• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.8
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• pp.87-92
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• 2022

The Al3003 aluminum plate was cut by grinding, milling, sawing, and shearing, and the hard-anodizing surface of the material was investigated. Large burrs were formed during grinding and milling. The brittle anodized film split and migrated along the deformed aluminum surface. During shearing, the hard-anodized film on the blade entry surface cracks and slides along the deforming aluminum. The cutting heat increased the ductility of the aluminum and further promoted burr formation. The oil-based coolant suppressed burrs and prevented chips from sticking to the endmill. It is better to avoid the high cutting speed and slow material feed rate conditions, which increase the cutting temperature and burr in the band saw.

• Design & Manufacturing
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• v.18 no.2
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• pp.1-8
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• 2024

Unlike the roll-to-roll process that uses a steel roll and a nip roll, a vacuum roll can hold and transfer a thin film using a single roll. To precisely manufacture a vacuum roll, a thin outer cylinder must be machined, which is assembled on the outside of the roll and contacts the film via vacuum pressure. In this study, the effects of jaw width and chucking force on the deformation of the outer cylinder during the turning process were investigated using analysis, and a precision machining and burr removal process was developed. The deformation of the outer cylinder decreased almost linearly with increasing jaw width and increased with higher chucking force and larger cylinder diameter. Additionally, the deflection due to the weight of the outer cylinder was approximately three times greater than that caused by film tension. For the machined outer cylinder, a burr removal experiment was conducted, and concentricity and cylindricity were measured. Using a device that removes burrs by rotating a wheel connected to the main shaft at high speed, it was found that burrs generated on the inner diameter could be removed very efficiently. On the vacuum side, the concentricity errors of the inner and outer diameters were 0.015 mm and 0.014 mm, respectively, and on the opposite side, they were 0.006 mm and 0.010 mm, respectively. Additionally, the measurement of Total Indicator Runout (TIR) according to the angle showed that the maximum cylindricity of the outer and inner diameters was 0.02 mm and 0.025 mm, respectively. Finally, through burr-height measurement at the hole boundary, it was found that the heights were within 0.05 mm.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.1064-1067
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• 2001

Micro drilling is used in the production of fuel injection nozzle, watch, camera, air bearing and pinted circuit boards(PCB) are demanded for high precision. Recently industries of precision production require more small hole, high aspect ratio and high speed working for micro deep hole drilling. But the undesirable characteristics of micro drilling is the small signal to noise ratios, wandering motion of drill, high aspect ratio and the increase of cutting force as cutting depth increase. So in this paper to obtain the optimization of cutting condition a study on the characteristics of micro deep hole drilling used Tool dynamometer is proposed.

• The Journal of the Korean bone and joint tumor society
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• v.1 no.1
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• pp.1-6
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• 1995

Giant cell tumors are primary bone tumors originating from non-osteoblastic connective tissue. The sites of involvement were commonly distal femur, proximal tibia, proximal humerus, distal radius and others (including os calcis, ilium and sacrum). Giant cell tumor located around knee joint has been difficult to treat because of local recurrence following curettage with or without bone graft. Although primary resections reduce recurrence of the lesion, the joint function will be markedly impaired. Marginal excision was very often complicated by a loss of joint integrity since all the giant cell tumors occupy juxtaarticular positions. Techniques involving physical adjuncts(high speed burr and electric cauterization) have been used in the hope of decreasing the rate of local recurrence and avoiding the morbidity of primary resection. A meticulous clinical, radiological and histological evaluation is needed to choose the correct treatment, keeping in mind the possibility of recurrence after each treatment modality.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.4
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• pp.403-408
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• 2013

In this paper, the characteristics of ablation processing of the eagle glass by pico-second laser are investigated. The laser ablation is used to process micro forms on materials. The ablation causes little thermal effect and little burr on the surface of eagle glass. In order to examine the characteristics of panic cracks, experiments are conducted under various cutting conditions such as a frequency of 600 kHz, laser powers, scan speeds and number of scan(NS). To minimize the panic cracks, the specimens are heated at $30^{\circ}C$, $45^{\circ}C$, and $60^{\circ}C$ for ten minutes respectively and then they are broken by hands. Laser powers, NS and scan speeds have an effect on glass cutting results. The ablation depths increase with an increase in the laser power and NS whereas the panic cracks decrease with an increase in scan speed. The high temperature on processed specimens reduces the panic cracks and makes good results of laser cutting. The optimal condition for eagle glass laser cutting is found to be at 30 W of laser power, 3 mm/s of scan speed and 500 of NS, respectively.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.3 s.96
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• pp.72-77
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• 1999

