Fasteners are crucial construction tools that hold materials together and provide the secure connections that you depend on. With millions of fasteners available in all kinds of sizes and materials, it is essential to know which is best suited to your application.
The three most common types of screws are self-tapping screws, self-drilling screws and self-piercing screws. Each design offers unique benefits that make it ideal for different materials and uses. Read on to determine which type of fastener is a match for your requirements.
Self-tapping, self-drilling and self-piercing screws have many similarities and differences, but they are primarily distinguished by their tip style and tapping abilities.
The ability of a screw to advance when turned while creating its own thread, versus, say, machine screws which require a pre-threaded nut or other female insert. Self-Tapping screws can cut their own threads as the screw is driven in to the material. Self-Tapping screws function by having a cutting edge which drills away the material, making a tiny hole for the screw to go into. This has nothing to do with the point of the screw but has everything to do with the threads which are designed to cut through the material.
There are two types of self-tapping screws: thread-cutting and thread-forming. A thread-cutting screw cuts material in its path as it is driven inward. These fasteners are normally made from stainless steel or carbon steel, and they see frequent use in wood and metal. Sometimes these screws can strip during disassembly because of the threads, so it is essential to repair this issue by using a slightly larger screw when you reassemble the project.
While thread-cutting screws remove some of the material as a user drives them, thread-forming screws deform the material as they are driven inward. Thread-forming screws are typically used in plastic. These screws cling tightly to the surrounding material, so ensure you tighten the screw the correct amount for a strong hold and intact material.
So how would you use self-tapping screws in metal, wood or plastic? Fortunately, these units function just like any other screw, meaning you drive them in with a screwdriver or a drill. If you drill a pilot hole for your self-tapping screw, you want to make sure that it is slightly smaller than the screw itself — if the hole is too big, the threads will not catch. You also want to ensure that the screw is positioned straight so that it aligns properly as you drive it in.
It is important to mention that the material you’re drilling should always be softer than the screw so that you don’t blunt the tip. The safest, and most common, type of self-tapping screw to use is stainless steel. This screw can penetrate many materials. Stainless steel screws have a strength ranging from 100,000 all the way to 150,000 tensile pounds per square inch (PSI).
These screws can typically hold around 80 to 100 pounds of weight, but the holding power depends on the length of the screw and the insertion angle. Self-tapping metal screws can become stronger with certain alloy compositions, depending on the amount of chromium or nickel.
Self-tapping screws are helpful in a variety of industries, with a few examples including:
Similar to sheet metal screws, but self-drilling screws have a drill-shaped point to cut through sheet metal or steel which eliminates the need for drilling a pilot hole. The area of the screw with a notched tip collects metal filings or wood chips. This reservoir allows the drill to move through the space without shavings blocking its forward motion.
We offer the best self-drilling screws that are designed for use in soft steel or other metals. Self-drilling screw points are numbered from 1 through 5, the larger the number, the thicker metal it can go through without a pilot hole. A 5 point can drill a 0.5 in (13 mm) of steel, for example.
Self-drilling screws are a popular choice for roofing, HVAC and other industrial applications because they do not require a pilot hole, which accelerates installation time and lowers costs. These screws can be used in both light- and heavy-gauge applications. Whatever the thickness of the metal may be, make sure the length of the drill point exceeds that thickness so you can properly install the fastener.
Externally threaded fasteners with the ability to self-pierce light-gauge metal and wood. Like self-tapping screws, self-piercing screws tap their own mating threads when driven. The main difference is that they have an extra-sharp point, which allows them to pierce sheet metal. This is also different from self-drilling screws, which have a tip like a drill bit. Self-Piercing zip screws are high-strength fasteners with sharp angles of 25 to 30 degrees.
Browse all of our screws using our Screw Index to find the fastener solutions that you need. We have screws in a vast array of sizes, head styles and coatings, so there is something in our inventory for virtually every application. If you do not see the screw that you are looking for, contact us and we will find it for you.
We also provide free samples before you buy as well as free quotes so that you will know exactly what you’re getting when you order from us. If you are not sure what you need, reach out online or call 800-483-6354 and our experts will work with you to find the perfect fit for your application.