MAGNETORHEOLOGICAL FINISHING PROCESS USING IN-SITU ROUGHNESS
FEEDBACK
FAIZ IQBAL
DEPARTMENT OF MECHANICAL ENGINEERING INDIAN INSTITUTE OF TECHNOLOGY DELHI
JANUARY 2019
MAGNETORHEOLOGICAL FINISHING PROCESS USING IN-SITU ROUGHNESS
FEEDBACK
by
FAIZ IQBAL
Department of Mechanical Engineering
Submitted
In fulfillment of the requirements of the degree of Doctor of Philosophy to the
INDIAN INSTITUTE OF TECHNOLOGY DELHI
JANUARY 2019
CERTIFICATE
This is to certify that the thesis entitled, “Closed loop control of ball end magnetorheological finishing process using in-situ roughness feedback” submitted by Mr.
Faiz Iqbal to the Indian Institute of Technology Delhi, for the award of the degree of Doctor of Philosophy, in the Department of Mechanical Engineering is a record of bonafide original research work carried out by him under my guidance and supervision.
The results contained in it have not been submitted in part or full to any other institute or university for the award of any degree/diploma.
Dr. Sunil Jha Professor Department of Mechanical Engineering Indian Institute of Technology Delhi New Delhi – 110 016, India
Place: New Delhi
Acknowledgements
I would like to express my sincere thanks to everyone who directly or indirectly participated or assisted me in this journey. Finally the Almighty’s grace and blessings with which I could successfully complete the highest degree in the engineering discipline in my life.
Foremost, I express my deep sense of gratitude and sincere thanks to my thesis supervisor Dr. Sunil Jha. His excellent guidance, constant encouragement and optimistic outlook have been a constant source of motivation for me throughout this research work. His expert guidance, encouragement, constructive criticism and inspiring advice on the subject enabled me to think in different dimensions of research and realize the value of hard work and investigating approach.
The technical and personal lessons that I learned by working under him are now base supports for the rest of my life. Besides being a source of immense knowledge and experience, Dr. Sunil Jha is very kind and caring with great compassion and love for the students. I will forever cherish my close association with him especially for the lessons I learnt from him in areas other than engineering or research.
I am very much thankful to my SRC chairman Prof. P. V. Rao and expert members Prof.
Sudarsan Ghosh and Dr. Gufran S Khan for their constructive criticism and valuable guidance during the course of my presentations. I am also thankful to Mr. Tulsiram, Mr. Ram Chander, Mr. Rishi Lal and other staff members of the mechanical department of IITD who helped me in successfully completing my experimental work.
I am thankful to Dr. Hemant Chouhan, Dr. Anant Kumar Singh (Asst. Prof., Thapar University, Patiala), Dr. M.S. Niranjan (Asst. Prof., Delhi Technological University, Delhi), Dr.
K. Saraswathamma (Asst. Prof. University college of Engg., Hyderabad).
I am sincerely thankful to my fellow research scholars at IIT Delhi, Dr Dilshad Ahmad Khan, Mr. Zafar Alam, Mr. Harish Chauhan, Mr. Hardik Patel, Mr. Ashish Sahu, Mr. Mayank Shrivastava who made my life enjoyable and memorable in the IIT Delhi campus. My fellow researcher and friend Mr Jitin Malhotra deserves a special mention and thanks from the depth of my heart. I would also like to thank Mr. Dinesh Khatri, Mr Anupam Gangwar, Mr. Mohd. Faisal and Mr. Sivasankar Ganesan for constantly helping me in the development of the i5-B CNC BEMRF system.
I am thankful to the project staff Mr. Navdeep Singh, Mr. Chandan Singh, Mr. Akshay Bhardwaj, Mr. Aman Kumar, Mr. Nikhilesh Bhakuni and Mr. Arun Kumar at automation lab who became great friends with me and helped me whenever necessary in this work.
I again pay my sincere thank to Dr. Dilshad Ahmad khan and Mr. Zafar Alam for helping me throughout the research work and forming a team with me so cherish able.
