Important Questions and Answers: Metal Joining Process

METAL JOINING PROCESS

1       List out any four arc welding equipment.

Ans: The most commonly used equipments for arc welding are as follows:

(a)             A.C or D.C. machine

(b)            Wire brush

(c)             Cables and connectors

(d)            Ear thing clamps

(e)             Chipping hammer

2       What are the special features of friction welding?

Ans:

•         Friction welding is a solid state welding process where coalescence is produced by the heat obtained from mechanically induced sliding motion between rubbing surfaces.

•       The work parts are held together under pressure.

•       Its operating is simple.

•       Power required for the operation is low.

•  It is used for joining steels, super alloys,    non-ferrous metals and combinations of

metals.

3.Define resistance welding process.

Ans: Resistance welding is a process where coalescence is produced by the heat obtained from resistance offered by the workpiece to the flow of electric current in a circuit of which the workpiece is a part and by the application of pressure.

4.What is the purpose of flux? (May 2008)

Ans:           1)       It acts as shield to weld.

2)                 To prevent atmospheric reaction of molten metal with atmosphere.

5.     How can slag inclusions in welding be avoided?

Ans:  Avoid multi layer welding

•           Reduce arc length

•           Increase electrode angle

•           Avoid using large electrode

6.     How does brazing differ from braze welding?

Brazing

The filler alloy is fed to one or more points  in  the  assembly  and  it drawn into the rest of the joint by capillary action.

Braze Welding     

The   filler   alloy   is      deposited directly  at     the  point    where  it  is desired.               

7                Why flux is coated on filler rods?

Ans:  The coating improves penetration and surface finish.

•       Suitable coating will improve metal deposition rates.

8                What is the application of carburizing flame?

Ans:

•         Carburizing flame is generally used for: o Welding of

low alloy steel rods

o Non-ferrous metals o High carbon steel

9 What are the diameter and length of the electrodes available in the market?

Ans:  Standard length of electrodes are 250 mm, 300 mm and 450 mm.

•         Standard diameters of electrodes are 1.6,2 ,2.5, 3.2, 4,5,6,7,8, and 9 mm.

10.            Classify various ARC welding processes

(i) Arc welding

•                Carbon arc

•                Metal arc

•                Metal inert gas

•                Tungsten inert gas

•                Plasma arc

•                Submerged arc

•                Electro-slag

11.            Classify various GAS welding processes

(ii) Gas Welding

•                  Oxy-acetylene

•                  Air-acetylene

•                  Oxy-hydrogen

12.Name the various methods of Resistance Welding

BUTT

Spot

Seam

Projection & Percussion.

13. What is ‘Brazing’

It is defined as the t3echnique of joining two dissimilar or similar materials by addition of special filler material. Brazing gives a much stronger joint than soldering but requires greater heat which cannot be obtained from copper in soft soldering.

14.Mention the applications of friction welding.

Used in refrigeration.

Used in super alloys.

Making simple forging.

Production of taper and reamer drills

Production of axle shafts , valves and gears.

15.Name the chemicals used in flux Manufacure.

1.Chlorides

2.Borax and boric acid. 3.Borates

4.Fluorides.