Guide to Different Rivet Nut Sizes
Leading Rivet Nut Manufacturer and Supplier in China
When it comes to ensuring strong and reliable connections in various applications, selecting the right rivet nut size is crucial. Understanding the different rivet nut sizes available is key to achieving optimal performance and stability. Whether you’re working with automotive, electronic, or industrial equipment, the right rivet nut size can make all the difference. In this guide, we’ll explore the different sizes of rivet nuts, their specific applications, and tips for selecting the best one for your project. Let’s dive into the world of rivet nuts and learn how to choose the perfect fit for your needs.
Table of Contents
When selecting or designing with rivet nuts, understanding their “sizes” is a crucial step. Rivet nut sizes are not just simple numbers but are a combination of several dimensional parameters. Below are the main parameters that define rivet nut sizes and their significance:
1. Thread Size
Thread size refers to the internal thread size of the rivet nut, which directly determines the size of the bolts or screws that can be paired with it.
Common thread sizes are divided into two main categories: Metric and Imperial.
- Metric Thread Sizes such as M3, M4, M5, M6, M8, M10, M12
- Example: M6 = Metric 6mm diameter, with a standard pitch of 1.0mm
- Imperial Thread Sizes such as #6-32, #8-32, 1/4-20, 5/16-18
- Example: 1/4-20 = 1/4-inch thread diameter, 20 threads per inch
When selecting, ensure the thread size matches the bolt specifications to avoid issues such as stripping threads or poor connection.
2. Body Diameter
Body diameter refers to the maximum diameter of the cylindrical part of the rivet nut, which is closely related to the size of the installation hole.
If the installation hole is too small, the rivet nut will not fit. If it is too large, the rivet nut may rotate or pull out during installation.
- Example: A M6 cylindrical rivet nut may have a body diameter of about 9.0mm, with a recommended installation hole size of 9.1–9.3mm.
Always check the recommended hole size in the product datasheet before drilling.
3. Total Length
Total length refers to the vertical length from the top edge to the bottom of the rivet nut.
This parameter determines the “embedment depth” after installation, which is especially important when space is limited or circuit boards need to be avoided inside devices.
- Example: For the same M6 threaded rivet nut, one may have a standard length of 13mm, while another may be an extended version at 20mm, with the latter possibly not fitting thinner enclosures or packaging spaces.
Hole size refers to the diameter of the pre-drilled hole. It must match the body diameter of the rivet nut to allow smooth insertion and secure locking.
- Example: For a specific M5 rivet nut, the recommended hole size is 7.1mm, so a 7.1mm drill bit should be used, not an arbitrary “similar-looking” size.
An incorrect hole size can lead to rotation, falling out, or failure to rivet properly.
Grip range refers to the thickness range of the material or workpiece that the rivet nut can securely fasten.
- Example: A M5 closed-end rivet nut may have a grip range of 0.5–3.0mm, indicating it is suitable for materials with a thickness between 0.5 and 3.0 millimeters.
- If the material thickness exceeds this range, the rivet nut may fail to provide an effective clamping force, or even detach from the material.
Always ensure that the material thickness falls within the rivet nut’s grip range when selecting.
6. Effect of Nut Type on Size
Different types of rivet nuts (such as cylindrical, hexagonal, closed-end, open-end) can have varying external dimensions and installation parameters, even if they share the same thread size:
- Cylindrical: Common for regular use, easy to install.
- Hexagonal: Used in applications where high resistance to rotation is required, installation hole needs to be hexagonal.
- Closed-End: Prevents moisture or dust from entering through the threaded hole, used in electrical or damp environments.
- Miniature: Suitable for extremely tight spaces or ultra-thin materials.
Thus, even an M4 rivet nut can have differences in total length, hole size, and installation method.
7. Overview of Metric and Imperial Standards
Metric:
- Commonly used in Asia, Europe, and other regions, with units in millimeters (mm).
- Examples include M6, M8, M10, which are compatible with most European-standard equipment and drawings.
Imperial:
- Commonly used in the United States, Canada, and other regions, with units in inches (inch).
- Examples include 1/4-20, 5/16-18, which are more compatible with American-standard screws and industrial systems.
If your project involves international supply chains, be sure to pay attention to standard differences to avoid selection errors due to different unit systems.
