• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1998.03a
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• pp.94-99
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• 1998

In bulk metal forming processes prediction of tool life is very important for saving production cost and achieving good material properties. Generally the service life of tools in metal forming process is limited to a large extent by wear, fracture and plastic deformation of tools. In case of hot and warm forging processes, tool life depends on wear over 70%. In this study finite element analyses are applied to warm forging and hot forging by adopting suggested wear model. By comparision of simulation and real profile of die, suggested model is verified

• Journal of the Korean Society for Precision Engineering
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• v.15 no.4
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• pp.118-124
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• 1998

The die wear is one of the main factors affecting die accuracy and tool lifetime. It is desired to reduce die wear by developing simulation method to predict wear based on process variables, and then optimizing the process. Therefore, this paper describes methodology of preform design for minimizing wear of finisher die in multi-stage cold forging processes. The finite element method is combined with the routine of wear prediction. The cold forging process is analyzed using developed simulation method. In order to obtain preform to minimize die wear, the Flexible Polyhedron Search(FPS) algorithm is used. The optimal preform shape is found from iterative deformation analysis and wear calculation.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1998.03a
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• pp.88-93
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• 1998

The service life of tools in metal forming process is to a large extent limited by wear, fatigue fracture and plastic deformation. In warm forging processes wear is the predominant factor for operating lives of tools. To predict tool life by wear, Archard's wear model is generally applied. Usually hardness of die is considered to be a function of temperature in Archard's wear model. But hardness of die is a function of not only temperature but also operating time of die. To consider softening of die by repeated operations, it is necessary to express hardness of dies by a function of temperatures and operating time. By experiment of reheating of dies, die softening curves were obtained. Finally modified Archard's wear model in which hardness of die was expressed as a function of main tempering curve was proposed.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.4 no.2
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• pp.31-37
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• 1995

This study is focused on the prediction of appropriate tool life by clarifying the correlation between progressive tool wear and AE signal. when rcutting SM45C by End mill in machining center. First of all, end mill have a problem that position of sensor sticking because it is revolution tool, but I think that it can be bained specific character according to sticking Sensor in the Vise. Consequently, the following results have been obtained; 1. Each cutting speed of feed rate over 0.1mm had a tendency to increase linearly according to the RMSAE 2. The level of AE signal at the same cutting area was more sensitive to depth of cut tharn the variation of feed rate 3. In the range of cutting duringqr about 75minqr atqr cutting speed 27m/min flankqr wear turns up aboutqr 0.21mm, aboutqr 0.29mm in the caseqr of about 65minqr at 33/min, qr hereby RMSAE increased rapidly at 0.2mm flank wear, also AE-HIT and CUM-CNTS.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1132-1133
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• 2006

Metal-bonded diamond impregnated tools are being increasingly used in the processing of stone and ceramics, road repair, petroleum exploration, etc. Although the main tool wear mechanisms have been identified, the scientific background is inadequate and fundamental research has to be carried out to better understand the tool field behaviour. This work addresses the complex issues of modelling abrasive wear of the metallic matrix under laboratory conditions. The generated data indicates that the matrix wear resistance can be assessed in a simple manner; whereas tests carried out on diamond impregnated specimens may aid prediction of the tool life in abrasive applications.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1998.06b
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• pp.54-59
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• 1998

In this study, two kinds of life prediction method for hot forming die are developed . One is empirical method requiring some experiment that evaluate thermal softening of die material accoring to operating conditions. The other is analyticl method that calcuate wear quantity of die occuring during the forming process. Wear is a predominant factor as well as plastic deformation and heat checking . And, these methods are applied to prodict tool life real die producting part for automobile. Thus , the applicability and the accuracy of the presented methods are investigated. Using the verified life prediction method above , optimal blocker die design minimizing the finisher die is done.

• Transactions of Materials Processing
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• v.31 no.1
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• pp.11-16
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• 2022

In this paper, wear characteristics of PVD coatings were compared on the die surface for cold stamping of MART1470 steel sheet with the finite element analysis and the pin-on-disc wear test. Three types of PVD coatings (CrN, TiAlCrN, and MoS2TiCr(W)N) were considered for the tool surface made of STD11 material. The stamping process of an auto-body part was analyzed with the finite element method. Ranges of process variables for the wear test such as contact pressure, relative speed, and sliding distance were predicted from analysis results. In order to quantitatively analyze wear characteristics of each coating, the amount of wear was measured and compared according to process variables with the pin-on-disc wear test. The influence of each process variable was investigated and the wear characteristics of the three coating layers were quantitatively compared. It was confirmed that the wear characteristics of MoS₂TiCr(W)N coating were better than those of CrN and TiAlCrN. It was noted that the proposed prediction approach could predict and respond to the wear phenomenon occurring in the stamping process.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.5
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• pp.98-107
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• 1995

The in-process detection of drill wear and breakage is one of the most importnat technical problems in unmaned machining system. In this paper, the monitoring system is developed to monitor abnormal drilling states such as drill breakage, drill wear and unstable cutting using motor current. Drill breakage is detected by level monitoring. Tool wear is classified by fuzzy pattern recognition. The key feature for classification of tool wear is the estimated flank wear which is calculated by the proposed flank wear model. The characteristic of the model is not sensitive to the variation of cutting conditions but is sensitive to drill wear state. Unstable cutting states due to the unsmooth chip disposal and the overload are monitored by the variance/mean ratio of spindle motor current. Variance/mean ratio also includes the information about the prediction of drill wear and drill breakage. The evaluation experiments have shown that the developed system works very well.

• Transactions of Materials Processing
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• v.33 no.2
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• pp.112-117
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• 2024

In this study, the friction and wear characteristics of Inconel 600 in the superplastic forming process of Ti6Al4V were evaluated through pin-on-disc tests. To achieve an efficient and systematic experimental design, the Taguchi method was employed. The wear track of the Inconel 600 pin showed scratches in the sliding contact direction, confirming that the wear mechanism is abrasive wear. Through sensitivity analysis such as ANOVA and Main effects, it was confirmed that both normal force and sliding distance have a significant impact on the wear. Changes in sliding velocity and distance did not affect the friction coefficient, which remained relatively constant at approximately 0.380. The wear prediction model for Inconel 600 in the superplastic forming of Ti6Al4V was constructed, which can be utilized as a guideline for the prediction and management of tool wear.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.11
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• pp.63-73
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• 1995

A mechanistic force system model considering the flank wear for the face milling process has been developed. The model predicts variation of the cutting forces according to flank wear in face milling over a range of cutting conditions, cutter geometries and cutting process geometries including relative positions of cutter to workpiece and rounouts. Flycutting and multitoth cutting teste were conducted on SS41 mild steel with sintered carbide tool. In order to verify the mechanistic force model considering the flank wear of cutting tools, a series of experiments was performed with single and multitooth cutters in various cutting conditions. The results show good agreement between the predicted and measured cutting force profiles and magnitudes in time and frequency domains.