The Simulation Of The Micro-Part's Weld Lines By Injection Molding

This paper has studied the MEMS's forming ways: Micro-injection forming. The purpose of this study is to conduct the investigation on the meld line's property of the polymer melt flowing with the different gating system. Through the numerical simulation, some conclusions can be getting:1. Considering the structure characteristics of micro parts, we systemically analyzed the main aspects including the microinjection device, the process of microinjection, and the influences of parameters on microinjection and mechanical property of micro parts. The above investigation provides the theoretical basis for the building of finite element model in numerical simulation.2. Combined Navier-Stokes micro-theological theory with FEM provided by Moldflow CAE software, the numerical simulation on the filling and forming processes of micro parts has been carried on. The simulation can given more details about the filling behavior and flowing characteristic of the polymer fluid in the micro-runner.3. The filling behavior are simulated in detail under the conditions of different process parameters and the numbers and location of the gate, which is the main factor affecting the micro parts quality. From the simulation, the effects of gate location and numbers on the numbers, distributions and locations of weld lines existing in injection. The results show that the location of gating system has the greater influence on filling time during microinjection.4. Through simulation of micro parts forming, the differences between microforming process parameters and traditional ones are analyzed and listed as follows: the temperature, pressure and velocity of microinjection are higher than those of traditional injection. Furthermore, it is pointed out that the temperature control systemis key problem for microinjection die design and the die temperature should be higher than the verification point of the material, which is different from the traditional relationship between injection die temperature and verification point.