Bonded Joint

Bonded Joint 

a permanent joint between parts of machines, building structures, furniture, and products of light industry; formed by an adhesive. It can hold together various materials, including materials of different types, by providing uniform distribution of stresses. Bonded joints are used in the fabrication of articles from steel, aluminum, brass, textolite, Micarta, glass, plywood, wood, cloth, plastic, cured rubber, and other materials that can be joined in various combinations. In the assembly of equipment and the construction of buildings such joints can replace welding and riveting.

Bonded joints are made with phenol formaldehyde, epoxy, and silicone cements. The thickness of the adhesive interlayer is usually 0.01–0.1 mm. Joints that experience shear or uniform separation strain are usually bonded. For steel articles such joints have a maximum shear strength of 20–35 meganewtons per sq m (or 200–350 kilograms-force per sq cm), and in a number of cases it is substantially higher. The strength of the glue line between plastics usually exceeds that of the materials themselves. Among the disadvantages of bonded joints are the shortness of their life compared to welded and riveted joints, particularly in the case of abrupt temperature changes, and their low strength under conditions of unilateral nonuniform separation strain (peeling off). Under such conditions the best results are achieved by using combination bonded-riveted or bonded-welded joints.

A. A. PARKHOMENKO