• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.9
• /
• pp.2386-2395
• /
• 1994

An experimental study on heat transfer and flow in compression molding of clss-B and A SMC(Sheet Molding Compounds) in a flat plate and a cross-sectional T-shape was carried out. The temperature was measured with thermocouples at two locations in the 4 layered SMC charge and pressure was measured at the center of the top mold during compression molding. Three different mold speeds, 15, 45, 50 mm/min and two different mold temperature, $130^{\circ}C{\;}and{\;}150^{\circ}C$ were used for compression molding experiments. Experiments with different colored SMC layers were used to study flow patterns at various compression stages. In oder to predict the pressure and load in SMC compression molding, slab method was used. The predicted values of pressure and load from the slab analysis were compared well with the measured data.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 1995.10a
• /
• pp.64-67
• /
• 1995

Transfer Molding is currently the most widely used process for encapsulation integrated circuits(;IC). Although the process has been introduced over 20 years ago, generating billions of parts each year, it is far from being optimized. With each new mold, epoxy mold, epoxy mold compound, and lead-frame, lengthy period and expensive qualification runs have to be performed to minimized defects ranging from wire sweep, incomplete fill, and internal voids etc. This studies describes how simulation can be applied to transfer molding to yield acceptable design and processing parameter. The non-isothermal filling of non-newtonian reactive epoxy molding compound(;EMC) in a multi-cavity mold is analyzed. Sensitivity analysis is conducted to investigate the influence of process deviations on the final molded profile. This study trend is carried out by following some heuristic process guidelines.

• Korea-Australia Rheology Journal
• /
• v.18 no.4
• /
• pp.217-224
• /
• 2006

Rapid flow advancement without void formation is essential in the liquid composite molding (LCM) such as resin transfer molding (RTM) and vacuum assisted resin transfer molding (VARTM). A highly permeable layer in multi-layered preform has an important role in improvement of the flow advancement. In this study, a multi-layered preform which consists of three layers is employed. Radial flow experiment is carried out for the multi-layered preform. A new analytic model for advancement of flow front is proposed and effective permeability is defined. The effective permeability for the multi-layered preform is obtained analytically and compared with experimental results. Compaction test is performed to determine the exact fiber volume traction of each layer in the multi-layered preform. Transverse permeability employed in modeling is measured experimentally unlike the previous studies. Accurate prediction of flow advancement is of great use for saving the processing time and enhancing product properties of the final part.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2002.10a
• /
• pp.284-287
• /
• 2002

During resin transfer molding(RTM) process, in case of thick parts, resin flow and void formation should be modeled three dimensionally even though for parts of small thickness, resin flow and void formation can be modeled two dimensionally. In this study, numerical simulations of three dimensional mold filling and void formation during RTM process.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2003.10a
• /
• pp.79-82
• /
• 2003

In case of performing resin transfer molding (RTM), race track effects and non-uniform fiber volume fraction may cause undesirable resin flow pattern and thus result in dry spots, which affect the mechanical properties of the finished parts. In this study, a real time RTM control strategy to reduce these unfavorable effects is proposed. Through numerical simulations and experiments, the validity of the proposed scheme is demonstrated.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.23 no.1
• /
• pp.38-41
• /
• 2010

Compared to conventional molding technology, the color uniformity of light direction emitted from LED is improved with PCB type lead frame technology in which metal thin film is used and transfer molding technology which makes the density of phosphor uniform by manufacturing high density LED lamp. The light efficiency and the color uniformity of the LED are improved by molding the phosphor layer outside of chip and controlling the thickness of the phosphor layer. CIE x,y difference of LED in major axis is also improved uniformly from 0 to 90 degrees.

• Proceedings of the KSME Conference
• /
• 2001.06c
• /
• pp.246-250
• /
• 2001

In resin transfer molding (RTM), resin is forced to flow through the fiber perform of inhomogeneous permeability. This inhomogeneity is responsible for the mismatch of resin velocity within and between the fiber tows. The capillary pressure of the fiber tows exacerbates the spatial variation of the resin velocity. The resulting microscopic perturbations of resin velocity at the flow front allow numerous air voids to form. In this study, a mathematical model was developed to predict the formation and migration of micro-voids during resin transfer molding. A transport equation was employed to account for the migration of voids between fiber tows. Incorporating the proposed model into a resin flow simulator, the volumetric content of micro-voids in the preform could be obtained during the simulation of resin impregnation.

• Transactions of Materials Processing
• /
• v.15 no.6 s.87
• /
• pp.436-440
• /
• 2006

A rapid tooling (RT) method fur the resin transfer molding (RTM) have been investigated. We fabricated a curved I-beam to verify the method. After creating a three-dimensional CAD model of the beam we fabricated a prototype of the model using a rapid prototyping (RP) machine. A soft mold was made using the prototype by the conventional silicone mold technique. The procedure and method of mold fabrication is described. The mold was cut into several parts to allow easier placement of the fiber preform. We conducted the resin transfer molding process and manufactured a composite beam with the mold. The preform was built by stacking up eight layers of delicately cut carbon fabrics. The fabrics were properly stitched to maintain the shape while placement. The manufactured composites beam was inspected and found well-impregnated. The fiber volume ratio of the fabricated beam was 16.85%.

• 기계와재료
• /
• v.13 no.2 s.48
• /
• pp.93-103
• /
• 2001

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.19 no.12
• /
• pp.87-97
• /
• 2020

In this study, a UV-cured GFRP molding is made using a combination of hand lay-up and resin transfer molding, and its properties are analyzed. The molded plates produced using various vacuum pressures (0 mmHg, -450 mmHg, and -760 mmHg) are examined via a comparison of hand lay-up molding and resin transfer molding. Tests are conducted by processing tensile specimens (ASTM D-5083), flexural test specimens (ASTM D-790), and ILSS test specimens (ASTM D-2344) according to each ASTM standard with a molded plate. Similarly, the UV-cured GFRP molding is compared against GFRP using epoxy. It was confirmed that the mechanical strengths of all the specimens increased when the vacuum pressure was increased and when UV curing was applied. This is believed to be because as the vacuum pressure increases, the pores of the cured specimen are removed, thereby reducing defects, and the bonding force between the glass fiber and the resin is stronger than that of the epoxy resin. It is expected that if resin transfer molding methods and UV-cured resins are used for molding GFRP composites in industry, products with better mechanical properties and faster curing time will be produced.