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Nuts

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Hex nuts are one of the most common types of fasteners, characterized by their six-sided (hexagonal) shape. They are used in conjunction with bolts, screws, or threaded rods to securely fasten materials together. Hex nuts are available in various materials, strengths, and thread types, making them suitable for a wide range of applications, from light-duty household use to heavy-duty industrial settings.

Locknuts

They achieve this through various mechanisms, such as nylon inserts, serrations, or clamping designs. Locknuts are commonly used in machinery, automotive, and construction applications to ensure that connections remain secure even in challenging conditions.

Flange Nuts

The most defining feature of flange nuts is the built-in, washer-like flange at one end. This flange is wider than the nut's body, helping to distribute the load over a larger surface area. This reduces the risk of damaging the surface being fastened.

Coupling Nuts

Coupling nuts are typically hexagonal, allowing them to be tightened or loosened with a standard wrench or socket. The hex shape provides good grip and torque for secure fastening.

Cap Nuts

Cap nuts, also known as dome nuts, are fasteners with a domed, closed end that covers and protects the exposed threads of a bolt or screw, offering both a secure connection and a neat, finished appearance while preventing damage, debris, and corrosion from affecting the fastener. They are commonly used in applications requiring both functionality and aesthetics, such as automotive, furniture, and outdoor structures.

Panel Nuts

anel nuts are much thinner than standard nuts, allowing them to sit flush or nearly flush with the surface of a panel. This makes them ideal for applications where space is constrained or where aesthetics require a minimalistic appearance.

Socket Nuts

Socket nuts, also known as socket head nuts or internal wrenching nuts, are specialized fasteners that feature an internal drive system, allowing them to be tightened or loosened using a tool that fits into the socket (such as a hex key or Allen wrench).

Tamper-Resistant Nuts

These nuts require special tools for installation and removal, making them highly secure and ideal for use in public spaces, high-security environments, and applications where theft or unauthorized access is a concern.

Push-Button Nuts

They typically feature a push-button mechanism that allows the nut to be threaded onto or off of a bolt or rod with a simple press, making them ideal for applications requiring frequent adjustments or where convenience is a priority.

Sealing Nuts

Sealing nuts, also known as self-sealing nuts, are specialized fasteners designed to provide both a secure mechanical connection and a reliable seal to prevent the leakage of fluids, gases, or contaminants through threaded joints.

Split Nuts

They are typically composed of two or more parts (halves or segments) that can be opened or closed around a threaded rod, allowing them to be installed or removed without having to fully unscrew the nut.

Slotted Round Nuts

Slotted round nuts, also known as castle nuts or castellated nuts, are specialized fasteners designed with slots (or notches) cut into the top of the nut.

Lug Nuts

These are the most common type of lug nuts used in everyday vehicles, featuring conical, flat, or spherical seats. They are designed to securely fasten wheels to the vehicle and are available in various sizes and materials.

Press-Fit Nuts

Press-Fit Nuts are specialized fasteners designed to be permanently installed into pre-drilled or pre-punched holes in sheet metal, soft metals, or plastic materials.

Weld Nuts

Weld nuts are specialized fasteners designed to be welded onto metal surfaces, providing a strong, permanent threaded connection for secure fastening in structural and heavy-duty applications.

Rivet Nuts

Rivet Nuts, also known as threaded inserts or blind rivet nuts, are fasteners designed to provide a strong, threaded attachment point in thin materials like sheet metal, plastic, or composite panels.

Clip-On Nuts

These nuts provide a secure attachment point for bolts or screws and are commonly used in applications where traditional nuts may be difficult to install due to limited space or access.

Screw-Mount Nuts

Screw-mount nuts, also known as threaded inserts or screw-in nuts, are specialized fasteners designed to provide a strong, reusable threaded connection in materials such as wood, plastic, metal, or composites.

Snap-In Nuts

Snap-in nuts are widely used in applications where traditional nuts cannot be used, such as thin materials, blind holes, or areas where access is limited. They are commonly found in automotive, electronics, and industrial applications.

Dowel Nuts

Dowel nuts are typically barrel-shaped and fit into pre-drilled holes in the material. The cylindrical body allows for a flush, concealed connection, often hidden within the material.

Adhesive-Mount Nuts

They are commonly used in applications where the material is too thin for drilling, where heat from welding could damage the material, or where access to the opposite side of the surface is limited.

Rivet-Mount Nuts

These nuts provide strong, reliable threads in materials too thin or soft to be tapped, such as sheet metal or plastic. Once installed, they create a permanent, reusable threaded hole for bolts or screws.

Tube-Connecting Nuts

These nuts are an essential part of tube fittings and ensure leak-proof connections in applications such as plumbing, hydraulic systems, pneumatic systems, and industrial fluid transfer.

Lead Screws and Nuts

These systems offer highly accurate linear motion, ideal for precise applications.

Bearing Nuts

They are commonly used in conjunction with bearings in rotating machinery, such as motors, gearboxes, and pumps, where they help prevent the bearing from moving axially or loosening during operation.

Shock Absorber Mounting Nuts

Typically, shock absorber mounting nuts are designed for high strength and durability, as they must withstand significant loads and repeated stress during vehicle operation.

