Machining

Machining

What is it? •  Machining: A subtractive

process used to get desired shape, size, and finish by removing surplus material in the form of chips by a cutting tool and by providing suitable relative motion between the workpiece and cutting tool

•  Cutting tool: removes excess m a t e r i a l t h r o u g h d i r e c t mechanical contact

•  M a c h i n e t o o l : p r o v i d e s necessary relative motion between the work-piece and tool

Basics of shape generation by machining •  Two relative motions (between work and tool)

generally needed to produce surfaces –  Cutting speed: line generated by it is called

generatrix: Primary cutting motion –  Feed speed: line generated by it is called

directrix: Secondary cutting motion

Relative motions needed for various types surface generation

Surface Obtained

Machining

Process

Generatrix (cutting)

Directrix (feed)

P l a n a r Surface

Shaping , Planing

S t r a i g h t Line

S t r a i g h t Line

Cylindrical

Turning Circular S t r a i g h t Line

P l a n a r Surface

Milling Circular S t r a i g h t Line

Surface of Revolution

Contour Turning,Boring

P l a i n Curve

Circular

TYPES OF MACHINING PROCESSES BASED ON ANGLE BETWEEN CUTTING

EDGE and CUTTING VELOCITY Oblique Machining Orthogonal Machining

Ø Cutting edge of the tool is inclined with normal to the cutting velocity.

Ø Cutting edge of the tool is p e r p e n d i c u l a r t o t h e direction of cutting velocity

Ø  Cutt ing Forces Act a l o n g A l l T h r e e Directions i.e. x, y, and z Axes.

Ø Cutting Forces Act Along x and z Directions Only i.e. No Cutting Force along y Direction

Ø Examples: Turning, Milling, Drilling, Shaping

Ø Examples: Sawing, Broaching, Parting-Off of Tube Wall

MI-102: Manufacturing Techniques I. I. T. ROORKEE

Using SINGLE-Point Cutting Tools

Using MULTI-Point Cutting Tools

Using ABRASIVES as Cutting Tools

Ø  Turning v  Step Turning v  Taper Turning v  Form Turning v  Contour Turing

Ø  Facing Ø  Necking Ø  Parting-Off Ø  Boring

v  Counter-Boring v  C o u n t e r -

Sinking Ø  Shaping Ø  Planing

Ø  Milling Ø  Drilling Ø  Reaming Ø  Knurling Ø  Tapping Ø  Hobbing Ø  Broaching Ø  Sawing

Ø  Grinding Ø  Honing Ø  Lapping Ø  Super-Finishing Ø  Polishing Ø  Buffing

Machining Processes

ACCORDING to TYPE of CUTTING TOOL


LATHE MACHINE and its OPERATIONS

Ø  Lathes are Machine Tools Designed Primarily to Do Turning, Facing, and Boring.

Ø  Because Lathes also can Do Facing, Drilling, and Reaming, their Versatility Permits Several Operations

DESIGN and TERMINOLOGY of the ENGINE LATHE

The Essential Components of an Engine Lathe are 1. Bed 2. Headstock Assembly 3. Tailstock Assembly 4. Carriage Assembly

5. Feed Rod 6. Leadscrew 7. Quick Change Gearbox


Tailstock

Bed Schematic Diagram of an Engine Lathe


Car r iage assembly

Ø  C a r r i a g e a s s e m b l y p rov ides t he m e a n s f o r mounting and moving cutting tools.

Ø  C a r r i a g e a s s e m b l y c o n s i s t s o f carriage, cross slide, compound rest, tool post

Leadscrew Ø  for cutting threads, a leadscrew is

u s e d t o p r o v i d e a u t o m a t i c movement to carriage.

Feed rod Ø  provides

t h e powered movement o f t h e carr iage and cross slide for automatic movement o f t o o l u s e d i n t u r n i n g operation

SIZE DESIGNATION of LATHES

Ø  Size of a Lathe is Designated by Two Dimensions: 1. Swing diameter: shows maximum diameter of work-

piece that can be rotated on a lathe. 2. Maximum Distance Between Centers: Indicates the

Maximum Length of Workpiece that can be Mounted Between Centers.

Example: A 14 x 48 Lathe designates that the swing is 14 in. and the maximum distance between centers is 48 in.

