As mentioned previously, the simulation of contact release can occur under specific circumstances, for example, when the motion of a mold is reversed, or when the forming pressure results in the material being pulled away from a mold. By default, the possibility of contact release is disabled for contact problems. When it is enabled, the detachment of the free surface from the wall occurs if

(17–3)

where is the local force density as defined in Equation 17–1, while is the adhesion force density. The quantity is a physical parameter that depends on the interaction between the deformed melt and the material of the plug. By default, the adhesion force density is set to zero.

Contact release can be enabled only for 3D and shell models, and requires that the melt sticks at contact (that is, .the slip coefficient in Equation 17–2 equals the penalty coefficient in Equation 17–1).