Effect of process conditions on the weld-line strength and microstructure of microcellular injection molded parts

2003 ◽  
Vol 43 (1) ◽  
pp. 157-168 ◽  
Author(s):  
Lih-Sheng Turng ◽  
Hrishikesh Kharbas
Keyword(s):  
Line Strength ◽  
Weld Line ◽  
Process Conditions ◽  
Molded Parts ◽  
Injection Molded

Weld Lining Strength of Injection Molded Jute/PLA and Jute/PP

2012 ◽  
Author(s):  
Cuntao Wang ◽  
Yuqiu Yang ◽  
Masuo Urakami ◽  
Hiroyuki Hamada
Keyword(s):  
Fiber Orientation ◽  
Line Strength ◽  
Weld Line ◽  
Fiber Bundles ◽  
Interfacial Property ◽  
Fiber Distribution ◽  
Molded Parts ◽  
Injection Molded ◽  
Hybrid Mixtures ◽  
Better Than

Weld lines are formed inevitably when two separate melt fronts rejoin during injection molding. It has been reported that weld lines greatly weaken the strength of injection-molded parts. Therefore, in this paper the weld property of injection molded jute /PLA and jute/PP dumbbell shape specimen with weld line was investigated by changing pellets materials. In the study pultrusion technique was adopted to fabricate jute/PLA and jute/PP long fiber pellets (LFT) and it was found that fiber bundles in LFT specimens were not separated and dispersed well. As a result, in this paper re-compound pellets of LFT, i.e. RP was made. Then LFT, RP, and hybrid mixtures with the hybrid ratios of LFT50:RP50 were used to mold dumbbell shape specimens with or without weld line. In particular, the influence of different pellets on weld line strength of injection molded jute/PLA and jute/PP dumbbell shape specimens with weld line was discussed based on tensile test and SEM observation. It was found that tensile strength of RP specimens was higher than that of LFT both for jute/PLA and jute/PP, because fiber distribution and interfacial property of RP was much better than that of LFT. Weld line strength of RP was improved than that of LFT both for jute/PLA and jute/PP. RP of jute/PLA was more effective to improve the weld property than that of jute/PP. Weld line strength of jute/PP LFT increased as holding pressure increased from 44 to 88 MPa and decreased at 132 MPa holding pressure. It depends on the co-effect of fiber orientation and voids content.

Weld line strength factors in a reinforced injection molded part: Relationship with predicted fiber orientation

2019 ◽  
Vol 39 (5-6) ◽  
pp. 219-230
Author(s):  
Maria C Quintana ◽  
Patricia Frontini
Keyword(s):  
Fiber Orientation ◽  
Line Strength ◽  
Weld Line ◽  
Process Condition ◽  
Simulation Software ◽  
Process Conditions ◽  
Significant Variable ◽  
Orientation Factor ◽  
Molded Part ◽  
Injection Molded

In this work, the residual strength of a fiber-reinforced injection molded part containing a hot weld line—or meld line—was evaluated. Injected plates were generated using a double-gated mold under four different process conditions. Quantification of the weld line detrimental effect was made in base on a fracture mechanics experiment. Specimens with and without the weld line—obtained from the same plates—were tested under a clamped single edge notched tension (SENT) configuration. For each set of process conditions, a relative weld line strength factor was defined in terms of the maximum applied stress intensity factor (KImax) as: KImax of specimens with weld line/KImax of specimens without weld line. In parallel, the fiber distribution pattern was obtained by process simulation software Moldex3D. An orientation factor was determined from simulation in order to quantify the effect of the local fiber orientation around the weld line. Optimal process condition and the most significant variable influencing the weld line strength were calculated via statistical analysis. Results showed a clear correlation between the weld line strenght factors and the orientaion factor. It was demonstrated that the fracture performance of the weld line region is controlled by the fiber orientation arrangement developed on that zone.

Geometry-Based Index for Predicting Sink Mark in Plastic Parts

1991 ◽  
Author(s):  
Kurt Beiter ◽  
Kosuke Ishii ◽  
Lee Hornberger
Keyword(s):  
Process Conditions ◽  
Plastic Part ◽  
Design Rules ◽  
Packing Pressure ◽  
Molded Parts ◽  
Injection Molded ◽  
Form Features ◽  
Plastic Parts ◽  
Sink Mark

Abstract This paper describes the development of geometry-based indices that predict sink mark depth in injection molded parts. Plastic part designers need such indices to incorporate manufacturability concerns at the conceptual stage of design. These indices apply to several form features so engineers do not have to check different design rules for each geometry element. First, we propose a geometry-based sink index that can be used to predict sink mark depth as a function of process conditions such as packing pressure. Next, we explain how this relationship is identified through experiments. We also describe HyperDesign/Plastics, a Macintosh-based design aid that incorporates the sink index.

