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  • ROUGH CUTTING OF GERMANIUM WITH POLYCRYSTALLINE DIAMOND TOOLS

    A THESIS SUBMITTED TO THE GRADUATE SCHOOL OF NATURAL AND APPLIED SCIENCES

    OF MIDDLE EAST TECHNICAL UNIVERSITY

    BY

    ALAR YERGK

    IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR

    THE DEGREE OF MASTER OF SCIENCE IN

    MECHANICAL ENGINEERING

    JULY 2010

  • Approval of the thesis:

    ROUGH CUTTING OF GERMANIUM WITH POLYCRYSTALLINE DIAMOND TOOLS

    submitted by ALAR YERGK in partial fulfillment of the requirements for the degree of Master of Science in Mechanical Engineering Department, Middle East Technical University by,

    Prof. Dr. Canan zgen ____________________ Dean, Graduate School of Natural and Applied Sciences Prof. Dr. Suha Oral ____________________ Head of the Department, Mechanical Engineering Prof. Dr. M. A. Sahir Arkan ____________________ Supervisor, Mechanical Engineering Dept., METU Examining Committee Members: Prof. Dr. Mustafa lhan Gkler ____________________ Mechanical Engineering Dept., METU Prof. Dr. M. A. Sahir Arkan ____________________ Mechanical Engineering Dept., METU Prof. Dr. Levend Parnas ____________________ Mechanical Engineering Dept., METU Asst. Prof. Dr. lhan Konukseven ____________________ Mechanical Engineering Dept., METU Prof. Dr. Can oun ____________________ Mechanical Engineering Dept., Gazi University

    Date: 06.07.2010

  • iii

    I hereby declare that all information in this document has been obtained and presented in accordance with academic rules and ethical conduct. I also declare that, as required by these rules and conduct, I have fully cited and referenced all material and results that are not original to this work.

    Name, Last Name: alar YERGK

    Signature:

  • iv

    ABSTRACT

    ROUGH CUTTING OF GERMANIUM WITH POLYCRYSTALLINE DIAMOND TOOLS

    Yergk, alar

    Ms., Department of Mechanical Engineering

    Supervisor: Prof. Dr. M. A. Sahir Arkan

    July 2010, 174 pages

    Germanium is a brittle semi-metal, used for lenses and windows in Thermal

    Imaging Systems since it transmits infrared energy in the 2 m - 12 m wavelength

    range at peak. In this thesis study, polycrystalline diamond is used as cutting tool

    material to machine germanium. Diamond is the hardest, most abrasion-resistant

    material and polycrystalline diamond is produced by compacting small diamond

    particles under high pressure and temperature conditions, which results more

    homogeneous, improved strength and a durable material. However, slightly reduced

    hardness is obtained when compared with natural diamond.

    Different from finish cutting, rough cutting, performed before finishing, is used to

    remove most of the work-piece material. During rough cutting, surface roughness is

    still an important concern, since it affects the finishing operations. Roughness of the

    surface of product is affected by a number of factors such as cutting speed, depth of

    cut, feed rate as cutting parameters, and also rake angle as tool geometry parameter.

    In the thesis, the optimum cutting and tool geometry parameters are investigated by

    experimental studies for rough cutting of germanium with polycrystalline diamond

  • v

    tools. Single Point Diamond Turning Machine is used for rough cutting, and the

    roughness values of the optical surfaces are measured by White Light

    Interferometer. Experiments are designed by making use of Full Factorial and

    Box-Behnken design methods at different levels considering cutting parameters

    as cutting speed, depth of cut, feed rate and tool geometry parameter as rake angle.

    Keywords: Ultra-precision Machining, Single Point Diamond Turning,

    Germanium, Polycrystalline Diamond Tool, Surface Roughness

  • vi

    Z

    POL-KRSTAL ELMAS TAKIMLARLA GERMANYUMUN KABA LENMES

    Yergk, alar

    Yksek Lisans, Makina Mhendislii Blm

    Tez Yneticisi: Prof. Dr. M. A. Sahir Arkan

    Temmuz 2010, 174 sayfa

    Germanyum gevrek, yar-metal bir malzemedir, lens ve pencere eklinde Termal

    Grntleme Sistemlerinde kullanlmaktadr. Germanyum, 2 m - 12 m dalga

    boyu aralnda yksek kzltesi enerji geirgenliine sahiptir. Bu tez almas

    srasnda germanyumun ilenmesinde, poli-kristal elmas takmlar kullanlmaktadr.

