Motivated by the ulbiquitous role of clusters in film growth, we study coalescence of metallic clusters (Ag.Cu.Pb). of size from 50 to 300, with an isothermal molecular dynamics simulation method using classical forces. A comparison is made between the melting behavior of the isolated clusters, onl one side. and classical theories of sintering, on the other side. An evident failure of the macroscopic models appears from this comparison and this casts considerable doubts on the adequacy of continuum models for low dimensional systems.