Nearly every piece of modern electrical equipment is surrounded by electromagnetic interference. Motors, power converters, wireless transmitters, and switching circuits all generate electromagnetic energy that can disrupt nearby electronics. Precision engineered EMI shielding enclosures contain this energy to prevent it from impacting critical circuitry. This preserves the integrity of the signals and keeps electrical equipment functioning properly. Unfortunately, EMI shielding enclosures can fail due to poor fabrication.

At Fralo Industries, we’ve spent decades fabricating and assembling sheet metal enclosures for industrial applications. In our guide below, we break down the most common reasons for EMI shielding enclosure failures and how our team works to prevent them. Read on and then give us a call for more information about our capabilities, materials, and expertise.

Insufficient Shielding at Seams and Joints

The seams of an EMI shielding enclosure are where most failures occur. A small gap along a welded or bolted joint can cause electromagnetic energy to leak through, but the amount of leakage is dependent on wavelength. An enclosure designed for low frequency protection may not shield effectively against high frequency signals. Misaligned panels and inconsistent seam spacing further increase the risk of leakage.

Because they eliminate gaps entirely, continuous weld seams deliver the strongest shielding performance. However, this means the enclosure won’t be able to be fabricated with removable panels that make maintenance more accessible. Bolted and removable panels require tight fastener spacing and flat surfaces to provide adequate EMI protection.

Poor Ventilation

Ventilation is another key aspect of EMI shielding enclosures as every opening could be a potential path for leakage. A fan opening needed for proper airflow can behave like an antenna aperture, radiating energy the enclosure was meant to contain.

For effective thermal management and EMI protection, multiple small perforations should be used instead of a few large openings. Conductive honeycomb vents, fine mesh screens, and filtered assemblies are just some of the fabrication strategies we use at Fralo to strike that perfect balance.

Incorrect Gaskets and Conductive Seals

EMI gaskets preserve electrical continuity across removable joints and access panels in applications where continuous welds aren’t practical. A compressed gasket seals the space between mating surfaces; if it fails, the enclosure may look acceptable during a walkthrough but still perform poorly during electromagnetic testing.

Common causes of gasket failure include:

  • Incorrect choice of gasket material for the frequency range
  • Insufficient compression across the joint
  • Discontinuities or gaps at the corners and cutouts
  • Poor surface preparation, such as leftover plating or paint
  • Gasket placement doesn’t align with faster locations

Gasket interfaces like groove depth and compression hardware should be considered early in the EMI shielding enclosure design process. Our engineers at Fralo determine the ideal gasket material and channel geometry prior to fabrication to prevent the need for extensive rework later down the line.

Cable Entry and Connector Issues

An unshielded cable can conduct electromagnetic energy through an otherwise sealed enclosure, making cable entry a critical challenge in EMI shielding enclosure design.

Bulkhead connectors and EMI rated cable glands provide controlled shield termination at the enclosure wall, while feedthrough filters protect power and control lines that cross the boundary. High power equipment adds mechanical demands because termination hardware must maintain electromagnetic performance under heavy cable loads. Fralo Industries designs EMI shielding enclosures with precisely located cutouts and bonding provisions for glands, connectors, and feedthroughs.

Fastener and Grounding Mistakes

Fasteners and mounting hardware have roles beyond holding EMI shielding enclosures together in a complete assembly. Each fastener location is a potential electrical bonding point. Inconsistent torque, low fastener density, or surface corrosion can quietly impede shielding performance over the equipment’s lifespan. This is why mechanical assembly and electrical performance need to be considered together.

Painted and power coating on enclosures further complicate designs because they act as insulation at bonding points. A fastener torqued through paint, for example, may hold the panel firmly but offer little electrical continuity. Bonding areas should also stay masked during finishing treatments or receive conductive plating, so grounding points and seam interfaces keep reliable contact.

Misaligned Material Selection

Material selection directly influences an EMI shielding enclosure’s performance just as much as its geometry. Steel, aluminum, and specialty alloys have different conductivity and permeability qualities. Treating attenuation requirements as a design afterthought can cause an enclosure to underperform despite having a sound seam and gasket.

EMI shielding enclosures intended for outdoor environments cause additional complications. NEMA rated enclosures and EV charging stations must maintain reliable shielding performance while being resistant to corrosion and other environmental threats.

For Proper EMI Shielding Enclosure Design, Call Fralo Industries

Fabricating effective EMI shielding enclosures requires proper seam geometry, ventilation, gaskets, cable entry, fastener bonding, and material selection. All these factors can shape how well an enclosure controls electromagnetic energy.

Fralo Industries’ sheet metal fabrication and assembly experience means every EMI shielding enclosure project is engineered with these design considerations in mind. Reach out to us today to learn more about our capabilities and technical expertise.