MANUFACTURING Processes and Techniques

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  • MANUFACTURING

    Processes and Techniques

    KINGDOM OF SAUDI ARABIA

    Prince Sattam bin Abdulaziz

    University

    Mechanical Engineering Department

  • OUTLINE

    THEORY OF METAL CUTTING

    TRADITIONAL AND NON-TRADITIONAL MACHINING

    PROCESSES.

    WELDING & CASTING.

    TOLERANCE AND FITS

    METAL FORMING

  • THEORY OF METAL CUTTING

  • MACHINING

    Positive rake angles:

    Make the tool more sharp and pointed.

    Reduce cutting forces and power

    requirements.

    Helps in the formation of continuous chips

    in ductile materials.

    Help avoid the formation of a built-up edge.

    Negative rake angles, by contrast:

    Increasing the strength of the cutting edge.

    Increase the cutting forces.

    Increase friction, resulting in higher

    temperatures.

    Improve surface finish.

    https://en.wikipedia.org/wiki/Ductilityhttps://en.wikipedia.org/wiki/Built-up_edgehttps://en.wikipedia.org/wiki/Built-up_edgehttps://en.wikipedia.org/wiki/Built-up_edge

  • WHY MACHINING IS IMPORTANT

  • CUTTING TOOL

  • TYPES OF CHIPS

  • TYPES OF CHIPS

  • The time to machine from one end of a cylindrical workpart to

    the other is given by:

    Where Tm = machining time, min; and L = length of the cylindrical workpart,

    mm (in)

    more direct computation of the machining time is provided by

    the following equation:

    Where Do = work diameter, mm (in); L = workpart length, mm (in);

    f = feed, mm/rev (in/rev); and v = cutting speed, mm/min (in/min).

    METAL CUTTING CALCULATIONS

  • The rotational speed in turning is related to the desired

    cutting speed at the surface of the cylindrical workpiece by

    the equation

    Where N = rotational speed, rev/min; v = cutting speed, m/min (ft/min); and

    Do = original diameter of the part, m (ft).

    The material removal rate.

    METAL CUTTING CALCULATIONS

  • The turning operation reduces the diameter of the work from

    its original diameter Do to a final diameter Df, as determined

    by the depth of cut d:

    The feed in turning is generally expressed in mm/rev (in/rev).

    This feed can be converted to a linear travel rate in mm/min

    (in/min) by the formula:

    Where fr = feed rate, mm/min (in/min); and f = feed, mm/rev (in/rev).

    METAL CUTTING CALCULATIONS

  • TRADITIONAL AND NON-TRADITIONAL

    MACHINING PROCESSES

  • TRADITIONAL MACHINING PROCESSES

    MACHINING BY CUTTING

    Turning Drilling

    Milling (face) Milling (peripheral)

  • TRADITIONAL MACHINING PROCESSES

    MACHINING BY CUTTING

    In shaping, the primary

    motion is performed by the tool,

    and feed by the workpiece.

    In Planing, the primary

    cutting motion is performed by

    the workpiece and feed motion

    is imparted to the cutting tool.

    Broaching: use of a multiple-tooth cutting tool moved linearly

    relative to the workpiece in the direction of the tool axis

  • TRADITIONAL MACHINING PROCESSES

    MACHINING BY ABRASION

    Surface Grinding

    Cylindrical Grinding

  • TRADITIONAL MACHINING PROCESSES

    MACHINING BY ABRASION

    Honing

    Lapping

  • NON-TRADITIONAL MACHINING PROCESSES

    MECHANICAL ENERGY PROCESSES

    Ultrasonic machining Water Jet Cutting (WJC)

    Abrasive Jet Machining (AJM)

    Speed 300 m/s

    0.025 mm

    fine abrasive particles

    0.05 to 0.125 mm

  • NONTRADITIONAL MACHINING PROCESSES

    ELECTROCHEMICAL MACHINING PROCESSES

    Electrochemical Machining (ECM)

    Electrochemical Grinding (ECG)

  • NON-TRADITIONAL MACHINING PROCESSES

    THERMAL ENERGY PROCESSES

    (Wire EDM)

    Plasma Arc

    Cutting

    (PAC)

    EDM

    Laser

    Beam

    Machining

    (LBM)

  • MULTIPLE CHOICE QUESTIONS

    (MCQ)

    - Complete the Tool and WP motions for traditional machine tools.