I am indebted to my father Late Mr. Iqbal Ahmad Khan whom I lost midway through this journey but his words of wisdom remain with me every second of my life. I am also indebted to my mother Mrs. Sadiqa Siddiqa for her blessings, motivations and constant support throughout the research work. I am thankful to my elder brother Mr. Saud I Khan for valuable advices and lessons of life and my sister Mrs. Farah Iqbal for providing me moral support and taking care of many social responsibilities, which helped me to focus on my work all the time.
I appreciate the extreme love and support of my wife Mrs. Najia Kirmani for her kind co- operation, great inspiration throughout the years we have been together which goes long before I started my journey at IITD. Without her support, this research contribution would have never been possible and thanks are not enough to express the feelings that I have for her.
At last, but not the least, I am thankful to everyone at IIT Delhi or outside who helped me directly or indirectly to complete this work.
I at the foremost am grateful to Allah (swt), the Almighty, for having blessed me to rise and take up this challenge.
(Faiz Iqbal)
ABSTRACT
The demand for nano finished components in the current market for precision finishing products is of utmost desirability. High precision finishing equipment are largely employed for meeting the market requirements in an era where aesthetics plays a role of game changer for precision finished final products or sub parts of a product. Beginning from the mid twentieth century the precision finishing had started to spread and demands were ever increasing for the same. The conventional finishing processes enabled the products to have a finish that pleased the user aesthetically and at the same time the smooth surfaces enabled freedom against friction.
The demand for even better performance in goods and functional freedom against friction kept on increasing as decades pass by; the conventional finishing processes became limited in their finishing capabilities and meeting the ever increasing demands of precision finishing.
Processes like grinding, lapping and honing were limited and they were being replaced by non conventional processes starting from super finishing through abrasive flow machining (AFM), magnetic abrasive finishing (MAF), magneto-rheological finishing (MRF), Magnetic float polishing (MFP), Elastic emission machining, Ion beam machining etc.
Some processes were better than others such as diamond turning, chemical mechanical polishing etc. As the late twentieth century approached the limitations of conventional finishing processes were soon a thing of the past as the non conventional advanced finishing processes made their way into the finishing market. While the conventional finishing processes were limited to producing surface finish ranging from 100 nm to 300 nm the non conventional advanced finishing processes could produce the same as low as 20 – 50 nm. And it could be
further lowered by carefully examining and optimizing the advanced non conventional finishing processes.
With the advanced finishing processes functionally all set and proven at the start of the twenty first century, the components to be finished were also evolving and alongside the finishing processes the shape of the surfaces to be finished began to vary drastically. From flat surfaces to regular curved geometries to freeform surfaces all were made possible by advanced machining capabilities of the twenty first century. With complex geometries, irregular curved surfaces and intricate corners, turns and deep freeform grooves becoming more frequent a part of the components requiring super finishing; the capabilities of advanced non conventional finishing processes became limited to regular geometries and flat or inclined surfaces only.
However as always the case, necessity is the mother of invention, the geometrical limitations of advanced finishing non-conventional processes were overcome by processes developed in the latter half of the first decade of twenty first century. One such advanced process is ball end magneto-rheological finishing (BEMRF) process. The BEMRF process started as a precision finishing advanced non conventional finishing process which could address the geometrical limitations of earlier mentioned processes. In the initial years the BEMRF was developed by researchers as a capable process for achieving nano finish on different materials and hence the initial literature available on BEMRF focuses on functional capabilities of BEMRF on different materials, qualitative and quantitative analysis of the same.
Initial work done on BEMRF for geometrical aspects addressed the capabilities of BEMRF on flat surfaces and improved it with a 3 axis BEMRF system; it also carried out
BEMRF on inclined surfaces. However even with the 3 axis system the available automation of the system was very limited and next to none.
In this research work the BEMRF process has been taken to new heights in its quest for overcoming the geometrical limitations of finishing processes. A new and improved 5 axis setup is developed for finishing of 3D surfaces, irregular curves, freeform features and deep or intricate grooves. Apart from the geometrical aspects the process automation of the BEMRF is developed with state of the art technologies with all the process parameters and machining parameters being controlled automatically. The control of the process is developed with CNC standards where everything is controlled through CNC part program.
