Fully threaded and partially threaded ASSY self-tapping screws are designed to tap their own hole as they are driven into place. Consequently, the ASSY fasteners need adapted equipment in order to be installed.
Depending on the size of the fastener installed, appropriate drilling tools should be used. Partially threaded 1/4” fasteners can be installed with a battery-powered drill, but larger diameter screws such as 3/8” or 1/2” fasteners mostly require more powerful installation tools. It is recommended to use 1/2” or 3/4” drills with low rpm and high torque capabilities. These types of drills are usually corded and have a double handle or additional mounted handle to withstand the high torque without tiring out the installer. Additionally, for installation through steel plates, it is recommended to either use torque-controlled equipment or to tighten the fasteners with a manual torque wrench once the fasteners reach the intended installation location. Information on maximum installation torque can be found in the Structural Screw Design Guide downloadable on our website.
The use of an impact drill is not recommended to install self-tapping ASSY screws. When using an impact drill with the ASSY screws, a torque differential between the screw head and the screw tip is exerted. Higher torque is usually exerted to the head of the screw and less torque transmitted to the screw tip. This differential is especially important when drilling in longer screws. The torque differential causes the screw to be pre-stressed well before it is fully installed, potentially reducing the capacity of the screw. The higher torque on the screw head can cause the screw head to break off and permanently damage the screw.
The AW Drive Bits are engineered for the proper installation of all ASSY screws. The bits are an evolved version of the Torx bit. They are designed to fit the ASSY Self-Tapping screws properly and offer exceptional durability as well as optimum torque transfer.
Drills with low rpm and high torque capabilities are required because:
1. It produces less torque on the screw head, preventing it from permanent damage.
2. It reduces the torque differential at the top and bottom of the screw, preventing premature stress on the screw.
3. It produces just enough torque at the self-drilling tip of the screw to ease the installation.
These drills must be used with the AW Bits to optimize the torque transfer between the drill and the screws.