Guide to UV Measurement
Process Window
The process window refers to the range of exposure conditions that will yield a properly cured coating suitable for its intended application. A minimal specification should include details on the specific lamp and bulb including power level and bulb spectral output along with a measured energy density including information on the specific device and the wavelength range over which the measurement was made. However, this is far from complete.
A complete specification for transferring a process would also include the type of lamp; the peak irradiance the focal properties of the reflector and, if it is defined, the distance from the focal plane of the reflector to the surface being exposed; a linespeed; the cure environment (e.g., air or inert); etc. Note that measurements made on the output of the UV source may depend on how the specific measurement device is configured so this information also needs to be understood and conveyed. Where possible, a range of acceptable values is preferred so that internal checks are available to indicate when the process is out of control. Remember, the more information you know about the cure conditions, the more able you will be in repeating and maintaining the process.
