How do self drilling and self tapping screws work

The two most common and efficient industrial fasteners in the commercial, industrial and construction markets are – self drilling and self tapping screws. They sound confusingly similar, but they have specific fastening functions. In order to not use them interchangeably, we need to know their specifications and how they work.

Self Tapping Screw

Self tapping screws are the ones that have the ability to tap threads into the material, be it wood, metal or brick. As one of the earliest engineered fasteners, self tapping screws were manufactured out of hardened steel, and their invention powered the Industrial Revolution.

These screws are also called:

• A sheet metal screw because of the reason of their prominent usage in the sheet metal trade.

• The other name for self tapping screw is sheet metal screw also because it contains form mating threads, tapping the threads in a pilot hole into which they are driven.

Other specifications:

• Their tips come in different shapes - pointed, blunt, and flat. If it is pointed, it is thread-cutting, i.e. in a pre-drilled hole, tapping and threading are done. If it is flat, it is thread-rolling, i.e. creating no space between the screw and the material by rolling or extruding the threads.

• Self tapping screws are quite versatile - they are suitable for use with metals, various types of plastics (plywood, fiberglass, polycarbonate) and forged metal like iron, aluminium, brass or bronze.

• They are commonly used for fastening aluminium sections, attaching metal brackets onto wood, inserting screws into plastic housings or masonry applications.

Self Drilling Screw

These screws carry a very peculiar construction. They have curved end shaped like a twisted grill and can fasten metal to metal and metal to wood.

The reason why these screws are the most preferred is:

• Their USP is that they connect components in one work step: they drill, form the thread and fasten.

• These screws come in stainless steel for weather-exposed areas and in zinc-plated steel for unweathered areas.

Other specifications:

• Their lengths can vary, but the drill points remain standard, usually donated by numbers 1 to 5, determining their length and thickness.

• They can work smoothly with light and low-density materials.

• Their widespread use includes cladding, metal roofing, steel framing, and other general construction tasks.

The self drilling and self tapping screws also come with an optional pre-assembled sealing washer. The purpose of a washer is to share the material's load with the screw, for spacing, absorbing vibration, etc. There exists a wide variety of screws and an even wider variety of construction accessories. Whatever it may be, find the products that best suit your needs at Ejot Octaqon.

Similarities

Both are more efficient fasteners than normal ones, thus being chosen for construction, HVAC (Heating, Ventilation and Air Conditioning) and other industries because of their ability to create a precise fit.

Notable Difference

• Self-tapping screws require a pilot hole because they cannot drill through metal and must tap their own threads.

• Self drilling screws do not require a pilot hole as they drill their own hole with the help of pilot wings. This accelerates the installation time and lowers the cost of additional drill bits.

Working

• Self tapping screws function by cutting into the screw's thread, producing a flute and cutting edge that resembles a tap.

• The same principles that govern drill bits and other cutting instruments also apply to self drilling screws. Cutting speed, feed rate, depth of cut, and the work material itself all affect how well a cutting tool performs.

Points to remember

• Before choosing the type of screw, always consider the thickness and hardness of the material.

• A more robust and durable screw will always prevent failure during and after construction.

• Applied force and drive motor speeds are often advised when fastening self tapping and self drilling screws.

Interestingly, all self drilling screws are self tapping, but not all self tapping screws are self drilling. This is because a self drilling screw is basically a self tapping screw with the additional feature of a drill point. In both cases, the screws create tightly fitting threads in the substrate by merging with it. Most often, hard steel or stainless steel that has undergone a hardening process has the ability to create both types of screws.

Conclusion

The design and framework of both self tapping and self drilling is for specific purposes, the significant difference being the need for a pilot hole; for eg: if the construction material is rough, it may be better to drill a pilot hole beforehand.

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