Type of lathes

•  Engine lathe, •  Speed lathe, •  Tool room lathe, •  Turret lathe, •  Automatic lathe, •  Numerical control lathe

ENGINE LATHE •  Most frequently used in

manufacturing •  They are heavy duty

machine tools with all the components have power d r i v e f o r a l l t o o l movements except on compound rest.

•  Most engine lathes are equipped with chip pans and a built-in coolant circulating system.


SPEED LATHE Ø Speed lathes usually

h a v e o n l y a h e a d s t o c k , a ta i ls tock , and a simple tool post

Ø Usually three or four speeds

Ø Mainly used for wood turning, polishing, or metal spinning

Ø Spindle speeds up to 4000 rpm.

Tool room lathe •  Greater accuracy and

usually a wider range of speeds and feeds than engine lathes.

•  D e s i g n e d t o h a v e greater versatility to meet the requirements of tool and die work

•  General ly used for machining smal ler parts

Turret lathe •  Hexagon Turret Replaces

the Tailstock •  Turret used for mounting

tools and feed into the work piece

•  Turret Lathes Use the 11 Station Tooling and so as to increase production rate by reducing tool changing time .

•  SIX Tools can be Mounted on the Hexagon Turret

•  Turret can be Rotated about the Vertical Axis to Bring Each Tool into the Operating Position

RAM TYPE

Ram and saddle type turret lathe •  Primary difference is

in mounting and size of two types.

•  Ram type is light, less rigidity and so for small jobs using fine cuts

•  Saddle type heavy, more rigid, large jobs and heavy cuts

SADDLE TYPE

RAM TYPE

Operation of lathe

Turning is the process of Machining external cylindrical and conical surfaces. –  Straight turning: for producing cylindrical shapes –  Taper turning: for producing conical shapes –  Facing: making edges square and clear –  Chamfering: slightly tapering and rounding off of

edges –  Threading: for producing threads –  Drilling: for creating /producing hole –  Boring: for enlarging hope and correcting shape –  Parting off or necking: separating or making square

groove –  Knurling: making impression for firm gripping –  Reaming: finishing purpose

Straight/cylindrical turning

Orthogonal turning Oblique turning


TAPER TURNING

Ø  Cutting tool is fed at an angle to the axis of rotation producing an external/internal conical surface.

Ø  Tapers generally specified in degrees of included angle between the sides (or rate of change in diameter along the length mm/mm)

Ø  FOUR Methods for Taper turning: Ø  Swiveling the Compound Rest: Only for

Short and steep Tapers Ø  Taper turning attachment: for fine taper-ness

less than 0.5mm/mm

Ø  Setting over tailstock: low taper in long jobs Ø  NC lathe with programmed both movements of

movement of tool

Swiveling the compound rest •  Tool is set at half of

taper angle w.r.t. lathe axis and moved with compound rest only

•  C r o s s s l i d e i s made free and tool is moved with help o f attachment at an angle

Taper turning attachment

Off setting the tail stock

Tool is moved with help of carriage parallel to the lathe axis

Contour turning Ø  The tool follows a contour

creating a contoured form on the turned part instead of parallel to the axis. Cross slide is made free to follow the path of contour.

FORM TURNING Ø  Cutting edge of Tool has a Specific

Form or Shape and is fed radially inward towards the axis of rotating work piece.

FACING Ø  Cutting tool is fed radially inwards

(at 90° w.r.t. the axis of rotation) into the rotating work piece.

Ø  End facing: facing by tool moving radially outward from the center

Ø  Shoulder facing: facing the stepped cylindrical work piece


Parting off & necking

Ø  Tool is fed perpendicular to the rotational axis

Ø  Necking is a making partial cutoff

Chamfering Ø  The tool is fed radially inward

used to cut an angle on the corner of the cylinder, forming a chamfer to avoid sharp edges.


DRILLING Ø  The tool (Drill) mounted on the

tailstock of the engine lathes is fed by hand against a rotating work piece along the axis of lathe.

BORING

Ø  Tool mounted to tailstock is fed parallel to the lathe axis after giving suitable depth of cut

REAMING Ø  I t i s semi - f in ish ing

operation that enlarges an existing hole. Tool is rotated and fed along rotational axis.

