How to ensure continuity in the casing overlap of HMI (Human Machine Delivery) systems?

Ensuring electrical continuity at HMI enclosure joints is fundamental to ensuring shielding effectiveness and grounding. Electrical continuity requires current to flow with low impedance between different parts of the enclosure. First, all independent metal components, such as the front and rear shells, mounting brackets, and shielding partitions, must have direct metal-to-metal contact at their joints. Contact surfaces should be flat, clean, and free of paint, oxide layers, or insulating coatings. Common methods for ensuring continuity include: using multi-point screw connections with toothed washers or washers with embedded wire under the screws to break through surface oxide layers; adding conductive gaskets at joints, such as beryllium copper springs, conductive rubber, or conductive cloth, which can fill gaps and provide multiple contact points after deformation under pressure; and using flexible conductive connecting strips, such as braided copper strips, for hinges or sliding parts. The design should avoid using conductive coatings or platings as the sole conductive path, as they are prone to wear or corrosion. The connection resistance of all joints should be as low as possible, typically less than 10mΩ. After assembly, the resistance of critical joints should be checked using a low-resistance tester. Eintech provides a variety of conductive pads, conductive connecting strips, and specialized gaskets to help designers build reliable low-impedance housing connection systems in HMI products.