The application of automotive plastic parts has significant advantages in reducing vehicle quality, saving fuel, promoting environmental protection, and being recyclable. Most automotive plastic parts are injection molded. Tiger skin patterns, poor surface reproduction, sink marks, weld lines, warping deformation, etc. are common defects in automotive injection molded parts. These defects are not only related to materials, but also to structural design and mold design. It has a lot to do with the molding process. Today I will share with you some common problems and solutions for bumper injection molding!
1. Pressure line
As shown in the figure, there are obvious pressure lines around the bumper fog lights, which affects the appearance and surface quality of the product. Since the bumper is a part of the outer surface of the car, the requirements for apparent quality are relatively strict. The occurrence of pressure lines will affect the apparent quality of the product. have a serious impact.
1. Main process parameters of materials
Name: bumper
Material: PP
Color: black
Mold temperature: 35℃
Gate method: needle valve gate
2. Possible cause analysis and improvement measures
Mold aspect: In this case, there is a gate G5 near the hole around the fog lamp. When the gate is opened, due to the influence of the hole, the pressure on both sides of the hole reaches a balanced pressure line again.
The pressure lines described in the case are actually undercurrent lines, which often appear in the area where weld lines are located. The mechanism of the occurrence of such pressure lines is shown in the figure below. The solution is to try to reduce the pressure difference around the weld lines, or to The pressure difference is not sufficient to move the solidifying melt.
Post time: Jan-16-2024