This set of Manufacturing Engineering Puzzles focuses on “Fusion Welding Processes-2”.
1. Which of the following is used to generate Acetylene gas?
c) Calcium carbonate
d) Calcium carbide
Explanation: Acetylene is a hydrocarbon consisting of two carbon atoms and two hydrogen atoms. The simplest process reacts calcium carbide with water to produce acetylene gas and a calcium carbonate slurry, called hydrated lime. The chemical reaction may be written as CaC2 + 2H2O → C2H2 + Ca (OH)2.
2. Striking voltage as compared to a voltage during arc welding is?
d) can’t say
Explanation: The minimum voltage enough to arc across a given gap is called as the striking voltage. It is more than the arc voltage in arc welding.
3. How many zones are there in a carburising flame?
Explanation: If the oxygen is insufficient for full combustion, the flame is known as a reducing, or carburizing, flame. The temperature of a reducing flame is lower; hence, such a flame is suitable for applications requiring low heat, such as brazing, soldering, and flame-hardening operations.
4. Due to which of the following reasons distortion in welding occurs?
a) Oxidation of weld pool
b) Use of high voltage
c) Improper clamping
d) Use of high current
Explanation: As if the clamping is improper the weld will not be at the right place.
5. In reverse polarity welding _____________
a) work piece is connected as negative, and holder is earthed
b) electrode holder is connected to negative and work piece to positive
c) electrode holder is connected to positive and work piece to negative
d) both electrode holder and work piece are connected to negative
Explanation: In direct current reverse polarity (DCRP) or direct current electrode positive (DCEP), when base metals relate to the negative terminal of the power source and electrode relates to the positive terminal.
6. Where does maximum flame temperature occur?
a) Next to inner cone
b) At the inner cone
c) At the tip of the flame
d) At the outer cone
Explanation: Maximum flame temperature occur at inner cone. As flame moves from inner to outer temperature drop takes places.
7. In which of the following welding processes, electrode gets consumed?
a) TIG welding
b) Resistance welding
c) Thermit welding
d) Arc welding
Explanation: As in arc welding, welding is totally dependent on electrode, so it will be consumed.
8. Which of the following statements about welding is incorrect?
a) Increased corrosion resistance
b) Even materials like stainless steel and aluminium can be welded
c) No flux required
d) High welding speed
Explanation: Flux is mainly used for the following purposes: (a) It prevents the oxidation o the surface of the weld which can contaminate the welded potion, (b) It helps in forming alloy at the welded portion which improves the strength, (c) In arc welding the flux coating helps in directing the spark that’s why the electrode is kept concave in shape so that spark can be precisely directed towards the cavity where welding has to be performed.
9. Where is half corner weld used?
a) where efficiency of the joint should be 50 percent
b) where longitudinal shear is present
c) where severe loading is encountered, and the upper surfaces of both pieces must be in the same plane
d) For welding materials heavier than 12 gauge
Explanation: The half-open corner joint is used for welding materials heavier than 12 gauge.
10. Which of the following percentage of carbon in steel is most weldable?
Explanation: Low carbon steel is typically the most readily welded steel in a room temperature environment.
11. In which of the following metals does the phenomenon of ‘weld decay’ occurs?
a) stainless steel
b) cast iron
c) carbon steel
Explanation: Weld decay is a form of intergranular corrosion, usually of stainless steels or certain nickel-base alloys, that occurs as the result of sensitization in the heat-affected zone during the welding operation.
12. On which of the following principles does the ‘positive pressure type torch’ work?
a) equal volume
b) positive pressure
c) equal pressure
d) equal flow
Explanation: There are two types of welding and cutting torches commonly used. They are the positive-pressure type (also known as an equal pressure type or medium type pressure type torch), and the injector type.
13. Why is post cleaning necessary at brazed joint?
a) to avoid corrosion
b) to avoid slagging
c) to avoid oxidation
d) to avoid scaling
Explanation: Depending on the brazing process, we may need to perform post-braze joint cleaning to remove residual flux. This step is crucial for several reasons; including the corrosive nature of most fluxes and the possibility that excess flux could contribute to joint failure. The most common cleaning methods involve water-specifically soaking/wetting and quenching.
14. While welding, which of the following material welding, neutral flame is not used?
a) cast iron
Explanation: The neutral flame has a one-to-one ratio of acetylene and oxygen. A neutral flame is named neutral since in most cases will have no chemical effect on the metal being welded. Neutral welding flames are commonly used to weld: mild steel, stainless steel, cast iron, copper, aluminium, etc.
15. Which of the following statements about “projection welding” is correct?
a) It is multi spot welding process
b) It is an arc welding process
c) It is a continuous spot-welding process
d) It is a process used for joining round bars
Explanation: Projection welding is a modification of spot welding in which the weld is localized by means of raised sections, or projections, on one or both workpieces to be joined. This is high-production process, and multiple projection welds can be arranged by suitable designing and jigging.
Sanfoundry Global Education & Learning Series – Manufacturing Engineering.
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