The automation of the process continues further with closed loop finishing capabilities developed for the same. Experimental investigations reveal transient phenomenon in roughness reduction and a particular set of machining parameters reduce the surface roughness only up to a critical value below which this parameter set must be changed to achieve further finish. Using experimental study the transient phenomenon is established and a database is formed for a range of roughness values. A parameter selection algorithm is developed which guides the finishing process with best set of machining parameters for the next machining cycle.
The finishing process is followed by workpiece cleaning cycle and then by the roughness measurement cycle all automatically through CNC part program. After every measurement cycle the roughness value is compared with the roughness target to be achieved and the parameter selection algorithm then suggests the next best parameter set which is automatically updated to the CNC part program for the next machining cycle. This way the whole process is carried out
automatically with minimal user intervention. The finishing process thus is carried in a closed loop manner with in-situ feedback from the roughness measurement cycle.
Using closed loop finishing roughness parameter Ra from 800 nm range is brought down to 60 nm range in finishing time of 200 minutes, the same roughness reduction is achieved in 360 minutes of finishing time if finishing is carried out using individual parameter set. Thus by implementing closed loop finishing the optimum time for roughness reduction is achieved while conducting the whole process automatically. The transient roughness reduction phenomenon after experimental validation is also mathematically modeled. EN31 steel has been chosen as a material for this research work. All the study is specific to EN31 steel which after suitable modifications according to various materials may be applicable to each of them. A fixed composition of MRP fluid is used from literature and the optimization study for the same has been put as a future scope of work. With suitable fluid optimization the roughness achieved may further be lowered.
सटीक पररष्करण उत्पाद ों के लिए वर्तमान बाजार में नैन र्ैयार घटक ों की माोंग अत्योंर् वाोंछनीयर्ा है। उच्च पररशुद्धर्ा
पररष्करण उपकरण बडे पैमाने पर बाजार की जरूरर् ों क उस युग में पूरा करने के लिए लनय लजर् लकया जार्ा है जहाों
स ोंदयतशास्त्र सटीक रूप से र्ैयार अोंलर्म उत्पाद ों या लकसी उत्पाद के उप भाग ों के लिए गेम चेंजर की भूलमका लनभार्ा है। बीसवीों
शर्ाब्दी के मध्य से सटीक पररष्करण का प्रसार शुरू ह गया था और उसी के लिए माोंग बढ़ रही थी। पारोंपररक पररष्करण प्रलियाओों ने उत्पाद ों क खत्म करने में सक्षम बनाया ज उपय गकर्ात क स ोंदयत से प्रसन्न करर्े थे और साथ ही साथ लचकनी
सर्ह ों ने घर्तण के खखिाफ स्वर्ोंत्रर्ा क सक्षम लकया।
दशक ों से गुजरर्े हुए बढ़र्े हुए घर्तण के खखिाफ माि और कायातत्मक स्वर्ोंत्रर्ा में और भी बेहर्र प्रदशतन की माोंग;
पारोंपररक पररष्करण प्रलियाएों उनकी पररष्करण क्षमर्ाओों में सीलमर् ह गईों और सटीक पररष्करण की बढ़र्ी माोंग ों क पूरा