Ø  Process involves pressing of two hardened rolls against the rotating work piece with sufficient force to form impression (the knurl) like raised diamond pattern.

knurling Ø  Roughening the surface of work

piece for better gripping. Ø  No machining operation only cold-

forming takes place

Work holding devices •  Face plate: for holding irregular

shape w/p •  Lathe centers: for holding long

jobs •  Chuck:

– 3 jaw chuck for circular or hexagonal section

– 4 jaw chuck for irregular shapes

– Magnetic chuck for holding soft metal

Mandrel

Collet

M a n d r e l : f o r holding hollow disc s h a p e w / p f o r machining of side faces Collet: for holing small diameter tool and work pieces


common cutting tool materials

v  For conventional machining processes, cutting tool material must be at least 35% to 50% harder than work material at the actual temperature of machining

1.  tool steels 3.  high speed steel (hss) 4.  cemented carbides 5.  coated carbides 6.  ceramics 7.  cermets (ceramic material in a metallic binder) 8.  polycrystalline diamond (pcd) and (CBN)

CUTTING TOOLS USED In a LATHE

Ø  Single Point Cutting Tools Ø  Bit-Type Cutting Tools Ø  Form Tools (tapering and Threading Tool)

Geometry of single point cutting tool

2nd mid term onwards

NOTE: TO ENCOURAGE A) BOOK

READING, B) SINCERE LISTENING OF

LECTURES AND C) PREPARATION OF

OWN NOTES, NO FURTHER PPTS OF

LECTUERS WILL BE UPLOADED.


FUNDAMENTALS of DRILLING OPERATIONS

Ø Drilling is a machining operation of creating a hole in a work-piece which can be through holes or blind holes, performed with a rotating cylindrical tool having TWO cutting edges called a twist drill.

Ø Rotating drill is fed into the stationary work-piece to form a hole whose diameter is determined by the drill diameter.


OPERATIONS RELATED to DRILLING

REAMING: A Semi-Finishing Operation to Ø  Slightly Enlarge an Existing Hole Ø  To Provide Better Tolerance on Hole Diameter Ø  To Improve Surface Finish

TAPPING: To Make INTERNAL Threads on an Existing Hole Using Taps

COUNTER-BORING:

Ø  Making of INTERNAL STEPPED HOLE in which a Lager Diameter Follows a Smaller Diameter Partially into the Hole

COUNTER-SINKING:

Ø  Similar to Counter-Boring, Except that the Step in the Hole is Cone Shaped for Flat-Head Screws and Bolts.

CENTERING or CENTER-DRILLING:

Ø  Dr i l l i ng o f a Start ing Hole t o Accurately Establish its Location for Subsequent Drilling.


TYPICAL SEQUENCE of OPERATIONS in a HOLE MAKING


CUTTING TOOLS USED in DRILLING

Ø  A Twist Drill has THREE Basic Parts: Body, Point, and Shank

Ø  A Twist Drill has TWO Helical Grooves Called Flutes Separated by Lands.

Ø  Flutes Act as Passageways for Extraction of Chips From the Hole

Ø  Point of the Twist Drill has the General Shape of a Cone having a Typical Value of 1180.

Geometry of Twist Drill.


DRILLING MACHINE

Ø  Drilling is Most Commonly Performed on a Drill Press.

Upright Drill Press.

DRILL PRESS Consists of Following Parts 1. Base, 2. Column 3. Power-Head 4. Spindle 5. Worktable These may be bench

or floor mounted depending on the size

Ø  D r i l l c a n b e f e d m a n u a l l y o r automatically

TYPES of DRILLING MACHINES

MAIN TYPE

Applications

1. BENCH Holes up to 0.5 in. Diameter can be Drilled. Very High Speed up to 30,000 rpm

2. UPRIGHT

Speeds Ranges from 60 to 3500 RPM

3. RADIAL

For Large Workpieces that Cannot Easily be Handled Manually.

4. GANG Mass Production variety of purposes such as Holes of Different Sizes, Reaming, Counterboring, on a Single Part.

TYPES of DRILLING MACHINES

MAIN TYPE

Applications, Designation

5. MULTI-SPINDLE

Mass Production Machines with as many as 50 Spindles Driven by a Single Power head and Fed Simultaneously into Work.

6. DEEP-HOLE

For Drilling Long (Deep) Holes in Rifle Barrels, Connecting Rods, and Long Spindles.

BENCH TYPE UPRIGHT DRILLING MACHINE

Milling

Ø  Milling is a machining operation in which a work-part is fed past a rotating cylindrical tool called milling cutter is multi point cutting tool.

Ø  In milling axis of rotation of the cutting tool is perpendicular to the direction of feed.

Ø  While in drilling, the cutting tool is fed in a direction parallel to its axis of rotation.

