PT Journal
AU Gondar, E
   Schrek, A
   Svec, P
TI Optimization of Overmolding Process of Metal-Plastic Part
SO Manufacturing Technology Journal
PY 2015
BP 334
EP 339
VL 15
IS 3
DI 10.21062/ujep/x.2015/a/1213-2489/MT/15/3/334
DE metal-plastic part; overmolding; crack; cold joint; residual stress
AB Metal-plastic parts with steel inserts prepared by overmolding technique showed several cracks. Cracks marked as no 1 and 2 were noticed immediately after overmoulding process. Cracks no 3 and 4 were propagated only several days after overmolding, during post crystallization of plastic. The superposition of both high residual stresses at the metal-plastic interface and creation of cold joints in overmolding plastic were the reasons of cracks initiations. Residual stresses at the metal-plastic interface exceeding the yield strength of plastic were confirmed by simulation in Moldflow software. The differences in the melt front temperature above 20 °C were simulated in the critical areas where the cold joints created in the real metal-plastic parts. Cracks no 1, 2 and 3 were eliminated by increasing of plastic thickness in the critical areas. Cracks no 4 were eliminated by decreasing of packing pressure, what also contributed to the elimination of cracks no 3.
ER