generation level of the equipment.
Example: A mercury lamp rated at 3 kW consumes 3 kilowatt-hours of electricity per hour during operation.
2.2 Radiant Power
- Definition: The actual ultraviolet (UV) energy emitted by the light source.
- Unit: Watt (W) or Milliwatt (mW).
- Physical significance: It refers to the effective output capacity of the light source.
- Relationship with power consumption:
Radiant Power = Power Consumption × Electro-optical Conversion Efficiency (η)
Mercury lamp: η ≈ 10%–20% (Most electric energy is converted into heat)
UV LED: η ≈ 30%–50% (Higher energy efficiency)
2.3 Irradiance
Definition: The radiant power incident on a unit area.
Unit: Milliwatt per square centimeter (mW/cm²).
Physical significance: It indicates the luminous intensity and penetration of UV light.
Formula: Irradiance = Radiant Power / Illuminated Area
2.4 UV Dose
Definition: The cumulative value of irradiance over exposure time.
Unit: Millijoule per square centimeter (mJ/cm²).
Physical significance: The key indicator determining sufficient curing performance.
Formula: UV Dose = Irradiance (mW/cm²) × Exposure Time (s)
3.Mechanism of Power Consumption Affecting UV Dose
3.1 Logical Relationship Chain
Power Consumption (kW)
↓ (Determines)
Radiant Power (W)
↓ (Divided by irradiated area)
Irradiance (mW/cm²)
↓ (Multiplied by exposure time)
UV Dose (mJ/cm²)
Conclusion:
Power consumption acts as the cause, while UV dose is the result. However, they do not follow a simple direct proportional relationship, as the conversion efficiency, optical path design and exposure time all exert significant influences in between.
3.2 Comparison of Different Types of Equipment
3.3 Clarification of Common Misconceptions
Misconception: Maximizing the power of a mercury lamp (e.g., 3 kW) will definitely deliver sufficient curing energy.
Facts:
- Lamp aging reduces radiant power. Though the power consumption remains 3 kW, the actual UV dose becomes inadequate.
- If the conveyor speed is too high, insufficient exposure time will result in low UV dose even with adequate irradiance.
Correct Practice: Always measure the UV dose (mJ/cm²) on the sample surface with a UV radiometer, instead of merely referring to the power reading on the equipment p4.anel.
4.SOP Recommendations for R&D and Testing
4.1 Formulation Development Phase
- Adopt UV-LED curing equipment (385 nm or 395 nm wavelength is recommended).
- The following parameters must be recorded:
Light source type (LED / Mercury lamp)
Wavelength
Measured irradiance (mW/cm²)
Exposure time (s)
Calculated UV dose (mJ/cm²)
- It is not allowed to only record “Lamp power: 100%”.
4.2 Troubleshooting for Customer Issues
When customers report “adequate power but incomplete curing”, please follow the checklist below:
- Has the UV dose been measured with a radiometer?
- Does the spectrum of the light source (mercury lamp or LED) match the photoinitiator in the formulation?
- Is the conveyor speed too high, leading to insufficient exposure time?
- Has the lamp or LED module suffered luminous attenuation due to aging?
5.Summary
- Power consumption is not equivalent to curing energy: the former is input power, while the latter is effective output.
- Irradiance is the key factor. It is the value in mW/cm² that truly determines the curing speed.
- UV dose serves as the golden standard. In formulation specifications, specify “Curing above XXX mJ/cm² is recommended” instead of “Use a 3 kW lamp”.
6.Appendix: Quick Reference Table
7.Frequently Asked Questions (Q&A)
Q1: Does equipment power consumption (kW) directly determine the curing result?
A: No. Power consumption refers to the input electricity, while curing energy is the effective output that decides the curing performance.
- Mercury lamp: A power consumption of 3 kW delivers approximately 300–600 W of UV radiant power (the rest is converted into heat).
- UV LED: A power consumption of 500 W delivers approximately 150–250 W of UV radiant power.
Conclusion: Always measure the UV dose on the sample surface practically. Do not judge the curing effect merely by the power reading on the equipment panel.
Q2: Will the curing speed be the same if both mercury lamp and UV LED deliver a measured UV dose of 1000 mJ/cm²?
A: Not necessarily. Curing speed is determined by irradiance (mW/cm²).
- High irradiance (mercury lamp): 1000 mW/cm² → Reaches 1000 mJ/cm² in 1 second (fast curing).
- Low irradiance (UV LED): 200 mW/cm² → Reaches 1000 mJ/cm² in 5 seconds (slow curing).
Conclusion: An identical UV dose means the final curing result is the same, but the curing process (speed) may differ.
Q3: Why does UV LED deliver poorer curing performance than mercury lamp even with the same UV dose?
A: This is mainly caused by differences in spectral matching.
- Mercury lamp: Features a broad spectrum (200–450 nm). Short-wave UV (UVC/UVB) can rapidly initiate surface polymerization.
- UV LED: Emits a narrow spectrum (e.g. 385 nm / 395 nm) with no short wavelengths, leading to different photoinitiation efficiency.
Solution: Select photoinitiators matching the LED wavelength in formulations, such as TPO and 819.
Q4: Can I purchase any UV radiometer (for measuring mJ/cm²) arbitrarily?
A: No.
- Radiometers for mercury lamps: Response range 315–400 nm (peaking at 365 nm). It will show lower readings when testing 395 nm UV LED.
- Radiometers for UV LED: Flat spectral response across 340–420 nm. It will produce higher readings when testing mercury lamps.
Recommendation: Choose a radiometer matched to your primary light source. Alternatively, specify the instrument model in test reports.
Q5: How to specify parameters professionally when recommending formulations to customers?
A: Avoid simply stating “A 3 kW mercury lamp is recommended”.
Recommended wording: This formulation requires a minimum irradiance of 300 mW/cm² and a total curing dose of no less than 1000 mJ/cm² for application.
Q6: Is it mandatory for R&D laboratories to equip mercury lamps?
A: It depends on your customer base.
- If focusing on electronics, 3C products and inkjet applications where UV LED is the mainstream: Purchase multi-band LED curing systems with switchable wavelengths (365/385/395 nm).
- If many customers still use traditional production lines with mercury lamps: It is recommended to keep or rent a mercury lamp unit for compatibility verification.
Q7: How to explain to customers the issue of “bright light yet incomplete curing”?
Adopt the following three-point troubleshooting guidance:
- Measure UV dose: Verify whether the actual UV dose reaching the product meets the standard.
- Check spectrum: Confirm if the light source wavelength matches the photoinitiator in the formulation (e.g., 395 nm LED paired with 184 photoinitiator).
- Inspect irradiance: Ensure the irradiance is sufficient to support the required production line speed.
Summary in one sentence:
Power sets the upper limit, irradiance determines curing speed, and UV dose governs the final curing result.
Post time: Jun-09-2026
