scholarly journals Surface Homogeneity of Injection Molded Parts

2018 ◽  
Vol 62 (4) ◽  
pp. 284-291 ◽  
Author(s):  
László Zsíros ◽  
József Gábor Kovács
Keyword(s):  
Injection Molding ◽  
Evaluation Method ◽  
Solid Phase ◽  
Color Space ◽  
Processing Parameters ◽  
Injection Molding Process ◽  
Mold Surface ◽  
Molding Process ◽  
Molded Parts ◽  
Injection Molded

In this paper we are presenting a novel method for color inhomogeneity evaluation. We proved that this method has a higher than 95 % linear correlation coefficient if results are correlated with human visual evaluations.We applied this evaluation method to analyze the homogenization in the injection molding process, therefore we measured the homogenization properties of various solid phase masterbatches on injection molded parts. We tested the effects of the processing parameters of injection molding and analyzed various dynamic and static mixers as well. We have also measured the influence of the mold surface texture on the sensation of inhomogeneities on the part surface.We have carried out our tests on an injection grade ABS material using various masterbatches. The method was based on the digitization of the molded flat specimens. The images of these specimens were evaluated with an own developed formula using the CIELAB color space resulting high correlation with human visual inspections.

Study on Improving the Life of Stereolithography Injection Mold

2012 ◽  
Vol 468-471 ◽  
pp. 1013-1016 ◽  
Author(s):  
Hua Qing Lai
Keyword(s):  
Injection Molding ◽  
Injection Molding Process ◽  
Injection Mold ◽  
Molding Process ◽  
Molded Parts ◽  
Injection Molded ◽  
Plastic Parts ◽  
Assembly Operations ◽  
Conventional Injection Molding ◽  
Shape And Size

Molding is one of the most versatile and important processes for manufacturing complex plastic parts. It is a method of fabricating plastic parts by utilizing a mold or cavity that has a shape and size similar to the part being produced. Molten polymer is injected into the cavity, resulting in the desired part upon solidification. The injection-molded parts typically have excellent dimensional tolerance and require almost no finishing and assembly operations. But new variations and emerging innovations of conventional injection molding have been continuously developed to offer special features and benefits that cannot be accomplished by the conventional injection molding process. This study aims to improving the life of stereolithography injection mold.

Dynamic Response Optimization for Cemented Carbide Injection Molding

2014 ◽  
Vol 68 (4) ◽  
Author(s):  
Sri Yulis M. Amin ◽  
Norhamidi Muhamad ◽  
Khairur Rijal Jamaludin
Keyword(s):  
Injection Molding ◽  
Palm Stearin ◽  
Processing Parameters ◽  
Cemented Carbide ◽  
Metal Injection Molding ◽  
Injection Molding Process ◽  
Molding Process ◽  
Response Optimization ◽  
Injection Molded ◽  
Injection Temperature

The need to optimize the injection molding parameters for producing cemented carbide parts via Metal Injection Molding process is crucial to ensure the system’s robustness towards manufacturer and customer’s satisfactions. Defect free product with best density can be produced while reducing time and cost in manufacturing. In this work, the feedstock consisting of WC-Co powders, mixed with palm stearin and polyethylene binder system was injection molded to produce green parts. Several processing variables, namely powder loading, injection temperature, holding pressure and flowrate, were optimized towards the density of the green body, as the response factor. By considering humidity level at morning and evening conditions as the noise factor, the results show the optimum combination of injection molding parameters that produces best green density. The green part exhibited best density by following this optimum processing parameters, A2B3C1D1, that are flowrate at 20 ccm/s, powder loading at 63% vol., injection temperature at 140°C, and holding pressure at 1700 bar.

scholarly journals Hierarchical Structure of iPP During Injection Molding Process with Fast Mold Temperature Evolution

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 424 ◽  
Author(s):  
Vito Speranza ◽  
Sara Liparoti ◽  
Roberto Pantani ◽  
Giuseppe Titomanlio
Keyword(s):  
Injection Molding ◽  
Surface Temperature ◽  
Hierarchical Structure ◽  
Flow Fields ◽  
Electrical Heating ◽  
Cavity Surface ◽  
Injection Molding Process ◽  
Mold Surface ◽  
Molding Process ◽  
Injection Molded

Mold surface temperature strongly influences the molecular orientation and morphology developed in injection molded samples. In this work, an isotactic polypropylene was injected into a rectangular mold, in which the cavity surface temperature was properly modulated during the process by an electrical heating device. The induced thermo-mechanical histories strongly influenced the morphology developed in the injection molded parts. Polarized optical microscope and atomic force microscope were adopted for morphological investigations. The combination of flow field and cooling rate experienced by the polymer determined the hierarchical structure. Under strong flow fields and high temperatures, a tightly packed structure, called shish-kebab, aligned along the flow direction, was observed. Under weak flow fields, the formation of β-phase, as cylindrites form, was observed. The formation of each morphological structure was analyzed and discussed on the bases of the flow and temperature fields, experienced by the polymer during each stage of the injection molding process.

