Rivet Nut Hole Size Chart
This page provides a comprehensive rivet nut hole size chart to help you determine the correct hole diameter for various rivet nut sizes and materials. Proper hole sizing is critical for secure fastening and optimal performance.
| Nut OD | Inch | Body Diameter (mm) | Recommended Hole Size (mm) | Grip Range (mm) | Typical Application |
| M3 | – | 5.0 | 5.1 – 5.2 | 0.5 – 1.5 | Electronics, thin sheet metal |
| M4 | – | 6.9 | 7.0 – 7.1 | 0.5 – 2.0 | Light machinery, automotive interiors |
| M5 | – | 8.4 | 8.5 – 8.6 | 0.5 – 3.0 | Appliances, furniture assembly |
| M6 | – | 10.0 | 10.1 – 10.2 | 1.0 – 4.0 | HVAC, structural panels |
| M8 | – | 13.5 | 13.6 – 13.7 | 1.0 – 5.0 | Automotive, heavy equipment |
| M10 | – | 16.5 | 16.6 – 16.7 | 1.0 – 6.0 | Industrial machinery, construction |
| M12 | – | 18.8 | 18.9 – 19.0 | 2.0 – 7.0 | Heavy machinery, structural steel |
| #6-32 | 0.138″ | 6.9 | 7.0 – 7.1 | 0.5 – 2.0 | Electronics, light assembly |
| #8-32 | 0.164″ | 8.4 | 8.5 – 8.6 | 0.5 – 3.0 | Appliances, automotive |
| #10-24 | 0.190″ | 9.7 | 9.8 – 9.9 | 0.5 – 3.5 | Office equipment, machinery |
| #10-32 | 0.190″ | 9.7 | 9.8 – 9.9 | 0.5 – 3.5 | Office equipment, electronics |
| 1/4”-20 | 0.375″ | 12.7 | 12.8 – 12.9 | 1.0 – 5.0 | Automotive, heavy-duty assemblies |
| 5/16”-18 | 0.438″ | 15.9 | 16.0 – 16.1 | 1.0 – 6.0 | Industrial equipment, construction |
| 3/8”-16 | 0.500″ | 18.0 | 18.1 – 18.2 | 2.0 – 7.0 | Heavy machinery, structural components |
| 1/2”-13 | 0.625″ | 22.0 | 22.1 – 22.2 | 3.0 – 8.0 | Structural steel, heavy equipment |
Note:
The hole diameter is slightly larger than the outer diameter of the rivet nut, which is conducive to insertion but should not be too loose.
This page provides a comprehensive rivet nut hole size chart to help you determine the correct hole diameter for various rivet nut sizes and materials. Proper hole sizing is critical for secure fastening and optimal performance.
1. Problems with Holes That Are Too Small
If the drilled hole is smaller than the recommended size, the following issues may occur:
- Rivet nut is difficult to insert: Excessive force may be required during installation, or the nut may not fit into the hole at all.
- Damage to knurls or splines: An overly tight hole can damage the external features of the rivet nut, compromising its anti-rotation or anchoring function.
- Risk of deforming the base material: Especially in softer materials like aluminum or plastic, forcing the nut in may cause cracking, bulging, or warping of the workpiece.
2. Risks of Holes That Are Too Large
If the hole exceeds the recommended diameter, the following problems may arise:
- Loose installation: Excess clearance between the nut and the hole wall prevents proper expansion during setting, resulting in a loose fit.
- Rotation or pull-out risk: The nut may spin or fall out under vibration or load, seriously affecting the joint’s strength and safety.
- Reduced anti-rotation performance: Hex or splined rivet nuts rely on tight-fitting holes for torque resistance. Oversized holes prevent proper engagement and rotation prevention.
3. Recommended Practice: Inspect the Hole After Drilling
To ensure accurate hole size, it is recommended to take the following steps after drilling:
- Use a vernier or digital caliper: Ideal for manual assembly or prototyping, calipers provide precise measurements of the hole diameter.
- Account for material-specific tolerances: Different materials may expand or deform slightly after drilling. Adjust drill size accordingly to compensate for thermal or mechanical effects.
Does Hole Size Vary by Material?
Yes, the recommended hole size can vary depending on the material being used. This is because different materials have different characteristics—such as strength, hardness, ductility, and machinability—which all affect how well a rivet nut installs and holds over time. Here’s a breakdown of recommendations based on common materials:
Steel Plate
- Tighter tolerance is recommended, with hole sizes kept as close as possible to the standard specification.
- Steel is hard and resistant to deformation, so oversized holes may prevent the rivet nut from anchoring securely.
- Use standard drill bits with precise machining to avoid issues like spinning or loosening of the nut.
