In this paper, the CFRP(Carbon Fiber Reinforced Plastic) parts were printed and cut in a large-scale additive and subtractive hybrid manufacturing system. A method to increase the strength and durability of a product by identifying the interlayer adhesion during the printing process of a large-scale additive manufacturing hybrid system was investigated. According to the printing conditions(CF content, deposition temperature, compaction process), the specimen was printed and cut to determine the tensile strength in the printing direction. As a result of the experiment, the highest tensile strength was shown when ABS-CF 20wt.% Compound was printed at 230℃ extrusion temperature, and the higher the CF content of the material, the lower the tensile strength. As a result of observing the inside of the test piece through an optical microscope, a large number of voids were kept inside the test piece. To remove voids generated inside the test piece, a compaction process was applied to the additive manufacturing hybrid system to prepare a test piece. As a result, void size decreased, and the strength of the part showed a tendency to increase. It is thought that additive manufacturing with high tensile strength can be obtained through studies on the optimization of deposition conditions in additive manufacturing hybrid systems.
Aluminum High Vacuum Die-casting process has become more prevalent in automotive manufacturing industry which require high productive rate, weldable process and heat treatment process. However, high pressure die castings usually contain gas porosity due mainly to the entrapment of air or gas in the die during the high speed injection of the molten metal into the die cavity.
Vacuum block system with disk spring was developed and vacuum chanel was optimized with numerical flow analysis. The porosity of die castings was analyzed by X-ray CT, and the effect of porosity on the mechanical properties was analyzed by hardness and tensile test. Tensile strength was improved 49.5% for 50mbar high vacuum die-casting process compare then 300mbar. And then, Surface property was analyzed with plunger velocity and fast shot set point.
In this study, Equivalent fracture strain and Fracture energy were evaluated with the small punch test(SP test) for friction stir welded(FSW) Al6061-T6 sheets. With the three rotation speeds and the three feeding rate, The nine different conditions of FSW were prepared for the SP test. The SP test specimens were manufactured and tested on the advancing side, center, and retreating side to the tool rotation direction. From the SP test data, the equivalent fracture strain and the fracture energy were analyzed. The high value of equivalent fracture strain was attained form tool rotational speed 900RPM and feeding rate 330mm/min. It is found that its characteristic is about 14% higher than the value of condition 1100RPM-330mm/min that have the lowest value. The high value of fracture energy was obtained from the tool rotation speed 900RPM and feeding rate 330mm/min. The lowest fracture energy, which from 1000RPM-300mm/min, was approximately 16% difference to the highest value.
The investigation on the lightweight of automobiles has been underway in commercial vehicles as well as passenger cars due to global warming and strengthening of European emission standards. In this study, the V-arm were developed for lightweight parts using aluminum alloy instead of steel with high pressure die casting processing. This study has focused on lightweight adaptive concept design. Several models of V-arm were designed and analyzed for the fluidity and solidification. V-arm was produced with ADC12 by high pressure die-casting process. The mechanical properties of developed V-arm were measured; such as tensile strength, elongation, shear strength, and durability. The possibility of mass production with the light weight aluminum V-arm substitute from the steel. The weight was reduced about 38% from 16kg to 9.98kg. The productivity was improved with decreasing the process from 8 to 5 by All-in-0ne process using high pressure die-casting.
Magnesium alloy is becoming known for the lightest material in the metallic materials. Recently the automotive industry has a variety application to the light weight parts replacement. This study focuses on the mechanical property improving through a tiny amount’s CNT addition into the magnesium alloy as AM60. The CNT material is an arduous combination of the metallic materials. Therefore this study is concentrating on the contact force growth for the CNT material. Consequently, the made CNT is produced by the CVD process using the magnesium catalyst. The CNT material has dispersive with mechanical process into the molten AM60 alloy. The mechanical experiment result that hardness is 18% increasing and tensile strength is 13% increasing, better than the raw AM60 alloy on this investigation.
The characteristics of CNT-Polyamide composites were analyzed, that is, tensile strength, electrical resistivity, and thermal conductivity were measured according to the align length of CNT. There have been researches on the influence of aligned CNT to improve the mechanical and thermal characteristics in different areas including absorption and shielding of electromagnetic wave, thermal distribution or absorption, and high-strength of CNT.
The aligned CNTs were synthesized by the ethylene gas with a CVD device preheated at 650℃. CNT-Polyamide composites were produced with the mixing of solution. CNT contents were controlled from 1phr to 50phr in the polyamide-ethanol solution, and blended with the 700W bar-type ultrasonic wave for 60 min.. And then CNT-polyamide were precipitated by CNT-polyamide-etnanol falling into the cold water. After dried 12 hours, CNT-polyamide composite were pressed at 150℃~180℃ with 400kgf to get the thickness of 1mm.
As the conclusions, aligned CNT bundles were dispersed by cutting of CNT to the aligned direction because of polyamide properties. Tensile strength and electrical resistivity were improved to the increase of aligned length of CNT. Thermal conductivity was little affected by the align length of CNT.