finer points

FinerPointsTHIS ISSUE

Calendar of Events

“BEST IN CLASS”Education Course –SuperabrasivesMaterials, Principles& Applications

SKYTEC BOLT – A newgeneration of metalbonded diamondwheels for grinding ofindexable inserts withelectrical dischargeconditioning.

IDA MemberCompanies

Thirteen Years AsThe Grinding Doc

Progress of GrindingTechnology ofMonocrystallineSilicon Carbide; forLonger Tool Life andHigher QualityFinished Surfaces

INTERTECH 2019 in New Orleans

In Memoriam: Jack Lunzer

THE LONGESTRUNNING

MAGAZINEDEDICATED

SOLELY TO THETECHNOLOGY AND

APPLICATION OFSUPERABRASIVES

Fall 2017 $9.00 USD

SUPERABRASIVE INDUSTRY REVIEWSuperabrasive Grinding & Education

10 18119 25

3

d e p a r t m e n t s

4 A Finer Point of View

6 Editorial

8 Calendar of Events

9 News & Notes

15 New Products

16 IDA Member Companies

27 Ad Insertion Order

28 MembershipApplication

30 In Memoriam:Jack Lunzer

COVER PHOTOPhoto courtesy of LACH DIAMOND INC.

shows Grinding of a PCD compact hoggeron a 3Dia-Saw-Grinder for diamond saws.

This tooth-by-tooth milling is for sharpeningas well as new production on any tooth

geometry and even for multiple productionprocesses. Diamond Saw Tools are used for

processing Wood and Plastics.

American Superabrasives Corp. / Vollstädt-Diamant ....................................................... 15

Apogee Precision Parts ............................................................................................................. 7

Bogimac NV-SA ......................................................................................................................... 6

Crystallume Engineered Diamond Products ...................................................................... 24

Element Six US Corporation ............................................................................................ OBC

The Grinding Doc ................................................................................................................ 20

ILJIN USA, Inc. ...................................................................................................................... 17

Lieber & Solow ......................................................................................................................... 5

Luoyang Qiming Superhard Material Co., Ltd. ............................................................... 21

Niabraze, LLC .......................................................................................................................... 29

Standard Die & Fabricating Inc. ........................................................................................ IBC

Trigon Technologies................................................................................................................ 14

Worldwide Superabrasives LLC ........................................................................................... IFC

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10 “BEST IN CLASS” Education Course – Superabrasives Materials, Principles& Applications

11 SKYTEC BOLT – A new generation of metal bonded diamond wheels for grinding of indexable insertswith electrical discharge conditioning.

18 Thirteen Years As The Grinding Doc

22 Progress of Grinding Technology of Monocrystalline Silicon Carbide; for Longer Tool Life and Higher Quality Finished Surfaces

25 INTERTECH 2019 in New OrleansFINER POINTS is the longest running publication devoted exclusively to the understanding, selection andapplication of diamond, cubic boron nitride and related materials. It is edited for recipients who are involved insome way with these “superabrasives”, either as providers of the materials, producers of products containing thematerials or users of these products (e.g., grinding wheels, dressing tools, drill bits, saw blades, sawing wires,cutting tools, polishing compounds, CVD film products, etc.).

FinerPoints

10

Superabrasive Grinding & Education FINER POINTS

A Finer Point of View... Industrial DiamondAssociation ofAmerica, Inc.

PRESIDENTEd FrancisCrystallume Engineered Diamond

VICE PRESIDENTShane HollenbaughYG-1 USA

SECRETARY/TREASURERKevin StilesRadiac Abrasives A Tyrolit Company

PAST PRESIDENTBen WilliamsFACT USA

BOARD OF DIRECTORS (term)Renee Nord (16-18)3M Abrasive Systems DivisionEric P. Bieberich (16-18)Fort Wayne Wire DieJim Long (17-19)Greenlee Diamond Tool CompanyMichael Lew (17-19)MWI Eloquence CorporationJulie Griffin (16-18)Precision eFormingMark Modersitzki (17-19)US Synthetic CorporationAaron Nolan (17-19)Worldwide Superabrasives Solids Division

EXECUTIVE DIRECTORMr. Terry M. KaneIndustrial Diamond Associationof America, Inc.P.O. Box 29460 • Columbus, Ohio 43229Phone: 614-797-2265FAX: 614-797-2264Email: [email protected]

BUSINESS MANAGERKathryn A. KaneIndustrial Diamond Associationof America, Inc.P.O. Box 29460 • Columbus, Ohio 43229Phone: 614-797-2265FAX: 614-797-2264Email: [email protected]

Website: www.superabrasives.org

FINER POINTS is the official publication of theIndustrial Diamond Association of America, Inc. and ispublished fours times a year. Contributions arewelcomed but the Editor reserves the right to accept orreject any material deemed inappropriate forpublication. All by-lined articles published in thismagazine represent solely the individual opinions of thewriters and not necessarily those of the IndustrialDiamond Association. Executive and Editorial Offices:Finer Points, P.O. Box 29460, Columbus, Ohio 43229,(614) 797-2265. Editor and Advertising, Terry Kane.Advertising rates and deadlines available upon request.Copyright Industrial Diamond Association of America.Material in FINER POINTS may not be reproduced inany form without express written consent.

ISSN: 1090-0896

4 FINER POINTS Superabrasive Grinding & Education

Welcome to the fall issue of FinerPoints. The time for summervacations has ended as the kidshead back to school, hopefully youwere able to take some time off,enjoy time with the family and getthrough that summer read you hadon your list. Reading and learningcan keep you growing and renewyour creative spirit to implementnew insight and goals in your life.

We get so mired in the day to daycrisis that we sometimes forget toraise our head up to see the peoplewe care about. We come hometired having spent all our energyon the battle at work that wefought all day. Stop, take a breathand keep moving forward. I try toread 10 to 20 books a year, someare easy fun reads and others Ihave to push myself to get through.The tough ones are often the onesthat I find the most interestingafter I have finished. A couple ofthe best books I’ve read so far, thisyear are “Shoe Dog” by and aboutPhil Knight the founder of NIKEand “A Man Called Ove” by FredrikBackman, the ultimate cranky old man.

Share some of your favorite bookswith family, friends and coworkers.Everyone appreciates a good story.Here are some notable people’sfavorite books; Amazon CEO JeffBezos said his favorite book was"The Remains of the Day" byKazuo Ishiguro, a novel about anEnglish butler after the WWII.Former Microsoft CEO Bill Gates'sfavorite book is J.D. Salinger's "TheCatcher in the Rye." Oprah Winfreyhas said "To Kill a Mockingbird"by Harper Lee is her all-timefavorite book. Warren Buffett, theBerkshire Hathaway CEO offeredup his favorite: "BusinessAdventures," by John Brooks.

An ending thought are theseexcellent quotes from TeddyRoosevelt and Dr. Seuss. “It is not

the critic who counts; not the manwho points out how the strongman stumbles, or where the doerof deeds could have done thembetter. The credit belongs to theman who is actually in the arena,whose face is marred by dust andsweat and blood; who strivesvaliantly; who errs, who comes upshort again and again, becausethere is no effort without error andshortcomings; but who doesactually strive to do the deeds; whoknows great enthusiasms, the greatdevotions; who spends himself in aworthy cause; who at best knowsin the end the triumph of highachievement, and who at theworst, if he fails, at least fails whiledaring greatly, so that his placeshall never be with those cold and timid souls who neither know victory nor defeat.” - Teddy Roosevelt.

“You have brains in your head. Youhave feet in your shoes. You cansteer yourself any way you choose”– Dr. Seuss.

Best regards,

Ed Francis, PresidentIndustrial Diamond Association of America

PRESIDENTEd Francis


EDUCATION VS TRAININGA few years back I was part of a company’s trainingprogram and in fact our department was calledManufacturing Training Programs. Our mission wasto create “training” programs on all the equipmentand processes throughout the plant and even toprepare those programs for our overseas plants. Ourpurpose was to “train” operators on individualoperations so they could perform specific functionsover and over again as one part of the productionprocess.

In other words we could “train” a person to operate a certain type of lathe ormachine to generate one specific shape, one after another. Once thatindividual could repeat the process over and over again, then we consideredthem “trained”. However, if we had rethought this and took the time to“educate” an operator on the intricacies and capabilities of any machine underany given situation and on any different material to generate a wide range ofparts, then we could say that operator was educated across the entireproduction line ...

