Effects of geometry and injection-molding parameters on weld-line strength

2005 ◽  
Vol 45 (7) ◽  
pp. 1021-1030 ◽  
Author(s):  
Cheng-Hsien Wu ◽  
Wan-Jung Liang
Keyword(s):  
Injection Molding ◽  
Line Strength ◽  
Weld Line

Application of ultrasonic-assisted injection molding for improving melt flowing and floating fibers

2016 ◽  
Vol 36 (2) ◽  
pp. 119-128 ◽  
Author(s):  
Yi-Jen Yang ◽  
Chung-Ching Huang ◽  
Jie Tao
Keyword(s):  
Injection Molding ◽  
Glass Fiber ◽  
Flow Behavior ◽  
Line Strength ◽  
Pressure Sensors ◽  
Weld Line ◽  
Flow Characteristics ◽  
Local Heat ◽  
Melt Flow ◽  
Ultrasonic Assisted

Abstract In this study, we investigated the use of ultrasonic technology in assisted injection molding and mold designs. We used an ultrasonic device installed in a mold to vibrate a melt directly, thereby converting kinetic energy into thermal energy. In addition, we developed three flat specimens of different thicknesses (3, 1, and 3-1-3 mm) produced by ultrasonic-assisted injection molds. An ultrasonic oscillation device 45 mm in diameter was placed in the cavity and used to vibrate a polycarbonate or a polycarbonate with 30% glass fiber melt at a frequency of 20 kHz. Furthermore, cavity pressure sensors were positioned at the front and rear of the vibration region for analyzing the melt flow behavior under ultrasonic-assisted injection molding conditions. Because of the absorption of ultrasonic energy, local heat was generated inside the resin, thus forming an oscillatory flow during the packing and holding stages, improving the flow characteristics of the melt, and changing the melt flow behavior around the skin layer to reduce the molecular orientation and high shear effect. The freezing rate of the melt was also reduced to eliminate the glass fiber streaks, floating fibers, and fiber orientation, particularly for thinner parts; the hesitation phenomena were then improved to increase the weld line strength.

Weld-Line Strength of Rubber in Injection Molding: Effect of Injection Factors and Compound Characteristics

2002 ◽  
Vol 75 (1) ◽  
pp. 83-92 ◽  
Author(s):  
M. Seadan ◽  
P. Pongbhai ◽  
P. Thairaj ◽  
T. Watana Kamtornkul
Keyword(s):  
Injection Molding ◽  
Cross Section ◽  
Line Strength ◽  
Weld Line ◽  
Circular Cross Section ◽  
High Viscosity ◽  
Mold Cavity ◽  
Cavity Pressure ◽  
Mooney Viscosity ◽  
Weld Area

Abstract The effect of injection molding system to weld-line strength in rubber O-rings was studied using a V-shape two-stage REP injection machine. Two types of injection molds were designed and built, a standard dumbbell mold with double gates and a circular cross-section O-ring mold. Several formulations of carbon black filled NR and SBR compounds were used and vulcanization temperature was either 180 or 200 °C throughout. The results show that mold cavity pressure, compound viscosity and compound scorch time are important variables for the weld-line strength of the products. The shot volume change had no direct effect on strength, but mold cavity pressure was an important factor; unfilled shot volume gave low cavity pressure thus lowering the weld-line strength of the O-rings. The compounds having 45 or lower Mooney viscosity, ML(1 + 4)120 °C, had the same weld area strength as that of the other regions of the O-ring, but the high viscosity compounds produced low weld-line strength. Only the compounds with Mooney scorch time shorter than 10 minutes gave low weld-line strength.

Effect of Weld Line Formation on Morphology and Mechanical Properties for 3D-MID Technology

2015 ◽  
Vol 659 ◽  
pp. 659-665
Author(s):  
Supakit Chuaping ◽  
Thomas Mann ◽  
Rapeephun Dangtungee ◽  
Suchart Siengchin
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Flexural Strength ◽  
Injection Molding ◽  
Filler Content ◽  
Research Work ◽  
Weld Line ◽  
Processing Conditions ◽  
High Reduction ◽  
Flexural Tests

The topic of this research work was to demonstrate the feasibility of a 3D-MID concept using injection molding technique and investigate the effects of two weld line types on the structure and mechanical properties such as tensile, flexural strength and morphology. In order to obtain more understanding of the bonds between polymer and metals, two different polymer bases of polyphthalamide (PPA) with the same type and amount of filler content were produced by injection molding at the different processing conditions. A mold was designed in such a way that weld and meld line can be produced with different angles by changing as insert inside of the mold. The mechanical properties such as stiffness, tensile strength and flexural strength were determined in tensile and flexural tests, respectively. The results showed in line with the expectation of high reduction on mechanical properties in area where weld/meld lines occurred. The result of tensile test was clearly seen that weld and meld line showed a considerable influence on mechanical properties. The reduction in tensile strength was approximately 58% according to weld line types, whereas in flexural strength was approximately 62%. On the other hand, the effect of the injection times and mold temperatures on the tensile strength were marginal.

Fracture Parameters of Short Carbon Fiber Reinforced Polycarbonate Composite Fabricated by Injection Molding Process

2015 ◽  
Vol 776 ◽  
pp. 186-192
Author(s):  
Myung Goo Hwang ◽  
Gin Ho Kim ◽  
Han Ju Park ◽  
Yong Gon Lee ◽  
Cheol Min Yang ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Injection Molding ◽  
Carbon Fibers ◽  
Weld Line ◽  
Micro Ct ◽  
Fiber Reinforced ◽  
Short Carbon Fiber ◽  
Injection Process ◽  
Carbon Fiber Reinforced ◽  
Short Carbon

This paper investigated the fracture behavior of the unavoidable breakage of carbon fibers and fiber orientation of short carbon fiber reinforced polycarbonate composite in injection process. In this experiment, short carbon fiber mixed compound of 1mm, 3mm, 5mm, 7mm length with 10wt.%, 15wt.%, 20wt.% in polycarbonate for injection molding were produced through the extruder. The dumbbell specimens for tensile evaluation were made by injection molding. The parent specimens were made by double gate method, the weld specimens were made by single gate method which was controlled by inserting a stopper through the runner of the mold cavity. Short carbon fiber reinforced PC composite was evaluated by micro-CT with regard to the particle size of short fiber with a diversified quantitative analysis through entire process of the injection process in composite. The quantitative distribution of fiber orientation was also examined by micro-CT with regard to normal direction or anisotropy. Weld line of short carbon fibers reinforced PC composite weaken the bonding strength by 50% compared to parent materials because the weld line is composed with concentrated anisotropy orientation of short carbon fiber in weld line. Evaluation of the mechanical properties of the injection specimens group was utilized by universal tensile strength tester. In addition, fracture surface of parent and weld materials was investigated by a SEM.

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