    Machining

    Process

    Tool and WP movements

    Turning WP Tool

    Drilling Tool Tool

    Milling Tool WP

    Shaping Tool WP

    Cylindrical

    grinding

    Tool WP

  • MULTIPLE CHOICE QUESTIONS

    - The process utilizing mainly thermal energy for removing material is

    (a) Ultrasonic Machining

    (b) Electrochemical Machining

    (c) Abrasive Jet Machining

    (d) Laser Beam Machining

    - Match the following traditional and non-traditional machining

    processes with the corresponding material removal mechanisms

    Machining process Mechanism of material removal

    P. Grinding 1. Abrasion

    Q. Turning 2. Erosion

    R. Chemical machining 3. Chip removal

    S. Electro-discharge

    machining

    4. Corrosive reaction

    T. Ultrasonic machining 5. Fusion and vaporization

    P-1 ; Q-3 ; R-4 ; S-5 ; T-2

  • WELDING & CASTING

  • TYPES OF WELDING

  • ARC WELDING

    MIG welding

    Submerged

    arc welding

    TIG Welding

    SMAW(MMA) welding

  • Coating is a combination of

    chemicals in SMAW(MMA)

    welding:

    Cellulosic electrodes

    contain cellulose

    Rutile electrodes titanium

    oxide (rutile)

    Basic electrodes contain

    calcium carbonate

    (limestone) and calcium

    fluoride (fluorspar)

    SMAW(MMA) & TIG WELDING

  • OXYACETYLENE WELDING

    Reducing or Carburizing: Excess

    acetylene (0.9:1) (Alloy steels and

    aluminium alloys)

    Oxidizing : Excess oxygen (1.5:1) (Brass, Bronzes, copper)

    Neutral : Equal acetylene & oxygen (low carbon steel, mild steels).

  • RESISTANCE WELDING

  • WELDING

    Types of welded joints:

  • SOLDERING AND BRAZING

  • SOLDERING &M.C.Q BRAZING The commonly used flux in brazing is

    Borax

    Rosin

    Lead sulphide

    Zinc chloride

    Which of the following is function(s) of flux used in brazing?

    i- Protect surface from oxidation

    ii- Reduce surface tension of filler

    iii- Assist its penetration

    i only

    ii only

    i and ii

    i, ii and iii

    In soldering the melting point of filler metal is

    a - below 420 C

    b- below 450 C

    c - below 460 C

    d - below 540 C

    The composition of soft solder is

    a- lead 37% tin 63%

    b- lead 50% tin 50%

    c- lead 63% tin 37%

    d- lead 70% tin 30%

  • SAMPLES OF M.C.Q WELDING Which of the following welding process uses non-consumable electrodes?

    TIG welding

    MIG welding

    Manual arc welding

    Submerged arc welding

    The temperature of oxy-hydrogen flame is __________ oxy-acetylene flame.

    same as

    less than

    more than

    In submerged arc welding, an arc is produced between a

    carbon electrode and the work

    metal electrode and the work

    bare metal electrode and the work

    two tungsten electrodes and the work

    In shielded arc welding

    large electrode is used

    welding rod coated with slag is used

    welding rod coated with fluxing material is used

    none of the above

    In electric resistance welding, voltage required for heating is

    1 to 5 volts

    6 to 10 volts

    11 to 20 volts

    50 to 100 volts

    The oxy-acetylene gas used in gas welding produce a flame temperature of

    1800C

    2100C

    2400C

    3200C

  • CASTING

  • PATTERN

    PATTERN

  • MOLDING MATERIALS

    Major part of Molding material in sand casting are:

    1. 70-85% silica sand (SiO2)

    2. 10-12% bonding material e.g., clay cereal etc.

    3. 3-6% water

    Classification of sand casting defects

  • CASTING WITH EXPENDABLE MOULD:

    INVESTMENT CASTING

  • PERMANENT MOULD CASTING: DIE CASTING

    In Die casting the molten metal is forced to flow into a

    permanent metallic mold under moderate to high

    pressures, and held under pressure during solidification

  • DIE CASTING

    This uses pressures up to 35 MPa and is used for zinc, tin, lead, and

    their alloys

    In this process, pressures as high as 150 MPa are used. The storing

    chamber is not heated. This process is used mainly for metals and alloys

    having relatively higher melting point e.g., aluminium, magnesium and

    their alloys.

  • CENTRIFUGAL CASTING

    - A permanent mold made of metal or ceramic is rotated at high

    speed (300 to 3000 rpm). The molten metal is then poured into

    the mold cavity and due to centrifugal action the molten metal

    conform to the cavity provided in the mould.

    - Castings are known for their higher densities in the outer most

    regions.

    - The process gives good surface finish

    - Applications: pipes, bushings, gears, flywheels etc.

  • SAMPLES OF M.C.Q CASTING

    Sand casting is which of the following types?

    (a) expendable mold, or (b) permanent mold.

    The upper half of a sand casting mold is called

    which of the following?

    (a) cope, or (b) drag.

    In casting, a flask is which one of the following?

    (a) beverage bottle for foundry men,

    (b) box which holds the cope and drag,

    (c) container for holding liquid meta

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