Aluminum Plate
- Slightly undersized holes (about 0.1mm smaller) can be acceptable, as aluminum is softer and allows the rivet nut to expand and grip the hole wall.
- If the hole is too large, aluminum’s low rebound force may lead to nut movement or rotation.
- It’s best to use drill bits designed for aluminum to ensure a clean hole and consistent size.
Plastic Plate
- Smaller hole sizes are recommended, as plastic is soft and prone to deformation under heat or pressure.
- An oversized hole may result in poor retention or complete pull-out of the rivet nut.
- Keep in mind that plastic may also shrink or creep over time, so allow for these effects during design and testing.
In practice, it’s important to adjust drill size and tolerance depending on the material. Performing a test installation before mass production is a reliable way to ensure proper fit. When in doubt, consult your rivet nut supplier for recommended hole size ranges specific to different materials.
What Are the Common Types of Rivet Nuts?
In practical applications, rivet nuts come in various types based on their external shape and anti-rotation features. Each type has different requirements for hole size, hole shape, and compatibility with different materials. Below is a brief introduction to three commonly used types:
- Features a smooth cylindrical exterior with no anti-rotation design.
- Suitable for softer materials such as plastic or aluminum sheets, relying on friction after installation to resist rotation.
- Requires a precise round hole within the recommended tolerance range.
- Easy to install and ideal for light-duty or non-structural applications.
- Has vertical knurls or splines on the outer surface to enhance anti-rotation performance.
- Suitable for metal materials such as steel or aluminum sheets, where the knurled surface grips the hole wall during deformation.
- Requires a standard round hole slightly larger than smooth body types to accommodate the knurls, but still ensures an interference fit.
- A widely used general-purpose type, ideal for medium-load applications.
- Shaped as a hexagonal prism and provides excellent resistance to rotation.
- Requires a hexagonal hole or a pre-machined anti-rotation groove in the panel to prevent spinning.
- Best suited for high-torque, high-vibration, or frequently assembled or disassembled applications.
- Demands higher precision in hole preparation, making it ideal for mass production and standardized installations.
What Tools Are Recommended for Install Rivet Nuts?
The choice of installation tools directly affects the quality and efficiency of rivet nut installation. Depending on the assembly volume, material type, and working environment, the following types of tools are commonly recommended:
- Ideal for small-batch or repair jobs.
- Simple to operate and do not require power; commonly used for small sizes such as M3 to M6.
- The downside is lower efficiency and limited control over consistency, as force is applied manually.
- Suitable for medium-volume production with higher installation efficiency.
- Often come with adjustable settings for stroke or pulling force, improving installation consistency.
- Commonly used in workbench or semi-automated production environments.
- Best suited for high-frequency, high-volume production.
- Provide stable pulling force and can be integrated with PLC systems or automatic feeding for semi- or fully-automated operation.
- Fast and consistent installation, making them the mainstream choice in industrial production lines.
d. Torque Control
- Regardless of the tool type, it’s recommended to use torque or stroke control to prevent over-tightening, which can lead to rivet nut failure or panel deformation.
- You can test the pull-out strength or rotational torque of sample installations to verify proper settings.
FAQs
1. Why Is the Rivet Nut Not Holding Tight?
There are several common reasons why a rivet nut may not hold securely:
- Hole Too Large: This is the most common issue. An oversized hole creates too much clearance, preventing the rivet nut from forming a tight fit and leading to looseness or detachment.
- Panel Too Thin or Soft: Materials like thin aluminum or plastic may not provide enough resistance, preventing the nut from expanding fully.
- Insufficient Installation Stroke or Torque: The tool may not be pulling the rivet nut completely into place—check the tool settings.
- Incorrect Nut Type: Using a smooth body rivet nut in high-load applications may not provide enough anti-rotation strength.
2. Can Rivet Nuts Be Installed Manually?
Yes, but there are limitations:
- Suitable for small sizes (M3–M6) and low-volume installations, such as prototyping or repairs.
- You can use a manual rivet nut tool, or in some cases, a DIY method using a bolt, nut, and wrench.
- However, manual installation has lower consistency and lacks precise control over stroke or torque, so it’s not recommended for mass production or load-critical applications.
3. What If the Hole Is Too Large?
If the hole is larger than the recommended size, consider the following solutions:
- Use a Larger Rivet Nut: For example, switch from M6 to M8, if the structure allows for a larger size.
- Select Reinforced Nut Types: Knurled or hex body nuts are more tolerant of oversized holes due to better anti-rotation features.
- Apply Hole Repair Methods: In non-metallic materials, structural adhesives or epoxy can help fill gaps and secure the nut.
- Welding or Re-Machining: In metal applications, high-precision areas may require welding and re-drilling for a proper fit.