करर्ी हैं। पीसने, िैलपोंग करने और सम्मान देने जैसी प्रलियाएों सीलमर् थीोंऔर इन्हें गैर पारोंपररक प्रलियाओों द्वारा अपघर्तक प्रवाह मशीलनोंग (एएफएम), चुोंबकीय अपघर्तक पररष्करण (एमएएफ), मैग्नेट -ररय िॉलजकि लफलनलशोंग (एमआरएफ), मैग्नेलटक फ्ल ट पॉलिलशोंग (एमएफपी) के माध्यम से शुरू लकया गया था। ), ि चदार उत्सजतन मशीलनोंग, आयन बीम मशीलनोंग आलद।
कुछ प्रलियाएों दूसर ों की र्ुिना में बेहर्र थीोंजैसे लक हीरा म ड, रासायलनक याोंलत्रक चमकाने आलद। बीसवीों शर्ाब्दी के
उत्तराधत के रूप में पारोंपररक पररष्करण प्रलियाओों की सीमाएों जल्द ही अर्ीर् की बार् थीों क् ोंलक गैर पारोंपररक उन्नर् पररष्करण प्रलियाओों ने पररष्करण बाजार में अपना रास्ता बनाया। जबलक पारोंपररक पररष्करण प्रलियाएों 100 एनएम से 300 एनएम र्क सर्ह पररष्करण उत्पादन र्क सीलमर् थीों, गैर पारोंपररक उन्नर् पररष्करण प्रलियाएों 20 - 50 एनएम के समान कम उत्पादन कर सकर्ी थीों। और इसे उन्नर् गैर पारोंपररक पररष्करण प्रलियाओों की सावधानीपूवतक जाोंच और अनुकूिन द्वारा और भी कम लकया
जा सकर्ा है।
उन्नर् पररष्करण प्रलियाओों के साथ कायातत्मक रूप से सभी सेट और इक्कीसवीों सदी की शुरुआर् में सालबर् हुए, समाप्त ह ने वािे घटक भी लवकलसर् ह रहे थे और पररष्करण प्रलियाओों के साथ-साथ समाप्त ह ने वािी सर्ह ों के आकार में काफी
लभन्नर्ा शुरू हुई। समर्ि सर्ह ों से िेकर लनयलमर् वलिर् भू-भाग ों र्क फ्रीफॉमत सर्ह ों क इक्कीसवीों सदी की उन्नर् मशीलनोंग क्षमर्ाओों द्वारा सोंभव बनाया गया था। जलटि ज्यालमर्ीय, अलनयलमर् घुमावदार सर्ह ों और जलटि क न ों के साथ, बारी-बारी से
पारोंपररक पररष्करण प्रलियाओों की क्षमर्ा केवि लनयलमर् ज्यालमर्ीय और फ्लैट या इच्छुक सर्ह ों र्क सीलमर् ह गई।
हािााँलक हमेशा की र्रह, आवश्यकर्ा आलवष्कार की जननी है, उन्नर् अोंलर्म गैर-पारोंपररक प्रलियाओों की ज्यालमर्ीय सीमाएाँ इक्कीसवीों सदी के पहिे दशक के उत्तराधत में लवकलसर् प्रलियाओों से दूर ह गईों। ऐसी ही एक उन्नर् प्रलिया बॉि एोंड मैग्नेट -ररय िॉलजकि लफलनलशोंग (BEMRF) प्रलिया है। BEMRF प्रलिया एक सटीक पररष्करण के रूप में शुरू हुई ज उन्नर्
गैर पारोंपररक पररष्करण प्रलिया है ज पहिे उखिखखर् प्रलियाओों की ज्यालमर्ीय सीमाओों क सोंब लधर् कर सकर्ी है। प्रारोंलभक वर्ों में BEMRF क लवलभन्न सामलिय ों पर नैन लफलनश प्राप्त करने की एक सक्षम प्रलिया के रूप में श धकर्ातओों द्वारा लवकलसर्
लकया गया था और इसलिए BEMRF पर उपिब्ध प्रारोंलभक सालहत्य लवलभन्न सामलिय ों, एक ही के गुणात्मक और मात्रात्मक लवश्लेर्ण पर BEMRF की कायातत्मक क्षमर्ाओों पर केंलिर् है। ज्यालमर्ीय पहिुओों के लिए BEMRF पर लकए गए प्रारोंलभक कायत ने सपाट सर्ह ों पर BEMRF की क्षमर्ाओों क सोंब लधर् लकया और इसे 3 अक्ष BEMRF प्रणािी के साथ बेहर्र बनाया; यह भी
BEMRF झुका सर्ह ों पर लकया जार्ा है। हािाोंलक 3 अक्ष प्रणािी के साथ भी लसस्टम का उपिब्ध स्वचािन बहुर् सीलमर् था और लकसी के बगि में नहीों था।
इस श ध कायत में BEMRF प्रलिया क पररष्करण प्रलियाओों की ज्यालमर्ीय सीमाओों क पार करने के लिए इसकी ख ज में
नई ऊोंचाइय ों पर िे जाया गया है। 3 डी सर्ह ों, अलनयलमर् घटर्ा, फ्रीफॉमत सुलवधाओों और गहरे या जलटि खाोंचे के पररष्करण के
लिए एक नया और बेहर्र 5 अक्ष सेटअप लवकलसर् लकया गया है। ज्यालमर्ीय पहिुओों के अिावा BEMRF की प्रलिया स्वचािन सभी प्रलियाओों और मशीलनोंग मापदोंड ों क स्वचालिर् रूप से लनयोंलत्रर् करने के साथ किा प्र द्य लगलकय ों की खथथलर् के साथ लवकलसर् की जार्ी है। प्रलिया का लनयोंत्रण सीएनसी मानक ों के साथ लवकलसर् लकया जार्ा है जहाों सीएनसी भाग कायतिम के
माध्यम से सब कुछ लनयोंलत्रर् लकया जार्ा है।
उसी के लिए लवकलसर् बोंद िूप पररष्करण क्षमर्ाओों के साथ प्रलिया का स्वचािन आगे जारी है। प्राय लगक जाोंच से