Although Education and Training seem to be interchangeable to most people,there is a clear difference between the two words. The impression thateducation and training are interchangeable is created by most of theinstitutions or organizations that substitute training for education. However,there is a vast difference between education and training and those of us whoare involved in higher learning have realized this through time and experience.

Education creates a foundation of knowledge about facts, concepts andprinciples. For instance, at the Industrial Diamond Association of America’sSuperabrasive Materials, Principles and Applications course attendeesgain the ability to solve problems and make critical decisions “on the job”because they have been educated. Attendees are not just “trained” as mostcourses promote, but are educated about superabrasive materials and have anin-depth knowledge to understand how and why these tools and abrasives areapplied in machining and grinding applications on myriad materials.

On the other hand, training is focused upon gaining a particular skill and is amethod that makes a person skilled only in a particular job or task, forinstance operating a particular grinder. This is not to say training is notimportant, it is. The trades would be in bad shape if there wasn’t skilledtraining, but if education is also introduced then the “trainee” is more well-rounded and a more valuable employee.

Throughout all industries we are hearing about losing the skilled workforce.Experts are retiring and the lack of new workers seeking jobs in the trades andmanufacturing has become a major problem. Organizations that arepromoting entry into the trades and manufacturing are to be commended.There are some professions where skills can be easily learned through practicaltraining rather than through formal education and concepts can beunderstood through training.

Training is an excellent start and a great way to introduce someone into aworkforce where skilled labor is sorely needed. To carry that one step further ahighly educated workforce will be able to perform more technical operationssuch as programming machines and making rational decisions for improvingmanufacturing operations.

Wise leadership will make the extra effort in educating their workforcerealizing that a more educated workforce contributes to the overallperformance and profitability of the company. Hopefully we will see thesecompanies represented at the Superabrasive Materials, Principles andApplications Course in November, where training is taken to the higher levelof education.

TERRY KANE, Editor


SEPTEMBER 19-21, 2017Wire Southeast Asia 2017Bangkok Trade & Exhibition Centre • Bangkok, Thailandhttp://www.wirenet.org/viewcalendar/viewevent/111wiresoutheast-asia-2017

SEPTEMBER 25-28, 2017The International CentreMississauga (Toronto), ON,Canada • http://cmts.ca/

SEPTEMBER 26-28, 2017AeroTech Congress &Exhibition Fort Worth, Texas, USA

Ft. Worth Convention Centerhttp://www.sae.org/events/atc/

OCTOBER 3-5, 2017Connecticut Convention Center

Hall A • Hartford Marriott Downtownhttp://www.metalengineeringexpo.org/

OCTOBER 9-14, 2017CSDA Training

Oct. 9-10 Slab Sawing & Core DrillingOct. 11-12 Wall Sawing & Hand SawingOct. 13-14 Wire Sawing 101, ICS Blount,Inc., Portland, OR • www.csda.org

OCTOBER 10-12, 2017Additive Manufacturing Conference 2017

Knoxville Convention Center, Knoxville, TNhttp://www.additiveconference.com/

OCTOBER 18-20, 2017Additive Aerospace Summit 2017DoubleTree by Hilton Los AngelesDowntown • http://infocastinc.com

OCTOBER 24-26, 2017GEAR EXPO 2017Greater Columbus Convention CenterColumbus, Ohio USA

OCTOBER 24-26, 2017TD Convention CenterGreenville, SC

www.southteconline.com

NOVEMBER 6-9, 2017McCormick PlaceChicago, ILwww.fabtechexpo.com/

NOVEMBER 29-30, 2017Industrial DiamondAssociation of AmericaSuperabrasive Materials,Principles & ApplicationsEducation Course Watch for details at:

www.superabrasiveseducation.com

DECEMBER 6-8, 2017Additive Manufacturing Americas 2017Pasadena Convention CenterPasadena, CA USAwww.amshow-americas.com

2018JANUARY 23-26, 2018

APRIL 9-11, 2018Industrial DiamondAssociation of AmericaBiennial Meetingin Conjunctionwith UAMA

Spring MeetingThe Naples Beach Hotel & Golf ClubNaple, Florida

2019MAY 29, 30 & 31, 2019

Hyatt Regency New Orleans

New Orleans, Lousiana USAwww.intertechconference.com

To have your event or conference listed,please send information to: Finer Points

Event Calendar • P.O. Box 29460,Columbus OH 43229 • Fax 614-797-2264

or email: [email protected]

Here today...But what about tomorrow? While hundreds of millions ofAmericans are enjoying the wonders of our national parks eachyear, the future of the very things they’re coming to see is atrisk. For example, although the Mexican black bear populationhas been slowly recovering at Big Bend National Park, theirongoing survival is threatened. Americans for National Parks isa coalition working to preserve these national treasures, and allthe priceless experiences they provide. Find out how you canhelp at: www.americansfornationalparks.org.

1300 19th Street, N.W., Suite 300 • Washington, D.C. 200361-800-NAT-PARK (628-7275)

A public service message.

9Superabrasive Grinding & Education FINER POINTS

WALL COLMONOY ANNOUNCES FALLSESSION OF MODERN FURNACE BRAZINGPreserving the tradition originated by the late RobertPeaslee, a brazing pioneer who invented the firstnickel-based brazing filler metal, Wall Colmonoy offersa fall session of Modern Furnace Brazing School onOctober 10-12, 2017 at Wall Colmonoy’s AerobrazeBrazing Engineering Center in Cincinnati, Ohio.Engineers, technicians, quality managers, productionmanagers, and others will participate in “hands-on”practical applications while learning about brazingtechnology from the industry’s leading brazingengineers. For over 60 years, Wall Colmonoyengineers have been gaining practical experience onactual problems in brazing plants around the world.Unlike other classroomonly seminars, Brazing Schoolattendees will tour the facility and see the actualbrazing application on the shop floor. They will alsohave the opportunity to apply different forms of fillermetal to supplied samples, have them vacuum brazedand discuss the outcomes. For seminar details andregistration information, contact Jim Nicoll, MarketingAssociate, at [email protected]

BUY AMERICAN AND HIRE AMERICAN” EXECUTIVE ORDERThe president’s executive order instructs federal

agencies to examine their purchasing systems tomore effectively favor buying American goods.The order follows a campaign promise to usepresidential authority to encourage companies tobuy American products and hire American

workers. The "Buy American" provision of theorder will reinforce a stricter adherence to laws that

require the federal government to purchase American-made products whenever possible. The "Hire American"

part targets government guest-worker programs, particularly the H-1B visaprogram. The order will crack down on “abuses” in such programs. The executiveorder won’t make immediate changes to the system but will direct the Labor,Justice, Homeland Security and State departments to undertake a wholesalereview of the H-1B visa program and to put forth recommendations that can beachieved administratively or through legislation. That could mean adjusting thewage scale the government uses to assess applicants, giving preference toworkers with advanced degrees or taking “a more vigorous stance” in enforcingviolations of the program in an effort to root out fraud and abuse.

HARLEY-DAVIDSON’SDECISION TO BUILD PLANTIN THAILAND RAISESEYEBROWS Harley-Davidson, the iconicmotorcycle brand is building aplant in Thailand, the companyconfirmed as it seeks new buyersin Asia and lower tariffs. Thefactory -- only the third Harley has built outside the United States -- highlights theirresistible draw of overseas plants for U.S. manufacturers. "We are expanding ourpresence in the Asia-Pacific market by building an assembly facility in the RayongProvince in Thailand," said Harley-Davidson spokeswoman Katie Whitmore. Shedeclined to say how much the plant was worth but said it would be up and runningin "late 2018." Harley has found it hard to resist the lure of overseas assembly lines -- both to be geographically closer to emerging markets and circumvent high tariffsthat favor local competitors. It already has assembly plants in Brazil and India thatput together bike kits made from parts from its U.S. factories. The Thai plant will dothe same. Harley has insisted the Thai plant will not result in American job losses,arguing instead it will enable them to grow their business using American-builtparts. "There is no intent to reduce Harley-Davidson U.S. manufacturing due to thisexpansion," Whitmore said. "Harley-Davidson U.S. manufacturing will continue tosupply the U.S. and certain other global markets," she added.