    Elmas, en sert, en yksek anma direnci olan malzemedir. Poli-kristal elmas,

    kk elmas paracklarn yksek basn ve scaklk altnda sktrlmasyla

    retilir. Poli-kristal elmas doal elmas ile karlatrldnda daha homojendir,

    daha yksek mukavemete sahip, dayankl bir malzemedir ancak sertlii daha

    dktr.

    Biti kesiminden farkl olarak, kaba kesim en ok malzemeyi yzeyden kaldrmak

    zere yaplr. parasnn yzey przll, daha sonra gerekletirilecek yzey

    ilemlerini etkiledii iin, kaba kesimde de nemli bir parametredir. rnn yzey

    przll ok sayda faktr tarafndan belirlenir. Kesme parametreleri olarak

    kesme hz, kesme derinlii, ilerleme hz ve takm geometri parametresi olarak

    tala as rnek verilebilir.

  • vii

    Bu tezde, poli-kristal elmas takmlarla germanyumun kaba ilenmesi iin en iyi

    kesim ve kesici takm parametreleri deneysel almalar yardmyla aratrlmtr.

    Elmas Ulu Torna Tezgahnda, poli-kristal elmas ularla germanyuma kaba ileme

    uygulanmtr ve optik yzeylerin przllk deerleri Beyaz Ik nterferometre

    cihaznda llmtr. Yaplan deneyler Tam Faktr ve Box-Behnken

    deneysel alma metotlaryla deerlendirilmitir. Deneysel alma metotlar farkl

    seviyelerde, kesme parametreleri olarak kesme hz, kesme derinlii, ilerleme hz

    ve takm geometri parametresi olarak tala as dikkate alnarak dzenlenmitir.

    Anahtar Kelimeler: Ultra Hassas leme, Elmas Ulu Tornalama, Germanyum,

    Poli-kristal Elmas Takm, Yzey Przll

  • viii

    To My Family

  • ix

    ACKNOWLEDGEMENTS

    The author wishes to express his sincere appreciation to his thesis supervisor Prof.

    Dr. M. A. Sahir ARIKAN for his guidance, advise, encouragements and helpful

    criticism throughout the throughout the research.

    The author would like to thank ASELSAN, Inc. and his manager in ASELSAN,

    Mr. hsan ZSOY, for his support and providing the facility in his study and let to

    use Single Point Diamond Turning Machine also by the author with

    encouragement. The author also has to thank to Mr. Tolga Ziya SANDER for his

    valuable and beneficial supports and advices in his study.

    Also, the author wishes to express his sincere appreciation to technical assistance

    Mr. lker SEZEN for his precious help with Single Point Diamond Turning

    Machine. Moreover, The author would like to thank Mr. A. E. Sinan ZHAN and

    Mrs. C. Duygu ztrk SELUK for their help.

    Additionally, the author would like to thank TBTAK for the support during his

    study. Last, but certainly not least, the author wishes to offer his deepest thanks to

    his parent for their continuous help and understanding during the thesis study.

  • x

    TABLE OF CONTENTS

    ABSTRACT..............................................................................................................iv

    Z .............................................................................................................................vi

    ACKNOWLEDGEMENTS ......................................................................................ix

    TABLE OF CONTENTS...........................................................................................x

    LIST OF TABLES ................................................................................................. xiii

    LIST OF FIGURES .................................................................................................xv

    LIST OF SYMBOLS ...............................................................................................xx

    CHAPTER

    1 INTRODUCTION ..............................................................................................1

    1.1 Motivation ...................................................................................................1

    1.2 Machining, Finish and Rough Cutting ........................................................5

    1.3 Ductile and Brittle Materials .......................................................................8

    1.4 Ultra-precision Machining ..........................................................................9

    1.5 Aim and Scope of Thesis...........................................................................10

    2 LITERATURE SURVEY.................................................................................13

    2.1 Introduction ...............................................................................................13

    2.2 Brittle and Ductile Modes of Machining...................................................17

    2.3 Critical Chip Thickness .............................................................................19

    2.4 High Pressure Phase Transformation ........................................................25

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    2.5 Machining by Polycrystalline Diamond (PCD) Tool................................29

    2.6 Rainbow Appearance of Diamond Turned Surfaces .................................33

    3 EXPERIMENTAL COMPONENTS................................................................36

    3.1 Introduction ...............................................................................................3