When an insert is overmolded, if it is not well constrained by metal pins in the mold, it may show some deflection and or deformation from its original position during the injection phase leading to undesirable variations in the (plastic) wall thickness. This might also affect the final shape and the (mechanical, electrical…) performances of the part. This is the reason why it is relevant to be able to anticipate it (and to predict it with some accuracy) in order to make suggestions about the design (part/mold), the number and position of metal pins (constraints), the gate position(s) and/or the process conditions.
Such simulations can be easily performed with Moldflow (assuming thermo elasticity). have a look at the core-shift (VE) page