खुरदरेपन में क्षलणक घटना का पर्ा चिर्ा है और मशीलनोंग मापदोंड ों का एक लवशेर् सेट सर्ह खुरदरापन क केवि एक महत्वपूणत मूल्य र्क कम कर देर्ा है, लजसके लिए इस पैरामीटर सेट क आगे खत्म करने के लिए बदिना ह गा। प्राय लगक अध्ययन का उपय ग कर क्षलणक घटना की थथापना की जार्ी है और खुरदरापन मूल्य ों की श्रेणी के लिए एक डेटाबेस का लनमातण लकया जार्ा है। एक पैरामीटर चयन एल्ग ररथ्म लवकलसर् लकया गया है ज अगिे मशीलनोंग चि के लिए मशीलनोंग मापदोंड ों के
सवोत्तम सेट के साथ पररष्करण प्रलिया का मागतदशतन करर्ा है।
खुरदरापन चि ह र्ा है। प्रत्येक माप चि के बाद खुरदरापन मूल्य की र्ुिना खुरदरापन िक्ष्य के साथ की जार्ी है और पैरामीटर चयन एल्ग ररथ्म लफर अगिे सवोत्तम पैरामीटर सेट का सुझाव देर्ा है ज स्वचालिर् रूप से अगिे मशीलनोंग चि के
लिए सीएनसी भाग कायतिम में अपडेट लकया जार्ा है। इस र्रह पूरी प्रलिया न्यूनर्म उपय गकर्ात हस्तक्षेप के साथ स्वचालिर्
रूप से की जार्ी है। इस प्रकार पररष्करण प्रलिया क खुरदरापन माप चि से इन-सीटू फीडबैक के साथ एक बोंद िूप र्रीके से
लकया जार्ा है।
800 एनएम रेंज से क्ल ज्ड िूप लफलनलशोंग रफनेस पैरामीटर रा का उपय ग करर्े हुए 200 लमनट के लफलनलशोंग टाइम में 60
एनएम रेंज र्क िाया जार्ा है, अगर लकसी पैरामीटर क सेट करर्े हुए लफलनलशोंग की जार्ी है, र् उर्ने ही समय में 360 लमनट की लफलनलशोंग में उर्नी ही कमी आ जार्ी है। इस प्रकार बोंद िूप क िागू करने से पूरी प्रलिया का सोंचािन करर्े समय खुरदरापन में कमी के लिए इष्टर्म समय प्राप्त ह र्ा है। प्राय लगक सत्यापन के बाद क्षलणक खुरदरापन घटाने की घटना भी
गलणर्ीय रूप से प्रलर्रूलपर् है। इस अनुसोंधान कायत के लिए EN31 स्टीि क एक सामिी के रूप में चुना गया है। सभी अध्ययन EN31 स्टीि के लिए लवलशष्ट है ज लवलभन्न सामलिय ों के अनुसार उपयुक्त सोंश धन ों के बाद उनमें से प्रत्येक पर िागू ह सकर्ा है।
एमआरपी र्रि पदाथत की एक लनलिर् रचना सालहत्य से उपय ग की जार्ी है और उसी के लिए अनुकूिन अध्ययन क भलवष्य के
काम के दायरे के रूप में रखा गया है। उपयुक्त िव अनुकूिन के साथ प्राप्त की गई खुरदरापन क और कम लकया जा सकर्ा
है।
TABLE OF CONTENTS
CERTIFICATE i
ACKNOWLEDGEMENTS ii
ABSTRACT v
LIST OF FIGURES xiv
LIST OF TABLES xx
1. INTRODUCTION AND LITERATURE REVIEW 1-22
1.1 Introduction 1
1.2 Ball end magneto-rheological finishing process 2
1.3 Literature review 4
1.3.1 Review of existing literature on BEMRF 4
1.3.2 Review of existing technologies on online roughness metrology 8 1.3.3 Review of attempts on control of machining processes. 13
1.4 Research gaps and motivation of the present work 16
1.5 Objectives of the present work 20
1.6 Thesis Organization 20
2. DEVELOPMENT OF 5-AXIS CNC BEMRF MACHINE TOOL WITH USER INTERFACE
23-65
2.1 i5-B CNC BEMRF machine tool 26
2.1.1 The machining area 26
2.1.1.1 Motion control hardware 25
2.1.1.2 BEMRF tool head 26
2.1.2 Workpiece cleaning system 28
2.1.2.1 Components of the workpiece cleaning system 30
2.1.2.2 The workpiece cleaning sequence 31
2.1.3 Roughness measurement system 34
2.1.3.1 Confocal sensor: working principle 35 2.1.3.2 Calibration and validation of confocal sensor 37 2.1.3.3 Roughness measurement by confocal sensor 39
2.1.4 Control Panel 42
2.2 Development of part program based process control and user interface 51
2.2.1 Manual controls of the i5-B CNC BEMRF system 52
2.2.2 CNC part program control of each cycle 53
2.2.2.1 Part program codes for finishing cycle 53 2.2.2.2 Part program codes for workpiece cleaning cycle 55 2.2.2.3 Part program codes for roughness measurement cycle 56 2.2.3 Integrated CNC part program for all three cycles 58
