• 대한기계학회논문집A
• /
• 제37권1호
• /
• pp.61-66
• /
• 2013

적층조형 방법의 개발로 열전도성 금형 혹은 형상적응형 냉각회로를 구비한 금형의 제작이 가능하게 되었다. 금형의 재질로 치수변화가 적은 P21 툴 스틸이 널리 사용되고 있지만, 열전도율이 낮기 때문에 냉각효율은 높지 않다. 이러한 점에서 열전달 효율을 극대화 시킬 수 있는 방법으로 P21 스틸과 구리(Cu)를 기능적으로 혼합한 기능성 경사 복합재(FGM)를 사용하는 방법이 검토되고 있다. 본 논문에서는 FGM 구조를 가지는 금형의 적층조형을 위한 예비연구로 P21-Cu 간의 1 차원 FGM 을 DMT 장비를 이용하여 제작하고, 열전달 관련 물성치를 평가하였다.

• 한국분말재료학회지
• /
• 제14권6호
• /
• pp.367-371
• /
• 2007

P/M high speed steel (1.26% C, 4.42% Cr, 6.54% W, 4.92% Mo, 3.21 % V, 8.77% Co, bal. Fe) was applied to hot former die. It showed that the die life became 2.7 times higher than that of cast/wrought SKH 55 tool steel which is commercially used. The increase of die life was corresponding to the improved hardness and transverse rupture strength of PM high speed steel due to the finer grain and carbide as well as the uniform carbide distribution. The P/M high speed steel with the promoted die life could be an alternative to the conventional SKH55.

• Journal of Welding and Joining
• /
• 제21권4호
• /
• pp.63-68
• /
• 2003

Scanning electron microscopy (SEM) has been used as a surface measurement instrument and a tool for lithography in semiconductor process due to its high density localized beam. For those purposes, however, the maximum current of SEM Is less than 100pA, which is not enough fo material processing. In this paper SEM was modified to increase the amount of current reaching a specimen from gun part where current is generated, the possibility of applying SEM to material processing, especially microjoining, was investigated. The maximum current of SEM after modifications was measured up to 10$\mu$A, which is about 10$^{5}$ times greater than before modifications. Through experiments such as eutectic solder wetting on thin 304 stainless steel foil and microjoining of 10$\mu$m thick 304 stainless steel, the intensity of electron beam of SEM proved to be great enough fur material processing as heat source. And a tight jig system was found necessary to hold materials close enough fur successful microloining.

• 대한기계학회논문집A
• /
• 제33권3호
• /
• pp.201-209
• /
• 2009

The objective of present research work is to design the heat conductive mould to improve cooling characteristics of the injection mould for a mouse. In order to obtain the high cooling rate of the mould, a heat conductive mould with three different materials was designed. The materials of the base structure, the mid-layer and the molding part of the heat conductive mould were chosen as Cu-Ni alloy (Ampcoloy 940) to improve the heat conductivity of the mould, Ni-Cu alloy (Monel 400) to reduce a thermal stress, injection tool steel (P21), respectively. Through the three-dimensional transient heat transfer analysis and the thermal stress analysis, the effects of the geometrical arrangement of each material on the cooling characteristics and the thermal stress distribution were examined. From the results of the analyses, a proper design of the thermal conductive mould was obtained.