• Journal of Korea Foundry Society
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• v.27 no.5
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• pp.217-220
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• 2007

절삭특성은 재료를 원하는 형상으로 가공하기 위해 재료의 불필요한 부분을 제거할 경우 그 가공성이 쉽거나 어려움에 대한 정도로 전의될 수 있는데 동합금 소재의 절삭특성은 절삭시 발생된 칩의 형상이나 길이를 측정하거나 또는 공구계에 부착된 토오크 미터에 의해 절삭력을 간접적으로 측정하는 방법 등이 사용되어 오고 있다. 상기의 평가방 법은 절삭특성의 간접적인 평가방법이라는 한계와 정확도에 문제가 있는 실정이다. 본 연구에서는 압전형 공구동력계(Piezoelectric Tool Dynamometer)를 쾌삭인청동합금 피절삭물에 직접 부착하여 절삭가공시 절삭력은 정량적으로 직접 측정하고자 하였다. 쾌삭인청동합금의 소둔 열처리 시간이 증가할수록 결정립의 성장에 의한 연화현상과 납입자의 군집화(Clustering)는 관찰되었으나 그로 인한 절삭력 및 절삭에 필요한 에너지의 변화는 뚜렷하지 않았다.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.6
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• pp.158-163
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• 2000

High speed machining of difficult-to-cut materials generates the concentrated thermal/frictional damage at the cutting edge of the tool and rapidly decreases the tool life. In this paper, the cutting environments, such as dry, fluid coolant, and compressed chilly air coolant, were investigated to improve the tool life. For this study, the compressed chilly air system was manufactured. The experiments were performed for various difficult-to-cut materials and various coated tools. The effectiveness of the developed methods on the basis of tool life was estimated. The results show that the cutting environment using compressed chilly air coolant provided better tool life than using the fluid coolant or using the dry.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.493-497
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• 2002

In the part industry, pipe has required high accuracy in surface roughness and size. Especially, when producing the high frequency welding pipe, cutting process is very important as the finishing process that remove the hot welding bead. The objective of this paper is to investigate the hot machining high frequency welded pipe by simulation and experimental tests. To test the cutting process as hot machining, all cutting environment is reproduced in turning with heating system, and the test is accomplished by comparing with room temperature machining and hot machining in consideration of cutting force, tool wear and cutting temperature.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.7
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• pp.53-63
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• 2022

Recently, the use of aluminum components in the reduction of the vehicle weight to improve fuel efficiency and reduce carbon dioxide emissions has increased. In the aluminum machining cutting process, hole-making is an important process that accounts for 30% of the machining process. Although many studies have been conducted using the continuously advancing hole processing technology, studies on the machinability of the tool depending on the type of chuck on the workpiece are still lacking. In this study, the machining performance of cemented carbide burnishing drills was compared and analyzed according to chuck type. The burnishing drill was used to create a hole in the AL6061 workpiece, and the surface roughness and dimensional accuracy of the hole were examined according to the type of chuck while monitoring the spindle load.

• Journal of the Korean Society of Safety
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• v.24 no.1
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• pp.1-6
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• 2009

In machining of ceramic materials, they are very difficult-to cut materials because of there high strength and hardness. Machining of ceramics are characterized by cracking and brittle fracture. Generally, ceramics are machined using conventional method such as grinding and polishing. However these processes are generally costly and have low MRR(material removal rate). This paper focuses on machinability evaluation of machinable ceramics for products with CNC machining center. Thus, in this paper, experiment applying cutting parameters is performed based on experimental design method. A design and analysis of experiments is conducted to study the effects of these parameters on the surface roughness by using the S/N ratio, analysis of ANOVA, and F-test. And multiple linear regression analysis is applied to compare experimental with predicted data in consideration of surface roughness. Cutting parameters, namely, feed, cutting speed and depth of cut are used to accomplish purpose of this paper. Required experiments are performed, and the results are investigated.

