As shown in figure 2, the inclusion of shoulders allows for an increase in the thickness
of the section of the mold where the hinge is to be formed, thus preventing any bowing
or breaking of the steel insert.
A typical land length is 0.060 in.( 1.5mm). A land that is too short will cause insufficient
back pressure, leading to non-uniform melt flow through the hinge and excessive stress
on bending. A land that is too long will result in high pressure drops, underpacking
across the hinge and a poor fit