Nuts
Nuts are internally threaded fasteners designed to mate with bolts, set screws and threaded studs. Together they create a strong, reliable clamping force that holds components and assemblies together. Although simple in appearance, nuts are available in a wide range of shapes, strengths and locking mechanisms to suit different engineering requirements.
FastenerFix primarily supplies standard regular hex nuts, but the wider family of nut types is outlined below for reference and general understanding.
How Nuts Work
A nut engages with the external thread of a bolt or screw to generate tension in the fastener and compression in the joint. The clamping force depends on the thread form, material grade, lubrication and tightening torque. Most nuts are hexagonal to allow tightening with standard tools, but specialised forms exist for restricted spaces or vibration‑prone environments.
Common Nut Types
Although FastenerFix currently supplies only regular hex nuts, the most common nut types are shown below for general reference.
- Hex Nuts – The standard form used in most bolted joints. Available in metric and imperial thread systems and in strength grades to match the corresponding bolt.
- Full Nuts vs Half Nuts – Full nuts provide maximum thread engagement. Half nuts (jam nuts) are thinner and often used as locking partners or where space is limited.
- Nyloc Nuts – Feature a nylon insert that provides frictional resistance to loosening. Suitable for vibration‑prone assemblies but not for high‑temperature environments.
- All‑Metal Lock Nuts – Use deformed threads or slotted designs to resist loosening without polymer inserts. Ideal for high‑temperature or heavy‑duty applications.
- Flange Nuts – Include an integrated washer‑like flange to spread load and reduce the need for a separate washer.
- Wing Nuts – Designed for hand tightening where tools are not required.
- Cap Nuts – Feature a closed end to protect the exposed bolt thread and improve appearance.
Materials and Strength Grades
Nuts are manufactured in a range of materials to suit different environments and mechanical requirements. The most common are:
- Carbon Steel – The standard choice for general engineering.
- Stainless Steel (A2 / A4) – Corrosion‑resistant and suitable for outdoor or marine environments.
- Brass – Used for electrical, decorative and low‑torque applications.
Strength grades for nuts are designed to match the tensile strength of the corresponding bolt. For example, a Grade 8 imperial nut or a Grade 10 metric nut is intended to pair with bolts of the same grade to ensure safe load‑bearing performance.
Thread Compatibility
Nuts must always match the thread system and pitch of the bolt or screw they are used with. Metric nuts pair with ISO metric bolts (e.g. M10 × 1.5), while imperial nuts follow systems such as UNC, UNF, BSW or BSF. Mixing thread forms is unsafe and will result in poor engagement or thread damage.
Compatibility of Hex Nuts Available from FastenerFix
The table below shows which of our stocked hex nuts are suitable for use with different bolt and screw materials and strength grades. Compatibility is based on mechanical strength, thread standards and good engineering practice.
| Bolt / Screw Material | Steel 6 AU (Self Colour) |
Steel 8 (Self Colour) |
Steel 8 (Zinc Plated) |
Steel 10 (Self Colour) |
Steel 10 (Zinc Plated) |
Steel 12 (Self Colour) |
Stainless A2 | Stainless A4 | Brass |
|---|---|---|---|---|---|---|---|---|---|
| Mild Steel | ✔ Suitable | ✔ Suitable | ✔ Suitable | ✔ Suitable | ✔ Suitable | ✔ Suitable | ✔ Suitable | ✔ Suitable | ✔ Suitable |
| Grade 8.8 Steel | ✔ Suitable | ✔ Recommended | ✔ Recommended | ✔ Suitable | ✔ Suitable | ✔ Suitable | ✔ Suitable | ✔ Suitable | ✖ Not recommended |
| Grade 10.9 Steel | ✖ Too weak | ✔ Suitable | ✔ Suitable | ✔ Recommended | ✔ Recommended | ✔ Suitable | ✔ Suitable | ✔ Suitable | ✖ Not recommended |
| Grade 12.9 Steel | ✖ Too weak | ✖ Too weak | ✖ Too weak | ✔ Suitable | ✔ Suitable | ✔ Recommended | ✔ Suitable | ✔ Suitable | ✖ Not recommended |
| A2 Stainless | ✔ Suitable | ✔ Suitable | ✔ Suitable | ✔ Suitable | ✔ Suitable | ✔ Suitable | ✔ Recommended | ✔ Suitable | ✖ Not recommended |
| A4 Stainless | ✔ Suitable | ✔ Suitable | ✔ Suitable | ✔ Suitable | ✔ Suitable | ✔ Suitable | ✔ Suitable | ✔ Recommended | ✖ Not recommended |
| Brass | ✔ Suitable | ✔ Suitable | ✔ Suitable | ✔ Suitable | ✔ Suitable | ✔ Suitable | ✔ Suitable | ✔ Suitable | ✔ Recommended |
Nuts should always match or exceed the strength of the bolt or screw they are paired with. Stainless steel and brass combinations may be suitable for low‑load applications, but high‑strength bolts (10.9 and 12.9) require matching high‑grade steel nuts to ensure safe clamping performance.