The miniature cartridge heaters, with a compact diameter of just 6mm and lengths ranging from 50mm to 100mm, are designed to fit into the tight spaces of medical diagnostic instruments. The US client, a leading producer of blood analysis equipment, specified that the heaters must achieve and maintain temperatures of 37°C ±0.5°C for accurate sample incubation. Our engineering team worked closely with the client's R&D department to optimize the heater design, incorporating a built-in J-type thermocouple for real-time temperature feedback to the equipment's control system.
The manufacturing process for these miniature heaters requires exceptional precision. The resistance wire, made of nickel-chromium alloy, is wound using computer-controlled machines that ensure consistent pitch and tension across each coil. The wound coils are then carefully inserted into thin-walled stainless steel 304 tubes, which were selected for their biocompatibility and compliance with FDA requirements for medical device components. The tube filling process uses ultra-high-purity magnesium oxide powder with a particle size distribution specifically chosen to maximize packing density in the small internal volume. A multi-stage swaging process gradually reduces the tube diameter while compacting the MgO powder to achieve the required dielectric strength and thermal conductivity.
