A preform made from two different materials that do not bond together by a bi-injection process, using the same mold, is presented. An outer layer of the preform can be first made, then an inner layer molded through a center hole in a bottom of the outer layer, and the two layers connected. Inner/outer preform materials can be different, such as PET/polyolefin or polyamide, or the same, such as PET/PET. To prevent mutual bonding during molding of the second layer, a non-stick coating may be sprayed onto a surface portion of the first layer prior to molding the second. In embodiments, manufacturing order can be either outer/inner, or inner/outer, and the non-stick coating sprayed on the inside/outside of the layer first molded.

A fusion tip of a heat fusion machine assembling a sub-material including a boss or rib with a base material and then heat-fusing the boss or rib to fix the sub-material and the base material includes a base tip including a pinhole formed vertically in a center and a tip head contacting the boss or rib during heat fusion and a fusion pin positioned in the pinhole and configured to move up and down separately from the base tip.

A caulking pin (15) is inserted into a mounting hole (21) provided in a metal case body (3), and the end portion of the caulking pin (15) is thermally caulked with a welding tip (24) to form a mold forming portion (17). A surplus absorption recess (31) is formed by enlarging the opening end of the mounting hole (21), and surplus resin is absorbed. The surplus absorption recess (31) is positioned inside a region of the mold forming portion (17). Therefore, the amount of molten surplus resin that protrudes outward from the welding tip (24) in the thermal caulking process is reduced.

A method of mechanically securing a first object to a second object, wherein the first object has a thermoplastic material in a solid state, the second object has a generally flat sheet portion having a second object edge. A third object is provided and arranged to provide an assembly including the first, second and third objects, in which assembly the second object edge is in contact with the thermoplastic material. Mechanical vibration energy is coupled into the assembly by means of a vibrating tool until a flow portion of the thermoplastic material due to friction heat generated between the second object edge and the thermoplastic material becomes flowable and flows around the second object edge to at least partially embed the second object edge in the thermoplastic material and the third object is caused to be embedded at least partially in the thermoplastic material of the first object.

A door assembly for a laundry appliance includes an inner frame, a window in the inner frame, an outer frame outboard of the inner frame and the window and a grille mounted to the outer frame. A method of assembling the door assembly may include forming a cap on one of the grille or the outer frame by heat stake welding. The grille is coupled to the outer frame by the heat stake welded cap as a result of forming the cap by heat stake welding.

A sonotrode for reshaping a connecting element to form a closing head of a rivet including a cavity at least partially having the negative shape of the closing head to be formed, wherein the cavity provides a contact surface designed to come in contact with the connecting element during reshaping, wherein the sonotrode defines a longitudinal axis (l), and wherein the contact surface in a cross section in at least one first plane parallel to the longitudinal axis (l) includes a first contour with a convex shaped outer section, so that a line connecting two points within the convex shaped outer section extends through the sonotrode and not through the cavity. A system including a sonotrode and a connecting element and to a method of reshaping a connecting element.