Screw Types and Usage Guide

Screws are common tools in our daily lives, used to connect parts and materials. But there are many types of screws. Do you know how to choose the right one?

Here, we’ll provide a detailed guide to screw classification and usage, hoping it will be helpful.

BDfastener supplies a wide range of high-quality screws, including metric and imperial machine screws, self-tapping screws, self-drilling screws, wood screws, drywall screws, concrete screws, sheet metal screws and screws for plastics. If you are looking for a reliable fastener supplier, please contact us.

Common Screw Drive Types

If you want to drive different types of screws, you’ll need different tools.

Slotted screw: It has a “line” on the top and is the most common type of screw. Generally, a flat-bladed screwdriver is sufficient, but you can use a coin or knife to tighten or loosen them. However, this type of screw is easy to slip during installation and is very unstable, so pay attention to safety.

Cross-slot screw: Its top is “cross-shaped”, which is safer and more reliable than the strip hole screw. We can drive it with a cross-type screwdriver and power tools.

Hex socket screws: Commonly used in prefabricated furniture (beds, desks, cabinets). An L-shaped hexagonal wrench (also called an Allen wrench) is required. The deep groove on the top makes the screw difficult to remove after tightening.

Square slot screws: This type of screw is rarely seen and is generally used inside some machines or in hidden places. A special square wrench is usually included in the package, which rarely comes off or slips during use.

Trox slot screws: The top of the torx screw is “hexagonal”, which has the best anti-falling effect when driving. During installation, you can tighten with great force without worrying about safety issues.

Screws for Wood

• Steel wood screws: Wood screws are easily identified by their threaded lower end and unthreaded upper end, typically requiring a pilot hole for tightening.
• Drywall screws: Mostly used to connect gypsum board and wood. They are very cheap, but they are thinner and more brittle than ordinary wood screws and are easy to break.
• Multipurpose screws: Typically made of hardened steel, they are very strong and have a self-drilling point, eliminating the need for a pilot hole. They are stronger than the previous two types of screws, but also more expensive.
• Corrosion-resistant screws: Primarily used for outdoor installations, they protect the screws from rainwater corrosion, extending their lifespan.

Screws for Drywall

• Drywall screws: They have a sharp, self-drilling tip and deep, long threads, effectively preventing loosening at the drilled hole. They can be used for both drywall and wall connections.
• Toggle bolts: Toggle bolts can be used when drilling holes through drywall to hang items, but the items hung cannot exceed their maximum weight capacity.
• Wall anchor bolts: They are generally used as fasteners for hanging items in drywall or hollow walls (such as drywall).

Screws for Metal

• Self-drilling screws: These have a drill-shaped tip that easily penetrates metal, eliminating the need for a pilot hole.
• Sheet metal screws: These are usually smaller in size and have sharp tips that can easily enter metal surfaces.
• Wood-to-metal screws: These screws are excellent for fastening wood to metal. The screws use a wing at the front to create a gap in the wood while drilling. This wing breaks off when the drill bit hits the metal component.

Screws for Concrete

Concrete screws are usually blue and generally come in two diameters: 4.76mm and 6.35mm. A 4.76mm screw is generally sufficient for most drilling needs; however, if the concrete is very hard, a 6.35mm screw may be necessary.

If the screw does not grip the concrete even after it is fully screwed in, the material the screw is being installed in may be too soft. In this case, it’s best to use a longer 6.35mm screw.

Concrete screws usually have a hexagonal or Phillips head. Hexagonal screws are easier to tighten, while Phillips head screws allow the flat head to remain flush with the surface.

For Screws on Plastic

Using screw connections on plastic can easily cause the plastic to burst. It’s best to use screws specifically designed for plastics, either thread-forming self-tapping screws or slotted, cutting-thread screws.

Self-tapping screws are suitable for thermoplastics (such as ABS, polycarbonate and polyethylene) and are commonly found on plastic items such as toys and beverage bottles. These screws easily create internal threads around the plastic, making it easy to fasten parts.

Cutting screws are suitable for thermoset plastics (such as epoxies, silicones, and polyurethanes). Since thermosetting plastics cannot be remelted and are very strong, a cutting edge at the front of the screw is used to remove some of the plastic to form the internal threads.

Conclusion

Screws, which may seem insignificant, come in many different types and uses. Only by choosing the most suitable screws in a specific environment can we be safer and more reliable.