Study of the Influence of Surface Mold Deposits on the Demolding Stage of the Injection Molding Process of Thermoplastics

2006 ◽  
Author(s):  
Mikae¨l Chailly ◽  
Vincent Gilbert ◽  
Jean-Yves Charmeau ◽  
Yves Bereaux
Keyword(s):  
Amorphous Polymer ◽  
Infrared Camera ◽  
Acrylonitrile Butadiene Styrene ◽  
Injection Molding Process ◽  
Mold Surface ◽  
Molding Process ◽  
Injection Process ◽  
Molded Parts ◽  
Styrene Acrylonitrile ◽  
Thermal Influence

Due to increasing expectings from the market, the aspect of molded parts has to be improved. Some of the defects observed such as scratches on these parts is related to the demolding stage. To limit this, we investigated the influence on demolding forces using various surface deposits on the mold surface, mainly PVD and PACVD deposits : Chromium nitrium (CrN), Titane nitrium (TiN), Diamond like Carbon (DLC), glassy deposit (SiOx), Chromium and polished steel on an cube-shaped insert in an instrumented mold (with force sensors). Injection campaign was led on three polymers which differ in terms of nature : an amorphous polymer (polycarbonate), a semi-crystalline one (polybutylene terephatalate) and one mix of copolymers (styrene acrylonitrile/ acrylonitrile butadiene styrene). We studied the evolution of these forces through the demolding stage. This allowed us to evaluate the work energy necessary to eject the part from the insert, and to correlate those data to shrinkage of the polymer part, adhesion between polymer and mold surface and friction coefficient between those surfaces during the demolding stage. We also measured the influence the surface temperature of the part just before the demolding stage thanks to an infrared camera to investigate the thermal influence of these deposits in the injection process. Our results show an influence of deposits on demolding forces which is strongly dependent on nature of the polymer (of course) but also on its chemical nature. They also have a slight influence on temperature of the part even if they are only a few microns thick. We therefore developped a method to evaluate surface deposits and their impact on demolding forces, in terms of adhesion polymer/treament and friction.

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.

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.

scholarly journals Effects of a Phosphorus Flame Retardant System on the Mechanical and Fire Behavior of Microcellular ABS

Polymers ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 30 ◽  
Author(s):  
Vera Realinho ◽  
David Arencón ◽  
Marcelo Antunes ◽  
José Velasco
Keyword(s):  
Flame Retardant ◽  
Impact Energy ◽  
Weight Reduction ◽  
Flame Retardants ◽  
Mechanical Performance ◽  
Fire Behavior ◽  
Acrylonitrile Butadiene Styrene ◽  
Injection Molding Process ◽  
Molding Process ◽  
The Impact

The present work deals with the study of phosphorus flame retardant microcellular acrylonitrile–butadiene–styrene (ABS) parts and the effects of weight reduction on the fire and mechanical performance. Phosphorus-based flame retardant additives (PFR), aluminum diethylphosphinate and ammonium polyphosphate, were used as a more environmentally friendly alternative to halogenated flame retardants. A 25 wt % of such PFR system was added to the polymer using a co-rotating twin-screw extruder. Subsequently, microcellular parts with 10, 15, and 20% of nominal weight reduction were prepared using a MuCell® injection-molding process. The results indicate that the presence of PFR particles increased the storage modulus and decreased the impact energy determined by means of dynamic-mechanical-thermal analysis and falling weight impact tests respectively. Nevertheless, the reduction of impact energy was found to be lower in ABS/PFR samples than in neat ABS with increasing weight reduction. This effect was attributed to the lower cell sizes and higher cell densities of the microcellular core of ABS/PFR parts. All ABS/PFR foams showed a self-extinguishing behavior under UL-94 burning vertical tests, independently of the weight reduction. Gradual decreases of the second peak of heat release rate and time of combustion with similar intumescent effect were observed with increasing weight reduction under cone calorimeter tests.

scholarly journals Electricity Consumption Estimation of the Polymer Material Injection-Molding Manufacturing Process: Empirical Model and Application

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1740 ◽  
Author(s):  
Ana Elduque ◽  
Daniel Elduque ◽  
Carmelo Pina ◽  
Isabel Clavería ◽  
Carlos Javierre
Keyword(s):  
Environmental Impact ◽  
Injection Molding ◽  
Empirical Model ◽  
Electricity Consumption ◽  
Injection Molding Process ◽  
Molding Process ◽  
Polymer Injection ◽  
Wide Range ◽  
Molded Parts ◽  
Polymer Injection Molding

Polymer injection-molding is one of the most used manufacturing processes for the production of plastic products. Its electricity consumption highly influences its cost as well as its environmental impact. Reducing these factors is one of the challenges that material science and production engineering face today. However, there is currently a lack of data regarding electricity consumption values for injection-molding, which leads to significant errors due to the inherent high variability of injection-molding and its configurations. In this paper, an empirical model is proposed to better estimate the electricity consumption and the environmental impact of the injection-molding process. This empirical model was created after measuring the electricity consumption of a wide range of parts. It provides a method to estimate both electricity consumption and environmental impact, taking into account characteristics of both the molded parts and the molding machine. A case study of an induction cooktop housing is presented, showing adequate accuracy of the empirical model and the importance of proper machine selection to reduce cost, electricity consumption, and environmental impact.

Effect of Powder Loading and Binder Materials on Mechanical Properties in Iron-ABS Injection Molding Process

2013 ◽  
Vol 315 ◽  
pp. 582-586 ◽  
Author(s):  
Nasuha Sa'ude ◽  
M. Ibrahim ◽  
Wahab Saidin
Keyword(s):  
Mechanical Properties ◽  
Injection Molding ◽  
Iron Powder ◽  
Acrylonitrile Butadiene Styrene ◽  
Injection Molding Process ◽  
Molding Machine ◽  
Molding Process ◽  
Injection Molding Machine ◽  
Feedstock Material ◽  
Butadiene Styrene

This paper presents the development of a new polymer matrix composite (PMC) feedstock material by the injection molding machine. The material consists of iron powder filled in an acrylonitrile butadiene styrene (ABS) and surfactant powder (binder) material. In this study, the effect of powder loading and binder content on the mechanical properties was investigated experimentally. The detailed formulations of compounding ratio by Brabender Mixer and injection molding machine of the sample specimen was used with various combinations of the new PMC material. Based on the result obtained, it was found that, higher powder loading of iron filler affected the hardness, tensile and flexural strength of PMC material. With 32% iron powder loading in ABS composites increase the flexural force, maximum stress and force of PMC material through an injection molding process.

Numerical Simulation of the LCP Hele-Shaw Flow Based on the Injection Molding Process

2014 ◽  
Vol 609-610 ◽  
pp. 681-686
Author(s):  
Chun Bo Liu ◽  
Jian Ye Sun
Keyword(s):  
Pressure Field ◽  
Velocity Fields ◽  
Injection Molding Process ◽  
Flow Front ◽  
Square Cavity ◽  
Molding Process ◽  
Center Layer ◽  
Application Range ◽  
Injection Process ◽  
Simulation Results

In order to broaden the application range of LCP, the simulation of the LCP Hele-Shaw flow in the square cavity was conducted. The temperature of the cavity was constant 300°C. In the simulation the Leslie-Ericksen and TIF theories were used. With this simulation results, we can predict the position of the flow front at any time during the whole injection process and grasp the change of the pressure field and the velocity field. The change of the pressure and the velocity fields were very slow, there was no distortion point in the whole flow field. In the layer near the wall, the directors arranged evenly according to the direction of the flow and in the center layer it was decided by the shear rate in the X-Y plane.

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.

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