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54
ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs. Singh/Melkote/Colton Grinding and Finishing Illegitimi non carborundum ver. 1 1

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  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Grinding and Finishing

    Illegitimi non carborundum

    ver. 1

    1

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Overview

    Processes

    Analysis

    2

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton 3

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Horizontal Grinding

    4

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton 5

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton 6

    Horizontal grinding Vertical grinding

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton 7

    Centered grinding

    Centerless grinding

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Creep Feed Grinding

    8

    Full depth and stock is removed with

    one or two passes at low work speed

    Very high forces are generated

    High rigidity and power

    Advantages Increased accuracy

    Efficiency

    Improved surface finish

    Burr reduction

    Reduced stress and fatigue

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton 9

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton 10

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton 11

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton 12

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Grinding Wheels

    13

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Grinding Wheels

    14

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Grinding Wheel Information

    15

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton 16

    Correctly Mounted Wheel

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Grinding Wheel Surface

    17

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Grind Wheel Dressing

    18

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Grinding Wheel Dressing

    19

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Grinding Chips

    20

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Chip formation geometry

    21

    D

    v

    V

    d

    t

    q

    l

    w

    t l

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Chip geometry

    As with rolling contact length, the chip length,

    l

    D = wheel diameter, d = depth of cut

    Material removal rate, MRR

    v = workpiece velocity, d = depth of cut, b = width

    of cut

    23

    dDl

    bdvMRR

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Material removal rate

    The chips have a triangular cross-section,

    and ratio (r) of chip thickness (t) to chip width

    (w)

    So, the average volume per chip

    24

    2010 tot

    wr

    wtlltwVolchip4

    1

    2

    1

    2

    1

    w

    t l

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Chips

    The number of chips removed per unit time

    (n), where c = number of cutting edges

    (grains) per unit area (typ. 0.1 to 10 per mm2,

    and V = peripheral wheel velocity

    25

    cbVn

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Combining

    26

    trw dDl

    chipVolnbdvMRR

    wtlVbcbdv4

    1

    dDttrbcVbdv 4

    1

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Chip thickness

    27

    dDrcV

    dvt

    42

    or

    D

    d

    rcV

    vt

    4

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Specific grinding energy, u

    Consist of chip formation, plowing, and sliding

    28

    slidingplowingchip uuuu

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Total grinding force

    Get force from power

    29

    MRRuPower

    bdvuVFgrinding

    V

    bdvuFgrinding

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Total grinding force

    From empirical results, as t decreases, the

    friction component of u increases

    30

    tu

    1

    tKu

    11 or

    substituting

    V

    bdv

    tKFgrinding

    11

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Total grinding force

    31 ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton GIT 2006

    Substituting for t

    V

    bdv

    D

    d

    rcV

    vKFgrinding

    4

    11

    rearranging

    dDV

    vrcdbKFgrinding

    41

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Force on a grain

    The force per grain can be calculated

    32

    AreauFgrain

    wtuFgrain2

    1

    rtw and

    tKu

    11

    ttrt

    KFgrain 2

    111

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Force on a grain

    33 ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton GIT 2006

    substituting for t, and rearranging

    D

    d

    rcV

    vr

    KFgrain

    4

    21

    D

    d

    cV

    rvKFgrain

    1

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Grinding temperature

    Temperature rise goes with energy delivered

    per unit area

    34

    area

    inputEnergyKT 2

    dt

    KKlb

    dlbuKT

    1122

    D

    d

    Vcr

    v

    dKKT

    4

    121

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Grinding temperature

    Rearranging

    = 1234

    4

    Temperatures can be up to 1600oC, but for a

    short time.

    35

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Grinding Ex. 1-1

    You are grinding a steel, which has a specific

    grinding energy (u) of 35 W-s/mm3.

    The grinding wheel rotates at 3600 rpm, has a

    diameter (D) of 150 mm, thickness (b) of 25 mm, and

    (c) 5 grains per mm2. The motor has a power of 2

    kW.

    The work piece moves (v) at 1.5 m/min. The chip

    thickness ratio (r) is 10.

    Determine the grinding force and force per grain.

    Determine the temperature (K2 is 0.2oK-mm/N).

    Room temperature is 20oC.

    36

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Grinding Ex. 1-2

    First we need to calculate the depth of cut.

    We can do this from the power.

    37

    bdvuMRRuPower

    sec60

    min1025

    min5.1352000

    2

    26

    3

    m

    mmmmd

    m

    mm

    sWW

    md 6104.91

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Grinding Ex. 1-3

    Now for the total grinding force

    38

    V

    bdvuFgrinding

    mm

    m

    rev

    mmrev

    mmmmmm

    mm

    sWFgrinding

    1000150

    min3600

    25104.91min

    150035

    3

    3

    NFgrinding 7.70

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Grinding Ex. 1-4

    Next, the force per grain

    39

    wtuFgrain2

    1 rtw

    ttruFgrain 2

    1

    and

    we need t

    mm

    mm

    mm

    grainsmm

    mm

    D

    d

    rcV

    vt

    150

    104.91

    105min

    1503600

    min15004

    4 3

    2

    mmt 31032.1

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Grinding Ex. 1-5

    Substituting

    40

    231032.1102

    135

    2

    1 ttruFgrain

    mmJFgrain /1005.34

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Grinding Ex. 1-6

    For the temperature, we need K1 and K2. K2 is

    given, so we need to calculate K1.