AN

D

NEWS&notes

THE INDUSTRIAL DIAMOND ASSOCIATION OF AMERICA (IDA)Presents

“BEST IN CLASS” Education CourseSuperabrasive Materials, Principles & Applications

YG-1 America, Inc. Advanced Manufacturing Center11001 Park Charlotte Boulevard • Charlotte, NC 28273 USA

VISIT: WWW.SUPERABRASIVESEDUCATION.COM FOR COMPLETE DETAILS

NEW SUPERABRASIVE EDUCATION COURSETWO FULL DAYS – November 29 & 30, 2017

ONE FULL DAY OF GRINDING • ONE FULL DAY MACHININGFEE: $525 USD – EARLY PAYMENT (BY OCTOBER 15, 2017): $475 USD

ATTENDEES MAY SELECT ONLY THE ONE DAY OF MACHINING OR GRINDING AT $275EARLY PAYMENT (BY OCTOBER 15, 2017): $250 USD

LIMITED SEATING, LAST COURSE WAS AT FULL CAPACITY, SO REGISTER EARLY TO GUARANTEE YOUR SPOT!

Classroom technical and instructional sessions will be highlighted by laboratory demonstrations and class interaction featuring:

Truing & Dressing Applications Thermal Testing & Evaluations Grinding Demonstrations and Surface Analysis And More! Machining of Exotic Materials

OBJECTIVE"Superabrasive Materials Principles and Applications" is sponsored by the IDA and designed specifically toeducate on the use of industrial diamond, cubic boron nitride (cBN) materials classified as superabrasives.It is Non-commercial, unbiased and representative of accepted principles and practices. Content willinclude a wide range of products and applications for the automotive, aerospace, medical, electronics,optics and other industries using superabrasives. The attendee will be educated in the primary areas ofgrinding and machining with peripheral explanation for other uses, such as non-abrasive applications.

WHO SHOULD ATTEND?This Course will educate End Users processing materials made from difficult to machine and grindmaterials such as hardened steel, stainless steel, superalloys, titanium, high silicon aluminum,composites, ceramics, bi-metals, metal matrix composites, cermets, glass, and more! It will alsoeducate Machine Tool Builders, Abrasive suppliers, Raw Material Suppliers, Machine Operators, WheelMakers, Tool Makers, Research Scientists, Academia, Engineers, Sales Personnel or anyone wishing tolearn more about superabrasives.

INSTRUCTORS ARE INDUSTRY EXPERTS WITH MANYYEARS COMBINED EXPERIENCE!

Each one has with “real world” knowledge of superabrasives, applications and characteristics. They havealready established manufacturing operations in aerospace, automotive and literally every other productionoperation around the world. Now, you can learn what superabrasives are, where they are used and thecharacteristics and properties that affect their performance in manufacturing operations. Do you want tounderstand wear mechanisms in machining and grinding? What is friability? What is a rake angle? Whataffects chip formation? What crystal is used in a given application? How does burn and thermal damageaffect structural integrity of a part? What is residual stress in metal components such as turbine engine fanblades? Why true & dress a wheel? What are the different coolant types and delivery systems? What isedge prep on a cutting tool and why is it performed? What is the Modulus of Resistance and what abrasiveperforms best on a particular workpiece material and why? If you currently are using conventionalabrasives you will learn the advantages of superabrasives and how they can be applied to increaseproductivity, reduce scrap and improve the cost effectiveness in manufacturing operations.



Modern indexable inserts consist of hard materials(tungsten carbide, cermet, ceramic, polycrystallinediamond (PCD), polycrystalline cubic boron nitride(PCBN)) and are usually ground after sintering to preciseshape and dimensions with diamond grinding wheels.Face grinding of the periphery (clearance surface) of theinserts is a very time consuming step besides grinding theradii and a possible chamfer due to the high stockremoval. Resin, metal and vitrified bonded diamond wheelshave been used usually over the last decades. Becausethe wheels are clogging, loading, wearing und losingshape, they have to be dressed conventionally usingwheels made of silicon carbide (SiC) or aluminum oxide(Al2O3) for cleaning and restoring a flat surface geometry.This article presents a new generation of metal bonded

grinding wheels which are dressed in process usingelectrical discharge conditioning (EDC). This combinedprocess called “PowerGrind” was developed andintroduced by the machine builder Agathon, Switzerland.

There are some basic requirements to grinding wheelsdressed by electrical discharge conditioning: Firstly, ahighly electrical conductance of the diamond wheel isnecessary: Due to he high current flow (up to 60 Amperesdischarge current, discharge time 1-2µs) during theelectrical discharge the body (carrier) of the wheel, the rimand the interface (glue or thin copper layer) between thebody and the diamond layer have to be electricalconductive. It was found out, that the resistance betweenthe diamond layer and body should be lower than 20mΩ,

SKYTEC BOLT – A NEW GENERATION of metal bonded diamond wheels for grinding of indexable inserts with electrical discharge conditioning

Author – Dr. KARL MAYRHOFER, R&D Resin and Metal Bonds, TYROLIT, AustriaPresenter – CHRISTOPHER GOLSER, Sr. Application Engineer, RADIAC ABRASIVES, USA

Figure 1 – SEM (scanning electron microscopy) of the surface topography of a metal bonded D28 grinding wheel after dressing with a 400 mesh

Aluminum oxide; 500-fold magnification.

Figure 2 – SEM (scanning electron microscopy) of the surface topography of a metal bonded D28 grinding wheel after EDC; 500-fold magnification.


respectively the conductance should be greater than 50S.Usually the rims are glued on aluminum cores which havea sufficient specific electrical conductivity (38*106 S/m).

Secondly, the bond must be machinable by EDC in orderto dress, sharp and clean the grinding wheel. Inconsequence metal bond with a low melting temperature ispreferred for a controlled wheel wear. Theoretically, aconductive highly metal (e.g. copper) filled resin bonddiamond wheel could be conditioned by EDC. But due tothe locally high temperature (T > 4000 K) caused by thespark discharges, the resin bond would be decomposed.Also a electrical conductive ceramic bond would work.

Thirdly, there are some requirements due to the grindingprocess: The grinding parameters (peripheral speed,infeed, stock) and the workpiece and material to beground have a great influence on evaluating the rightgrinding wheel specification: The type of diamond, the gritsize and size distribution and the concentration (amount ofthe diamond in the rim, 25 Vol.% = C100) and bond areprimarily crucial for the grinding of the inserts. The bond isresponsible for the diamond retention. In case of insertgrinding the bond should not be too tough because ofclogging the wheel with the hard material of the workpiece.Concerning these requirements, grinding wheels withdifferent types of diamond, different grit sizes andconcentrations retained in different metal bonds weretested to achieve an optimal grinding result. After then thegrinding parameters in conjunction with the PowerGrindProcess were optimized. The grinding was performed onan AGATHON 400 Penta CNC machine (Switzerland)equipped with electrical discharge conditioning in process(PowerGrind). The grinding oil was a low viscositydielectricum (=non electrical conductive fluid) enablingelectrical discharge machining, lubricating and cooling. Inthis paper the surface topographies of a spark eroded andconventionally dressed metal bonded diamond wheel arecompared (figure 1, 2). Further, the influence of the metalbond (figure 3, 4), the influence of EDC (figure 5, 6,7), andthe grit size (fig.8,9) on grinding forces are discussed.

Additionally some productivity enhancements arepresented. Finally a conclusion is drawn. Figure 1 showsthe surface topography of a metal bonded D28 grindingwheel dressed conventionally with a ceramic bonded 400mesh Aluminum oxide dressing wheel: The surfaceappearance is chopped, edgy and shows many ruptures.The diamonds show signs of mechanical damage. Themetal bond is plastically deformed. Figure 1 SEM(scanning electron microscopy) of the surface topographyof a metal bonded D28 grinding wheel after dressing witha 400 mesh Aluminum oxide; 500-fold magnification

Figure 2 shows the surface topography of the metalbonded D28 grinding wheel after electrical dischargeconditioning. The resulting topography seems more open,skeleton like and with predominantly round shapes. Thediamonds are not mechanically damaged. Some of thediamonds are covered with molten bond material. Thesurface of the diamonds seems higher than in Figure 1 forthe conventional case although the identical grindingwheel was used.

