Method for securing a second object to a first object

A method of mechanically securing a first object to a second object, the method comprising the steps of:

• providing the first object comprising a thermoplastic material in a solid state;
• providing the second object with a generally flat sheet portion having a second object edge;
• providing a third object;
• positioning the first object, the second object and the third object to provide an assembly comprising the first, second and third objects, in which assembly the second object edge is in contact with the thermoplastic material of the first object;
• while the second object edge is in contact with the thermoplastic material of the first object, coupling mechanical vibration energy into the assembly by means of a vibrating tool until:
• a flow portion of the thermoplastic material of the first object due to friction heat generated between the second object edge and the thermoplastic material of the first object becomes flowable and flows around the second object edge to at least partially embed the second object edge in the thermoplastic material of the first object;
• and
• the third object is caused to be embedded at least partially in the thermoplastic material of the first object,
• stopping mechanical vibration and causing the thermoplastic material of the first object to re-solidify, whereby re-solidified thermoplastic material of the first object at least partially embedding the second object edge anchors the first object to the second object and whereby re-solidified thermoplastic material anchors the third object to the first object.