    41

    trKttrt

    KttruFgrain 2

    1

    2

    11

    2

    111

    mKN 611 1032.110

    2

    11005.3

    m

    NK 31 102.46

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Grinding Ex. 1-7

    substituting

    42

    Kmmm

    N

    N

    mKT

    640104.91

    1032.1

    12.462.0 6

    6

    CTTT initial 66064020

    dt

    KKT 1

    12

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Honing and Superfinishing

    Honing tool used to improve

    the surface finish of bored or

    ground holes.

    Schematic

    illustrations of the

    superfinishing

    process for a

    cylindrical part.

    (a) Cylindrical

    mircohoning, (b)

    Centerless

    microhoning.

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Lapping

    (a) Schematic illustration of the lapping process. (b)

    Production lapping on flat surfaces. (c) Production lapping

    on cylindrical surfaces.

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Polishing Using Magnetic

    Fields

    Schematic illustration of polishing of balls and rollers

    using magnetic fields. (a) Magnetic float polishing of

    ceramic balls. (b) Magnetic-field-assisted polishing of

    rollers. Source: R. Komanduri, M. Doc, and M. Fox.

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Abrasive-Flow Machining

    Schematic illustration of

    abrasive flow machining to

    deburr a turbine impeller.

    The arrows indicate

    movement of the abrasive

    media. Note the special

    fixture, which is usually

    different for each part

    design. Source: Extrude

    Hone Corp.

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Robotic Deburring

    A deburring operation on a robot-held die-cast

    part for an outboard motor housing, using a

    grinding wheel. Abrasive belts or flexible

    abrasive radial-wheel brushes can also be used

    for such operations. Source: Courtesy of

    Acme Manufacturing Company and

    Manufacturing Engineering Magazine,

    Society of Manufacturing Engineers.

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Conformal Hydrodynamic Nanopolishing:

    Case-study

    Applications

    Optics

    Defence & Nuclear

    Electronics

    Industrial

    Existing Methods

    Diamond Turning

    Precision Grinding

    Lapping

    Ion Beam Polishing

    Spot Hydrodynamic Polishing

    Challenges

    Most processes can polish only flat

    surfaces; concave/profiled surfaces

    are difficult to superfinish

    Concave surface on hard brittle

    materials, such as single crystal

    sapphire can not be finished via form

    grinding due to process-induced

    cracks

    Diamond turning center can be used

    for non ferrous materials but it is a

    super-precision machine-tool (The

    equipment cost is ~ 20 crores besides

    the expensive operational cost)

    1

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Conformal Hydrodynamic

    Nanopolishing Process and Machine

    Process Description

    Improvement over existing spot hydrodynamic polishing methods

    Superfinish hard and brittle concave surfaces, specially, sapphire and hardened steels

    Mitigates existing surface microcracks

    Polishing action due to elastohydrodynamic film in the slurry submerged rotating conformal contact (silicone ball in the cavity being polished) 1st Generation

    2nd Generation Conformal Hydrodynamic Nanopolishing Machine

    Delivered to Precison Engineering Division BARC

    (designed and fabricated in the Machine Tools Lab

    at IIT Bombay)

    2

    ../../Presentations/iit kanpur/100_2423.mov../../Presentations/iit kanpur/100_2423.mov../../Presentations/iit kanpur/100_2423.mov../../Presentations/iit kanpur/100_2423.mov

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Novelty and Technology Breakthrough

    Existing hydrodynamic polishing employs spot polishing unable to

    polish small cavities (< 6mm in dia)

    More than 3 degrees of freedom required to polish the entire cavity

    effectively

    Small actuation system and polishing tool is required

    Conformal contact has a rotating soft tool which conforms to the shape

    of the cavity

    Axis of this tool is inclined at 45 and the workpiece is rotated inside a

    slurry filled tank which ensures non-zero relative motion between tool

    and workpiece at every location in the cavity

    The entire cavity can be polished at once which will be much cheaper

    and faster than programming the tool path

    Alternative to expensive Diamond Turning

    Can finish wide range of materials ceramics (sapphire, glass) and

    hardened steels

    3

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Technology Outcomes Superfinished surfaces in

    steels (< 3nm 3D surface roughness)

    Crack-free surface of < 100 nm 3D surface roughness in single crystal sapphire cavity

    Process knowhow and machine transferred to Precision Engineering Division, BARC for strategic applications in a nuclear device

    The superfinished obtained at a fraction of cost of Diamond turning

    It can also be used by gem polishers which could reduce the health hazard by reducing the dust inhalation and automation is possible

    Nanometric finish on hardened steel

    Crack-free superfinished surface on single

    crystal sapphire cavity

    4

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Economics of Grinding and Finishing

    Operations

    Increase in the cost of

    machining and finishing a

    part as a function of the

    surface finish required.

    This is the main reason

    that the surface finish

    specified on parts should

    not be any finer than

    necessary for the part to

    function properly.

  • ME 338: Manufacturing Processes II Instructor: Ramesh Singh; Notes: Profs.

    Singh/Melkote/Colton

    Summary

    Overview of processes

    Analysis of process

    Example problem

    54