Figure 3 shows the forces during grinding of two V-shapedtungsten carbide inserts with a pure copper bonded D28

Figure 3 – Normal (blue) and tangential (red) forces (Newton) when face grinding with pure copper bonded D28 grinding wheel, EDC ON; workpiece:

V-shaped tungsten carbide insert.

Figure 4 – Normal (blue) and tangential (red) forces (Newton) when face grinding with optimized bronze bonded D28 grinding wheel, EDC ON;


Figure 5 – Normal (blue) and tangential (red) forces (Newton) when face grinding; EDC OFF; bronze bonded D28 grinding wheel; workpiece:



diamond wheel. The four ground face sides correspond tothe peaks of the four normal forces and respectively to thefour signals of the tangential forces. As can be seen thewheel was slipping because the tangential force becamenegative. Due to the high normal forces of 380N andtemporarily negative tangential forces, the pure copperbonded diamond wheel was overloaded. After facegrinding the two radii were ground corresponding to thenegative peaks of the normal forces. The normal forceswere for kinematic reason negative because the grindingwheel was moving back from the insert.

Figure 4 depicts the grinding forces when a optimizedbronze bonded D28 wheel was grinding two V-shapedtungsten carbide inserts. There was no slipping of thewheel observed and the maximum normal forces weremuch lower (280N) in comparison to the copper bondedwheel. So the bond of the diamond has an huge impact ongrindability!

Figure 5 and 6 demonstrate the impact of the in processdressing with EDC on grinding forces. Figure 5 depicts thegrinding forces when 10 pieces V-shaped tungstencarbide inserts were ground without EDC. As can be seen,the normal forces grew from insert to insert starting at 300Newton and reaching 380 Newton after 12 inserts. Thetangential force were constantly at 100 Newton. Then thegrinding was repeated under identical conditions with theexception that EDC was on. The normal forces keptconstantly at 300 Newton (figure 6).

The friction coefficient µ is the ratio of the tangential force(Ft) and the normal force (FN) and a measure of thegrindability: µ = Ft / FN Figure 7 shows the frictioncoefficient calculated from the force data yielded in figure5 and 6 over 10 inserts. When the grinding wheel waselectrical discharge dressed in process (EDC ON), thenthe friction coefficients are always significantly higher thanwithout EDC (EDC OFF).

Figure 8 shows the normal forces (blue) and tangentialforces (red) when C-shaped tungsten carbide inserts wereground with a metal bonded D12 grinding wheel. When thegrit size of the diamond was doubled to D25 (fig.9), themaximum normal forces decreased significantly form 280to 210 Newtons.

The results of table 1 and table 2 show examples of thevery high potential of grinding inserts with metal bondedgrinding wheels dressed in process with electricaldischarge conditioning. In table 1 a productivitycomparison is drawn between a resin bonded D46 wheel,dressed conventionally, and a metal bonded D28 wheel,dressed with spark eroding. The indexable insert was a

Figure 6 – Normal (blue) and tangential (red) forces (Newton) when face grinding; EDC ON; bronze bonded D28 grinding wheel; workpiece:


Figure 7 – Influence of EDC on friction coefficient.

Figure 8 – Normal (blue) and tangential (red) forces (Newton) when face grinding with a bronze metal bonded D12 grinding wheel, EDC ON;

C-shaped tungsten carbide insert.

ultra fine grade tungsten carbide with a side length ofsome centimeters. Despite the one third lower grit size ofthe metal bonded wheel, the cycle time wass more than ahalf lower (108 seconds) because the infeed was morethan doubled. Additionally, the edge chipping of theinserts was reduced significantly to 12µm.

The second application example is a rhombus shapedindexable insert made of solid pCBN with a side length ofabout 2 centimeters. Again, EDC enables a much higherproductivity. The cycle time in this example can bereduced by 60%, again using a finer diamond grit

The new metal bonded high concentrated fine gritdiamond wheel can be easily and optimal dressed inprocess with electrical discharge conditioning. Inconsequence the grinding wheel is during grinding always flat, clean and sharp. Due to lower grinding forcesthe infeed speed can be tremendously increased bydeclining cycle times. Using smaller grit sizes (D12) andhigher concentration enables reduced edge chipping ofthe inserts.

Figure 9 – Normal (blue) and tangential (red) forces (Newton) when face grinding with a bronze metal bonded D25 grinding wheel, EDC ON; workpiece:

C-shaped tungsten carbide insert.



HIGH PERFORMANCE TOOLHOLDERFOR MICRO MACHININGSpecial consideration must be made formicro-machining, which is why SCHUNK isoffering the TRIBOS-RM precision toolholderas the best solution for micro machining withthe ISO interface. The one-piece, rotationallysymmetric design ensures long life of themachine spindles and the completetransmission of power. Unlike heat shrink clamping, the TRIBOS-RM achieves steady tool clamping that will not distort thetoolholder. The user will always benefit from a precise run-outaccuracy of less than 0.003 mm, which is optimal with smalltools for micro machining. The TRIBOS-RM is designed for highspindle speeds of up to 60,000 rpm in high-speed cutting,making it ideal for the high speeds involved in micro-machining.Sizes ISO 10 D 1 - 6 mm are available. The balancing grade is G2.5 at 25,000 rpm.

Announcements&PRODUCTS

LACH DIAMONDAT PRODUCTRONICAMUNICH/ GERMANYNOVEMBER 14-17The productronica is the world’sleading trade fair for innovativeelectronics production. Lookingback on 40 years, LACH DIAMANT was worldwide the first manufacturerpresenting polycrystalline (PCD)diamond tools for cutting, scoring, sawing and milling for PCBproduction. The developers of LACH DIAMANT in Hanau, inSaxonia, and of LACH DIAMOND INC., Grand Rapids Michiganwere always known as “pioneers of innovation”. In Munich, LACHDIAMOND will show visitors precise solid carbide saws for PCBdepanelling with cutting width to the smallest width of 0.3 mm;higher feed rates are guaranteed with correspondingly higherthroughputs. For more information visit: www.lachdiamond.com

LARSON ELECTRONICS, ANNOUNCED A NEW EXPLOSION PROOF HIGH BAY LED LIGHT FIXTUREThis hazardous location light is approved for use within environments where flammable or combustible gases,vapors, dusts, and fibers exist or stand the potential to exist and is ideal for a variety of applications. ThisClass 1 Divisions 1 and 2, Class 2 Divisions 1 and 2 explosion proof LED light fixture has no exposed glassand provides 17,500 lumens of light while only drawing 150 watts. A special heat dissipating design and LEDtechnology helps this fixture to achieve a 60,000 hour rated lifespan with 80% lumen retention. Thepolycarbonate lens on these explosion proof high bay LED fixtures eliminates that liability by catching and

trapping any glass fragments in the event that the light within the lens is broken. The company offers an extensive catalog ofindustry-grade lighting and power distribution products for manufacturing, construction, oil and gas, military, marine and automobile.


