Aspects of Radiometry and UV Exposure Verification for UV Curing of Complex Surfaces and 3-D Objects

By R.W. Stowe

Three-dimensional processing presents some new and different problems for radiometry. Parts have complex surfaces, so the irradiance levels will vary by location. For optimized lamp positioning and process verification, this could require irradiance and energy measurements at almost every point on the surface.

The motion can range from the straight-through linear travel of a paint line past a fixed set of lamps, to compound motion of chain-on-edge conveyors, to combinations of part motion and limited lamp motion, and to totally robotically controlled mo­tion of lamps themselves.

The exposure (time-integra­tion of the irradiance profile) at any point will result from the combined effects of part geometry, relative surface velocity, and lamp configuration.

While large-part 3-D processing, such as automotive body components, receives considerable attention, most industrial 3-D coating and curing is for smaller components, ranging from cell phone covers, to auto­motive lighting, to containers and furniture, where it becomes difficult to equip the surfaces with sufficient instrumentation for exposure verification and quality control.