2.2.4 User Interface 60
2.2.5 Novelties and contributors of i5-B CNC BEMRF system 63
2.2.6 Conclusion 65
3. Development of parametric database for EN31 steel in BEMRF process
66-95
3.1 Optimization of machining parameters 67
3.1.1 Experimental conditions 68
3.1.2 Design of experiments 69
3.1.3 Response surface regression analysis 71
3.1.3.1 Effect of Magnetizing Current 78
3.1.3.2 Effect of working gap 79
3.1.3.3 Effect of tool rotational speed 80
3.2 Time based roughness reduction study 82
3.2.1 Transient roughness reduction phenomenon 82
3.2.2 Experimentation 86
3.2.3 Results and discussion 87
3.2.4 Conclusion 94
4. MODELLING OF SURFACE ROUGHNESS REDUCTION OF EN31 STEEL IN BEMRF PROCESS
96 -115
4.1 Mechanism of material removal 96
4.2 Modeling 97
4.2.1 Structure of MRP fluid 99
4.2.2 Forces: Normal, Shear and Resistive 100
4.2.3 Surface roughness model for BEMRF process 104
4.3 Transient surface roughness reduction 107
4.3.1 Modeling of transient roughness reduction 108
4.3.2 Results and discussions 114
4.3.3 Conclusion 115
5. CLOSED LOOP BALL END MAGNETORHEOLOGICAL FINISHING AND APPLICATIONS
116-143
5.1 Closed loop finishing in optimum time 117
5.1.1 The NC part program for automated BEMRF process 117
5.1.2 The parameter selection algorithm 120
5.1.3 Testing of the closed loop finishing process 125 5.1.4 System limitations and implementation in practice 127 5.2 Applications of closed loop ball end magnetorheological finishing 128
5.2.1 Localized finishing 128
5.2.2 Constant work gap perpetuation 135
5.2.2.1 Role of working gap on forces in BEMRF process 136 5.2.2.2 The perpetuation process 138 5.2.2.3 Experimentation for perpetuation process 140 5.2.2.4 Experimental results of perpetuation process 140
6. CONCLUSIONS AND FUTURE SCOPE OF WORK 144-148
6.1 Conclusions 144
6.2 Future scope of work 146
REFERENCES 149
APPENDIX-1 157
Specifications of hardware used in i5-B CNC BEMRF system
APPENDIX-2 159
Dimensional drawings and CAD models of components of i5-B CNC BEMRF system
APPENDIX-3 168
List of CNC codes and their functions
PUBLICATIONS 171
AUTHOR BIOGRAPHY 176
LIST OF FIGURES
Fig.1.1 BEMRF tool head: A schematic representation. 3
Fig.1.2 On-line surface roughness measurement by light scattering 9 Fig.1.3 (a) A part of speckle pattern image (8bit) obtained by using a CCD
from a surface with Ra = 0.695 µm. (b) Binary speckle pattern image of the image shown in (a). (c)The area marked with a cross in (b) is
zoomed-in to show the pixel values 11
Fig.1.4 A Schematic diagram of turning operation showing image capture
direction and b roughness profile captured 12
Fig. 1.5 Alignment processes of reference points 14
Fig.1.6 FTS mounted on X axis 15
Fig.2.1 Five axis arrangement of i5-B CNC BEMRF system 26
Fig.2.2 CAD model of BEMRF tool head assembly 28
Fig.2.3 Pneumatic and electrical circuit diagrams of workpiece cleaning system 30
Fig.2.4 Stages of workpiece cleaning process 31
Fig.2.5 BEMRF tool head and confocal sensor 34
Fig.2.6 Schematic diagram of confocal sensor on BEMRF tool head (a) sensor position during finishing process (b) sensor position during
measurement 35
Fig.2.7 Working principle of confocal sensor 36