3M Abrasive Systems Divisionwww.mmm.com

ABC & Warren/Amplex Superabrasiveswww.saint-gobain.com

Abrasive Technologywww.abrasive-tech.com

Abrasivos Austromex, S.A. DE C.V.www.austromex.com.mx

Action Superabrasive Products, Inc.www.actionsuper.com

Advanced Abrasives Corporationwww.advancedabrasives.com

American Superabrasives Corp.www.diamonds-abrasive.com

Anco Industrial Diamond Corp.www.ancodiamond.com

Apogee Precision Partswww.natchain.com

Asahi Diamond Americawww.asahidiamond.com

Bogimac NV-SAwww.bogimac.com

Bruce Diamond Corp.www.brucediamond.com

Cdp Diamond Products Inc.www.cdpdiamond.com

CemeCon, Inc.www.cemecon.com

Chardon Tool & Supply Co., Inc.www.chardontool.com

Continental Diamond Tool Corp.www.cdtusa.net

Crystallume EngineeredDiamond Productswww.crystallume.com

Cutting Edge Services Corporationwww.cuttingedgeservices.com

Decatur Diamond, LLCwww.sp3cuttingtools.com

Delaware Diamond Knives Inc.www.ddk.com

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Diamond Industrial Toolswww.todit.com

Dianamic Abrasive Products Inc.www.dianamic.com

DiCoat Corporationwww.dicoat.com

Eastwind Lapidary, Inc.www.eastwinddiamondabrasives.com

Element Sixwww.e6.com

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FACT USAwww.wmstrading.com

Fives Landis Corp-Citco/Gardnerwww.fivesgroup.com

Fort Wayne Wire Die Inc.www.fwwd.com

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The Grinding Docwww.TheGrindingDoc.com

HK Technologieswww.clevelandvibrator.com

Iljin USA, Inc.www.iljindiamond.com

Industrial Diamond Laboratories Inc.www.industrialdiamondlabs.com

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Lands Superabrasives Co.www.landssuperabrasives.com

Lieber & Solow Co.www.lieberandsolow.com

Megadiamond Inc.www.megadiamond.com

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Noritake Co Inc.www.noritake.com

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Precision Eformingwww.precisioneforming.com

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Radiac Abrasives Inc.A Tyrolit Companywww.radiac.com

Rollomatic, Inc.www.rollomatic.ch/en/contact/usa

Sandvik Hyperionwww.hyperion.sandvik.com

Saint-Gobain Surface Conditioning Group(Saint-Gobain Ceramic Materials)www.innovativeorganics.com

Scio Diamond Technologywww.sciodiamond.com

Spec Toolwww.spec-tool.com

Standard Die & Fabricating Inc.www.standarddie.com

Sumitomo Electric Carbide Inc.Materials Groupwww.sumicarbide.com/diamondgroup

Superabrasives Inc.www.superabrasives.com

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THIRTEEN YEARS ASTHE GRINDING DOC

Thirteen years ago I quit my joband went on the road as The

Grinding Doc, itinerantgrinding expert. Over the nextthirteen years I learned a lot,

about grinding and abouthuman nature.

I did a Bachelor’s at the University of Texas at Austin, a Master’s from Penn State,and a Ph.D. from Trinity College in Dublin, Ireland, all in mechanical engineering.The research focus of my Ph.D. was grinding. I then worked several short contractsfor companies in England and Sweden that were suffering from “grinding burn,”followed by two years at a steel company in Sweden doing research on the“grindability” of different steel grades. During that time I started writing aquestion/answer column on grinding for the trade magazine Cutting ToolEngineering. I needed a catchy name. I figured that if Dr. Phil could give advice onpsychology and Dr. Deepak Chopra could give advice on spiritual enlightenment, Icould give advice on grinding. I called myself “The Grinding Doc”. The name stuck.

In 2004 I went on the road as The Grinding Doc, independent grinding expert. Iadvised companies on grinding research, did grinding troubleshooting, particularlyfor burn, developed a three-day grinding education course, and developed “TheGrindometer” power meter for evaluating grinding cycles. When I started, most ofmy experience was grinding tool steel, but I gradually branched out into otherindustries on carbide tooling, aerospace, gears, bearings, crankshafts, camshafts,rolls and even gemstones. I read all the books and academic literature I could find. Ispent my days on the shop floor measuring power, wheel wear and surface finishand evenings processing the results ... I learned a lot.

The grinding world is a small place so my work took me around the globe. I spentmonths on the road – a week at a company in Spain, three weeks at three differentcompanies in Sweden, a week at a company in Slovenia, two weeks between jobsprocessing the results on my laptop at the beach in Croatia, then a three-day coursein England followed by trips China, Korea and Australia. During one period, I livedout of a suitcase for 18 months, without a home. I was learning so much, so I keptgoing.

Thirteen years later I’ve visited hundreds of companies in over 30 countries andspent countless hours on the shop floor battling burn, chatter, long cycle-times andgeneral grinding headaches. Here’s what I’ve learned so far that may help others toimprove grinding operations.

1. Master the fundamentals.Grinding is like golf. You can have the most expensive club in the world, but if youhave a bad swing, you’ll be a bad golfer. Many grinders think they just have to getthe right wheel and that burn problem will go away. It won’t. When I was fresh outof my Ph.D., I also was guilty of the “find the perfect wheel” mentality. What Ilearned – the hard way – was that if you’ve got a good understanding of grinding,dressing and cooling fundamentals and set up the process correctly, just about anywheel will do. Nowadays when I go to a company with burn problems, they call mea few weeks before and say, “Dr. Badger, what test wheels would you like us toorder?” They’re surprised when I say, “None. We’ll get rid of the burn with the wheel

A NOTE FROMTHE EDITOR...

The Grinding Dochas done an

incredible jobimproving grindingoperations aroundthe world. At the

Industrial DiamondAssociation’s

SuperabrasiveMaterials,

Principles andApplications

Course (see page10), where Dr.

Badger is one ofour featured

instructors, Jeff andI were talking abouthis evolution as agrinding master.When we were

talking I asked Jeffif he could set downa short summary of

what he haslearned, because

his experiencecould help many

others involved ingrinding solvesome of their

problems. Thisarticle is a very

good summation ofwhat The GrindingDoc has learned …Maybe we can alllearn a little from

his trials andtribulations!”



you have.” They reply, “But you don’teven know which wheel we have.” And Isay, “I don’t, but I’m sure it’s fine.” Wespend three days on things like wheelwear, chip-formation, removal rates,aggressiveness, dressing overlap ratiosand speed ratios, coolant pressures andvelocities, RPM ratios and a host ofother fundamental concepts. We thenspend about 10 minutes on wheelchoice. That’s not to say a better wheelwon’t help you. But the place to start is with the fundamentals.

2. Don’t tell people how to grind – give them the tools and knowledge about grinding and turn them loose.

Early in my career, I’d get on a machine and change the parameters to produce a super, no-burn, chatter-free processwith a short-cycle-time. The customer would say, “Yes, that works great. Thank you. We’ll run it.” And they would, for afew weeks. But when I’d return a year later I’d notice that they were running with the original parameters. Why? Becausethey didn’t have “ownership” of the technology, and when something changed (the dressing diamond flat becamelarger, the part size changed), they went back to what they knew. Now I spend three days educating them on thefundamentals of grinding and turn them loose to come up with their own ideas. When I return a year later, I’m amazedat what they’ve accomplished – not just on one machine, but on all their machines

3. Do your homework. Every time I get into a new type of grinding – be it material type, grinding geometry, dressing type – I spend a few daysdigging through the literature and find out what others have already done. Some of these articles go back to the 1950s.But they allow me to get my head around the grinding operation much more quickly.

4. It’s ok to say, “I don’t know.” Early in my career, I felt the need to act as if I knew everything about grinding. As I became more confident in myknowledge, I found it easier to say, “I don’t know.” Nowadays, I say it all the time – without flinching. In fact, I enjoy itwhen there’s something I don’t know. I have access to all the books and literature and am friendly with most of theother experts. If I come across something tricky, I’ll spend the weekend digging into the literature and making phonecalls to find the answer.

5. Respect machine operators, they are the true heroes of the industry. Most machine operators have no training in grinding. We give them a machine and a blueprint and say, “Here, makethis happen.” They have to produce a part within specific tolerances and surface finish without burn and chatter, allwith a short cycle time, using a machining process on which they’ve had no formal training. It blows my mind that theyare able to pull it off. It’s an art form as much as a technical skill.

6. Get out of the Ivory Tower. I spent my Ph.D. years hearing things like “minimum chip-formation energy based on a nonlinear, multivariable stochasticdistribution of asperity heights” and thought: “Do people in the realproduction world really talk like this?” I quickly learned that theanswer is a resounding NO! There are two grinding worlds: theacademic world and the real world. When I started working in thereal world, I discovered that just about everything I learned in theacademic world had no practical application. It was like I wasstarting all over again. Having said that, I later learned to appreciatehow understanding the subject from the bottom up – which I

What I’ve learned so far ...BY DR. JEFFREY A. BADGER, THE GRINDING DOC

www.TheGrindingDoc.com


developed in the academic world – enabled me toquickly understand what was happening in themachine. But I just had to get in the real world andsuffer through it.

