Optimization of heat-assisted machining process of die steel SKD11 /
One of the prominent materials widely used in die is SKD11 steel blocks. Conventional route of die machining consist of machining of unhardened SKD11 steel blocks, followed by finishing and hardening process. This research proposes a new route of dies machining, by machining of hardened SKD11 and fo...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
Kuala Lumpur :
Kulliyyah of Engineering, International Islamic Universiti Malaysia,
2017
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| Subjects: | |
| Online Access: | Click here to view 1st 24 pages of the thesis. Members can view fulltext at the specified PCs in the library. |
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| Summary: | One of the prominent materials widely used in die is SKD11 steel blocks. Conventional route of die machining consist of machining of unhardened SKD11 steel blocks, followed by finishing and hardening process. This research proposes a new route of dies machining, by machining of hardened SKD11 and followed by finishing process. This could shorten the lead time and is expected to able to achieve better surface finish and dimension stability. As SKD11 is considered as hard to machine material, this study aimed to improve machinability of hardened SKD11 using heat-assisted method. The objective of the research is to find the optimize heat-assisted machining parameters such as cutting speed, feed and depth of cut to suits hardened SKD11 steel block machining. Under this research, two machining methods, turning process in room temperature machining and heat-assisted machining were compared. In this work, TIG welding was used as heat source to thermally soften the workpiece prior to material removal. Machining was performed under a range of cutting speeds (ranging from 30 to 60 m/min), feeds (ranging from 0.03 to 0.07 mm/rev) and depth of cut (ranging from 0.5 to 0.1 mm). For heat-assisted machining, the temperature (ranging from 250 to 450 0C) was applied. Each individual effect of machining parameters on responses such as tool wear, surface roughness and vibration amplitude for both machining conditions were investigated and compared. RSM models for SKD11 machining under normal and heat-assisted were developed and optimum machining for desired responses were identified. For individual experiments the machining parameters does not show significant effect to the responses. However, comparison of both experiments showed a significant drop of 11% for flank wear and 18% for nose wear and 15% reduction in vibration amplitude and higher surface roughness were detected when the heat was applied prior to the machining. RSM models of heat-assisted machining showed that temperature does not give significant to surface roughness value. Perturbation plot shows that tool wear increase with increase in cutting speed in linear form and vibration amplitude reduces with increase of temperature in quadratic form. The results showed that optimum cutting speed, feed and temperature is at 34.50 m/min, 0.03 mm/rev and 374.81 0C with 86.4% desirability for heat-assisted machining. Comparing the feasible region of the RSM overlay plot for both machining method showed that heat-assisted machining does not give significant improvements to hardened SKD11 machinability. The heating method with TIG welding may be one of the factors of inconsistency of the results. Heat assisted machining method for hardened die steel SKD11 can be further developed and investigated. However, the temperature required consistency in order to ensure on the results is reliable for industrial applications. |
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| Physical Description: | xvii, 117 leaves : illustrations ; 30cm. |
| Bibliography: | Includes bibliographical references (leaves 104-108). |