Simplified Version of Polymer Rotational Molding Manufacturing Method

2016 ◽  
Vol 699 ◽  
pp. 97-103 ◽  
Author(s):  
Laurenţiu Slătineanu ◽  
Oana Dodun ◽  
Margareta Coteaţă ◽  
Gheorghe Nagîţ ◽  
Irina Beşliu
Keyword(s):  
Liquid Phase ◽  
Rotation Speed ◽  
Rotational Molding ◽  
Slow Speed ◽  
Molding Process ◽  
Manufacturing Method ◽  
Polyurethane Resin ◽  
Liquid Material ◽  
Complex Equipment ◽  
Plastic Parts

Rotational molding is a manufacturing method which supposes the rotation of the mold, during the solidification of the liquid phase material, so that finally a part having a hollow could be obtained. The method could be applied in manufacturing of metallic and nonmetallic parts. Usually, the equipment for rotational molding ensures slow speed rotating of the mold around two axes placed perpendicularly each other and this fact led to relatively complex equipment for achieving rotational molding. The capacity of the liquid material to entirely cover the internal walls of the mold depends essentially on the liquid material viscosity, on the rotation speed and on the movements applied to the mold. Simplified equipment including a single rotation movement could be materialized. In order to test such a solution, a preliminary experiment was designed and materialized, by using a device adapted on universal lathe. Thus, the objective of the research presented in the paper was to study if it is possible to achieve plastic parts made by rotational molding using a single rotation movement. A polyurethane resin obtained from two liquid components was used in order to obtain the liquid material that could be introduced in the mold. The research results proved the possibility to use simplified equipment for achieving a rotational molding process, at least in certain cases and with some technological limits.

Dynamic Modeling of Thermal Processes in Rotational Molding

Volume 3 ◽  
2004 ◽  
Author(s):  
Kalyanjit Ghosh ◽  
Srinivas Garimella
Keyword(s):  
Heat Transfer ◽  
Energy Consumption ◽  
Plastic Material ◽  
Liquid Pool ◽  
Transient Heat Transfer ◽  
Rotational Molding ◽  
Molding Process ◽  
Heating And Cooling ◽  
Consumption Rates ◽  
Plastic Parts

Transient heat transfer phenomena in the rotational molding of plastic parts are modeled in this study. Natural convection and radiation from the furnace and flue gases to the mold housing are analyzed. Other models include transient heat transfer through the mold, single-phase conduction through the particulate plastic material prior to phase change, melting of the plastic, and heating of the liquid pool. Subsequent staged cooling and solidification of the mold and plastic using a combination of free and forced convection and radiation is also modeled. Information about the properties of the plastic in powder, liquid and solid forms is obtained from the literature. Assumptions about the behavior of the plastic powder and the molten plastic during the rotational operations are also made in accordance with the available literature. The mold wall, melt and solidified plastic regions are divided into a number of finite segments to track the temperature variation with time during the molding process. The corresponding variations in masses and thicknesses of the melt and solidified plastic regions are also estimated. Consequently, the energy consumption rates in the process are estimated. The model is applied to a specific molding process in a commercial rotational molding plant. Parametric studies of the effect of heating and cooling durations on the plastic temperatures and the energy consumption rates are also conducted. These analyses provide insights about opportunities for optimization of the heating and cooling schedules to reduce overall energy consumption and also improve throughput.

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.

Towards Optimal Flow Uniformity: Stiffener Layout Design Evaluation of Injection Moulded Plastic Part

2012 ◽  
Vol 428 ◽  
pp. 33-37
Author(s):  
Yi Min Deng ◽  
Bao Shou Sun ◽  
Hua Bo He ◽  
Fu Zhan Shangguan
Keyword(s):  
Process Conditions ◽  
Flow Uniformity ◽  
Plastic Part ◽  
Moulding Process ◽  
Manufacturing Method ◽  
Part Geometry ◽  
Stiffener Layout ◽  
Plastic Parts ◽  
Stiffener Layout Design

Injection moulding is an important manufacturing method for plastic parts. There are however many moulding quality defects caused by inappropriate setting of moulding process conditions, as well as the poorly designed plastic part geometry. Often, stiffeners are used in a plastic part to increase its strength. However, if the stiffeners are not designed properly, they will introduce one or more moulding quality problems, which in turn will worsen the part strength rather than increasing it. Although there have been quite a lot of researches on optimising moulding quality, it is often difficult to minimize multiple quality defects simultaneously. In this paper, we propose to employ flow uniformity as the optimisation objective to address this problem. A number of stiffener layout designs are evaluated in terms of this objective to determine the best design, where standard deviations of filling times and pressures at the extremities of the plastic part are used to measure the uniformity of flow. A simple case study is also presented to demonstrate the applicability of the proposed methodology.

Influence of Moisture on Flax Fiber in Polyethylene Composite Product Manufactured by Rotational Molding Process

2002 ◽  
Author(s):  
S. Panigrahi ◽  
L. G. Tabil ◽  
W. J. Crerar ◽  
S. Sokansanj ◽  
T. Powell ◽  
...  
Keyword(s):  
Flax Fiber ◽  
Rotational Molding ◽  
Molding Process ◽  
Polyethylene Composite ◽  
Composite Product

Determination of Organochlorine Pesticides in Water Samples through Hollow Fiber Membrane-Liquid Phase Microextraction Using Ionic Liquid Material as Extractant

2013 ◽  
Vol 675 ◽  
pp. 260-263 ◽  
Author(s):  
Du Shu Huang ◽  
Ya Shun Chen ◽  
He Ping Yan ◽  
Na Wu ◽  
Wei Liu ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Liquid Phase ◽  
Organochlorine Pesticides ◽  
Hollow Fiber ◽  
Water Samples ◽  
Hollow Fiber Membrane ◽  
Fiber Membrane ◽  
Liquid Phase Microextraction ◽  
Liquid Material

A novel method for determination of organochlorine pesticides residuals (2,4-DDT and 4,4-DDT) in water samples through hollow fiber membrane-liquid phase microextraction using ionic liquid material as extractant coupled with high performance liquid chromatography has been developed. The effect of extraction parameters including pH of the feed solution, stirring rate and extraction time was investigated. The proposed method provided enrichment efficiency of 323 and 289 for 2,4-DDT and 4,4-DDT respectively. The method had good linear range of 0.5-50 μg /L and the limits of detection of the pesticides were 0.1 μg /L.