Different Rivet Nut Sizes of Rivet Nut Types
Common Head Types:
- Reduced Head: The head is very small, suitable for situations where space is limited.
- Flat Head: Sits flush with the surface after installation, ideal for applications where a flat surface is required.
- Countersunk Head: Can be fully recessed into the material, suitable for high aesthetic requirements or situations where protruding structures need to be avoided.
Common Size Range:
- Metric: M3 – M12
- Imperial: #6-32 to 1/2-13
- Grip Range: 0.5 – 6.0mm (depending on the model)
Applications:
- General machinery assembly, sheet metal enclosures, electronic devices, etc.
- Suitable for automation equipment installation, most widely used basic type.
Types:
- Full Hex: The entire rivet nut is hexagonal, offering excellent resistance to rotation.
- Half Hex: Only the rivet zone is hexagonal, making installation more flexible.
Common Size Range:
- Metric: M4 – M10 (M6 and M8 are the most commonly used)
- Imperial: 1/4-20, 5/16-18, etc.
- Recommended Installation Hole: Requires punching or milling hexagonal holes (e.g., a 9.0mm hexagonal hole for M6).
Applications:
- Suitable for high vibration or high torque applications, such as automotive chassis and reinforced structures in enclosures.
- Recommended for installation areas where the nut should not rotate or loosen.
3. Closed-End vs Open-End Rivet Nuts
Closed-End Rivet Nuts (Blind Rivet Nuts)
- The tail is closed to prevent dust, moisture, or liquid from entering the internal threads.
- Common Size Range: M3 – M8
- Total Length is usually slightly longer than open-end rivet nuts (the closed tail adds about 1–2mm).
Applications:
- Electrical equipment, outdoor applications, damp or corrosive environments (e.g., distribution boxes, offshore equipment).
- Prevents internal liquid accumulation, electrical short circuits, or screws from penetrating parts.
Open-End Rivet Nuts (Standard Rivet Nuts)
- The tail is open, allowing through-type connections, suitable for most general structures.
- The most extensive variety of sizes, lower cost, and the widest application range.
Applications:
- Industrial automation equipment, mechanical enclosures, furniture hardware, general steel sheet connections, etc.
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How to Choose the Right Rivet Nut Sizes?
1. Choose the Right Grip Range Based on Material Thickness
When installing a rivet nut, it is fixed by deformation in the material. Therefore, the grip range must cover the thickness of the target material.
- Grip Range Definition: The thickness range of the material that the rivet nut can securely fix (e.g., 0.5–3.0mm).
- Selection Suggestions:
- If the material thickness is 2mm, choose a model with a grip range of 1.5–2.5mm or 1.0–3.0mm. Avoid selecting models where the upper and lower grip limits are exactly equal to the material thickness to ensure clamping strength and safety.
- If the grip range is too small, the nut cannot deform fully to fix securely. If the range is too large, it may not clamp tightly or may fail during installation.
2. Match the Body Diameter with the Hole Size
The rivet nut needs to be inserted into a pre-drilled hole in the material, so the hole diameter must match the body diameter of the rivet nut.
- Matching the Body Diameter with the Installation Hole is Critical:
- If the hole is too small: the nut cannot be inserted or may damage the body.
- If the hole is too large: the rivet nut may loosen after installation, failing to secure properly.
- Selection Suggestions:
- M6 round body open-end rivet nuts typically fit an installation hole diameter of 9.0mm.
- For hex body types, hexagonal punching is required, and the across-flat dimensions should be checked.
3. Select the Thread Size Based on Load Requirements
The thread size of the rivet nut (e.g., M4/M5/M6) determines the size of the screws that can be installed, which directly impacts the strength and load-bearing capacity of the connection.
- Common Selection References:
- M3/M4: Suitable for light load connections, such as electronic devices and metal enclosures.
- M5/M6: Suitable for medium load applications, such as sheet metal components and bracket installations.
- M8/M10 and above: Suitable for high-load connections, such as automotive chassis and heavy frames.
- Selection Suggestions: Based on the specific load requirements of the application, it is recommended to choose a thread size with a higher safety factor, ensuring a tight match between the screw and the nut.