This paper presents 2-dimensional vibration cutting increases dynamic stiffness of tool support and improves the quality of machined surface in micro-machining. 2-dimensional vibration cutting is generated by two piezo actuators arranged orthogonally. A sine-type voltage is input to one actuator and a phase-shifted sine-type voltage is input the other. Then the vibration device actuates the tool in a 2-D elliptical motion with pulsed cutting force. It is a characteristic of 2-D vibration cutting that some negative thrust force occurs as the direction of friction on a tool rake surface is reversed. It helps not only chip flow smoothly and continuously but also cutting force be reduced. The quality of machined surface by 2-D vibration cutting depends on such parameters as vibration amplitude, frequency, cutting speed, depth of cut, etc. Compared to conventional cutting through tool path simulation and experiments under several conditions, the 2-D vibration cutting is verified to bring forth a great decrease of cutting forces, much better surface roughness and moreover much less burr.

• Laser Solutions
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• v.11 no.4
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• pp.29-34
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• 2008

Ultraviolet laser micromachining has increasingly been applied to the electronics industry where precision machining of high-density, multi-layer, and multi material components is in a strong demand. Due to the ever-decreasing size of electronic products such as cellular phones, MP3 players, digital cameras, etc., flexible printed circuit board (FPCB), multi-layered with polymers and metals, tends to be thicker. In present, multi-layered FPCBs are being mechanically cut with a punching die. The mechanical cutting of FPCBs causes such defects as burr on layer edges, cracks in terminals, delamination and chipping of layers. In this study, the laser cutting mechanism of FPCB was examined to solve problems related to surface debris and short-circuiting that can be caused by the photo-thermal effect. The laser cutting of PI and FCCL, which are base materials of FPCB, was carried out using a pico-second laser(355nm, 532nm) and nano-second UV laser with adjusting variables such as the average/peak power, scanning speed, cycles, gas and materials. Points which special attention should be paid are that a fast scanning speed, low repetition rate and high peak power are required for precision machining.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.5
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• pp.773-777
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• 2012

Recently UV laser micromachining processes is widely introduced to meet the needs of advanced components of IT, BT and ET industries. Due to the characteristics of non-contact and high-speed laser processing, UV laser micromachining is applied to manufacture very thin substrate such as polymer, metals and composite. These minimum line width obtained by UV laser micromachining is generally determined from laser wavelength, optical lens and its numerical aperture. In this paper we will show the lens effect of water droplet on the surface of workpiece to reduce the line width when UV laser light is irradiated and focused through the water droplet. Because of the refraction effect generated by the semi-spherical or spherical shape of water droplet, we can find smaller line width. And water droplet could not only protect thermal deformation, but also carry away burr around micro dent. Firstly fundamental theory of minimum line width was derived from relationship between the geometry of water droplet and laser light trace, and then experimental and simulation results will be finally compared to verify the effectiveness of water droplet lens effect of UV laser micromachining process.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.5
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• pp.535-540
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• 2011

It is well known that abrasive waterjet (AWJ) was developed as a kind of high-density energy processing technologies. AWJ is used to obtain cutting quality of various materials such as metal, ceramics, glass and composite materials within a short manufacturing time because of the characteristics of heatless and noncontact processing. However, surface roughness and dimension error like round, burr, taper vary severely according to the processing conditions such as pressure, cutting speed, orifice diameter, stand off distance and abrasive flow rate. In this paper, the effect of the shape of mixing chamber on surface quality is studied. Three types of mixing chamber - round, parabolic, elliptical - are suggested and each performance is compared to that of cylindrical mixing chamber experimentally. From the result, is proved to be the optimal mixing chamber in the aspect of surface quality the parabolic one.

• Design & Manufacturing
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• v.13 no.2
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• pp.44-48
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• 2019

Motor core products are used as materials for electrical steel sheets and cold-rolled steel sheets according to the performance of motors. The cemented carbide material of the mold punch applied to the motor core material causes many troubles due to abrasion and burr problem. The selection of these materials has a great effect on the production life, mass production, product quality as well as mold life. The cemented carbide applied to the products of the motor core is recognized as a very important part. In this study, cold rolled steel sheet was applied to motor core SCP-1 steel 1.0mm, and The effects of abrasion and punching oil on the shear process were investigated for the selection of cemented carbide. Experiments were conducted to select and apply cemented carbide only for the motor core punch optimized for cold rolled steel. The results showed that the cemented carbide material of $CDK3^{***}$ produced the least wear and burrs.