Fig.2.8 Schematic of confocal controller and data flow 37
Fig.2.9 (a) Scanning of Taylor Hobson roughness standard by confocal sensor
(b) Taylor Hobson roughness standard 38
Fig.2.10 Roughness parameter values for Taylor Hobson standard data by
confocal sensor given by Mountains Map software. 39
Fig.2.11 Measurement of the surface by confocal sensor 40
Fig.2.12 Electrical control panel of i5-B CNC BEMRF system 42
Fig.2.13 i5-B CNC BEMRF system wiring diagram – PART 1 44
Fig.2.14 i5-B CNC BEMRF system wiring diagram – PART 2 45
Fig.2.15 i5-B CNC BEMRF system wiring diagram – PART 3 46
Fig.2.16 Architecture of i5-B CNC BEMRF system 47
Fig.2.17 3D workpiece finished by i5-B CNC BEMRF system 49
Fig.2.18 The i5-B CNC BEMRF system 50
Fig.2.19 Screenshot of development application of the PLC program 61 Fig.2.20 Runtime application - Manual mode screen 62
Fig.2.21 Runtime application - Automatic mode screen 63
Fig.3.1 Effect of magnetizing current on percentage reduction in Ra value 78
Fig.3.2 Effect of working gap on percentage reduction in Ra value 79 Fig.3.3 Effect of tool rotational speed on percentage reduction in Ra value 80 Fig.3.4 (a)Contour (I vs N), (b)3D plot of variation of % ∆Ra value with I and N, (c)
Contour (G vs I) and (d)3D plot of variation of % ∆Ra value with G and I 81 Fig.3.5 Schematic representation of irregularities on a surface and their interaction with abrasive particles. (a) Higher roughness peaks resulting in less area of contact and less stresses. (b) Lower roughness peaks resulting in more area
of contact and more contact stresses. 83
Fig.3.6 Microscope Images of BEMRF processed surface at different stages of
machining time with parameter set 1i 87
Fig.3.7 Graphical representation of time based surface roughness reduction for four machining parameter sets, 1i (first set), 2i (second set), 3i (third set) and 4i
(fourth set) 88
Fig.4.1 Dimensions of BEMRF tool (in mm) of the i5-B CNC BEMRF system 99 Fig.4.2 Uniformly distributed structure of CIP chains and abrasives trapped in them
100 Fig.4.3 Roughness peak as (a) a cone and (b) cone dissected into series of discs
having a gradually increasing dia. 101
Fig.4.4 (a) Chunk of a roughness peak displaced by an abrasive, (b) Cross sectional view of section B-B’ showing area of abrasive particle A and area removed
material A’. 102
Fig.4.5 Assumed relation between disc diameter and cone height 104
Fig.4.6 Initial roughness profile 105
Fig.4.7 Path covered by an abrasive on workpiece 106
Fig.4.8 Material removal in BEMRF process 107
Fig.4.9 Roughness peak showing critical disc which abrasive is unable to remove 108
Fig.4.10 Comparison of theoretical and experimental results 113
Fig.5.1 NC part program dedicated to automatic BEMRF process 118
Fig.5.2 Schematic representation of data flow for roughness measurement, parameter selection and parameter updating 120
Fig.5.3 Screenshot of the parameter selection algorithm 121
Fig.5.4 Flowchart for closed loop process of ball end finishing 124
Fig.5.5 Finishing results by closed loop finishing and comparison with finishing results by all parameter sets individually 125
Fig.5.6 Schematic diagram showing (a). Grinding process with no error, (b).