4. Typical Size Selection Chart (Example)
| Thread Size | Installation Hole Diameter (Round Body) | Recommended Grip Range | Typical Applications |
| M3 | 5.0 – 5.1 mm | 0.5 – 1.5 mm | Small electronic enclosures, lightweight aluminum sheet connections |
| M4 | 6.0 – 6.1 mm | 0.5 – 2.5 mm | Hardware enclosures, household appliance panels |
| M5 | 7.0 – 7.1 mm | 0.5 – 3.0 mm | Medium-load machinery, metal brackets |
| M6 | 9.0 – 9.1 mm | 0.5 – 3.5 mm | Automotive sheet metal, industrial control boxes, furniture structures |
| M8 | 11.0 – 11.1 mm | 1.0 – 5.0 mm | Heavy-duty installations, frame systems |
Note: Specific sizes may vary depending on product type (e.g., open/closed, hex/round) and the manufacturer. Always refer to the technical specification sheet or confirm with the supplier when selecting.
Summary Suggestions:
When choosing rivet nut sizes, it is recommended to first confirm the following:
- Material thickness → Corresponding grip range
- Installation hole diameter → Precisely match the body diameter
- Thread size → Select based on load capacity and application requirements
- Refer to the selection chart or supplier’s technical documentation → Accurately determine the appropriate model
Different Rivet Nut Sizes Comparison Chart
| Thread Size (Metric) | Thread Size (Imperial) | Installation Hole Diameter | Grip Range | Standard Length | Typical Applications |
| M3 | #6 | 5.0 mm | 0.5–1.5 mm | 6–8 mm | Electronic devices, lightweight metal enclosures |
| M4 | #8 | 6.0 mm | 0.5–2.5 mm | 8–10 mm | Household appliance enclosures, precision machinery |
| M5 | #10 | 7.0 mm | 0.5–3.0 mm | 10–12 mm | Medium-load machinery |
| M6 | #12 | 9.0 mm | 0.5–3.5 mm | 12–15 mm | Automotive, metal frame structures |
| M8 | #14 | 11.0 mm | 1.0–5.0 mm | 15–20 mm | Heavy machinery, frame systems |
| M10 | #16 | 13.0 mm | 1.5–6.0 mm | 18–22 mm | Heavy-duty structures, construction equipment |
| M12 | #18 | 15.0 mm | 2.0–7.0 mm | 22–25 mm | High-strength connections, automotive industry |
Parameter Explanations:
1. Thread Size (Metric and Imperial):
- Metric (M3–M12): Indicates the diameter of the thread in millimeters.
- Imperial (#6–5/16): Represents the standard imperial thread sizes, commonly used in the United States and other regions with the imperial system.
2. Installation Hole Diameter:
- The installation hole diameter refers to the diameter of the drilled hole in the material. It needs to match the external diameter of the rivet nut to ensure stability and a secure fastening during installation.
3. Grip Range:
- The grip range refers to the thickness range of the material that the rivet nut can securely fix. When selecting, ensure the material thickness falls within the specified grip range to ensure a strong fastening.
4. Standard Length:
- The standard length is the typical length of the rivet nut, referring to the total length of the nut. When selecting, consider how it matches the installation hole to ensure adequate clamping force.
Recommended Rivet Nut Sizes by Application
1. Automotive Industry: M6–M10 for Body Structure
In the automotive industry, especially in body structure connections, rivet nuts play an essential role. Since the body structure needs to withstand significant external forces, the rivet nut sizes should be larger, with M6–M10 being the recommended range. These sizes provide sufficient clamping force and load-bearing capacity, ensuring the stability of vehicle components under high-speed driving and other harsh conditions.
- Advantages of M6–M10:
- Suitable for the vehicle’s frame, chassis, engine bay, and interior fastening.
- Provides strong fastening force to meet the automotive industry’s requirements for shock resistance and vibration control.
- Suitable for thicker metals or composite materials, ensuring a stable connection.
2. Electronic Devices: Thin Sheets Recommended M3–M5
In the design of electronic devices, the focus is often on lightweight, precision, and efficient assembly, so rivet nuts are mainly used for thin sheet materials. For thin sheet materials, M3–M5 rivet nuts are recommended. These sizes effectively secure thin metal enclosures, PCBs, and other lightweight structures without adding excessive weight.
- Advantages of M3–M5:
- Suitable for thin sheet materials like electronic device enclosures, computer accessories, communication equipment, etc.
