SELF TAPPING SCREW

The invention relates to a retaining screw produced by cold rolling, having a self tapping thread and designed to be screwed for example into thermoplastic material. Said screw has a virtually end-to-end cylindrical thread as well a s thread teeth, the thread crest of which has the same height on the whole length, while the free space between two teeth remains the same all along the thread . The screw presents the following characteristics: either 1) the thread out er diameter Do and the thread inner diameter Dk represent the ratio Q1=Do/Dk, i n a magnitude of 1.2 to 1.4; 2) the axial distance P between two thread teeth gives with the height H of the latter a ratio Q2=P/H, in a magnitude of 2.75 to 2. 9; 3) the point angle of the thread teeth is about 30.degree.; or 1) the thread outer diameter Do and the thread inner diameter gives a ratio Q1=Do/Dk, in a magnitude of 1.25 to 1.65; 2) the axial distance P between two thread teeth gives with th e height H of the latter a ratio Q2=P/H, in a magnitude of 2.35 to 2.7; 3) the point angle of the thread teeth is about 30.degree..