Quantitative Study of Shrinkage and Warpage Behavior for Microcellular and Conventional Injection Molding

Materials ◽  
2005 ◽  
Author(s):  
Adam Kramschuster ◽  
Ryan Cavitt ◽  
Don Ermer ◽  
Chris Shen ◽  
Zhongbao Chen ◽  
...  
Keyword(s):  
Injection Molding ◽  
Hold Time ◽  
Fractional Factorial ◽  
Injection Molding Process ◽  
Molding Process ◽  
Injection Speed ◽  
Microcellular Injection Molding ◽  
Molded Parts ◽  
Injection Molded ◽  
Factorial Design Of Experiments

This research investigated the effects of processing conditions on the shrinkage and warpage (S&W) behavior of a box-shaped, polypropylene part using conventional, microcellular, and microcellular co-injection molding. Three sets of 26-1 fractional factorial design of experiments (DOE) were employed to perform the experiments and proper statistical theory was used to analyze the data. After the injection molding process reached steady state, molded samples were collected and measured using an optical coordinate measurement machine (OCMM), which had been evaluated using a proper repeatability and reproducibility (R&R) measurement study. By analyzing the statistically significant main and two-factor interaction effects, the results show that the supercritical fluid (SCF) content (nitrogen in this case, in terms of SCF dosage time) and the injection speed affect the S&W of microcellular injection and microcellular co-injection molded parts the most, whereas pack/hold pressure and pack/hold time have the most significant effect on the S&W of conventional injection molded parts. Also, this study quantitatively showed that, within the processing range studied, a reduction in the S&W could be achieved with the microcellular injection molding and micro- cellular co-injection molding processes.

scholarly journals Effect of Femtosecond-Laser-Structured Injection Molding Tool on Mechanical Properties of the Manufactured Product

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2187
Author(s):  
Krisztián Kun ◽  
Zoltán Weltsch
Keyword(s):  
Mechanical Properties ◽  
Injection Molding ◽  
Femtosecond Laser ◽  
Polymer Surface ◽  
Processing Parameters ◽  
Injection Molding Process ◽  
Mold Surface ◽  
Molding Process ◽  
Melt Temperature ◽  
Polymer Product

During the injection molding process, the melt travels with a flow due to friction. As the velocity of the layers next to the wall is less than that of those flowing in the middle of the channel, a fountain flow is formed at the melt front. The temperature of the polymer surface decreases from the melt temperature to the contact temperature after contacting the mold surface. Based on all this, a complex shell–core structure is formed in injection-molded products, which can be influenced by the processing parameters and the surface of the tool insert. This paper focuses on investigating the effect of the microstructures replicated from the insert to the polymer product on its mechanical properties. During the research, two microstructured surfaces were created, with different effects on the melt flow formed by the femtosecond laser. These were compared with a ground insert to analyze the effects. For examining the effect of technological variables on the mechanical properties, an experimental design was used. The structure created by the femtosecond laser on the surface of the tool influenced the mechanical properties of the polymer products. Recognizing the effect of microstructures on the melt front and, through this, the change in mechanical properties, a predefined polymer product property can be achieved.

scholarly journals Shrinkage and Warpage Minimization of Glass-Fiber-Reinforced Polyamide 6 Parts by Microcellular Foam Injection Molding

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 889 ◽  
Author(s):  
Youngjae Ryu ◽  
Joo Seong Sohn ◽  
Chang-Seok Yun ◽  
Sung Woon Cha
Keyword(s):  
Injection Molding ◽  
Polyamide 6 ◽  
Injection Molding Process ◽  
Microcellular Foam ◽  
Molding Process ◽  
Glass Fiber Reinforced ◽  
Molded Parts ◽  
Injection Molded ◽  
Process Factors ◽  
Foam Injection Molding

Shrinkage and warpage of injection-molded parts can be minimized by applying microcellular foaming technology to the injection molding process. However, unlike the conventional injection molding process, the optimal conditions of the microcellular foam injection molding process are elusive because of core differences such as gas injection. Therefore, this study aims to derive process conditions to minimize the shrinkage and warpage of microcellular foam injection-molded parts made of glass fiber reinforced polyamide 6 (PA6/GF). Process factors and levels were first determined, with experiments planned accordingly. We simulated designed experiments using injection molding analysis software, and the results were analyzed using the Taguchi method, analysis of variance (ANOVA), and response surface methodology (RSM), with the ANOVA analysis being ultimately demonstrating the influence of the factors. We derived and verified the optimal combination of process factors and levels for minimizing both shrinkage and warpage using the Taguchi method and RSM. In addition, the mechanical properties and cell morphology of PA6/GF, which change with microcellular foam injection molding, were confirmed.