7. Company culture matters. Within an hour of setting foot into a company, I get avibe. And that vibe almost always ends up being right.What’s the general mood of the company? Are theoperators going to be cooperative or are they going toresist? Optimistic or defeated? I’ve been to companieswhere operators and engineers have a healthyskepticism, but are also open-minded and enthusiasticabout learning. I’ve been to companies where themanagement and shop-floor are at war with each other.I’ve been to Company A, and then two weeks later toCompany B. Both companies are making the sameproduct with more or less the same machines, wheelsand coolants. Months later I hear back from CompanyA and they’re very satisfied. With what they learned,

they’re cutting cycle times, reducing wheel costs and dealing with grinding problems in ascientific way. They’re scheduling a follow-up visit. I then call Company B and am toldnothing has changed. Why? It seems to be company culture and attitude.

8. Keep learning. I did a Ph.D. in grinding and for over 20 years I’ve done nothing but grinding, in a variety of industries and applications.I’ve read hundreds of academic articles and every book ever written on the subject. I’ve spent years camped out ongrinding machines. Yet every day I’m overwhelmed by what I don’t know and so I press on ...


Progresses of GrindingTechnology ofMonocrystalline SiliconCarbide; for Longer Tool Life and HigherQuality Finished SurfacesIn order to accelerate the mass production of SiC power semiconductordevices, which possess a higher performance than Si based powersemiconductor devices, lowering the machining cost and obtaininghigher-quality finished surfaces in the wafer thinning process are crucial. This paper will introduce the latest progresses of grinding technologies of SiC wafers, which can significantly reduce the machining cost and improve the quality of finished surfaces.

1. Introduction Power Semiconductor Devices and SiC

Due to the growing concern of energy depletion, power semiconductordevices that enable more efficient use of electricity in many fields such asautomobiles, trains, and power grids, are gathering more attention andprojected to be increasingly prevalent. Currently, the most commonly usedmaterial for power semiconductor devices is silicon (Si). However, theperformances of Si-based power semiconductor devices have almost reachedthe limitation of the physical property of Si, and it is said that it cannot meetthe forthcoming requirements for power semiconductor devices, e.g., higheroperating temperature and voltage resistance. Silicon carbide (SiC), on theother hand, possesses superior physical properties and is considered as amore promising material for next-generation power semiconductor devices. Byemploying SiC, power semiconductor devices can work in the said severeconditions and reduce the losses of electricity thanks to its high switchingperformance.

Obstacles in Commercial Use of SiC Power Semiconductor Devices

In spite of said merits of SiC-based power semiconductor devices, SiC is ahard-to-cut material and its wafer fabrication is extremelydifficult. Figure.1 shows the SiC wafer fabrication process.Slicing of ingots, thinning by lapping, and ChemicalMechanical Polishing (CMP) are the major processes.Among them, the thinning process by lapping is one of themost costly and time-consuming processes mainly due tofollowing two reasons:

1. Low lapping rateBecause of the hardness of SiC, the lapping rate usuallyremains a few microns per hour. Therefore, wafer thinningby 100µm, which is the typical removal amount, takes 24 to48 hours per wafer.

2. Surface roughness and flatnessIn order to reduce machining time of CMP, making flat and

Shuichi AMINO, Tomohiro ISHIZU,

Nobuhide NAKAMURA, and Toshiya TAKAHASHI

A.L.M.T. Corp.

smooth wafers in the lapping process, which is the front-end of CMP, is crucial. However, by its nature of lapping,edges of wafers are primarily machined, causingdeterioration of flatness. The reality is that more time isneeded in the lapping process to obtain flat wafers.Furthermore, this deterioration in flatness becomes moreevident in wafers with larger diameter. Also, scratches areoften left on wafers on account of aggregation of ultrafineabrasive grains in the slurry. To remove those scratches,more CMP time is needed. Therefore, an alternativethinning method which can greatly reduce process timeand cost is desired.

Grinding - A Better Choice for Machining of SiC Wafers

A.L.M.T. has been working on the development of fixedabrasive grinding wheels for SiC for years in the aim ofhigh-efficiency, low cost, and high-quality finishedsurfaces in SiC wafer thinning. The proposed waferthinning consists of 2 steps, i.e., rough grinding and finishgrinding. It was proven in the previous study that waferthinning by fixed abrasive grinding is much faster than theconventional lapping process without deterioration of theflatness of wafers; 240 µm wafer thinning of 3” SiC wasdone in less than 0.2 hours while Total Thickness Variation(TTV) of the wafer was maintained within 1µm. Theseachievements paved the way for high productivity in SiCwafer fabrication.

Nevertheless, there are still many challenges to betackled in this process, and A.L.M.T. has been constantlydeveloping new grinding technologies. In this paper,progresses of grinding technologies of SiC wafers that isexpected to accelerate the commercial use of SiC powersemiconductor devices are going to be introduced. Thenext section focuses on the reduction of wear of roughgrinding wheels, which will reduce the machining cost ofSiC wafers. In the following section, how smoothersurface can be obtained by grinding will be discussed.This will also contribute to the reduction of total cost ofSiC wafer fabrication. The last section summarizes thisstudy.

2. Reduction of Wheel Wear in RoughGrinding for Cost Reduction

BACKGROUND – One of the major obstacles in SiC waferfabrication is the considerable machining cost. Sincealmost 90% of the material removal is done in roughgrinding, reducing wheel wear in rough grinding greatlycontributes to the lower machining cost. Moreover, thediameter of SiC wafers most commonly used is currently intransition from 4” to 6”. In general, wafer thinning suffers

larger grinding force and wheel wear as the diameter ofwafers increases. In light of this fact, grinding wheelswhich can machine 6” SiC wafers cheaply are demanded.Hence, understanding on the machinability of 6” SiCwafers is essential.

In this section rough grinding of both 4” and 6” SiC wafersis performed to demonstrate their machinability. Then,through tests of two newly developed grinding wheels,how wheel wear can be reduced will be discussed.

Method

The schematic of thegrinding of monocrystallineSiC wafer is shown inFigure 2. Thespecifications of thegrinding wheels and theconditions of the tests areshown in Table 1. Threegrinding wheels, i.e., aconventional grindingwheel which is capable of

grinding 4” SiC wafers and two newly developed wheels,are examined. Among the two newly developed wheels,one has enhanced retention of abrasive grains byoptimizing the compounding ratio of diamondsuperabrasive and vitrified bond, namely ‘high-retention’.The other one, namely ‘micro-fracture’, is intended tofracture the surface of the grinding wheel more minutelythan the conventional wheel. For the convenience offollowing discussions, each combination of wafer diameterand wheel is abbreviated as shown in Table 2.

In the test, normal grinding force and wear ratio areevaluated. Wear ratio and grinding ratio are defined as:

(the wheel wear in thickness)(wear ratio) = _________________________________

(the removal of wafer in thickness)


Figure 1: Comparison of Process Time

Figure 2: Schematic ofMachining Process by Rotary Type Grinder

Therefore, a smaller wear ratio indicates that the grindingwheel has a longer tool life.

Results and Discussion

First, 4”-conv and 6”-conv were tested. The results areshown in Table 2. In the table, data are shown as relativevalue with the average of 4”-conv being 1. The normalgrinding force of 6”-conv increased by 2.4 timescompared to those of 4”-conv. This is directly attributed to

the 1.5 times larger area of contact between the waferand the grinding wheel than that of the grinding of the 4”.Because of this larger area of contact, the force exertedto each abrasive grain disperses making the depth ofeach cutting abrasive smaller. As a consequence, thegrinding process becomes more like rubbing. Similarly,the 2.6 times larger wear of 6”-conv can be alsoexplained by the depth of each cutting abrasive.Because the process is more like rubbing, each abrasivegrain attrits and comes off by a self-dressing effectwithout cutting the workpieces. Lastly, while the normalgrinding force of 4”-conv is almost constant (not shownhere), that of 6”-conv increased monotonically at first anddecreased suddenly at workpiece no.7 as shown inFigure 3. This sharp fall of normal grinding force indicatesa large fracture of wheel surface. It is considered that theretention of abrasive grains is not optimal. From thoseresults, the lower machinability of 6” SiC wafers is simply understood.