Effect of process conditions on birefringence development in injection-molded parts. I. Numerical analysis

1995 ◽  
Vol 55 (13) ◽  
pp. 1757-1769 ◽  
Author(s):  
Shia Chung Chen ◽  
Yung Cheng Chen
Keyword(s):  
Numerical Analysis ◽  
Process Conditions ◽  
Molded Parts ◽  
Injection Molded

scholarly journals Effect of Melt Temperature and Hold Pressure on the Weld-Line Strength of an Injection Molded Talc-Filled Polypropylene

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Yuanxin Zhou ◽  
P. K. Mallick
Keyword(s):  
Line Strength ◽  
Weld Line ◽  
Yield Strain ◽  
Stress Strain ◽  
Melt Temperature ◽  
Strain Behavior ◽  
The Core ◽  
Nonlinear Constitutive Model ◽  
Softening Behavior ◽  
Injection Molded

Tensile stress-strain behavior coupled with fractography was used to investigate the weld-line strength of an injection molded 40 w% talc-filled polypropylene. The relationship between processing conditions, microstructure, and tensile strength was established. Fracture surface of the weld line exhibited skin-core morphology with different degrees of talc particle orientations in the core and in the skin. Experimental results also showed that the thickness of the core decreased and the thickness of the skins increased with increasing melt temperature and increasing hold pressure, which resulted in an increase of yield strength and yield strain with increasing melt temperature and increasing hold pressure. Finally, a three-parameter nonlinear constitutive model was developed to describe the strain softening behavior of the weld-line strength of talc-filled polypropylene. The parameters in this model are the modulus E, the strain exponent m, and the compliance factor β. The simulated stress-strain curves from the model are in good agreement with the test data, and both m and β are functions of skin-core thickness ratio.

OPTIMUM DESIGN OF PROCESS CONDITIONS TO MINIMIZE RESIDUAL STRESSES IN INJECTION-MOLDED PARTS

1998 ◽  
Vol 21 (2) ◽  
pp. 141-155 ◽  
Author(s):  
Shinill Kang ◽  
C. A. Hieber ◽  
K. K. Wang
Keyword(s):  
Residual Stresses ◽  
Optimum Design ◽  
Process Conditions ◽  
Molded Parts ◽  
Injection Molded

A modified model predictions and experimental results of weld-line strength in injection molded PS/PMMA blends

Polymer ◽  
2004 ◽  
Vol 45 (9) ◽  
pp. 2911-2920 ◽  
Author(s):  
Shaoyun Guo ◽  
A. Ait-Kadi ◽  
M. Bousmina
Keyword(s):  
Line Strength ◽  
Weld Line ◽  
Experimental Results ◽  
Modified Model ◽  
Model Predictions ◽  
Injection Molded ◽  
Pmma Blends

scholarly journals Enhancing the weld line strength of injection molded components

2019 ◽  
Author(s):  
A. Geyer ◽  
C. Bonten
Keyword(s):  
Line Strength ◽  
Weld Line ◽  
Injection Molded

A Study on the Welding Line Strength of Composite Parts with Various Venting Systems in Injection Molding Process

2017 ◽  
Vol 737 ◽  
pp. 70-76
Author(s):  
Pham Son Minh ◽  
Thanh Trung Do ◽  
Tran Minh The Uyen ◽  
Phan The Nhan
Keyword(s):  
Line Strength ◽  
Weld Line ◽  
Injection Pressure ◽  
Tensile Tests ◽  
Injection Molding Process ◽  
Molding Process ◽  
High Injection Pressure ◽  
Molded Parts ◽  
Negative Effect ◽  
Welding Line

The welding line characteristics of injection molded parts with various venting systems were researched in this paper under the tensile tests of ISO 527. A mold was designed in such a way that specimens with and without a venting system can be developed separately. Both PA66 and PA66 + 30%GF materials were used in this study. Without the venting system, results showed that the weld line strength was only increased when the injection pressure varied from 0.9 MPa to 1.1 MPa, if continuously increasing the injection pressure, the weld line strength will get the negative effect. When the venting system was used, the decrease of the weld line strength with the high injection pressure was eliminated. With the use of 1.3 MPa injection pressure, when increasing the venting gap from 0.02 mm to 0.10 mm, the weld line strength varied from 10.45 MPa to 11.4 MPa with the PA66 material and from 30.8 MPa to 32.95 MPa with the PA66 + 30%GF material. With the case of without venting system, the air trap at the microstructure of weld lines was clearly observed. This trouble was removed when the venting gap value of 0.10 mm was used.

Correlation Between Mechanical Properties in Standard Test Specimens and Injection Molded Thin-Wall Parts

2013 ◽  
Author(s):  
Laurentiu I. Sandu ◽  
Felicia Stan ◽  
Catalin Fetecau
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Yield Strength ◽  
Injection Molding ◽  
Process Conditions ◽  
Thin Wall ◽  
Optimal Process ◽  
Melt Temperature ◽  
Molded Parts ◽  
Injection Molded

In this paper, we investigated the effect of injection molding parameters on the mechanical properties of thin-wall injection molded parts. A four-factor (melt temperature, mold temperature, injection speed and packing pressure) and three-level fractional experimental design was performed to investigate the influence of each factor on the mechanical properties and determine the optimal process conditions that maximize the mechanical properties of the part using the signal-to-noise (S/N) ratio response. The mechanical properties (e.g., elastic modulus, yield strength and strain at break) were measured by tensile tests at room temperature, at a crosshead speed of 5 mm/min, and compared with those of the injection-molded specimens. The experimental results showed that the tensile properties were highly dependent on the injection molding parameters, regardless of the type of the specimens. The values of Young modulus and yield strength of the injection-molded specimens were lower than those of the injection-molded parts, while the elongation at break was considerably lower for the injection-molded parts. The optimal process conditions were strongly dependent on the measured performance quantities (elastic modulus, yield strength and strain at break).

Sign in / Sign up

Export Citation Format

Share Document