A process of joining two parts together where one part (the plastic part) has a protrusion that is inserted through a hole in the second part. (The protrusion is usually cylindrical, either solid or hollow. The second part is often metal.) A spot welding horn with a specially contoured tip then touches and ultrasonically melts the plastic protrusion, thereby forming a head on the protrusion which mechanically joins the two parts. Ultrasonic staking provides an alternative to welding when the two parts consist either of dissimilar materials which cannot be welded, or when simple mechanical retention of one part relative to another is adequate (i.e. as distinct from molecular bonding).

Figure 1 shows one staking configuration. For other configurations see Sonics[5] and Dukane[5].

Synonyms — heading, reforming, riveting

Standard ultrasonic flared stake
Figure 1. Standard flared stake