Energy directors are effective with most thermoplastics, but some less so than others. Amorphous materials are generally easy to weld and once softened will generally retain enough heat while traveling away from the energy director to bond when clamp force is applied. Semi-crystalline materials are considerably less well behaved. Once away from the immediate area of the energy director recrystalization begins and inhibits bonding. The shear joint was developed to specifically address these issues. The telescoping nature of the joint during welding ensures the greatest amount of joint area is involved in process until final clamp force is applied. Shear joints are also effective with amorphous materials, and generally provide greater assurance of leak-free seals where used.