HORIZONTAL TYPE VERTICAL TYPE

Ø Geometric form created by milling is a plane surface and other geometries are created either by controlled cutter path or the cutter shape.

Ø  Typical feature of milling:

Ø  it is an interrupted cutting operation

v  the teeth of the milling cutter enter and exit the work during each revolution.

v so cycle of impact force and thermal shock in every rotation.

v  the tool material and cutter geometry must be designed to withstand these conditions.

TYPES of MILLING OPERATIONS

PERIPHERAL MILLING FACE MILLING axis of tool is parallel to the surface being machined

axis of tool is perpendicular to the surface being machined

machining is performed by cutting edges on the outside periphery of the cutter.

machining is performed by cutting edges on both the end and outside periphery of the cutter.

TYPES of PERIPHERAL or PLAIN MILLING

TYPES of FACE MILLING

(a) slab milling: basic form of peripheral milling in which the cutter width extends beyond the work-piece on both sides.

(a) conventional face milling: the diameter of the cutter is greater than the work-part width, so that the cutter overhangs the work on both sides.

(b) slot milling (slotting): the width of the cutter is less than the work-piece width. very thin cutter can be used to mill narrow slots or to cut a work-part in two, called saw milling.

(b) partial face milling: the cutter overhangs the work on only one side.


TYPES of PERIPHERAL MILLING TYPES of FACE MILLING

(c) side milling: cutter machines the side of the workpiece.

(c) end mill ing: the cutter diameter is less than the work width, so a slot is cut into the part.

(d) straddle milling: the same as side milling, only cutting takes place on both sides of the work.

(d) profile milling: this is a form of end milling in which the outside periphery of a flat part is cut.


TYPES of PERIPHERAL TYPES of FACE MILLING a c c o r d i n g t o t h e r o t a t i o n direction of the cutter two types: (e) up or conventional: the direction of motion of the cutter is opposite to the feed direction.

(e) pocket milling: another form of end milling, this is used to mill shallow pockets into flat parts.

(f) down or climb milling: the direction of cutter motion is in the feed direction

(f) surface contouring: a ball-nose cutter is fed back and forth across the work along a curvilinear path at close intervals to create a 3-dimensional surface form.


UP Milling DOWN Milling The direction of motion of the cutter is opposite to the feed direction.

The direction of cutter motion is in the feed direction

It is milling “against the feed."

It is milling “with the feed."

Cutting force direction is tangential to the periphery of the cutter which tends to lift the work piece as the cutter exits the material.

Cutting force direction is downward, tending to hold the work aga inst the milling machine table.

DIFFERENCES


Type Applications (a) column and knee type (general purpose)

à for slab, side, or straddle milling. à well suited for face and end milling operations à for milling to produce twist drills), milling cutters, and helical gear teeth, etc.

(b) bed type (manufacturing)

à for making heavy cuts à simultaneous milling of two or three surfaces in a single pass

(c) planer milling machines

à for machining a wide variety of surfaces on heavy workpiece in a single setup.

TYPES of MILLING MACHINES


Milling cutter Ø  Milling cutters are classified on the basis of

methods of mounting and direction of rotation.

Ø  Method of mounting Ø  arbor cutters have a center hole for mounting on

an arbor. Ø  shank cutters have either a tapered or a straight

shank.

v tapered shanks cutters can be mounted directly in the milling machine spindle.

v straight shank cutters are held in a chuck.

Arbor for a Horizontal Spindle Milling

Ø  BASED ON DIRECTION OF ROTATION (Applies only to Face and End Milling Cutters)

v  A right-hand cutter must rotate counterclockwise when viewed from the front end of the machine spindle.

v  A left-hand cutter must rotate clockwise.

Typical geometry of milling cutter


GRINDING Ø  Grinding is a finishing process using abrasives (i.e. Al2O3,

SiC, B4C, Diamond, CBN, etc.) bonded in form of Wheel operating at Very High Surface Speeds.

Ø  Similar to the Milling, Cutting in grinding can be either the Periphery or the Face of the Grinding Wheel.