Grinding process linear positioner having a tilt ‘δ’ degrees and (c). Angular vice used to tilt the workpiece by ‘δ’ degrees 130
Fig.5.7 Colored plots of height data of (a) Type A - Grinding error and (b) Type B -
Manual lapping error workpieces 132
Fig.5.8 3D plots of (Type A) workpiece (a) with tilt error (b) error removed by localized finishing by BEMRF process and (c) complete surface nano
finished by BEMRF process 133
Fig.5.9 3D plots of (Type B) workpiece (a) with error by manual lapping (b) error removed by localized finishing by BEMRF process and (c) complete surface nano finished by BEMRF process 134 Fig.5.10 Effect of work gap on forces in BEMRF process 136 Fig.5.11 Height data scanned by confocal sensor with and without tilt error 138 Fig.5.12 Variation in Z height in data with and without tilt error 138 Fig.5.13 Control of work gap perpetuation process 139 Fig.5.14 Experimental results of perpetuation process in graphical representation 141
Fig.5.15 Initial surface before finishing 142
Fig.5.16 Surface finished with tilt error 143
Fig.5.17 Surface finished with tilt error but with perpetuated work gap 143
LIST OF TABLES
Table 2.1 Stages of workpiece cleaning process 32
Table 2.2 List of control automation hardware in control panel 42 Table 2.3 Positions of motion axes during finishing of a 3D workpiece 48
Table 2.4 Finishing cycle parameters and CNC codes 53
Table 2.5 Cleaning system parameters and associated M codes 55 Table 2.6 List of M codes specially defined for roughness measurement cycle 57 Table 2.7 Elements and their contributors of i5-B CNC BEMRF system 64 Table 3.1 Coded levels and corresponding actual values of process parameters 69
Table 3.2 Plan of experiments and response summary 70
Table 3.3 Sequential model sum of square for machining parameters 72
Table 3.4 Lack of fit test for machining parameters 73
Table 3.5 Analysis of variance of machining parameters with all model terms 73 Table 3.6 ANOVA for % change in Ra after dropping the insignificant terms 75
Table 3.7 Other ANOVA parameters 76
Table 3.8 Coefficient of model terms (coded form) after dropping insignificant model terms and the range of confidence interval for machining parameters 77
Table 3.9 Indentation diameter and indentation depth for each machining parameter set 85 Table 3.10 Selected parameter sets and machining conditions for time based study 86 Table 3.11 Time based experimental results and Ra for each parameter set 90 Table 3.12 Roughness profiles after saturation of each parameter set 92 Table 3.13 Database from time based experimental results and ΔRa for each parameter
set 94
Table 4.1 Selected parameter sets 109
Table 4.2 Calculated values of𝐴′, d and D for four parameter sets 110 Table 4.3 Stagnation height, Rt and Ra for four parameter sets 111 Table 4.4 Number of passes and stagnation time achieved for four parameter sets 112 Table 4.5 Comparison of theoretical and experimental results 112 Table 5.1 Comparison of finishing time achieved by individual parameter sets and closed
loop finishing 126
Table 5.2 Ra and Sa values before and after localized finishing 135 Table 5.3 Selected parameter sets and machining conditions for experiments in
perpetuation process 140
Table 5.4 Experimental results obtained after finishing in all three cases 140