Ball Screws and Nuts

Ball screws and nuts are precision mechanical components used to convert rotational motion into linear motion with high efficiency and accuracy. They are commonly used in industrial machinery, CNC machines, robotics, and aerospace applications due to their ability to provide smooth, precise movement and handle heavy loads with minimal friction.

Rod End Nuts

Rod End Nuts are specialized fasteners used in conjunction with rod ends, also known as heim joints or spherical bearings, which are commonly found in mechanical linkages, control systems, and suspension components.

Cylinder Mount Nuts

Cylinder Mount Nuts are specialized fasteners used to securely attach components to cylinders, such as hydraulic or pneumatic cylinders, in industrial and mechanical applications. These nuts are designed to handle high pressures and forces, ensuring that the cylinder remains securely mounted to the corresponding structure or equipment.

LILY Bearing stocks 11,219 nuts across 29 types — from general-purpose hex nuts to vibration-resistant locknuts and weld-mount styles — in both Inch (8,083 SKUs) and Metric (3,136 SKUs) thread systems. Use the filters below, or the comparison table, to narrow down by nut type, thread size, or system of measurement.

Compare Common Nut Types

Type	How It Works	Common Materials	Best For	Watch Out For
Hex Nuts	General-purpose six-sided nut; clamp load is distributed across the flats, no built-in anti-loosening feature	Steel, 18-8 & 316 stainless, brass, bronze, aluminum, nickel alloy, titanium, nylon and other engineered plastics	Everyday assembly across inch and metric threads	Add a lock washer or switch to a locknut in vibration-prone assemblies
Locknuts	Nylon insert or all-metal prevailing-torque/serrated design grips the bolt threads to resist back-out	Steel, stainless steel, brass, aluminum, titanium	High-vibration machinery, automotive, and rotating equipment	Nylon-insert types have a lower temperature ceiling than all-metal locknuts
Flange Nuts	Built-in washer-style flange spreads clamp load over a wider bearing surface; serrated versions bite into the mating face	Steel (multiple grades), 18-8 stainless steel, brass, fiberglass	Softer or thin materials prone to surface damage or loosening	Flange diameter needs enough clearance on the mating part
Cap Nuts	Domed, closed top fully covers the bolt's exposed threads	Steel, stainless steel, brass, aluminum, plastic	Exposed threads on visible or safety-sensitive assemblies	Bolt length must not exceed the nut's internal depth
Coupling Nuts	Extended internally-threaded body joins two externally threaded rods or studs end to end	Steel, 18-8 stainless steel, brass, aluminum, plastic	Extending threaded rod length or joining two studs	Confirm both mating threads match in size and pitch
Weld Nuts	Pilot(s) on the base are designed for spot- or projection-welding to a parent metal surface	Steel, stainless steel	Permanent threaded attachment points on sheet metal or tubing	Requires welding equipment to install — not a bolt-on fastener
Rivet Nuts	Internally-threaded body sets by pulling/deforming into a pre-drilled hole; also called threaded inserts	Steel, aluminum, stainless steel	Thin sheet metal, tubing, or blind/one-sided access holes	Needs a rivet-nut setting tool, not a standard wrench

Beyond these seven, LILY Bearing also stocks panel, socket, snap-in, clip-on, dowel, press-fit, sealing, and screw-mount nuts, along with lead screw and ball screw nuts for linear motion assemblies — use the category filters to browse the full range.

Locking & Vibration Resistance

A standard hex nut has no built-in resistance to loosening under vibration. Nylon-insert locknuts add a plastic ring that grips the bolt threads but have a lower usable temperature range than the base metal. All-metal (serrated or prevailing-torque) locknuts use deformed or serrated threads instead of plastic, so they hold up in higher-temperature environments. Flange nuts with serrations bite directly into the mating surface rather than gripping the bolt. For applications where a mechanical, tool-verifiable lock is required — such as axles or aerospace hardware — slotted round (castle) nuts paired with a cotter pin remain the standard choice.

Need a Custom Nut or a Part Cross-Reference?

Working from an existing McMaster-Carr or manufacturer part number? Our team can cross-reference it to an equivalent LILY Bearing nut, or quote a custom material, thread, or finish. Request a Quote or Contact Us.

Frequently Asked Questions

What's the difference between a hex nut and a locknut?

A standard hex nut relies only on thread friction and has no resistance to loosening under vibration. A locknut adds a nylon insert or an all-metal prevailing-torque/serrated feature that actively grips the bolt threads to resist back-out.

Do you stock both inch and metric nuts?

Yes. LILY Bearing carries 8,083 Inch-thread and 3,136 Metric-thread nuts, spanning sizes from miniature instrument threads up through standard structural sizes. Use the System of Measurement filter to narrow results to one system.

Can I cross-reference a McMaster-Carr or manufacturer part number to a LILY Bearing nut?

In many cases, yes. Our product pages list interchange data against common manufacturer part numbers, and our team can confirm or source an equivalent for parts not yet listed. Contact Us with the part number you're matching.

Which nut type resists vibration best?

For most vibration-prone assemblies, a nylon-insert or all-metal prevailing-torque locknut is the standard choice. For applications needing a mechanically verifiable lock, such as axles, a slotted round (castle) nut secured with a cotter pin provides a positive, tool-checkable connection.