Banana and Abaca Fiber-Reinforced Plastic Composites Obtained by Rotational Molding Process

2013 ◽  
pp. 130614085148001 ◽  
Author(s):  
Z. Ortega ◽  
M. D. Monzón ◽  
A. N. Benítez ◽  
M. Kearns ◽  
M. McCourt ◽  
...  
Keyword(s):  
Fiber Reinforced ◽  
Rotational Molding ◽  
Molding Process ◽  
Fiber Reinforced Plastic ◽  
Plastic Composites ◽  
Reinforced Plastic

The effect of pressure variations on the formation of gas inclusions in the rotational molding process

2015 ◽  
Vol 35 (5) ◽  
pp. 481-491 ◽  
Author(s):  
Martin Löhner ◽  
Dietmar Drummer
Keyword(s):  
Cycle Time ◽  
Polymer Melt ◽  
Low Pressure ◽  
Rotational Molding ◽  
Molding Process ◽  
Inclusion Removal ◽  
Heating And Cooling ◽  
Polymer Powder ◽  
Major Disadvantage ◽  
Plastic Processing

Abstract The major disadvantage of rotational molding is the cycle time, which is very long compared to other plastic processing methods. A major percentage of the cycle time besides heating and cooling results from the time necessary to remove gas inclusions from the polymer melt, which are trapped while sintering the polymer powder. In this work the formation of gas inclusions is investigated by conducting a cycle time variation on a uniaxial rotational molding machine. The influence of low pressure during melting on the formation of inclusions is investigated by examining sintering experiments with a pressure variation during the melting of the polymer. Sintering experiments are conducted with different melt residence times to investigate the mechanisms of gas inclusion removal. By comparing the time to reach a pore-free polymeric melt, the cycle time reduction potential under low-pressure application while melting the polymeric powder is estimated.

Study of the complementary usages of selective laser sintering during the high volume production of plastic parts

2016 ◽  
Vol 22 (4) ◽  
pp. 735-742 ◽  
Author(s):  
Tomaz Brajlih ◽  
Matej Paulic ◽  
Tomaz Irgolic ◽  
Ziga Kadivnik ◽  
Joze Balic ◽  
...  
Keyword(s):  
Selective Laser Sintering ◽  
High Volume ◽  
Laser Sintering ◽  
Time Cost ◽  
Content Type ◽  
Manufacturing Method ◽  
Product Availability ◽  
High Volume Production ◽  
The Times ◽  
Plastic Parts

Purpose This paper aims to present a comparison between selective laser sintering and injection moulding technology for the production of small batches of plastic products. Design/methodology/approach The comparison is based on analysing the time–cost efficiencies of each manufacturing process regarding the size of the series for the selected product sample. Both technologies are described and the times and costs of those individual processes needed to create a final product are assessed when using each of the manufacturing processes. Findings The study shows that the time-cost efficiency of the selected laser sintering technology increases according to the complexity of the product and decreases with increasing series size and product volume. Research limitations/implications The study and absolute values of the presented results are limited to a selected plastic product, but the series size-focused efficiency analysis could be expanded to general cases. Originality/value The presented analysis could be used as a general guideline for a decision-making process regarding the more efficient manufacturing method. In addition, the results show the viability of using selective laser sintering during the early stages of production when fast product availability is required, regardless of the series size. Also, some complementary effects of using both technologies in the serial production of the same part are discussed.

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.

Metal Injection Molding Process of Mo2FeB2 Boride Base Cermets

2007 ◽  
Vol 534-536 ◽  
pp. 377-380 ◽  
Author(s):  
Hirofumi Tashiro ◽  
Koro Hirata ◽  
Yuji Yamasaki ◽  
Kenichi Takagi
Keyword(s):  
Mechanical Properties ◽  
Liquid Phase ◽  
Injection Molding ◽  
Sintering Temperature ◽  
Casting Machine ◽  
Dimensional Accuracy ◽  
Metal Injection Molding ◽  
Processing Route ◽  
Injection Molding Process ◽  
Molding Process

Mo2FeB2 boride base cermets produced by a novel sintering technique, called reaction boronizing sintering through a liquid phase, have excellent mechanical properties and wear and corrosion-resistances. Hence, the cermets are applied to the injection molding die-casting machine parts and so on. Metal injection molding (MIM) is a suitable processing route for the mass production of complex shaped and high performance components. In general, it is difficult for the liquid phase sintered materials to be applied to the injection molding process because significant shrinkage and deformation occur during sintering. In this study, the MIM process was applied in the production of Mo2FeB2 boride base cermets parts. We investigated that the effect of deoxidization and sintering temperature on mechanical properties and deformation of the cermets. As a result, deoxidization temperature of 1323K and sintering temperature of 1518K were suitable. The MIM products of the cermets showed allowable dimensional accuracy and the same mechanical properties as the press-sintered.

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