Figure 3:Comparison ofNormal Force

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celebrations, the most popular of which isCarnival, often referred to as Mardi Gras.Carnival officially begins on the Feast of theEpiphany, also known as the "Twelfth Night".Mardi Gras (French for "Fat Tuesday"), thefinal and grandest day of festivities, is thelast Tuesday before the Catholic liturgicalseason of Lent, which commences on AshWednesday. The largest of the city's manymusic festivals is the New Orleans Jazz &Heritage Festival. Commonly referred tosimply as "Jazz Fest", it is one of the largestmusic festivals in the nation, featuringcrowds of people from all over the world,coming to experience music, food, arts,and crafts.

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In order to reduce both normal grinding force and wear,grinding of 6” SiC wafers by two newly developedgrinding wheels is examined. The results are shown inTable 2 and Figure 3. First, the high-retention wheel, whichis intended to reduce the wear by retaining the abrasivegrains more solidly, ended up in divergence of normalgrinding force and crack of machined wafers. It isconsidered that the retention of abrasives was too strongfor attired abrasive grains to come off, leading to anexcessive number of effective cutting edges. On the otherhand, the micro-fracture wheel, which is designed tofracture the surface of the wheel more minutely, succeededin reducing the normal grinding force to 75% with respectto 6”-conv. Additionally, the normal grinding force of the 6”-micro fluctuates little upon increase of number of groundworkpieces, which is desirable for mass production. Alsothe wear of 6”-micro was reduced to 30% of 6”-conv. It isnoteworthy that 6”-micro has even smaller wear than 4”-conv. These results indicate that maintaining sharp edgesof abrasive grains on the surface of grinding wheel byprompting minute fractures is effective to extend the toollife and reduce grinding force in 6” SiC wafer grinding.

SummaryIn this section, the machinabilities of 4” and 6” SiC waferswere examined. By the conventional wheel, the wear of 6”SiC wafers increased by 2.4 times, showing lowmachinability of 6” SiC. However, it was understood thatthe wheel wear and grinding force can be reduced to agreat extent by optimizing the fracture scale of thegrinding wheel. In this study, the wear was reduced toone third, indicating the machining cost can also bereduced to one third. This will significantly reduce themachining cost of SiC wafers. Also, further improvementsin efficiency can also be expected by optimizing theability.

3. Newly Developed Wheel for Finish Grinding

BACKGROUND - In the last section, the developments ofrough grinding wheel are reviewed from the view point ofcost reduction through the extension of tool life. However,obtaining a smooth and flat finished surface can alsocontribute to the reduction of total machining cost. Thus,demands on finish grinding are also increasing. In thissection, progresses of finish grinding are going to beintroduced.

So far, only surface roughness and flatness of finishedSiC wafers are entirely focused. This is because asmoother surface is more advantageous to reduce thetime of CMP, in which Ra=0.1 nm is typically required.Similarly, because wafers need to be evenly polished inCMP, flat wafers are preferred. Thus, smooth and flatwafers help the reduction of CMP time, and consequentlyreduce the total machining time and cost. Roughness andflatness of wafers are still important evaluation indices.

On the other hand, recent studies suggest a possibilitythat defects, including strains on wafer surface introducedin the machining process, are often not removedcompletely even after CMP. This may deteriorate thequality of the epitaxial layer, which lowers theperformances of SiC devices. However, whichevermachining process is causing those defects is notunderstood well.

In this section, the latest finish grinding technologies areintroduced. Finish grinding with different diameters ofultrafine diamond superabrasives is performed first. Next,the strain of each wafer, as well as measurements donebefore e.g., surface roughness and flatness, areevaluated. By comparing them to those of lapped wafers,finish grinding is characterized. Finally, how the yield rateof SiC wafer fabrication can be increased is proposed.

Method

In the following, D50 denotes the median diameter ofdiamond superabrasive. The grinding conditions areshown in table 4. In this section, 3” SiC wafers are usedas workpieces. Diamond abrasives (D50 = 0.5, 0.3 and0.1 µm) are employed in grinding wheels. These grindingwheels employ a special dispersing technique to avoidthe aggregation of ultrafine diamond abrasives. Twowafers for comparison provided by cooperative groupsare also evaluated; one was lapped by 0.1µm diamondpowder and the other was polished by 0.5µm diamondpowder. In the test, cooperative groups are alsoevaluated; one was lapped by 0.1µm diamond powderand the other was polished by 0.5µm diamond powder. Inthe test, surface roughness, Transmission ElectronMicroscopy (TEM) images, and strain of wafer surfacesare evaluated. The surface roughness and strain of thewafer surface are measured by optical surface profilerand Electron Back Scattering Diffraction (EBSD),respectively. Note that those measurements are not doneto all samples due to limited resources.

Results and Discussions

The results are shown in Table 5. First grinding of SiCwafers (pre-ground #2000) was possible for D50=0.5 and0.3 µm wheels. In contrast, that of D50=0.1µm wheel wasobtained via #8000 (D50=0.5µm) surface. All machiningprocesses with removal stock of 10 µm took only a fewminutes, and much higher efficiency than lapping wasalso confirmed in finish grinding. TTV of all ground waferswere within 1 µm.

Comparing the surface roughness between grinding andlapping, 3 dimensional roughness (Sa) of the lapped



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How long has your company been engaged in ____ 1. _______________________________________________________________________________________superabrasive/ultra-hard material industry?_______ 2. _______________________________________________________________________________________

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_______ Regular MembershipAny company and/or individual classified as a superabrasive/ultra-hard material supplier, tool maker, machine tool builderor related business which HAS an office and a local, state or province business license in the United States, Canada orMexico is eligible for membership in this category. Only one individual shall be designated by each member company asthe IDA Delegate with voting and other privileges described in the By-Laws.

(DUES CATEGORY)The dues category for Regular Members is determined by annual sales volume expressed in US $ as indicated below.Check to appropriate category:_____ Category 1 $2,750 per year Over $20,000,000 Annual Sales_____ Category 2 $2,090 per year $10,000,000 - $19,999,999 Annual Sales_____ Category 3 $1,850 per year $6,000,000 - $9,999,999 Annual Sales_____ Category 4 $1,450 per year Under $2,000,000 - $5,999,999 Annual Sales_____ Category 5 $1,095 per year Under $1,999,999 Annual Sales

______ International MembershipAny company and/or individual in the diamond and/or cBN business which DOES NOT have an office and a local, state orprovince business license in the United States, Canada or Mexico is eligible for membership in this category. AnInternational member shall have all the privileges of regular membership, except that he/she cannot vote at anymembership meetings, participate in statistical reporting for the North American market, hold proxies or serve in any office inIDA. Annual fee for International Member is $3990 per year.

_______ Associate MembershipAvailable for companies having a principal office in the U.S.A., Canada or Mexico, which are providing products orservices to companies within the superabrasive/ultra-hard material industry, but are not engaged in selling, using ordealing in industrial diamonds, cubic boron nitride, compacted diamond/cbn, diamond film or products containingdiamonds/cbn. An Associate member shall have all the privileges of regular membership. Annual fee for an Associate is$600 per year.

_______ End User/Contractor MembershipAvailable for any global companies or individuals, which USE products classified as superabrasives or ultra-hard materials,but are NOT ENGAGED IN SELLING industrial diamonds, cubic boron nitride, compacted diamond/cbn, diamond film orproducts containing diamonds/cbn. An End User/Contractor member shall have all the privileges of regular membership,except that the Delegate cannot vote at any membership meetings, participate in statistical reporting for the North Americanmarket, hold proxies or serve in any office in IDA. Annual fee for an End User/Contractor is $400 per year.

_______ Academia/Research MembershipAny non-profit Academic institution or R & D organization is eligible for membership in this category. An Academia/Research/ member shall have all the privileges of regular membership, except that the Delegate cannot vote at anymembership meetings, participate in statistical reporting for the North American market, hold proxies or serve in any office inIDA. Annual fee for Academia/Research is $175 per year.

_______ Student MembershipAny FULL TIME Student NOT ENGAGED IN SELLING industrial diamonds, cubic boron nitride, compacted diamond/cbn,diamond film or products containing diamonds/cbn is eligible for membership in this category. A Student shall have all theprivileges of regular membership, except that he/she cannot vote at any membership meetings, participate in statisticalreporting for the North American market, hold proxies or serve in any office in IDA.Annual fee for a Student Membership is$100 per year.

