Last Updated on June 21, 2021 by Marsh Fasteners
When it comes to fasteners, screws are extremely common. They come in a variety of different shapes and sizes, each of which has a unique application. It is important not to get confused between screws and bolts. While they serve a very similar purpose, small fasteners are generally called screws, whereas the larger types are referred to as bolts. Below, we look at some of the different types of screws as well as when you would be most likely to use them.
Wood screws are perhaps the most common type of screw. As the name suggests, these fasteners are used mainly for woodworking applications. They are used to connect two or more wooden objects and have sharp points to help them dig into the wood.
Sheet Metal Screws
Far more versatile than their name suggests, these are usually the sharpest screws and are made to cut into sheet metal, wood or plastic. They have a full-thread shank and are self-tapping with specially hardened, sharp threads that allow them to cut into most materials, forming their own internal thread as they go. There are two basic types of sheet metal screws: self-tapping and self-drilling. Self-tapping screws require a pre-drilled hole, while self-drilling ones have a drill-point tip that allows them to cut through any material, even without a pre-drilled hole.
These screws are crafted with threading that extends all the way up the shaft. Also known as coach bolts, these are essentially very large wood screws coated with zinc to protect them against corrosion. They are extremely sturdy screws that are used to connect heavy materials bearing large loads.
Deck screws are usually used in wood and come with a unique notched point ideal for removing wood chips. They are very similar to wood screws but have a larger surface area, enabling them to bear larger loads. They are usually made of coated steel or copper, making them highly corrosion resistant.
These large-headed screws are generally used to fasten machine parts in home appliances and consumer electrical devices. They have cylindrical shafts, flat points and are usually used without a nut. They are tightened directly into a pre-drilled hole and generate a lot of clamping force when tightened.
Similar to cap screws in some respects, machine screws are generally fastened with nuts. They are much smaller than the average screw and are typically used to fasten metal parts together in machine components or in construction projects. They can only be used in pre-thread holes and have finer, more accurate threads than most other screw types.
Drive Styles and Screw Heads
Screws are also usually categorized according to their drive style, the most common ones being slotted, star, and square and Phillips (which is the most common variety that looks like a cross). Each screw will also have a different head. These heads may include bugle heads, fillister heads, and button flange heads, to name a few.
Screws may also be classified according to their threading. Coarse and fine threading varieties are available with coarse threading screws being a great choice for extra retention and gripping power.