The increasing use of carbon fiber composites in high-volume production is driving the need to know cure state in real time. Dielectric cure monitoring (also called Dielectric Analysis, or DEA) is the only method that can probe material properties during manufacturing, and a past study had demonstrated its ability to reduce average SMC press cycle times by detecting end of cure. Compared to a timer set at 60 seconds, the 10 second reduction in SMC molding time, attributed to DEA, was estimated to save $70,000/year/press in labor costs alone.1

Dielectric sensors normally require filters to block conductive fibers and prevent short circuiting of the electrodes. Filters, however, must be replaced manually after each test and add time, effort and cost, so it is necessary to avoid them in rapid, repetitive operations.

For cure monitoring without filters, Carbon+Unitrode sensors from Lambient Technologies have a rugged, insulating coating that allows direct contact with carbon fiber composites. As a result, Carbon+Unitrode sensors can be used in manufacturing to observe the entire cure, and can detect end of cure for opening a press or mold.