MasTechFlexibleModularMasterProgrammeinTechnologySemestre 1Universitaire years2013-2014Mastech 2013AbrasiveMachininggandFinishingOperationsDeveloped by:MIle.BEN HASSAN ChahrazedMr. mar ZarrroukiSupervised by:Mr.Mnasri AbdelhakMr.Mihai NicolescuMr.Mnasri kaisMr.Mnasri Rachid
Mastech 2013 Semestre I Universitaire years 2013-2014 Abrasive Machining and Finishing Operations Developed by: Mlle. BEN HASSAN Chahrazed Mr: Omar Zarrrouki Mr.Mnasri Abdelhak Mr.Mnasri kais Mr.Mnasri Rachid Supervised by: Mr. Mihai Nicolescu ( ENIM)
IntroductionSome manufacturing processes cannot produce therequired dimensional accuracy or surfacefinishAn abrasive is a small, hard particle having sharpedges and an irregular shapeAbrasives is removing of small amounts of materialfrom a surface through a cutting process that producestiny chipsGrinding wheels can sharpenknives and toolsSandpaperoremeryclothcansmoothensurfacesandremovesharp corners
Introduction Some manufacturing processes cannot produce the required dimensional accuracy or surface finish An abrasive is a small, hard particle having sharp edges and an irregular shape Abrasives is removing of small amounts of material from a surface through a cutting process that produces tiny chips Grinding wheels can sharpen knives and tools Sandpaper or emery cloth can smoothen surfaces and remove sharp corners
IntroductionGrinding wheelWorkpiece(a)(c)(b)(d)ThinabrasivedisksWorkpieceGrindingwheelWorkpiece(e)(f)(g)
Introduction
AbrasivesandBondedAbrasivesAbrasives that are commonly used:ConventionalabrasivesSuperabrasives2.Above abrasives are harder than conventional cutting-tool materialsCubic boron nitride and diamond are the twohardestmaterials known;referred to as superabrasivesFriability defined as the ability of abrasive grains tofractureinto smaller pieces
Abrasives and Bonded Abrasives Abrasives that are commonly used: 1. Conventional abrasives 2. Superabrasives Above abrasives are harder than conventional cuttingtool materials Cubic boron nitride and diamond are the two hardest materials known; referred to as superabrasives Friability defined as the ability of abrasive grains to fracture into smaller pieces
AbrasivesandBondedAbrasivesAbrasiveTypesCommonly found in nature are emery, corundum(alumina), quartz, garnet and diamondAbrasives that have been made syntheticallyAluminum oxide1Seeded gel23.SiliconcarbideCubicboron nitrideDiamond5
Abrasives and Bonded Abrasives Abrasive Types Commonly found in nature are emery, corundum (alumina), quartz, garnet and diamond Abrasives that have been made synthetically: 1. Aluminum oxide 2. Seeded gel 3. Silicon carbide 4. Cubic boron nitride 5. Diamond
AbrasivesandBondedAbrasivesAbrasiveGrainSizeAbrasives are very small when compared to the size ofcutting tools and insertsAbrasives have sharpedges and allow removal ofsmall quantities of materialVery fine surface finish and dimensional accuracy canbe obtained using abrasives as toolsSize of an abrasive grain is identified by a grit numberSmaller the grain size, larger the grit number
Abrasives and Bonded Abrasives Abrasive Grain Size Abrasives are very small when compared to the size of cutting tools and inserts Abrasives have sharp edges and allow removal of small quantities of material Very fine surface finish and dimensional accuracy can be obtained using abrasives as tools Size of an abrasive grain is identified by a grit number Smaller the grain size, larger the grit number
AbrasivesandBonded Abrasives:GrindingWheelsEach abrasive grain removes only a very small amountof material at a timeHigh rates of material removal can be achieved whenlarge number of these grains act togetherDonebyusingbonded abrasivesBondGrindingPorositywheelGrainBond fractureMicrocracksGrainfractureWorkpieceAttritious wearWheelsurtace
Abrasives and Bonded Abrasives: Grinding Wheels Each abrasive grain removes only a very small amount of material at a time High rates of material removal can be achieved when large number of these grains act together Done by using bonded abrasives
AbrasivesandBonded Abrasives:BondTypesCommon types of bonds:1.Vitrified:Consistoffeldsparand claysStrong, stiff,porous, and resistant to oils acids, andwater2. Resinoid:Bonding materials are thermosetting resinsResinoid wheels are more flexible than vitrifiedwheels
Abrasives and Bonded Abrasives: Bond Types Common types of bonds: 1. Vitrified: Consist of feldspar and clays Strong, stiff, porous, and resistant to oils acids, and water 2. Resinoid: Bonding materials are thermosetting resins Resinoid wheels are more flexible than vitrified wheels
AbrasivesandBonded Abrasives:BondTypes3.Reinforced Wheels:Consist of layers of fiberglass mats of various meshsizes4.Thermoplastic:Used in grinding wheelsWith sol-gel abrasives bonded with thermoplastics5.Rubber:Using powder-metallurgytechniquesLower in cost and areusedfor small productionquantities
Abrasives and Bonded Abrasives: Bond Types 3. Reinforced Wheels: Consist of layers of fiberglass mats of various mesh sizes 4. Thermoplastic: Used in grinding wheels With sol-gel abrasives bonded with thermoplastics 5. Rubber: Using powder-metallurgy techniques Lower in cost and are used for small production quantities
TheGrindingProcessGrinding is a chip-removal process that uses anindividual abrasive grain as the cutting toolGrainVChipWearflatAbrasivegrainChipoWorkpieceWorkpiece10μm
The Grinding Process Grinding is a chip-removal process that uses an individual abrasive grain as the cutting tool