Fabrication and Property Characterization of Long-Glass-Fiber-Reinforced Polypropylene Composites Processed Using a Three-Barrel Injection Molding Machine

Abstract

Processing equipment and parameters will highly influence the properties of long-fiber-reinforced injection-molded thermoplastic composites, leading to different fiber lengths and orientations. Thus, maintaining fiber length during the injection molding process is always a big challenge for engineers. This study uses long-glass-fiber-reinforced polypropylene with 25 mm fiber length and a special-built novel injection molding machine with a three-barrel injection unit, including a plasticizing screw, an injection plunger, and a packing plunger, to fabricate injection molding parts while retaining long fiber length. This study also discusses the influence of process parameters, such as back pressure, screw speed, melt temperature, and different flow paths, on the properties of long-glass-fiber-reinforced composites. The experiment results show that a higher screw speed and back pressure will reduce the fiber length in the injection-molded parts. However, using appropriate parameter settings can maintain the fiber length to more than 10 mm. It was found that by increasing the back pressure, the cross direction of the fiber orientation can be increased by up to 15% and the air trap volume fraction can be decreased by up to 86%. Setting appropriate back pressure under a low screw speed will increase the tensile strength. Finally, it was found that the single-edge-gate path results in a higher tensile strength than that of the single-sprue-gate path due to the retainment of longer fiber length in the injection-molded part.

Optimization of Ultrasonic Welding Process Parameters to Enhance Weld Strength of 3C Power Cases Using a Design of Experiments Approach

“…Figure 2 shows the 3D CAD model and dimensions of a power case. Both the cover and chassis of a 3C power case were fabricated by plastic injection molding via polycarbonate (PC) [24] using a plastic injection molding machine (KT2S, Kinki Inc., Taipei city, Taiwan) [25]. The process parameters involve injection pressure of 18 MPa, injection speed of 80 mm/s, and cooling time of 10 s. The length, width, and height of the cover are 42.8 mm, 26 mm, and 51.8 mm, respectively.…”

Experimental Study of Fiber Orientation on the Mechanical Properties of Glass Fiber Reinforced Thermoplastic Composites

“…Under the influence of Finite Element Analysis results, the steel car door has been modified with glass fiber composite materials. Liou et al [12] have made an experimental investigation to perform process characterization for the specimen laminates. It is observed that the process parameters have played no role to affect the fiber angles because of the lengthy fibers.…”

Internal Gas-Assisted Mold Temperature Control for Improving the Filling Ability of Polyamide 6 + 30% Glass Fiber in the Micro-Injection Molding Process

“…This influence is more important in the micro-injection molding process, in which the melt flow length must be increased in the product’s micro-features. Because micro-injection molds are low cost and have the potential for high-volume production, they are used to manufacture a variety of polymer components in the injection molding field [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. Therefore, the most common applications of micro-injection molding are in micro-devices [ 9 , 10 ], optical structures [ 11 , 12 , 13 , 14 ], and micro-fluidic devices [ 15 , 16 , 17 ].…”