Effect of Weld Line Defects on Electrical Conductivity of Injection Molded Parts with Carbon Nano Fibers/PP Composites

2011 ◽  
Vol 233-235 ◽  
pp. 1136-1140
Author(s):  
Lei Xie ◽  
Xiao Yong Tian ◽  
Wang Qing Wu ◽  
Di Chen Li ◽  
Bing Yan Jiang ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Injection Molding ◽  
Conductive Polymer ◽  
Weld Line ◽  
Injection Molding Process ◽  
Molding Process ◽  
Molded Part ◽  
Molded Parts ◽  
Line Defects ◽  
Injection Molded

As well known, the weld line defect in injection molding process results detrimental to mechanical properties and surface quality. However, the electrical conductivity of the injection molded part is influenced as well. In this study, in order to reveal the mechanism of the weld line affecting the electrical conductivity of injection molding parts, the conductive polymer composites with various carbon nanofibers filling contents were compounded. Those composites were formed as the tensile samples with and without weld line defects by injection molding process. According to the electrical resistance measurements for the samples, it can be found that at relative low filling content of 10wt%, the weld line contributes to increase the electrical conductivity of the injection molding parts due to its effect on nanofibers’ orientation. However, when the filling content is higher than 20wt%, this effect is not significant any more.

Optimization of Injection Molding Process Parameters to Increase the Tensile Strength in Polyamide-Specimen Using the Taguchi Method

2011 ◽  
Vol 341-342 ◽  
pp. 395-399 ◽  
Author(s):  
S. Esmail Mirvar ◽  
Ramin Mohamadi Kaleybar ◽  
Ahmad Afsari
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Injection Molding ◽  
Process Parameters ◽  
Processing Parameters ◽  
Design Parameters ◽  
Injection Molding Process ◽  
Molding Process ◽  
Pressure Time ◽  
Injection Molded

Mechanical properties of plastic play an important role in defining the quality of injection molded products. Many studies have shown that mechanical properties of a product are influenced by the process parameters governing the injection-molding processes .This study employs Taguchi design parameters, to systematically investigate the influence of injection molding processing parameters on the tensile strength of Commercial grade Polyamide (PA-6). The result shows that the holding pressure time has main effect on the tensile strength, followed by cooling time, and holding pressure. Finally, a specimen produced according to the general form of the predictive equation of process parameters and verification test is performed on that. Test results show that the experimental value of tensile strength is very close to the estimated value.

A Study on the Birefringence Measurement in Injection Molded Parts Using Two Different Laser Sources and R-G-B Separation of White Light

2006 ◽  
Vol 326-328 ◽  
pp. 187-190
Author(s):  
Jong Sun Kim ◽  
Chul Jin Hwang ◽  
Kyung Hwan Yoon
Keyword(s):  
White Light ◽  
Low Cost ◽  
Main Idea ◽  
Injection Molding Process ◽  
Molding Process ◽  
Laser Method ◽  
High Productivity ◽  
Molded Parts ◽  
Injection Molded ◽  
Plastic Parts

Recently, injection molded plastic optical products are widely used in many fields, because injection molding process has advantages of low cost and high productivity. However, there remains residual birefringence and residual stresses originated from flow history and differential cooling. The present study focused on developing a technique to measure the birefringence in transparent injection-molded optical plastic parts using two methods as follows: (i) the two colored laser method, (ii) the R-G-B separation method of white light. The main idea of both methods came from the fact that more information can be obtained from the distribution of retardation caused by different wavelengths. The comparison between two methods is demonstrated for the same sample of which retardation is up to 850 nm.

Robust Parameter Design of the Precision Injection Molding Process

1994 ◽  
Author(s):  
Sornkrit Leartcheongchowasak ◽  
Merwan Mehta ◽  
Hamid Al-Kadi ◽  
Keith Sequeira ◽  
Brian Snow ◽  
...  
Keyword(s):  
Injection Molding ◽  
Taguchi Methods ◽  
Injection Molding Process ◽  
Robust Parameter Design ◽  
Molding Process ◽  
Product Lines ◽  
Molded Parts ◽  
Robust Parameter ◽  
Independent Process ◽  
The Right

Abstract The most important problem, causing defective parts, in the injection molding process, is nonuniform shrinkage of molded parts. This leads to an iterative trial-and-error cycles of modification of mold cavity and core to arrive at the right dimensional size required which can occasionally to complete retooling. For this process, there are many factors that can be thrown out of control. Using the traditional scientific approach, engineers have longed to understand the mechanics of the process to control it, with limited success. In this paper, a design of experiments setup, using the Taguchi Methods, was done to reduce the nonuniform shrinkage. The company where the experiment was carried out is a precision parts molder for their own product lines. By using the internal experts from the company, a list of independent process parameters with no interactions which were thought the most responsible for dimensional size were listed. As there were 13 such parameters, it was decided to use the L27 orthogonal array. The optimum value that the company experts thought would produce the right part were used as the settings for the initial experiment. The 27 experiments were then performed, allowing sufficient time to let the machine stabilized between the experiments. The S/N ratio calculation for 27 experiments was explained. Next the calculations for the percentage that each parameter contributes to the dimension was determined. Finally, a confirmation experiment was performed to verify the results.

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