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.

INJECTION MOLDING OF FLAT GLASS FIBER REINFORCED THERMOPLASTICS

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2555-2560 ◽  
Author(s):  
KAZUTO TANAKA ◽  
TSUTAO KATAYAMA ◽  
TATSUYA TANAKA ◽  
AKIHIRO ANGURI
Keyword(s):  
Mechanical Properties ◽  
Injection Molding ◽  
Glass Fiber ◽  
Cross Section ◽  
Fiber Length ◽  
Flat Glass ◽  
Circular Cross Section ◽  
Fiber Reinforced ◽  
Glass Fiber Reinforced ◽  
Fiber Attrition

During an injection molding of composite materials, fiber attrition occurs and the average fiber length is reduced. In order to control the breakage of fibers and degradation of mechanical properties during processing, Flat glass Fiber (FF), that has oval cross-section shape, has been developed to use for glass fiber reinforced thermoplastic (GFRTP). Using FF as reinforcement of GFRTP has advantages as following: (1) Fluidity of FF is better than conventional Normal glass Fiber (NF) with 'circular' cross-section; (2) Fiber breakage during the injection molding process using FF is smaller than that using NF. In this study, the mechanical properties of FF and NF were compared for reinforcement of long fiber thermoplastics pellets (LFT pellets). We have also investigated the effect of screw design on fiber damage and the mechanical properties. The mechanical properties of specimens molded by FF reinforcement LFT (FF-LFT) pellets were superior to these of NF reinforcement LFT (NF-LFT) pellets. The former could give composites with higher fluidity and longer residual fiber length. Moreover, FF was able to strengthen injection-molded samples with higher fiber content than NF. Low shear type screw was effective to prevent the fiber attrition during plasticization process, hence leads to better mechanical properties of GFRTP

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.

scholarly journals Effect of micro injection molding parameters on cavity pressure and temperature assisted by Taguchi method

Mechanika ◽  
2019 ◽  
Vol 25 (4) ◽  
pp. 261-268
Author(s):  
Quan Wang ◽  
Chongying Yang ◽  
Kaihui Du ◽  
Zhenghuan Wu
Keyword(s):  
Injection Molding ◽  
Experimental Work ◽  
Complex Geometry ◽  
Mold Temperature ◽  
Mold Cavity ◽  
Injection Molding Process ◽  
Cavity Pressure ◽  
Molding Process ◽  
Melt Temperature ◽  
Packing Pressure

The injection molding process is one of the most efficient processes where mass production through automation is feasible and products with complex geometry at low cost are easily attained. In this study, an experimental work is performed on the effect of injection molding parameters on the polymer pressure and temperature inside the mold cavity. Different process parameters of the injection molding are considered during the experimental work including packing pressure, packing time, injection pressure, mold temperature, and melt temperature. The cavity pressure is measured with time by using Kistler pressure sensor at different injection molding cycles. The results show the packing pressure is significant factor of affecting the maximum of diverse spline cavity pressure. The mold temperature is significant factor of affecting the maximum cavity temperature. The results obtained specify well the developing of the cavity pressure and temperature inside the mold cavity during the injection molding cycles.

Visual Experiment Study on the Influence of Mold Structure Design on Injection Molding Product’s Defects

2009 ◽  
Vol 87-88 ◽  
pp. 31-35 ◽  
Author(s):  
Peng Cheng Xie ◽  
Bin Du ◽  
Zhi Yun Yan ◽  
Yu Mei Ding ◽  
Wei Min Yang
Keyword(s):  
Injection Molding ◽  
Experimental Method ◽  
Direct Observation ◽  
Weld Line ◽  
Structure Design ◽  
Mold Cavity ◽  
Experiment Study ◽  
Forming Process ◽  
Visualization System ◽  
Visual Method

Injection molding visualization is the experimental method of direct observation on the melt filling behavior in the mold cavity. By using developed visualization system, the influence of mold structure design on the injection molding product’s defects, such as jetting and weld were studied in this paper. The forming process of jetting was observed by the visual method, and results show that it is useful to avoid jetting by locating gate correctly. According to the generation of weld line in single gate cavity, an improved measure to adjust the weld locations by adding overflow traps was proposed. The result indicates that the overflow trap is good for adjusting weld location and makes the defects appear in the unimportant points of surface. Another experiment on the forming process of weld line in two-gate cavity with setting different distance parameters were carried out. The result shows that increasing of gates distance may significantly affect the performance of weld line.

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
Sign in / Sign up

Export Citation Format

Share Document