As the use of the thermoplastic materials becomes conventional in numerous parts and various applications, incidence of various types of failure becomes inevitable. Failure of injection molded parts can be a cause of economic and legal problems, as well as causing health damage or death. Public perception of plastics is adversely affected by their failures, such as the bad reputation that early plastics earned with toys that broke too easily. As the injection molding process is very complex, finding the cause of failure is very complicated. In industrial mass scale production, determining the cause of failure is key point in customer-supplier relationship. In the presented study, a type of injection molded product from HDPE affected by occurrence of cracks was investigated by mechanical, thermal testing and spectral analysis. Mechanical properties were evaluated by the uniaxial tensile test and the SHORE hardness test. Thermal properties of the samples were evaluated by DSC/TGA analysis and for the spectral analysis a Raman spectroscopy device was used. Obtained results provided information about fluctuating quality of used material, coupled with non/stable molding conditions and small molding window. All those aspects caused molded in stress, which was released in the form of crack during the installation.
