• Journal of Powder Materials
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• v.15 no.5
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• pp.359-364
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• 2008

To satisfy the demand of higher cutting performance, mechanical properties with tungsten carbide (WC-Co) tool materials were investigated. Hardness and transverse rupture strength with WC grain size, Co content and density were measured. Compared to H, K, and S manufacture maker as tungsten carbide (WC-Co) tool materials were used for high-speed machining of end-milling operation. The three tungsten carbide (WC-Co) tool materials were evaluated by cutting of STD 11 cold-worked die steel (HRC25) under high-speed cutting condition. Also, tool life was obtained from measuring flank wear by CCD wear measuring system. Tool dynamometer was used to measure cutting force. The cutting force and tool wear are discussed along with tool material characteristics. Consequently, the end-mill of K, H manufacture maker showed higher wear-resistance due to its higher hardness, while the S maker endmill tool showed better performance for high metal removal.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.125-126
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• 2006

The characteristics of the tool system give many effects into the costs and qualities for the finished components. Therefore, a tool life is one of the important issues on cold forging industry. However, since variables related with tool life are many complicated, the studies for solution should be investigated by the systematic research approach. In this study, heat-treatment of tool material is investigated to improve the tool life. Deep cryogenic treatment of tool steel is very efficient to improve the wear resistance due to the fine carbide. And, it is investigated that the shape and dimension of tool give effect into both tool life and quality of forged product.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.9
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• pp.90-96
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• 2021

As real-time data of factories can be collected using various sensors, the adaptation of intelligent unmanned processing systems is spreading via the establishment of smart factories. In intelligent unmanned processing systems, data are collected in real time using sensors. The equipment is controlled by predicting future situations using the collected data. Particularly, a technology for the prediction of tool wear and for determining the exact timing of tool replacement is needed to prevent defected or unprocessed products due to tool breakage or tool wear. Directly measuring the tool wear in real time is difficult during the cutting process in milling. Therefore, tool wear should be predicted indirectly by analyzing the cutting load of the main spindle, current, vibration, noise, etc. In this study, data from the current and acceleration sensors; displacement data along the X, Y, and Z axes; tool wear value, and shape change data observed using Newroview were collected from the high-speed, two-edge, flat-end mill machining process of SKD11 steel. The support vector machine technique (machine learning technique) was applied to predict the amount of tool wear using the aforementioned data. Additionally, the prediction accuracies of all kernels were compared.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2003.11a
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• pp.85-90
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• 2003

Although wear resistance of material improves with increasing its hardness, it is known that the wear resistance of steel is varied with hardness of counter material. In this context, wear properties of steel must be depended on the difference of hardness between the testpiece and the counter material. In this study, using the pin-on-disc type wear machine, annealed carbon steels were tested against ahoy tool steels with various levels of hardness. Then the changes of wear properties of carbon steel according to the hardness of counter material were investigated and the morphology of worn surface after test were evaluated. The results indicate that if there are no remarkable difference of hardness between them, wear resistance of carbon steel in running-in wear decreases with increasing the hardness of counter material. However, its wear properties at the range of high sliding speed have no relation with hardness of counter material. It is clear that wear properties is influenced by the formation of oxide of steel on their worn surface during wear.

• Journal of the Korean Society for Heat Treatment
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• v.28 no.3
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• pp.139-145
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• 2015

Effects of austenitizing, cryogenic treatment and tempering conditions on the phase change, microstructure and Vickers hardness value have been studied in STD11 steel for tool and die. The volume fraction of retained austenite increased with a rise in austenitizing temperature, while the volume fraction of eutectoid $M_7C_3$ carbides decreased. The retained austenite could be reduced by cryogenic treatment i.e., maintaining at $LN_2$ temperature ($-196^{\circ}C$) for 12hrs but a little amount of retained austenite did not transform to martensite further although holding time increased to 24 hrs or more. The microstructure of the quenched and then cryogenictreated specimen showed nano-sized and needle-shaped carbides in matrix due to the decomposition of martensite by tempering, but that of the one without cryogenic treatment still revealed retained austenite by tempering even at $500^{\circ}C$.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.32-37
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• 2001

