• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.491-495
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• 2004

The industries use polymer materials for many purposes for they have many merits. The costs of these materials take up too great a proportion of the overall cost of products that use these materials as their major material. It is advantage for polymer industries to reduce these costs. The microcellular foaming process was developed in the early 1980s to solve this problem and proved to be quite successful. Microcellular foaming process uses inert gases such as $CO_2$, $N_2$. As these gases solve into polymer matrices, many properties are changed. The microcellular foaming process makes the glass transition temperature of polymers to low, and diminish the residual stress of polymer matrices. Besides, the microcellular foaming process has several merits, impact strength elevation, thermal insulation, noise insulation, and raw material saving etc. This characteristic of microcellular foaming process has influenced by cell morphology. The cell morphology means cell size and cell density. The cell morphology has influenced by many factors. The examples of factor are pressure drop rate, foaming temperature, foaming time, saturation pressure, saturation time etc. Among their factors, pressure drop rate is the most important factor for cell morphology in microcellular foaming injection molding process. This paper describes about the cell morphology change in accordance with the pressure drop rate of microcellular foaming injection molding process.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.6 s.171
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• pp.168-174
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• 2005

Nowadays, the companies use polymer materials for many purposes fur they have many advantages. The costs of these materials take up too high a proportion of the overall cost of products that use these materials as their major material. It is advantage for polymer industries to reduce these costs. The microcellular foaming process was developed in the early 1980s to solve this problem and proved to be quite successful. Microcellular foaming process uses inert gases such as $CO_2,\;N_2$. As these gases solve into polymer matrices, many properties are changed. The microcellular foaming process makes the glass transition temperature of polymers to low, and diminish the residual stress of polymer matrices. Besides, the microcellular foaming process has several merits, impact strength elevation, thermal insulation, noise insulation, and raw material saving etc. In previous research, many facts of microcellular foaming process are founded its characteristics. But previous researcher found the characteristics of microcellular foaming process with pure gas, for example $CO_2,\;N_2$ and so on, they did not found the characteristics of microcellular foaming process with one more gases. If one more gases inlet the resin, the characteristics of microcellular foaming process is changed very amazingly. In this paper, discuss on the characteristics of microcellular foaming process wi th gas cocktail about cell morphology.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.341-345
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• 2001

New technoloty called microcellular foaming process was developed at MIT in 1980's. Although it has many good things, it could not be used it all sides of manufacturing plastics. Because it takes a long time for making foamed goods. So microcellular foaming injection molding process appeared to solve this problem. The first purpose of this research is to measure the impact strength as foaming magnitude of microcellular foamed plastics. There are two methods such as batch process and microcellular foaming injection molding process in making foamed plastics. According to the experimental data, the impact strength of each specimen was measured to find out the influence of foaming magnitude of microcellular foamed plastics.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.9
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• pp.71-77
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• 2008

Microcellular foaming plastics create a sensation at polymer industrial for lowering product costs and overcoming a lowering of mechanical intensity. Among many advantages, microcellular foaming plastics is well known to have a good acoustical properties. This research based on the experiment of sound absorption and transmission characteristics inquire into acoustical properties of microcellular foaming plastics. Difference of transmission loss of microcellular foaming plastics and solid materials was defined as cell effect. Also, cell effect is expressed by sound reflection and sound absorption. This study is expected to fundamental research to present economical, functional alternative plan for products using sound absorption and transmission materials.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.419-420
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• 2007

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.853-858
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• 2001

Generally, mixed materials of LDPE, EVA and foaming agent are manufactured by crosslinking foaming or chemical foaming process. Above materials were used in a microcellular foaming injection molding process. Influence of each factor such as injection type, temperature of barrel, rate of mixed materials and contents of foaming agent was estimated by DOE(Design of Experiments). As a result of experiments, injection type and rate of LDPE, EVA have an influence on foaming rate. This data can be used in field of application of LDPE and EVA.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.4
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• pp.637-644
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• 2001

Polymer materials have a lot of merits including the low cost and the easiness of forming. For these reasons they are widely using at many manufacturing industries. Microcellular foaming process appeared at MIT in 1980s to save a quantity of material and increase mechanical properties. There are many process variables in appling microcellular foaming process to the conventional injection molding process. They can be solved by using Axiomatic Design Method which is very useful design method for designing a new product. Its main character is scientific and analytical. The information about the thickness of cavity plays an important role in making an effective foam. The goal of this research is to design mold system for advance of foaming magnitude with axiomatic design method. There is a relation between the change of cavitys thickness and foaming magnitude made after inserting a gas. R/t is a conception that indicate proportion between radius and thickness of cavity in mold system. By means of SEM observation of side surface of cavity sample, foaming magnitude of polymer in microcellular foaming process is decreasing gradually as the value of R/t is increasing. In this paper, an advanced mold system was presented by mapping the relation between functional requirements and design parameters.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.751-752
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• 2012

• Journal of the Korean Society for Precision Engineering
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• v.17 no.10
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• pp.186-191
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• 2000

We use so many plastic products in everyday. Because polymer materials have a lot of merits including low cost and easiness of forming, they are widely using at many manufacturing industries. Microcellular foaming process appeared at MIT in 1980's to save a quantity of material and increase mechanical properties. The information about the thickness of cavity plays an important role in appling microcellular foaming process to the conventional injection molding process. It is essential to make an effective foam. The goal of this research is to measure the relation between the change of cavity's thickness and foaming magnitude made after inserting a gas. R/t is a conception that indicate proportion between radius and thickness of cavity in mold system. By means of SEM observation of side surface of cavity sample, foaming magnitude of cavity is mold system. By means of SEM observation of side surface of cavity sample, foaming magnitude of polymer in microcellular foaming process is decreasing gradually as the value of R/t is increasing. The proposed foaming magnitude changes data of polymer in relation to mold system can be applied in more extensive injection molding process, such as optimum design of mold for microcellular foaming process.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.621-626
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• 2001

Microcellular foaming process was developed at MIT in 1980's to save a quantity of raw materials and improve mechanical properties. There are many process variables in appling microcellular foaming process to the conventional injection molding process. Of all process variables, part dimension control and shrinkage are the most influential on the post molded dimension. The post molding dimensional change of thermoplastic resins is important to tool designers for predicting the specific difference of molded part vs. actual mold cavity. Generally, articles injection molded are smaller in size than the cavity; hence, the term shrinkage factor is used to define the allowance a designer specifies. It is important to consider the factors that influence molded part dimension. According to ASTM Designation: D 955, shrinkage from mold dimensions of molded plastics was measured. In injection molding, the difference between the dimensions of the mold and of the molded article produced therein from a given material may vary according to the design and operation of the mold. In this paper, shrinkage data of molded plastic parts was obtained. It can be an important information for designing optimum mold system in a microcellular foaming injection molding process.