Precision Engineering for Global OEMs

Custom Terminal Box services

From rapid prototyping to high-volume production, Supro MFG delivers one-stop precision metal fabrication with ISO-certified quality. Reduce your lead times and production costs with our expert DFM support.

1-3 day Rapid Prototyping & Agile Supply Chain Delivery.
On-time delivery of high quality product commitments.
Extensive Material Selection & Industrial-Grade Finishing.
Direct-from-Factory Pricing & Transparent Costing.
ISO 9001-2015 / IATF 16949:2016 certified system.
Integrated Assembly: Delivering finished, ready-to-use products, not just components.

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Rapid Prototypes, DFM Optimization, On-Time Delivery, Real Manufacturer Quote.

Rapid stamping die Turnaround

Committed to exceeding expectations for quality and rapid turnaround, and meeting high-quality sheet metal parts.

Consistency & high quality

Whether it is rapid prototyping & large-volume manufacturing, we will implement it according to customer needs and standards.

Low Cost Effective

Integrate product design, bending, stamping, cutting, surface treatment, etc. to provide a series of manufacturing solutions.

Precision Metal Fabrication Services in China | Custom OEM Solutions & Rapid Prototyping

Your Strategic Partner for Terminal Box Fabrication

At Supro MFG (Supro Manufacturing Co., Ltd.), we don’t just manufacture parts; we engineer reliability. As a leading China metal fabrication factory, we bridge the gap between complex design and cost-effective production. By leveraging our ISO 9001:2015 & IATF 16949 certified facilities and a seasoned engineering team, we provide 3,000+ global clients with unparalleled custom metal fabrication services—direct from the source with transparent, manufacturer-level pricing.

We specialize in the high-quality manufacturing and assembly of custom metal parts, with processing capabilities encompassing: sheet metal fabrication, metal stamping, CNC machining, laser cutting, metal welding, metal spinning, deep drawing, aluminum extrusion, die casting, as well as customized finished product assembly and surface treatment services.

From concept prototypes to mass production,

Supro MFG is your most reliable partner and you will benefit from our manufacturing services.

What Is a Terminal Box?

A terminal box is a professionally designed electrical enclosure intended to house and protect critical electrical connections, terminal blocks, and relay systems from harsh environmental conditions.

To meet stringent NEMA and IP protection rating requirements, Terminal Boxes must effectively prevent the ingress of moisture, particulate matter, and mechanical stress. We manufacture these enclosures using high-precision laser cutting and CNC press brakes, with 14- to 16-gauge premium stainless steel or galvanized steel sheet as raw materials. Combined with seamless welding and high-quality powder coating processes, this ensures structural rigidity and exceptional corrosion resistance in demanding industrial environments.

At Supro MFG, we leverage our deep expertise in custom sheet metal fabrication to provide one-stop terminal box solutions—precisely tailored to your project requirements through precision punching, custom dimensions, and integrated mounting solutions.

Securing Your Designs with Enterprise-Grade Confidentiality at Every Stage of Manufacturing

Your Innovation, Protected:
Uncompromising IP Security & NDA Compliance

At Supro MFG, we understand that your designs are your most valuable assets. As a strategic sheet metal stamping partner, our commitment to your intellectual property is absolute. We operate under a strict Zero-Leak Policy, ensuring that every blueprint, CAD file, and prototype remains strictly confidential within our secure engineering ecosystem.

We proactively offer comprehensive Non-Disclosure Agreements (NDAs) that align with international legal standards, providing you with a transparent and enforceable framework for cooperation. Beyond legal paperwork, our internal protocols include segmented data access, secure server encryption, and rigorous staff training on IP sensitivity. Whether you are a startup scaling a disruptive product or an OEM managing sensitive aerospace components, Supro MFG acts as a secure extension of your own facility. Partner with a metal stamping manufacturer that values your competitive advantage as much as you do.

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Common Issues with Terminal Boxes

When procuring terminal boxes for industrial or commercial applications, consistent quality is critical to ensuring electrical safety and system longevity. Substandard manufacturing quality can result in failure to meet NEMA/IP protection ratings, equipment downtime, or safety hazards. Based on actual quality control data, the following is our analysis of several common defects in terminal boxes, including their root causes and the rigorous engineering solutions we have implemented to prevent them.

Failure of IP/NEMA Protection Ratings (Weld Porosity and Gaps)

Minor gaps or porosity in welds can allow moisture and dust to penetrate, causing the terminal box to fail leak-tightness tests. The root causes include inconsistent manual welding speeds, insufficient shielding gas, or improper heat control, which lead to pinholes.

We employ automated robotic TIG/MIG continuous seam welding technology to ensure 100% airtight joints. Every batch undergoes rigorous visual inspection and penetrant testing to guarantee complete leak-tightness.

Powder Coating Peeling or Flaking

The surface coating of the Terminal Box is prone to peeling during installation, leading to rapid corrosion of the exposed metal. The root cause of this issue is improper surface preparation, resulting in residual cutting oil, scale, or dust on the substrate prior to coating, or incorrect oven temperature settings.

All Supro Terminal Boxes undergo a rigorous five-stage chemical cleaning and phosphating process before coating. We continuously calibrate our ovens and use the ASTM D3359 cross-hatch test to verify adhesion.

Dimensional Distortion and Bending Deviations

Distortion of the terminal box body can cause door panels to install unevenly or result in misalignment of mounting holes with on-site equipment. The root causes include: failure to account for material springback, fluctuations in sheet metal yield strength, or the use of worn bending machine dies.

Our engineers program precise springback compensation parameters into CNC press brakes equipped with active angle measurement capabilities. Additionally, we implement a rigorous tooling maintenance program to ensure micron-level precision.

Deep Dents and Surface Scratches

Unsightly dents and deep scratches on the outer surface of the terminal box not only compromise aesthetics but also create weak points susceptible to corrosion. The root causes are: intermetallic friction generated on standard V-die dies during the bending process, or a lack of protective measures during sheet metal transportation.

We strictly use polyurethane die tape on our bending dies to eliminate creases. All high-quality sheet metal is sourced from suppliers that provide factory-applied PVC protective film, which remains on the parts until final assembly.

No design files? Let Supro MFG do it for you.

We often come across clients who have no professional design drawings and documentation, only a creative idea, which leads to the project being at a standstill.

If you are in this situation, then contact our team of experts.

Supro MFG, as an industry-leading custom metal fabricator, has an ever-experienced team of engineers who utilize their extensive fabrication experience and technical expertise to build your idea into a real product and create design files such as STEP/STP/SLDPRT/DXF/PDF/PRT/DWG/AI.

That’s what makes SUPRO MFG so great, and 2,000 corporate, entrepreneurial, artist, and other purchasers from around the world enjoy working with us and benefiting from our one-stop manufacturing services.

A part is only as good as its finish.

High-Performance Surface Finishing: Aesthetics Meets Durability

At Supro MFG, we understand that professional custom metal fabrication requires more than just structural integrity—it demands surface treatments that withstand harsh environments and strict aesthetic standards.

Our integrated finishing shop provides a seamless transition from the production line to the final coating, ensuring tight control over lead times and quality.