As increasing underground facilities, more effective management is needed nowadays. It is important to get an accurate information of underground facilities to manage that, so some methods of detecting location - electromagnetic induction method, ground penetration radar method, sonic method - are used to obtain the information of underground facilities. In this study, a magnetic method to detect underground facilities was developed. In the magnetic method, underground facilities are detected by a detector and the magnetic marker which is a permanent magnet and used to marking the location by attaching underground facilities. A proper characteristic of the magnetic marker was optimized by maxwell 20 magnetic field analysis tool, a test field was constructed with the magnetic marker, PVC pipe, and steel pipe under ground 1.5m, and the detector was made by modifying a common ferromagnetic detector. Magnetic strengths of the magnetic marker were measured by the detector at each location in the test field, and analyzed by magnetic field analysis tool in the same condition. In the result, the underground pipes were detectable within the deviation ${\pm}20cm$ at PVC pipe and ${\pm}10cm$ at steel pipe respectively. The steel pipe was more detectable by ferromagnetism. The developed magnetic method can be applied to maintain and manage underground facilities.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.35-40
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• 2006

Ultrasonic cold forging technology (UCFT) utilizing ultrasonic vibration energy is a method to induce severe plastic deformation to a material surface, therefore the structure of the material surface becomes a nano-crystal structure from the surface to a certain depth. It improves the mechanical properties; hardness, compressive residual stress, wear and fatigue characteristics. Applying UCFT to a rolling process in the steel industry is introduced in this study. First, the UCFT specimens of a tool steel (SKD-61/equivalent H13) are prepared and tested to verify the effects of the UCFT in a variety of mechanical properties, the UCFT is applied to the trimming knives in a cold rolling process. It has been determined that UCFT improves the mechanical properties effectively and becomes a practical method to improve productivity and reliability by about two times compared with the conventionally treated tooling in the trimming process in a cold rolling line.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.4
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• pp.118-124
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• 2012

In this study, we turning mold steel (SKD61) using whisker reinforced ceramic tool (WA1) to get affected factor to surface roughness and regression equation. For this study, we adapt system of experiments. Results are follows; From the analysis of variance, it was found that affected factor to surface roughness was feed rate, cutting speed, depth of cut in order. From multi-regression analysis, we calculated regression equation and the coefficient of determination($R^2$). $R^2$ was 0.978 and It means regression equation is significant. Regression equation means if feed rate increase 0.039mm/rev, surface roughness will increase $0.8391{\mu}m$, if cutting speed increase 50m/min, surface roughness will decrease $0.034{\mu}m$, if depth of cut increase 0.1mm, surface roughness will increase $0.0203{\mu}m$. From the experimental verification, it was confirmed that surface roughness was predictable by system of experiments.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.219-220
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• 2006

Laser surface hardening technologies have been used to improve characteristics of wear and to enhance the fatigue resistance for mold parts. The objective of this research work is to investigate the influence of the process parameters, such as power of laser and defocused spot position, on the characteristics of laser surface hardening for the case of SKD61 steel. CW Nd:YAG laser is selected as the heat source. The optical lens with the elliptical profile is designed to obtain a wide surface hardening area with a uniform hardness. From the results of the experiments, it has been shown that the maximum hardness is approximatly 740 Hv when the power, focal position and the travel of laser are 1,095 W, +1mm and 0.3 m/min, respectively. In addition, the hardening width using the elliptical lens was three time larger than that using the defocusing of laser beam.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.4 s.193
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• pp.57-67
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• 2007

Laser surface hardening technologies have been used to improve characteristics of wear and to enhance the fatigue resistance fur mold parts. The objective of this research work is to investigate the influence of the process parameters, such as power of laser and defocused spot position, on the characteristics of laser surface hardening for the case of SKD61 steel. CW Nd:YAG laser is selected as the heat source. The optical lens with the elliptical profile is designed to obtain a wide surface hardening area with a uniform hardness. From the results of the experiments, it has been shown that the maximum average hardness is approximatly 780 Hv when the power, focal position and the travel of laser are 1,095 W, 0mm and 0.3 m/min, respectively. In samples treated with lower scanning speeds, some small carbide particles appear in the interdendritic regions. This region contains fine martensite and carbide in proportions which depend on the local thermal cycle.