The Difference Between Self-Drilling and Self-Tapping Screws

Whether you’re a DIY novice or construction expert, it’s always important to understand what tools are available to you. This includes knowing the difference between self-drilling and self-tapping screws. Although they may look similar in appearance, they each have their own functions and benefits. So, what is the difference between self-drilling and self-tapping screws, and what are the properties of each?

Self-Drilling Screws

Self-drilling screws, also recognised as Tek Screws due to the brand that made them so popular, can be identified by the shape of the screw itself. It slightly curves at the end with a shape like a twist drill.

Self-drilling screws are designed for a number of different functions and applications and are similar to drywall screws, with the most common uses being to:

•  secure metal to wood
• fix metal onto metal

For example, self-drilling screws would be ideal for tasks such as attaching sheet metal onto metal frames, or fitting framework onto a car.

These screws are available in a variety of different lengths, with the drill points being identified by their number (numbers 1 through to 5) in accordance with both their length and thickness. Generally speaking, as the drill point number increases, the volume of metal they can drill through can be increased too.  The way that self-drilling screws differ from others, is that they do not require a pilot hole to cut and fasten, resulting in time being saved during your construction. 

The Advantages Of Using Self-Drilling Screws 

The main advantage of using self-drilling screws is the money you can save. Due to the screws not needing a pilot hole to cut and fasten them, you can save money by not needing to pay out for additional drill parts. This function also makes the screws simpler to use, saving you the added task of drilling and then fastening.

Self-Tapping Screws

As the name implies, self-tapping screws are screws that can be tapped into various types of materials. These can include multiple types of metal, polycarbonate, wood, brick, plywood and both cast and forged materials such as aluminium, brass or iron.

These screws are commonly used for securing metal brackets onto wood or inserting screws into sturdy applications such as plastic housing. Self-tapping screws may sometimes also be referred to as sheet metal screws, tapping screws, metal screws or tapper screws for short.

Available in a range of different tip shapes, the screw’s tip will vary depending on the type of thread function it has. For example, a pointed screw tip will be for thread-cutting, which taps and creates threads in a pre-drilled hole. Flat screw tips are thread-rolling; it rolls and extrudes threads while creating no clearance between the material and the screw.

The main factor to consider with self-tapping screws is that unlike self-drilling ones, they can not drill through metal without a pilot hole being pre-drilled or pre-punched before installation.

With help from a drill, a pilot hole can be formed that’s slightly smaller than the screw. This then allows the threads of the self-tapping screw to dig into the material while the screw is being installed, securing and fastening the two materials together.

It’s important to consider the size of the punch hole (and the drill used for it) as this needs to be exact when using self-tapping screws. If the hole is slightly too big, the screw can fast become loose or fail to thread through at all, and if the hole is too small, the screw can split the material due to excessive pressure.

The Advantages Of Using Self-Tapping Screws

One of the main advantages of using self-tapping screws is the variety available. Self-tapping screws are available in a range of different sizes and types depending on the project or use you have for them. This makes the screws almost customisable for specific types of installation, giving you confidence in knowing you’re using the right type to give you the finish you desire. Self-tapping screws are particularly ideal in softer materials such as resin or plastics and need just a minor amount of pressure given to them using a screw gun or screwdriver.

Conclusion

To sum it up, although both self-tapping and self-drilling screws may seem similar, their purposes are ideal for different installations. A self-tapping screw can usually be identified as having a pointed, blunt or flat tip. The main difference between the two is that a self-tapping screw does need a pilot hole to be made before installation, and a self-drilling screw does not.