• Korean Journal of Metals and Materials
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• v.46 no.6
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• pp.390-401
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• 2008

The objective of this study is to evaluate various machining characteristics of AlN-hBN machinable ceramics in micro end-milling process for its further application. First, AlN based machinable ceramics with hBN contents in the range of 10 to 20vol% were prepared by hot-pressing. Material properties of the composites, such as relative density, Vickers hardness, flexural strength, Young's modulus and fracture toughness were measured and compared. Then, micro end-milling experiments were performed to fabricate micro channels using prepared system. During the process, cutting forces, vibrations and AE signals were measured and analyzed using applied sensor system. Machined micro channel shapes and surface roughness were measured using 3D non-contact type surface profiler. From the experimental results, it can be observed that the cutting forces, vibrations and AE signal amplitudes decreased with increasing hBN contents. Also, measured surface roughness and profiles were improved with increasing hBN contents. As a result of this study, optimum machining conditions can be determined to fabricate desired products with AlN-hBN machinable ceramics based on the experimental results of this research.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.5
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• pp.1176-1181
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• 1995

Microdrilling is one of the most difficult operations because of the poor chip discharge and the weakness of tool. This study is concerned about the development of a microdrilling monitoring system that is useful for minimizing the tool breakage and enhancing the machinability in the air spindle based microdrilling. The system is composed of a drilling state detection unit and an adaptive step-feed control unit that controls the micro-stepping motor driven spindle axis. Drilling states such as overload, tood breakage are recognized by the change of the air spindle speed which is measured via the reflective photo sensor. Based on the monitoring results, the adaptive step-feed control algorithm adjusts the step increment to keep the decrease of spindle speed within a specified range. The results of evaluation tests have shown that the developed system is very effective to prevent the breakage of microdrill and improves the productivity in comparison with the conventional microdrilling.

• Design & Manufacturing
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• v.14 no.1
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• pp.36-41
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• 2020

Recently, due to the development of MEMS technology, researches for the production of effective micro structures and shapes have been actively conducted. However, the process technology based on chemical etching has a number of problems such as environmental pollution and time problems due to multi-process. Various processes to cope with this process are being studied, and one of the mechanical etching processes is the powder blasting process. This process is a method of spraying fine particles, which has the advantage of being an effective process in manufacturing hard brittle materials. However, it is also a process that adversely affects the material surface roughness and material properties due to the impact of the injection of fine particles. In this study, after fabricating micro-channels in fused silica glass with excellent optical properties among the hard brittle materials, we used the nano indentation system to analyze the micro parts using nano-particles as well as machinability and surface roughness analysis of the processed surface. The analysis was performed for the effective processing of powder blasting.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.10
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• pp.92-98
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• 2002

End mill is an essential tool to generate complex surface in workpiece and it has been developed with various materials and tool shapes. The most important factor to evaluate the performance of end mill is still the wear characteristics of flank face. In addition to the flank wear, the tool edge roughness generated by the chipping is another important factor in aspects of material property and machinability evaluation and affects the quality of machined surface. Up to now, there is no direct method for measurement of tool edge roughness. In this study, the tool edge roughness of flat end mill is indirectly measured along the axial direction of workpiece. The theoretical equation is derived in consideration of tool geometry. Finally, the optimal conditions to measure the tool edge roughness by the proposed method are presented through the theoretical review and experimental identification.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.217-218
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• 2006

This paper presents an investigation on the characteristics for new micro tool dynamometer by using the ultrahigh-speed air turbine spindle. Recently, the ultrahigh-speed micro flat endmilling has been investigated actively due to request of accuracy improvement and productivity of die and mould manufacturing. To perform efficient ultrahigh-speed micro flat endmilling, evaluation of ultrahigh-speed machinability must be studied preferentially and it can be identified by investigation of cutting force. The cutting forces in ultrahigh-speed micro flat endmilling can be measured by micro tool dynamometer. But general dynamometer has low natural frequency and so is improper for measuring very high frequency cutting forces in ultrahigh-speed micro flat endmilling. In this study, the micro tool dynamometer which has very high natural frequency is newly designed.