Thread rolling screws are designed for reliable and secure fastening into materials such as plastic. They have a trilobular lobed cross-section, and form threads in pre-existing holes by pushing material outward during installation. When installed in sheet metal, thread rolling screws often require an extruded hole; the extrusion forms a lead-in and provides extra length for improved retention. Thread rolling screws are popular for applications where the loose chips formed by thread cutting processes must be avoided.
