When overmolding an insert made of a thermoplastic (TP)  with another TP, there are some basic rules to follow to ensure and get a (relative) good adhesion. Besides some chemical, thermal and rheology compatibility/similarity (when overmolding dissimilar materials), the most important one is to get a local melting at the interface to favor the polymer chains entanglement and therefore get a real bond (not just a sticking).  It is possible using a rather simple approach to assess qualitatively if we can get a good bond (or not). In case a quantitative strength is required, for instance in the overall performances of the assembly, FEA can be used with more advanced approaches. This is briefly discussed in this document, still under construction.