Recently, with the expansion of application of polymer composite materials, high levels of deformation compensation actions have been developed. However, there is a problem of high-temperature viscoelasticity that occurs over time after completing the injection molding process. In this study, changes of mechanical properties of the Moldflow program for injection molding were analyzed to verify the viscoelasticity phenomenon through deformation analysis. In addition, deformation analysis of plastic injection molded products according to arrangement of three ribs was conducted and two products with different geometric shapes of the same function were compared. As a result, it was possible to reflect the viscoelastic effect by reducing the elastic modulus and shear modulus of the material. It was confirmed that the geometric shape with thick ribs formed in multiple longitudinal directions was mainly responsible. On the surface of the product where the rib arrangement was parallel and perpendicular to the flow direction, the orientation was orthogonal to the linear direction and the maximum residual stress was 81.17 MPa, which showed the largest value. It was judged that viscoelastic phenomena could be predicted and that an arrangement of parallel and perpendicular ribs that might intersect should be avoided.

CFRP (Carbon Fiber Reinforced Plastic) is a composite material formed using carbon fibers and epoxy resin matrices. It has low productivity and suffers from machining defects during precision machining. Laser machining of CFRP is associated with the problem of heat damage to the epoxy resin. EDM of CFRP can process various shapes with a shaped tool, however it has a lower material removal rate compared to laser, and the non-conductive epoxy resin layer on the surface must be removed before EDM processing. In this study, we have proposed a laser EDM hybrid machining in which CFRP was pre-processed with a laser and then post-processed by EDM. The laser pre-processing conditions were selected by adjusting the laser power and the number of repetitions to minimize thermal damage. According to EDM conditions, the size of the thermal damage area occurring in the epoxy resin, the change in the side gap, and the change in the processing time were investigated. Using the hybrid processing, micro-holes with a diameter of 150 μm were machined, and square-shaped micro-holes were also machined. To improve productivity, a multi-tool capable of processing four square shapes was manufactured, and multi-processing was performed.

CFRP (Carbon fiber reinforced plastic) has been widely used in different industries such as aerospace, automobile, sports and medical. Laser processing of CFRP has a great potential for industrial applications. In this paper researched the micro cutting and drilling of CFRP with 0.5 mm thickness using 1064 nm ytterbium nanosecond pulsed fiber laser. It also investigated machining characteristics of micro cutting and drilling according to laser power, frequency, scan speed and number of scan (or irradiation). Complete cutting and through-hole drilling were achieved with low frequency when the laser power was low and with low and middle frequency when the laser power increased. However, those were not achieved a frequency of 100 kHz. The cutting width increased when the power increased and decreased when the frequency and the scan speed increased. The hole size increased when the power and the number of irradiation increased and decreased when the frequency increased. In the case of micro hole array, the hole was blocked during the next hole machining when the hole spacing was narrow. The resin was melted by the heat thus blocking the pre-drilled hole. We devised the laser scan method, and the micro hole array with narrow hole spacing was fabricated successfully.

The recent development of core techniques in the IT industry can be summarized as a technical advancement for safety and convenience, and mechanical technology for being “eco-friendly” and lightweight. Under these circumstances, research of lightweight material has become attractive. In this study, CFRP (Carbon Fiber Reinforced Plastic) laminate specimens are subjected to a tensile test using the UTM(Universal Testing Machine, AG-IS 100 kN) to estimate their mechanical properties in terms of the Hole machining impact evaluation. The FEM (Finite Elements Method) analysis method is applied and the material properties obtained from basic experiments such as the Tensile test, the compressive test, and the shear test. CFRP materials properties from a previous study, as well as a finite element analysis program for Hole machining CFRP was compared with the experiments.