Periphery

Face


Ø  Comparison between Grinding and Milling in terms of:

v  Size: finer in grinding than milling

v  number of Cutting teeth: more in grinding than

milling

v  Orientation of cutting teeth: random in grinding

and the same is fixed in milling

v  Cutting Speeds: Higher in grinding speed than

Milling

v  Self-Sharpening Feature exists with grinding but

not with milling


TYPES of GRINDING OPERATIONS Ø Grinding is mainly for Finish Parts of part Created by

Other Operations. Ø Accordingly, Grinding Machines have been Developed

to Grind v Plain Flat Surfaces, v External and Internal Cylinders, and v Contour Shapes such as Threads. v Tool Rooms operations for processing Cutting

Tools. Ø Main Types of Grinding Operations are

1.  Surface Grinding, 2.  Cylindrical Grinding, 3.  Centerless Grinding, 4.  Creep Feed Grinding, 5.  Other Grinding Operations

Surface Grinding

Ø  Surface Grinding for Plain Flat Surfaces. Ø  Workpiece is Normally Held in a Horizontal Orientation.

Ø Face Grinding: Performed using Flat Face of the wheel which Rotates about the Vertical Axis.

Ø Peripheral Grinding: P e r f o r m e d u s i n g Per iphery o f the G r i n d i n g W h e e l r o t a t i n g t h e Horizontal Axis,

Ø  In either case, the Relative Motion of the Workpiece is Achieved by Reciprocating (Flat) or by Rotating (Circular) the Work Past the Wheel.


Cylindrical Grinding

Ø  Used for Rotational Parts.

Ø  Cylindrical Grinding Operations can be Divide into TWO Basic Types: (A) External Cylindrical Grinding; (B) Internal Cylindrical

Grinding.

External Cylindrical Grinding

Ø  Also Called Center-Type Grinding to Distinguish it from Centerless Grinding, is Performed much like a Turning Operation.

Ø  There are Two Types of Feed Motion Possible, v Traverse Feed: Grinding Wheel is Fed in a Direction Parallel to

the Axis of Rotation of the Workpiece (Fig. a) ü  Infeed: Typical range from 0.0075 to 0.075mm.

ü  A Longitudinal Reciprocating Motion parallel to work axis is sometimes to either the Work or the Wheel to Improve Surface Finish.

v Plunge-Cut: Grinding Wheel is Fed Radially into the Work. Formed Grinding Wheels use this type of Feed Motion (Fig. b)

Internal Cylindrical Grinding

Ø  The Workpiece is Usually held in a Chuck and Rotated

Ø  Wheel Diameter must be Smaller than the Original Bore Hole so needs High Rotational Speeds in Order to Achieve the Desired Surface Speed.

Ø  Grinding Wheel is Fed in either of Two Ways: Traverse Feed or Plunge Feed

APPLICATIONS: Ø  Used to Finish the Hardened Surfaces

of Bearing Races and Bushing Surfaces.

APPLICATIONS: Ø  Parts Include Axles, Crankshafts, Spindles, Bearings and

Bushings, and Rolls for Rolling Mills

Centerless Grinding Ø  The Workpiece is NOT Held Between Centers so Reduction in

Work Handling Time therefore for High volume Production.

Ø  EXTERNAL Centerless Grinding: Consists of Two Wheels v  Grinding Wheel: Rotating at Surface Speeds of 1200 to

1800 m/min.

v  Regulating Wheel: Rotating at Lower Speeds and is Inclined at a Slight Angle to Control through Feed of the Work

Long Rods are Supported by a Rest Blade and Fed through Between the Two Wheels


INTERNAL Centerless Grinding:

Ø  Two Support Rolls are Used to Maintain the Position of the Work in Place of the Rest Blade.

v The Regulating Wheel is Tilted at a Small Inclination Angle to Control the Feed of the Work Past the Grinding Wheel.

v ADVANTAGE: Provides Very Close Concentricity Between Internal and External Diameters on a Tubular Part Such as a Roller Bearing Race

Creep Feed Grinding (Developed Around 1958).

Ø Grinding using Very High Depths of Cut and Very Low Feed Rates.

Ø Depths of Cut in Creep Feed Grinding are 1,000 To 10,000 Times Greater than in Conventional Surface Grinding and Feed Rates are Reduced by About the Same Proportion.

Conventional Surface Grinding Creep Feed Grinding


Other Grinding Operations

Ø  TOOL GRINDERS: used for Sharpen and Recondition Cutting Tools.

Ø  JIG GRINDERS: Used to Grind Holes in Hardened Steel Parts to High Accuracies e.g. Press Working Dies and Tools.

Ø ABRASIVE BELT GRINDING: Uses Abrasive Particles Bonded to a Flexible Cloth Belt Support by Roll or Platten Located Behind the Belt, and Work is Pressed Against it.

