Also known as Tec, assembled in self tapping screws of all processes in the pre-drill preparation is the most costly. Self tapping screws, first drill, and aperture required restrictions. In some ways costs can be cut without pre-drilled. This is a combination of drilling, tapping, and tighten the self-drilling tapping screws in a job. Self drilling screw surface and core hardness self-tapping screws a little higher than the average, this is because the self drilling screws a drilling operation and self drilling screws there need to be run through test, to test the screw can drill and tap in the time allotted. Above for the four self tapping screws of the design and development process, there are two other special thread for the design of the screw, the first for; HIGH LOW SCREWS self tapping screws in plastic or other low-density material. Double thread design, high thread (large outer diameter) has a sharper thread angle is 30 degrees, the thread type. Thread (smaller diameter) with 160 degree thread angle, only half of high-thread. Combination of high-low thread design reduces rotational torque, improves pullout strength, significantly reduced the combined risk of rupture of the workpiece and the other a dry wall assembly uses in the construction industry. With such self-tapping screws thread design particularly suitable for plastic parts and wood.