# 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

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

MACHINING PROCESSES

MACHINING BY CUTTING

Turning Drilling

Milling (face) Milling (peripheral)

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

MACHINING BY ABRASION

Surface Grinding

Cylindrical Grinding

MACHINING BY ABRASION

Honing

Lapping

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

ELECTROCHEMICAL MACHINING PROCESSES

Electrochemical Machining (ECM)

Electrochemical Grinding (ECG)

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

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

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

• 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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