TOOL GRINDERS ABRASIVE BELT GRINDING

GRINDING WHEEL Ø  Grinding Wheel is Usually Disk-shaped and is

Precisely Balanced for High Rotational Speeds. Ø  A Grinding Wheel Consists of Abrasive Particles held by

Bonding Material in position. Ø  Parameters of the Grinding Wheel used for

designation: (1) Type of Abrasive Particle Material, (2) Size of Abrasive Particles, (3) Bonding Material, (4) Wheel Grade, (5) Wheel Structure

Ø  All these parameters affect Desired Performance of Grinding in terms of surface roughness and metal removal rate i.e. rate of cutting.


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Grinding Wheel Parameters 1. ABRASIVE PARTICLE MATERIAL: Desired Properties

of an Abrasive Material Used in Grinding Wheels Include v High Hardness v High Wear Resistance v High Toughness v Friability: Capacity of the Abrasive Material to

Fracture when the Cutting Edge of the Grain Becomes Dull, thereby Exposing a New Sharp Edge.

Ø Hardness, Wear Resistance, and Toughness are Desirable Properties of Any Cutting Tool Material.

Ø Commonly Abrasives are v Aluminum oxide (Al203),Silicon carbide (SiC),

Cubic Boron Nitride (CBN), Diamond


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2. SIZE of ABRASIVE PARTICLES: (also called

Grit Size) affects Surface Finish and Material

Removal Rate.

Ø  Small Particle Size Produces Better

Finishes, while Larger Particle Size Produce

Larger Material Removal Rates.

Ø Selection of Abrasive Particle Size also

Depends on the Type of Work Material.

Ø Harder Work Materials Require Smaller

Particle Size to Cut Effectively, while Softer

Materials Require Larger Particle Size.

3. BONDING MATERIALS: The Bonding Material Must v Hold the Abrasive Grains Rigidly so as to get desired

the Shape and Structural Integrity of the Grinding Wheel.

v Should be able to Withstand under v  the Centrifugal Forces v High Temperatures generated during Grinding v Good impact Resistance to avoid Shattering in

Shock Loading v Allowing debonding of Worn Abrasive Grains so that

New Grains are Exposed. Ø  Commonly Bonding Materials in Grinding Wheels: Ø  Vitrified bond:

(A) Silicate Bond:. (B)  Rubber Bond: (D) Resinoid Bond: (E) Shellac Bond: (F) Metallic Bond:


4. GRINDING WHEEL STRUCTURE: Refers to the Relative Spacing of the Abrasive Grains in the Wheel. A Grinding Wheel Contains Air Gaps/Pores, Abrasives and Bond Material.

Ø  The Volumetric Proportions of Grains, Bond Material, and Pores can be Expressed as Pg + Pb + Pp = 1; Where Pg = Proportion of Abrasive Grains; Pb = Proportion of Bond Material, and Pp = Proportion of Pores (Air Gaps) in the Total Wheel Volume

Ø  Wheel Structure is termed as "Open" or "Dense” as per spacing between abrasives

Ø  An Open Structure has large Air Gaps than the Abrasives and reverse is true for dense structure.

Ø  A Dense Structure is One in which Pp is Relatively Small, And Pg is Larger.

Ø  Open Structures offers high MRR and poor surface finish .

Ø  Dense Structures are Used to Obtain Better Surface Finish and Dimensional Control.

Bond Material


5. GRINDING WHEEL GRADE: Indicates the Bond Strength of the Grinding Wheel in Retaining the Abrasive Grits during Cutting. Ø Depends on the type and Amount of Bonding

Material. Ø Grade is termed as “Soft”, medium, “Hard”. Ø  "Soft" Wheels Lose Grains Readily, while “Hard"

Wheels Retain their Abrasive Grains.

Selection of grade Ø Soft Wheels are Generally Used for Applications

Requiring Low Material Removal Rates and Grinding of Hard Work Materials.

Ø Hard Wheels are Typically Used to Achieve High Material Removal Rates and for Grinding of Relative Soft Work Materials.

Grinding Wheel Designation Ø  The Grinding Wheel Parameters are Concisely

Designated in a Standard Grinding Wheel Marking System Defined by the American National Standards Institute (ANSI).

Ø Designated Using Numbers and Letters to Specify: in sequence of Abrasive Type, Abrasive Grit Size, Wheel Grade, Wheel Structure, and Bond Material.

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