Abstract: A system and method for inductive heating, in which a power source provides current pulses with high-frequency harmonics to a heater coil, the coil generating a magnetic flux for inductive heating of an article. The high-frequency harmonics enhance a relative proportion of inductive heating, compared to resistive heating of the heater coil. Providing these high-frequency harmonics, occurring above the border frequency of the heating system, enables the system to deliver an increased proportion of inductive heating, compared to resistive heating, without requiring an increase in the Root Means Square (RMS) current in the coil. Providing better coupling between the coil and the core, such as by embedding the coil wholly or at least partially in the core, and providing a magnetic yoke to close the loop with the core, can provide a significantly decreased border frequency.

Abstract: A thermoplastic article is produced by welding or injection molding. The mechanical performance of the article is optimized by a method employing a plurality of test samples also produced by welding or injection molding. For welding, each test sample comprises two thermoplastic workpieces welded at an interface having a preselected shape. The test samples are prepared using different welding conditions and tested. The results are used to select injection molding conditions for the first and second workpieces. For injection molding, each test sample is prepared with a knit line having a preselected shape. The test samples are injection molded using different conditions and tested. The results are used to select welding conditions for the first and second workpieces. The test samples are much easier to prepare than samples that have to be machined from full-scale articles made under the requisite variety of experimental conditions heretofore required for process optimization.

Abstract: A system and method for inductive heating, in which a power source provides current pulses with high-frequency harmonics to a heater coil, the coil generating a magnetic flux for inductive heating of an article. The high-frequency harmonics enhance a relative proportion of inductive heating, compared to resistive heating of the heater coil. Providing these high-frequency harmonics, occurring above the border frequency of the heating system, enables the system to deliver an increased proportion of inductive heating, compared to resistive heating, without requiring an increase in the Root Means Square (RMS) current in the coil. Providing better coupling between the coil and the core, such as by embedding the coil wholly or at least partially in the core, and providing a magnetic yoke to close the loop with the core, can provide a significantly decreased border frequency.