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WORK SHOP PRATICE

ME/MT/CH/RE 1962 – SKILL

DEVELOPMENT

A H VITHANAGE

100560P

CHEMICAL AND PROCESS ENGINEERING



Practical 1 : Machining of Thread and Taper

Machining processes used in the practical are as follows

1. Facing

2. Drilling

3. Taper Turning

4. Threading



Practical 2 : Welding

Shielded Metal Arc Welding (SMAW)

Shielded Metal Arc Welding uses a consumable electrode coated in flux

(flux – potash, charcoal, coke, borax, lime, lead sulfide and etc) to lay the weld. Electric current

from the welding power supply, is used to form an electric arc between the electrode and the

metal to be joined. As the weld is laid, the flux coating of the electrode vaporizes and then

becomes a layer of slag, which protects the weld area from atmosphere.

Because of the simplicity of both its process and equipment, shielded

metal arc welding is one of the most popular of various welding processes. Although there are

new welding methods being developed, shield metal arc welding continues to be used

extensively in the construction of steel structures and in industrial fabrication. This welding



process is used primarily to weld iron and steels, but aluminium, nickel and copper alloys can

also be welded with this method.

Purposes of the coating of the electrode used in shielded metal arc welding

Gives off gases as it decomposes to prevent weld contamination

Introduces deoxidizers to purify the weld

Causes weld-protecting slag to form

Improves the arc stability

Provides alloying elements to improve the weld quality

Oxy-Fuel Gas Welding



Oxygen-acetylene welding was developed by two French engineers in

1903. In oxy-fuel gas welding fuel gases and oxygen is used to weld metals. Apart from welding

this method can also be used to cut metals too. Pure oxygen is used to increase the flame

temperature to allow localized melting of the material (e. g. steel) in a room environment. A

common propane/air flame burns at about 3,630 °F (2,000 °C), a propane/oxygen flame burns at

about 4,530 °F(2,500 °C), and an acetylene/oxygen flame burns at about 6,330 °F (3,500 °C).

In oxy-fuel welding, a welding torch is used to weld metals. Welding

happens when the two pieces of metals are heated to a temperature that produces a shared pool of

molten metal. The molten pool is generally supplied with additional metal called filler. Filler

material depends upon the metals to be welded.

Resistance Spot Welding



Resistance spot welding is a process in which contacting metal surfaces

are joined by the heat obtained from resistance to electric current flow. Work-pieces are held

together under pressure exerted by electrodes. Normally the sheets are in the 0.5 to 3 mm (0.020

to 0.12 in) thickness range. The process uses two shaped copper alloy electrodes to concentrate

welding current into a small "spot" and to simultaneously clamp the sheets together. Forcing a

large current through the spot will melt the metal and form the weld. As the huge energy is

delivered to the spot in a very short time, welding occurs without excessive heating to the rest of

the sheet.

It is used in a wide range of industries but notably for the assembly of

sheet steel vehicle bodies where more than 100 million welds are made per day in Europe alone.

High quality welds can also be made in stainless steels, nickel alloys, aluminium alloys and

titanium for aerospace application.

Practical 3 : Sheet Metal Forming



Industrial applications of sheet metal

1. In Airplane wings

2. For vehicle bodies

3. For conductor pipes and gutters

4. Used in the making of air conditioners to provide the self-contained unit for the

refrigeration system

5. For tables and storage units

6. Manufacturing of toys



Practical 4 : Wood Work

work shop pratice - my

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