Sealing Blind Rivet Nuts for EV Battery Enclosures | Stainless Steel & Carbon Steel Threaded Inserts

Sealing Blind Rivet Nuts for EV Battery Enclosures

High-Strength Threaded Fastening with Waterproof Sealing for Thin Sheet Structures

Blind rivet nuts are widely used in the assembly of electromechanical and light-industrial products, such as automobiles, aerospace equipment, instruments, furniture, and architectural structures. They provide reliable threaded connections in thin sheet metals and pipes ranging from 0.5 mm to 6 mm in thickness, where conventional tapping or welding methods are difficult to apply.

By combining the working principles of core-pull rivets and welded nuts, blind rivet nuts create strong, reusable internal threads in thin materials while allowing installation from only one side of the workpiece. This makes them an efficient fastening solution in modern manufacturing.

In electric vehicle battery enclosure systems, sealing blind rivet nuts are particularly important because they provide both structural fastening and environmental sealing, ensuring the safety and reliability of battery systems operating under harsh conditions.

Challenges of Traditional Fastening in Thin Sheet Metal

Traditional fastening solutions often face limitations in thin sheet structures:

• Thread tapping is difficult in thin sheet metal

• Welding nuts may burn through thin materials or tubes

• Welding can cause deformation in lightweight aluminum      structures

• Metal-to-metal contact between inserts and sheet material may      result in poor sealing performance

To address these issues, sealing blind rivet nuts incorporate specialized sealing structures that prevent leakage paths and ensure airtight, waterproof performance.

Material Options for Blind Rivet Nuts

Blind rivet nuts are available in multiple materials to meet different mechanical strength, corrosion resistance, and weight requirements.

Stainless Steel Rivet Nuts

Common stainless steel grades include:

• 304 Stainless Steel (18-8)

• 316 Stainless Steel

• 316L Stainless Steel

These materials provide:

• excellent corrosion resistance

• resistance to moisture and mild chemicals

• long service life in outdoor or wet environments

Stainless steel rivet nuts are commonly used in EV battery enclosures, electrical housings, and marine or outdoor equipment.

Carbon Steel Rivet Nuts

Carbon steel rivet nuts are typically produced from 08A steel and can be surface-treated with zinc plating or other coatings.

Advantages include:

• high mechanical strength

• cost-effective large-scale production

• suitable for structural automotive components

They are widely used in automotive chassis systems and industrial equipment assemblies.

 Aluminum Rivet Nuts

Aluminum rivet nuts provide:

• lightweight fastening solutions

• good corrosion resistance

• compatibility with aluminum sheet materials

They are often used in lightweight structures and aerospace applications.

 Copper Rivet Nuts

Copper rivet nuts offer:

• excellent electrical conductivity

• corrosion resistance

• suitability for electrical equipment assemblies

They are commonly used in electrical devices and specialized industrial equipment.

Structural Design of Sealing Blind Rivet Nuts

To achieve both strong fastening and sealing performance, sealing blind rivet nuts incorporate several structural features.

Closed-End Rivet Nut Design

Closed-end rivet nuts prevent water or dust from entering through the threaded body of the insert.

This design significantly improves the airtightness of sealed enclosures.

Flange Sealing Structure

The flange area may include:

• integrated sealing rings

• plastic sealing layers

• elastomer gaskets

These components create a compression seal between the rivet nut and the installation surface, preventing leakage paths.

Cold Extrusion Riveting Structure

During installation, the rivet nut body is deformed by cold extrusion, forming a backside flange that clamps the sheet metal securely.

This structure provides:

• excellent thin-wall riveting performance

• strong vibration resistance

• stable long-term fastening reliability

Installation Method

Blind rivet nuts are installed using a rivet nut gun or rivet nut tool.

Installation steps include:

1. Drill or punch a hole in the sheet material.

2. Insert the rivet nut into the hole.

3. Use a rivet nut tool to pull the threaded mandrel.

4. The rivet nut collapses and forms a backside flange.

5. The flange compresses against the sheet surface to form a      secure connection.

Because installation requires access to only one side of the material, blind rivet nuts are ideal for closed structures such as tubes, cabinets, and battery housings.

Application in Electric Vehicle Battery Enclosures

Electric vehicle battery packs serve as the vehicle's primary energy source, and their safety directly affects the vehicle's overall safety.

Battery packs are typically installed under the vehicle chassis, where they are exposed to water, dust, vibration, and road debris.

Therefore, battery enclosures must meet at least:

IP67 protection rating

This rating ensures protection against dust intrusion and temporary water immersion.

Key Sealing Interfaces in Battery Pack Design

The sealing design of EV battery enclosures focuses on several critical interfaces.

Upper and Lower Battery Box Connection

Battery packs usually consist of an upper cover and a lower enclosure frame.

These two components are connected through flanged structures combined with sealing gaskets.

Blind rivet nuts are installed on the flange of the lower enclosure to provide threaded fastening points for bolts.

When the bolts are tightened, the sealing gasket is compressed between the flanges, ensuring uniform sealing pressure and maintaining the IP67 protection level.

High and Low Voltage Connector Interfaces

Battery packs contain multiple electrical connectors for high-voltage and low-voltage systems.

Sealing rivet nuts provide secure fastening points for connector mounting structures while preventing moisture intrusion into electrical components.

External Device Mounting Interfaces

Sensors, controllers, cooling systems, and protection components require secure installation points on the battery enclosure.

Blind rivet nuts provide strong threaded connections without damaging thin enclosure panels.

Typical Rivet Nut Specifications Used in Battery Packs

In EV battery enclosure manufacturing, commonly used rivet nuts include:

• Thread sizes: M5 and M6

• Structure: Flat head semi-hex body

• Material thickness compatibility:      approximately 2.5 mm stepped sheet structures

Blind hole rivet nuts are typically installed on:

• enclosure sealing surfaces

• enclosure frame structures

• bottom plates connecting battery modules

These inserts ensure secure fastening between the upper cover and enclosure frame while maintaining sealing integrity.

Advantages of Blind Rivet Nuts in Modern Manufacturing

Blind rivet nuts offer several advantages over traditional fastening methods.

Strong Reusable Internal Threads

They create strong internal threads in thin-sheet materials, enabling repeated assembly and disassembly.

One-Side Installation

Blind installation allows fasteners to be installed in locations where the back side of the structure is inaccessible.

Improved Manufacturing Efficiency

Rivet nut installation is fast and compatible with automated production lines, increasing manufacturing efficiency.

Improved Structural Appearance

Compared with welded nuts, rivet nuts provide a cleaner and more aesthetically pleasing installation, which is beneficial for visible structural components.

Typical Industrial Applications

Blind rivet nuts are widely used across multiple industries, including:

• automotive manufacturing

• electric vehicle battery systems

• aerospace structures

• electrical cabinets and chassis enclosures

• ventilation equipment and fans

• square and round tubular structures

• architectural metal assemblies and fences

Their ability to provide strong threaded connections in thin materials makes them an essential fastening solution in modern engineering.