High-Frequency Induction Heating Machine: Practical Testing Guide for Flexible Cable Extensions and Open Induction Coils

For large workpieces and heavy equipment repair or processing on industrial sites, the workpiece may be difficult to move into a fixed induction coil. A flexible cable extension combined with an open induction coil provides a practical solution for localized heating with a high-frequency induction heating machine. However, the extension cable and open coil can directly affect power output and heating uniformity, so standardized heating tests are important for stable production. Based on years of induction heating equipment development experience, Dongguan Jinruihang Technology Co., Ltd. has organized a practical testing process for high-frequency induction heating machines using flexible cable extensions and open induction coils, providing a reference for equipment selection and process setup. [Official Website] https://cn.jinruihang.com [Contact Us]

I. Equipment Preparation Before Testing

Before starting the heating test, check the overall condition of the induction heating system. First, inspect the high-frequency induction heating unit and confirm that the water-cooling system, overload protection and temperature-control modules are operating properly, with the required safety accessories in place. Next, verify the specifications of the flexible cable extension and open induction coil. The cable cross-section, cooling-water flow rate and coil turns should match the output parameters of the main unit. Incompatible accessories may lead to excessive power loss, cable overheating or insufficient heating performance. An open induction coil is a non-closed-loop induction component, so the coil opening gap and copper-tube wall thickness can directly change the magnetic-field distribution. Before testing, check that the coil has no cracks, the water circuit is not blocked, and the insulation around the connection points is intact.

II. Equipment Installation and Connection Setup

Securely connect the flexible cable extension to the output terminals of the high-frequency induction heating machine and tighten the connections to ensure stable high-frequency current transmission. Connect the matching water-cooling lines to provide effective heat dissipation during operation. Then install the open induction coil at the end of the flexible cable. The open coil should not touch the workpiece directly; maintain an appropriate working gap. A gap that is too small may cause arcing or dielectric breakdown, while a gap that is too large can significantly reduce heating efficiency. The shape of the open coil can be adjusted moderately according to the workpiece geometry to suit localized heating of irregular workpieces and large structures.

III. Parameter Setup and Practical Heating Test

Set the equipment power, heating time and operating frequency according to the workpiece material, thickness and target process, such as annealing, hardening, brazing or heat-assisted disassembly. Because the magnetic-field distribution of an open coil differs from that of a conventional closed-loop coil, the coil angle and its position relative to the workpiece may need to be adjusted several times to improve heating uniformity.

Start the equipment and conduct the heating test while recording voltage, current and actual output power throughout the process. Check the flexible cable extension for abnormal heating or vibration. Use an infrared thermometer or thermocouple to measure workpiece temperature, monitor the heating rate and surface-temperature distribution, and pay particular attention to temperature differences on the two sides of the coil opening. During on-site setup, one side of an open coil may become hotter while the other side heats more slowly. This is a common open-coil behavior that can be improved by adjusting power and coil-to-workpiece distance.

IV. Performance Evaluation and Equipment Optimization

After testing, evaluate the stability of the complete system. First, check the heating result: whether the workpiece reaches the required process temperature, whether the heated area is uniform, and whether localized overheating occurs. Then inspect the flexible cable extension and open induction coil for heat generation during extended operation and temperature rise at the connection points, and assess whether the accessories can withstand the thermal stress associated with high-frequency operation.

If heating is slow, temperature differences are large, or the cable overheats, first adjust the power settings and optimize the coil position and orientation. If accessory wear is significant, replace the flexible cable with a suitable specification or have a new open induction coil made for the application. Jinruihang Technology can customize flexible cable assemblies, open coils and profile-shaped induction coils according to customer working conditions, supporting 3–500 kW high-frequency, ultrasonic-frequency and medium-frequency induction heating equipment for on-site repair and localized heat-treatment applications on large equipment.

V. Safety Considerations for On-Site Testing

High-frequency induction heating tests involve high temperatures and high-frequency electrical energy. Keep flammable and explosive materials away from the test area and provide appropriate fire-fighting equipment. Do not touch the coil, flexible cable connections or hot workpieces during heating to avoid burns and high-frequency arcing hazards. Operators should follow the equipment operating manual. If abnormal sounds or excessive cable heating occur, stop the machine, disconnect the power and inspect the system before continuing. Do not operate equipment with unresolved faults.

This testing process helps verify whether the flexible cable extension and open induction coil combination is suitable for the intended production application, reducing the risk of defects or equipment damage when moving directly into production. Dongguan Jinruihang Technology Co., Ltd. focuses on induction heating process solutions and has more than 20 years of R&D experience. Its equipment covers hardening, annealing, brazing, heat-assisted disassembly and melting applications. Coil and flexible-cable customization is available, together with 7×24-hour technical after-sales support. Visit the official website for more technical information.

Dongguan Jinruihang Technology Co., Ltd. Official Website: cn.jinruihang.com

Keywords: high-frequency induction heating machine, flexible cable extension, open induction coil, induction heating, handheld high-frequency induction heater, localized heat treatment, brazing and annealing testing