Thread forming screws do not contain cutting slots and do not produce chips.
They are generally used with plastics with a modulus smaller than 3000 MPa.
The figure below shows some examples.
These standard screws with their 60º thread angle generate relatively high
radial and hoop stresses. The wider thread spacing of the types AB and B is
recommended over the type C for most applications. The gimlet point of the
type AB necessitates extra long bosses as the tapered point does not
contribute to the strength of the connection.