A tapping screw is a screw that creates its own hole when it is driven into a material, rather than needing to be driven into a pre-drilled hole. There are two basic types of tapping screws, thread forming and thread cutting.
The primary difference between thread forming and thread cutting screws is how the holes are made.
- Thread cutting screws have cutting edges and chip cavities that actually cut into the material, removing the material from the part they are driven into.
- Thread forming screws do not actually remove any material, but rather they displace it, or push it aside so that the material flows around the screw’s threads.
In general, because they do not require the use of nuts and only need to allow for access from one side of the material, thread tapping screws permit rapid insertion and so contribute to increased productivity
Thread forming, also known as cold forming, is typically used when larger stresses are needed. This method will stand up to better loosening because no material is removed, creating a fit with zero clearance. Thread forming screws are generally able to stand up against loosening without the needs for lock washers or other devices designed to prevent loosening.
Thread forming is typically used for steels, stainless steels, light metals and light metal alloys. Generally, materials that produce a continuous chip when drilling are good candidates for thread forming.
Since thread cutting screws have edges designed to help them penetrate the material, they require less force for insertion, making them ideal for use in materials where disruptive stresses are not wanted or when using thread-forming screws would require too much torque.
Thread forming is believed to provide multiple advantages, including cutting time and increasing strength and durability. Since the material is cold worked, the threads produced are typically stronger and taps can be operated at higher speeds than available for thread cutting. Thread forming also provides for better size control, while improving tool life and productivity.
For more information about Thread Tapping and how Advantage Machining can improve your product requirements, Contact Us today!