Research On Influence Of Processing Parameters To Quality Of Injection Molded Parts

Injection molded products become smaller, lighter and more accurate as the fast development of industry of 3C(Computer, Communication & Consumer Electronics), and the thinner wall will cause the bigger ratio of flow length to thickness, then multi-gate will be used to solve the issue. At the same time, the weld line may generate. Usually, the position of weld line is the stress concentration and it is harmful to application. Nowadays the demand of people to the external appearance and inherent quality is becoming higher level; therefore it is vital to forecast weld line position, strength and also to enhance the strength of weld line.The thesis investigated the weld line and its properties of thin wall plane parts of PC, ABS, PA6, and nano-composite PA6 via tensile experiments which are based on the ASTM method. The various thickness of different materials respectively is as below: PC (0.8mm, 1.0mm, 2.5mm); ABS(0.8mm, 1.0mm, 1.2mm, 2.5mm); PA6(1.0mm, 2.5mm) and nano-composite PA6(1.0mm,2.5mm). Because different polymer have different stress-strain curve, then mechanical properties can represent the quality of products, and the weld line and the properties of the thin-wall plane injection products were researched based on tensile strength. Utilizing linear regression, referencing existing model of self diffusion, we discuss the influence of processing parameters on the quality of weld line, including thickness, melt temperature, mold temperature, holding pressure and injection velocity. The mechanical properties of various thicknesses and different processing parameters were discussed. The calculation parameters of PC, ABS were adjusted to test the applicability of semi-experimental formulation. And the specific semi-experimental formulations were found and tested to forecast the degree of bonding for PA6 and nano-composite PA6. In addition, finding the fluctuation effects of computing parameter D (a parameter of molecular chain to overcome energy obstacle to reach the stabilized conditions, the D value influences the velocity of diffusion of molecular chain) on the error between experimental and simulated results of bonding degree.According to experiment and calculation data, conclusions have been made as...