In this work, a PAM(Plasma Assisted Machining) technology was applied to milling of high manganese steel, a typical hard-to-machine materials. For this purpose, a transferred type of arc plasma torch was coupled with a 3-axis milling machine, then, used to heat and soften the surface of a high manganese steel plate in front of a 16 mm end mill with 2 blades and hard coatings. From the test results, it was concluded that the cutting load can be significantly reduced down to 57 % by plasma heating with the power level of 3.9 kW, ensuring the improvement of tool life and surface roughness in milling of high manganese work pieces.

Currently, due to the development of technology, the industry is proceeding with the development of advanced materials with high performance such as light weight, heat resistance and electric conductivity. Carbon Fiber Reinforced Plastics (CFRP) is an excellent material with high heat resistance, high strength and thermal shock resistance. In order to obtain excellent hole shape in CFRP drilling, we compared the modified drill shape and the conventional carbide drill. On the other hand, we determine the proper helix angle by observing the CFRP surface according to the helix angle at the trimming of the end mill proceeding after the hole machining.

Cutting tools tend to wear gradually with progressing of machining process due to extremely high surface loads and temperature from the relative motions between tool and workpiece. Especially, the high cutting temperature is a dominant factor in the relation to tool life. High-pressure coolant has been reported as an effective method to prevent the severe wear from cutting temperature. This research investigates efficient supplying conditions of high-pressure coolant with the CFD results from a internal-flush drilling process. The flow rate of coolant is increased drastically up to three times under 70 bar compared to conventional way.

There is a growing demand for improving the welding quality by reducing the machining error and improving the quality of the machined surface in the beveling for the improvement of the welding groove of the thick plate. For this purpose, it is necessary to develop an automatic beveling machine that adopts a cutting method that replaces the conventional oxygen flame cutting method. In this study, the cutting characteristics according to the machining conditions were evaluated during the face milling applied to the thick plate welding groove. We measured and evaluated cutting force for the machining conditions such as cutting depth, feed rate, chamfer angle, workpiece material, and material of the tool. We expect that this study is used as basic data for designing the stiffness of the spindle, the strength of the fixture and the power of the spindle and the feeding device when designing the automatic beveling machine.

This study investigates on the tuning stainless steel(STS630) to understand for groove cutting characteristics. For this purpose, we observed the cutting force according to feed rate and cutting speed variation and performed the computational analysis due to groove cutting depth. In groove cutting of stainless steel, there were principal force, feed force and radial force by arranging the highest cutting force in order. In case of wall thicknesses of 0.3mm and 0.5mm at groove cutting, principal force increases according to the increase of feed rate but it is not related to cutting speed. We found the unstable region of cutting force that is caused to the friction resistance of cutting tool and elastic deformation of groove wall. In computational analysis, we confirmed that the more feed rate increases, the more strain increases around the tooth root.

목적: 본 연구의 목적은 새롭게 개발하여 국산화한 안경테용 셀룰로오스 아세테이트(Cellulose Acetate; CA) 소재의 가공품질 및 생산성 향상을 위해 절삭성에 관한 연구를 수행하였다. 방법: 다양한 절삭 및 이송속도의 변화조건 하에서 절삭성이 평가되었다. CA 소재의 절삭실험은 절삭력, 표면조도 및 칩형상 등의 분석이 이루어졌으며, 이를 통해 절삭성을 평가하였다. 결과: 주축회전수 20,000과 30,000 rpm을 제외하고 고속영역에서 절삭력이 낮게 나타났으며, 고속회전 시 표면조도가 저속회전 조건 보다 우수하였다. 절삭력과 표면조도의 상관관계는 고속회전 조건에서는 크지 않은 것으로 나타났다. 결론: 국산화를 위해 새롭게 개발한 안경테용 CA 소재의 고품위 가공의 절삭성 평가를 수행한 결과 주축 회전수 20,000과30,000rpm을 제외하고 고속영역에서 절삭성이 양호하였으며, 표면조도는 날당이송 0.1mm 이외의 조건에서 주축회전수가 증가할수록 양호해졌고, 칩형상도 고속회전 및 저이송 조건으로 갈수록 균일 한 형태의 칩이 발생됨을 알 수 있었다. 이상과 같은 실험결과를 종합하여 새롭게 개발된 CA 소재의 절삭성을 평가할 수 있는 기초자료를 확보할 수 있었다.

The purpose of this study is to investigate cutting characteristics and wear behavior in SCM440 steel with different cutting tools, CBN(Cubic Boron Nitride) and coated CBN. During the test coated CBN toolespecially with TiAlN showed better wear resistance behavior than orginal CBN tools. In the interruptedcutting condition, axial groove affected tool surface with impact force during the turning operation. Foradvantageous turning parameter in the interrupted process it is recommendable that lower speed. Also surface roughness showed better behavior in the coated CBN tool conditions than normal CBN conditions. Mainly this is caused by reduced friction between material and tool surface with coated layer.

This study presents a single machine scheduling algorithm to minimize total cost(lateness cost, earliness cost and failure cost) by controlling machining speed. Generally, production scheduling uses the information of process planning and machining speed

High-pressure abrasive entrained jet have rapidly become important machining technology over the last two decades. However, suspension jet by high-pressure has been recently developed for packaging sawing. Ideally, diamond materials should be used for components in abrasive water-jet systems that are subject to high erosive conditions. Using the diamond orifices improve maintenance and extend wear part life. This paper gives insights to using an abrasive suspension jet with diamond orifice. The influences of orifice material and orifice design are evaluated.

  재료의 중량과 강도는 기계부품 특히 항공기의 부품에 중요한 요소가 되므로 가볍고 강인한 열처리 강화 알루미늄이나 티타늄 등이 많이 사용된다. 그러나 알루미늄은 용융점이 낮기 때문에 기계 가공 시 발생되는 열에 의해 부품이 얇고 길수록 쉽게 변형된다.   본 연구는 end milling 가공에서 최적의 절삭 parameter를 선정하여 열 변형을 최소화한다. 밀링 가공의 절삭속도, 이송속도, 절삭 깊이를 실험 인자로 정하여 다구찌 방법으로 실험을 계획

To provide an aqueous rust inhibitor for metalworking lubricant having low toxicity and excellent rust resistance, we synthesized diester of malonic acid by three consecutive esterifications with over 98% of conversion. This substituted malonic diester could be used as an additive to mineral oil based metalworking lubricant. These metalworking lubricant compositions were showed excellent rust resistance and suitable for various metals and different metalworking processes including hot rolling and cold rolling of aluminum and aluminum alloys.

Machinability improvement by the use of liquid nitrogen in cryogenic machining has been reported in various studies. This has been mostly attributed to the cooling effect of liquid nitrogen. However, No study has been found in discussion on whether liquid nitrogen possesses lubrication effect in cryogenic cutting. This paper presents lubrication mechanism related to chip microstructure. The friction reduction was further reflected In larger shear angle and less secondary deformation in the chip microstructures.