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UV printing requires printing equipment to be equipped with a matching UV curing device. When the substrate passes through the UV curing device, ultraviolet light emitted by the UV lamp irradiates the surface of the substrate, thereby curing the UV ink (or UV varnish). So how can you achieve a satisfactory UV curing effect? Read on:

I. Control of UV Lamp Surface Temperature
Generally, the ideal surface temperature of a UV lamp is 200℃. Excessively high temperature will shorten the service life of the UV lamp, cause expansion and deformation, lead to the “self-fogging” phenomenon, and even melt and deform the reflective aluminum plate of the UV lamp housing.

On the other hand, the temperature should not be too low either. When the surface temperature of some UV lamps drops below 170℃, the ultraviolet radiation energy decreases, resulting in increased current. Over time, transformers or capacitors may burn out due to overcurrent.

To prevent a series of problems caused by excessively high UV lamp surface temperature, the following measures can be taken:

1. Adopt UV-LED light sources, which convert light energy to emit high-purity monochromatic ultraviolet light at a wavelength of 365nm. As a kind of cold light source, its radiation energy can be highly concentrated in the ultraviolet band responsible for curing as the lamp surface temperature rises, delivering curing performance comparable to high-pressure mercury lamps.
2. Install reflectors to concentrate the ultraviolet radiation energy emitted by the UV lamp onto the substrate surface for full utilization, while reducing the lamp surface temperature.
3. Use UV cooling systems with combined air cooling and water cooling. First, install water jackets to maintain an appropriate operating temperature for the UV lamp via water cooling. Second, use air cooling to lower the ambient temperature, ensuring suitable printing conditions without damaging surrounding components. Air cooling requires an air pump and a proper air duct system, with fan power matched to the UV lamp power. Air volume is generally calculated as follows:
   Air Volume (m³/h) = 150 (m³/h·kW) × UV Lamp Power (kW)
   The effectiveness of air cooling can be judged by inspecting the air exhaust duct for damage, air leakage, deformation, or blockages. In actual production, special high-temperature resistant exhaust ducts are commonly used. II. Control of Substrate Surface Temperature
   Even when the UV lamp surface temperature is kept within a reasonable range, substrates made of certain materials may become brittle or deformed. In severe cases, this can damage surrounding components and even cause fire hazards.

Therefore, for thin substrates or those with low heat resistance, curing tests must first be conducted to verify their suitability for UV printing production. For substrates less affected by temperature, UV radiation heat can be fully utilized to accelerate curing speed. Evidently, the substrate surface temperature is not necessarily better when lower; it should be controlled within an appropriate range.

Effective measures to reduce substrate surface temperature include:

1. Use optical sheets to isolate the UV lamp radiation energy from the substrate. This method is commonly applied in UV printing for easily deformable substrates.
2. Add a water cooling device to the substrate pallet. A typical solution is to modify the internal structure of the pallet and circulate cold water. This prevents overheating on the substrate surface without affecting the coating temperature, delivering excellent performance.