Types of Socket Head Cap Screws

Socket head cap screws (also called socket set screws) have a domed or hex-shaped top that fits into a socket on the bottom of the screw. They use an internal hexagonal drive for installation and can be tightened or loosened with a hex key. These screws are used in a wide variety of applications, including machine parts and automotive components. They are also commonly seen in woodworking, metal stamping dies, plastic injection molds and power tools. These screws generate a compressional or clamping force to hold the components together and resist movement or loosening, but they are not designed for shear applications.

There are several types of socket cap screws available, ranging from the high-strength caps to the low-profile button heads. Each type has advantages and disadvantages in different applications. The most important factors in choosing the right socket head screw for an application are the strength requirements and the appearance of the finished product.


Hex bolts or hex nuts have a six-sided hexagonal head and external threading, which makes them easy to tighten with wrenches. Hex bolts are generally stronger than traditional screws and can take more torque.

Button Head Socket Cap Screw

The rounded head of the button head socket cap screw provides a larger load-bearing surface that is more resistant to loosening than the flat head of other screw types. Its lack of sharp edges also reduces the risk of snagging clothing or other items on moving machinery.

Other types of socket head cap screws include:

Cheese Head Socket Cap Screw

The flat disc top of the cheese head is similar to a mushroom head, but it has a lower profile and can be covered to hide its appearance. It can also sit flush with the surface and its projecting collar around the head disperses the load of the screw more evenly. These screws are often used in thinner materials or where there is less room to accommodate the head height of a standard socket head cap screw, but they cannot withstand the same preload as a traditional cap screw.

Low Head Socket Cap Screw

The head of a low-head socket cap screw is 50% lower than the standard head height. These screws can be used where there is limited space to accommodate the head height of a conventional socket cap screw but where maximum tensile strength is required.

Socket screws come in a variety of lengths and materials, with coarse and fine thread options for each. They are most often made of low-carbon steel, but can be found in stainless and alloy steel as well. They are typically coated with zinc, black oxide or another finish to protect them from corrosion. They are available in metric sizes, as well. For more information about our selection of socket head cap screws, contact us today. We can help you find the perfect fastener for your application. button head cap screw

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