Convenient Socket Head Screw Assortment: Metric Options

Socket head cap screws are a type of fastener with a cylindrical head and hexagonal drive hole. They are typically made from alloy or stainless steel and are available in a range of sizes, from M3 to M36. Socket head cap screws are commonly used in industrial and scientific applications and can be purchased in bulk or individually. Various online retailers offer socket head screw assortment kits, which typically include a range of screw sizes and grades. These kits often come in compartmentalised containers for easy storage and organisation.

Socket Head Cap Screws & Hex Nuts

Socket head cap screws, also known as Allen screws or Allen head bolts, are machine screws with external threading. They are designed to be driven with an internal hex socket drive, which matches a hex key or Allen wrench. This type of screw is advantageous when working in tight spaces, as they require less surface area to be wrenched internally.

Socket head cap screws can be either fully or partially threaded. On fully threaded screws, the thread length equals the screw length, allowing the screw to be installed all the way into a threaded hole. Conversely, partially threaded screws have an unthreaded portion under the head, resulting in varying thread lengths. The unthreaded portion of a partially threaded screw is stronger than the threaded section, giving it more holding power when force is applied from the side.

Socket head cap screws are typically made from alloy steel or stainless steel, but can also be made from silicon bronze or Ni-Cu Alloy Steel. They come in a variety of finishes, including black oxide, zinc plating, and plain finish. Black oxide provides corrosion resistance and a sleek black appearance, while zinc plating also offers corrosion protection. Plain finish screws are untreated and lack a protective coating.

When it comes to size, socket head cap screws typically range from M3 to M36 in metric measurements. The M3 and M4 nominal screw sizes have two drilled holes spaced 180 degrees apart, while nominal screw sizes M5 and larger have six drilled holes spaced 60 degrees apart, unless the purchaser specifies two drilled holes.

In addition to screws, hex nuts are also an important component in fastening applications. They are paired with bolts or screws to create a strong and secure connection. Hex nuts come in various sizes and materials, such as alloy steel or stainless steel, to match the specific screw or bolt they will be used with.

Socket Shoulder Bolts

Shoulder bolts feature an unthreaded, smooth, cylindrical section that is larger in diameter than the threaded portion. This shoulder determines the nominal size of the screw and extends beyond the surface into which the thread is driven. The smooth surface of the shoulder allows for a tight fit and prevents attached parts from rotating or sliding around the screw, making these bolts ideal for precision applications where accurate positioning is critical.

Inch-sized shoulder bolts are specified by the shoulder diameter and length, followed by the overall length, while metric sizes are denoted by shoulder diameter, thread diameter, and shoulder length. For example, a metric shoulder screw with a 6 mm shoulder diameter, a 5 mm thread diameter, and a 20 mm shoulder length would be listed as M6-M5 x 20 mm.

Commercial-grade shoulder bolts typically have a hex socket drive, which is beneficial when installing the screw in tight spaces. They are usually made from alloy steel with a black oxide finish or uncoated stainless steel. Precision shoulder screws, on the other hand, may feature a hex-socket or slotted drive, or even special tamperproof drives like Torx or six-lobe styles. They are manufactured from stainless steel and are useful as precision spacers and bearing surfaces.

Flat Head Socket Cap Screws

When purchasing flat head socket cap screws, it is important to consider the size and dimensions of the screws. Drilled head metric hexagon socket head cap screws are typically available in sizes ranging from M3 to M36. The positioning of the drilled holes on the head of the screw can also be specified by the purchaser, ensuring proper hole alignment.

Button Head Socket Cap Screws

Socket head cap screws are a type of screw with a cylindrical head and hexagonal drive hole. They are typically used in applications where the head of the screw needs to be flush with the surface of the material or where there is limited space. Button head socket cap screws are a specific type of socket head cap screw that features a rounded head, similar to a button, giving them a lower profile than other screw types. They are commonly used in applications where a smooth, finished appearance is desired, such as in furniture or automotive assembly.

Assortment kits are a convenient option for those who require a variety of sizes or quantities. These kits typically include screws, bolts, washers, nuts, and sometimes storage containers or trays. The number of pieces in these kits can vary widely, ranging from a few dozen to over a thousand. When purchasing an assortment kit, be sure to check the product details to ensure that the kit includes the specific types and sizes of screws you need.

When working with metric socket head cap screws, it is important to understand the sizing conventions. Metric socket head cap screws are typically designated by the letter "M" followed by a number that indicates the nominal size of the screw, such as M3 or M4. The nominal size corresponds to the diameter of the screw in millimetres, with standard sizes ranging from M3 to M36. It is also important to consider the thread pitch, which can vary depending on the size and type of screw.

Socket Set Screws

Socket Set Screw Head Styles

The headless or blind design of socket set screws means that they are driven with an internal-wrenching drive, most commonly a square or hex key. Square head set screws, on the other hand, feature an external square head that enables wrench tightening, even in tight spaces.

Socket Set Screw Point Styles

There are several types of socket set screw point styles, each with its unique features and applications:

• Cup point set screws: Feature a hex drive and a cup-shaped indentation. The thin edge of the cup end digs into the contact surface for high holding power.
• Knurled cup set screws: Similar to cup point set screws but with serrated ridges or knurls in the indented cup, providing a powerful grip that resists loosening caused by vibration.
• Dog point and half-dog point set screws: Have a protruding tip with a flat surface on the end opposite the hex drive. The protrusion should fit into a matching hole in the workpiece.
• Oval point socket set screws: Feature a rounded, oval-shaped point that minimises surface damage and allows for slight adjustments without loosening the screw.
• Flat point set screws: Possess a flat surface at the end opposite the hex socket drive, minimising surface damage and making them ideal for applications where frequent resetting and relocation are necessary.
• Cone point set screws: Have a sharp, cone-shaped point that delivers the strongest torsional and axial holding power. They are often used in permanent settings or as a pivot or hanger.

Socket Set Screw Materials

Socket Set Screw Finishes

Frequently asked questions