- Ensures precise installation, preventing loosening caused by vibrations or external forces.
- Provides sufficient fastening force, suitable for thinner metal sheets or plastic housings.
3. Household Appliances and Furniture: Medium Thickness Sheets Recommended M4–M6
Household appliances and furniture production typically use materials of medium thickness, making it crucial to choose the right size rivet nut. For these applications, M4–M6 rivet nuts are recommended. These sizes provide good clamping force without significantly increasing the overall weight of the product. They are ideal for connecting appliance enclosures, cabinet structures, etc.
- Advantages of M4–M6:
- Suitable for household appliance enclosures, furniture frames, storage cabinets, etc.
- Offers sufficient load-bearing capacity to ensure stability during long-term use.
- Suitable for various materials, such as medium-thickness steel plates and aluminum alloys.
Summary - Recommended Rivet Nut Sizes by Application
When selecting the appropriate rivet nut size, it is crucial to consider the requirements of the application. Below are the recommended sizes for common applications:
- Automotive Industry: M6–M10, suitable for body structures that bear larger loads.
- Electronic Devices: M3–M5, suitable for thin sheets and precise installation scenarios.
- Household Appliances and Furniture: M4–M6, suitable for medium-thickness sheets, ensuring stable connections.
By selecting the appropriate rivet nut size based on different industry needs, the stability, load-bearing capacity, and production efficiency of the connection can be ensured.
Common Mistakes When Selecting Different Rivet Nut Sizes
1. Installation Hole Too Large or Too Small
Error Explanation:
- If the size of the installation hole is not appropriate, it may prevent the rivet nut from being properly installed, affecting the stability of the connection.
- If the hole diameter is too small, the rivet nut may not fit properly, potentially causing damage or installation difficulties.
- If the hole diameter is too large, the rivet nut may not be properly secured, leading to loosening or rotation.
Solution:
- When selecting a rivet nut, ensure that the installation hole size matches the required dimensions for the rivet nut. Each rivet nut typically has a recommended range for the installation hole diameter.
- Ensure the hole size accommodates the rivet nut’s outer diameter and provides sufficient clamping force, avoiding holes that are too large or too small.
2. Ignoring Grip Range, Leading to Rotation or Loosening
Error Explanation:
The grip range of a rivet nut refers to the thickness range of materials that the rivet nut can securely hold. If the selected grip range is incorrect, the rivet nut may not fully secure the material, resulting in rotation or loosening. This is especially problematic in high-vibration or high-load applications, where insufficient gripping force can lead to an unstable connection, compromising the product’s safety and durability.
Solution:
- When selecting a rivet nut, ensure that the grip range matches the thickness of the material. For thin materials, choose a rivet nut with a smaller grip range; for thicker metals, select a rivet nut with a larger grip range.
- Make sure the grip range of the rivet nut matches the material thickness to avoid insufficient clamping, ensuring the rivet nut performs optimally.
3. Using Incorrect Sizes and Surface Treatments for Different Materials
Error Explanation:
Different materials require different rivet nut sizes and surface treatments. Ignoring material differences may result in the rivet nut not providing sufficient connection strength or corrosion resistance. For example, aluminum alloys and stainless steel have significantly different hardness, and using the same size rivet nut could lead to an insecure connection or rusting.
Solution:
- Select the appropriate rivet nut size based on the material type and application environment. For instance, steel and aluminum require different rivet nut specifications and surface treatments.
- For rivet nuts used in harsh environments (e.g., marine or chemical settings), choose those with corrosion-resistant treatments (such as zinc-plating, stainless steel, or surface coatings).
- When selecting, consider whether the rivet nut’s material and surface treatment match the installation material to prevent poor connection quality or corrosion issues.
Summary - Common Mistakes When Selecting Different Rivet Nut Sizes
Choosing the correct rivet nut size is crucial. Below are common mistakes and their solutions:
- Installation Hole Too Large or Too Small: Ensure the installation hole size matches the rivet nut’s requirements.
- Ignoring Grip Range: Choose the appropriate grip range based on the material thickness to avoid rotation or loosening.
- Using Incorrect Sizes and Surface Treatments for Different Materials: Select the appropriate rivet nut size and surface treatment based on the material and application environment.
By avoiding these common mistakes, you can ensure the effective installation and long-term stability of the rivet nut connection.
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