_______ Senior MembershipAny individual who has worked for and/or retired from an IDA Member company or is no longer active in the diamond orCBN business is eligible for membership in this category. A senior member shall have all the privileges of regularmembership, except that he/she cannot vote at any membership meetings, participate in statistical reporting, hold proxies orserve in any office in IDA. Annual fee for a Senior is $75 per year.

Name of Delegate Member:___________________________________________________________________________________

Title: _______________________________________________________________________________________________________

E-Mail: _____________________________________________________________________________________________________

* Applications for ALL Memberships are reviewed by the Board of Directors and must be approved by a two-thirds vote.

_______ Affiliate MembershipEach company that enrolls as an IDA Member is entitled to have a second person at that company designated an AffiliateMember. The first Affiliate member will receive IDA material at no further cost. Additional persons at Member companies canbe added as Affiliate Members to receive IDA materials. Annual fee for additional Affiliates is $100 per person. Name of 1stAffiliate Member (no charge):

Name of 1st Affiliate Member (no charge): ______________________________________________________________________

Name of 2nd Affiliate Member ($100): __________________________________________________________________________

Name of 3rd Affiliate Member ($100): __________________________________________________________________________

If your company wants more Affiliate Members, please attach additional sheets.

WHAT IS THE IDA?The Industrial Diamond Association ofAmerica, Inc. is a non-profit tradeassociation and was incorporated onMarch 29, 1946 in the State of New York.It is the oldest and most prestigiousassociation in the superabrasive/ultrahardmaterials industry. Activity and focus hasevolved from natural diamond tosuperabrasives and most recently, to allultrahard materials including CVDDiamond. Members include materialsuppliers, tool manufacturers, componentproducers, machine tool builders, endusers, academia/research affiliates andother companies related to the research,manufacture, application, use and sales ofsuperabrasives.

WHAT DOES THE IDA DO? Oversees Statistics Reporting Program Establishes Industry Standards Interacts With Global Associations And Organizations Creates And Distributes Market Studies & Data Organizes And Presents Technical Seminars &

Conferences Serves As A Government Liaison For Industry

Guidelines And Regulations Participates As Member Of World Diamond Council Provides Safety / Regulatory Reports And Advisement Resource For General Information And Consultation

OTHER MEMBER SERVICES PUBLISHES QUARTERLY MAGAZINE HOLDS ANNUAL CONVENTIONS HOSTS IDA WEBSITE WITH MEMBER FOCUS

AND DIRECTION PROVIDES SPECIFIC ASSISTANCE ON

INDIVIDUAL MEMBER ISSUES CREATES AND DISTRIBUTES PUBLICATIONS

ON PRODUCTS AND APPLICATIONS ACTS AS A COLLECTIVE VOICE FOR

INDUSTRY CONCERNS

FAX completed membership form to 614-797-2264

surface is inferior even to that of the D50=0.5 µm grindingas far as is confirmed. Similarly, TEM images reveal thatthe depth of the damaged layer of the lapped wafer(D50=0.1µm) is larger than that of the grinding(D50=0.5µm). These results are likely caused by anaggregation of ultrafine diamond powder in the abrasiveslurry. On the other hand, thanks to the special dispersiontechnique, it doesn’t occur in ground wafers. Furthermore,clear damages are hardly found on the wafer ground by awheel with D50=0.1µm. This damage-free grinding

technique can be applied to SiCdevice thinning, where wafers areexpected to be thinned to less than100µm and cracks of thinned wafersfrequently occur.

From the results of EBSD, it isclarified that both grinding andpolishing resulted in compressivestrains on the wafer surface. Thedepth of strain on the wafer groundby the D50=0.5µm wheel was 3 to4µm at best, which is not comparableto that of the polished wafer (around2µm). However, while the strains onground wafers are uniform in depthand spread evenly, some localizedand deep strains are observed onpolished wafers. This fact may lead toa conclusion that grinding haspotential to reduce CMP time more.This is because the total removal ofCMP should be set to remove thedeepest strain.

SEM observations shown in Figure 4 reaffirmed the above.On ground wafers, geometric patterns or grinding markare present, and they look uniform in depth. On the otherhand, the polished wafer has random patterns and lookssmooth on first glance. However, the presence of deepand localized scratches is apparent. This is assumed tocorrespond to the deep strain observed in EBSD. Notethat those scratches are commonly seen regardless offields of SEM.


SummaryIn this section, finish grinding of SiC wafers with variousdiamond abrasive diameters was performed, and thequalities of the wafer surface were evaluated. It wasshown that smoother and overwhelmingly more efficientthinning than the conventional lapping process is possibleby grinding. Also, by applying a proper dispersiontechnique, grinding can reduce damages on wafersurfaces over lapping. The average depth of strain onground wafers was not comparable to that of polishedwafers. However, uniform strain and scratch-free featuresof grinding may be preferred in mass production.

4. ConclusionStudies were made to overcome the obstacles lying in theSiC wafer thinning process and the following isunderstood:

1. As wafer diameter transitions to 6”, the machinabilitybecomes greatly more difficult.

2. By applying newly developed grinding wheels thatare designed to prompt the minute fractures of thewheel surface, the wear of rough grinding wheelsand consequently the machining cost of SiC waferscan be reduced significantly.

3. Roughness and depth of the damages on finishground wafers are smaller than that of lappedwafers.

4. Average strains on ground wafers are deeper thanthat on lapped wafer. However, uniform strains ofground wafers may work better. Yet further detailedanalysis is required.

These progresses in machining of SiC wafers areexpected to further accelerate SiC device industries andcontribute to a more ecological society.


Figure 4: Scanning Electron Microscope (SEM)Images of Machined Surfaces

InMemoriam

The Editor of Finer Points just learned that

JACK LUNZERa longtime contributor to the

Diamond Industry passedaway last December.

This recognition for Jack is way overdue ...

JACK LUNZER passed away at Fairport, his London home, on Sunday,December 18, 2016 after a long illness. He was 92. Burial was at EnfieldCemetery, and Shiva is being observed at Fairport. Jack and his belovedlate wife Ruth, nee Zipel, were the parents of five daughters: MargaretRothem, Myra Waiman, Fiona Scharf, Alison Goldberg, and Caroline Landau.Jack had 14 grandchildren and 22 great grandchildren. He was a man ofsuperb intellect, incredible charm, and extraordinary devotion to the Jewishpeople. His life was a remarkable adventure from beginning to end. Hehelped build Spitfire fighter planes in World War II; He fought to break up theDeBeers diamond cartel in Africa; He had close relationships with manyAfrican leaders and referred to them as his "brothers"; He served asHonorary Consul of Guinea to the United Kingdom; He was summoned tothe White House by President Reagan who sought his advice about certainsituations in West Africa and through his company IDC Ltd., was recognizedas a world leader in the industrial diamonds and abrasives industry.However, more important to him than business was his passion for Hebrewprinted books and manuscripts. He created the Valmadonna Trust Library,which is recognized by bibliophiles and scholars as the finest collection inthe world of Hebrew printed books from the 15th through the 17th century.Jack made items from the collection available to scholars and librarians fromall corners of the Jewish and non-Jewish worlds, and he readily shared withthem his encyclopedic knowledge. Jack was also a true baal tzedakah. Hisphilanthropy to all Jews in need, Jewish educational and cultural institutions,and synagogues was extraordinarily generous, and all who came to Fairportseeking help received it. Jack never sought recognition for his generosity.Jack was also a man who spoke many languages and loved to conversewith people from Europe, Asia, and Africa in their native tongues. Hisconversations typically began "Where are you from?", and after the reply,Jack would take over. He had an insatiable curiosity about the world. Heoften had illustrious guests staying at Fairport, such as Clair Booth Luce,Grace Bumbry, and Shaka Stevens, and they were treated to Jack's charmand hospitality. Traversing multiple countries in his trademark white safarisuit, Jack was an adventurer the world doesn't seem to produce anymore; A larger than life man to whom mere words cannot do justice. Now he isresting in peace next to his beloved Ruth, who shared much of his journey,and they are smiling in gratification that all of their daughters, grandchildren,and great grandchildren lead their lives with adherence to and love for theirJewish faith and heritage. Jack was inspirational to them all, and that is hisgreatest legacy. Fiona, Michael, William, Andrew, Naomi and Aaron Scharf.

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