Part Details Review
| Bosses |
Bosses are typically cylindrical projections from the part surface with holes designed to receive screws, threaded inserts, or other types of fastening hardware. Assembly is achieved by installing either a self-threading screw directly into a hole in the boss or by installing a machine screw into a metal insert which is preinstalled in the boss. Metal inserts are secured in the boss during or after molding using ultrasonic energy or heat insertion technique.
Bosses can be used as reinforcements around holes for mounting screws. If the screws are installed directly into the base wall, the length of thread engagement will be limited to the thickness of the base wall, which may not be sufficient. Bosses are also helpful in ensuring a consistent height of the assembled components.
Figure shows typical boss geometry. The diameter of the hole in the boss should be equal to the minor diameter of the screw or that of the metal insert. All corners, especially the inside corners, should have appropriate radii. Other important aspects of design such as height of the boss, depth of the hole and attachments are discussed in details elsewhere in the checklist.
