Here are the top 50 commonly asked questions in Casting Forming & Welding interviews. Whether you’re just starting your preparation or need a quick refresher, these questions and answers will help you tackle your interview with confidence.
Basic Casting Forming & Welding Interview Questions with Answers
1. What is casting?
Casting is a process in which molten liquid metal will be allowed to solidify in a predefined cavity. After solidification, by breaking the mould, the required shape of the object can be produced.
2. What metals are commonly used for casting?
The most commonly used metals in casting are aluminum, magnesium, and copper alloys.
3. What are the advantages of casting?
Casting is a simple and less expensive process. Any material/object regardless of its ductility, brittleness and complexity, can be produced. Large sized objects can also be produced by the casting process.
4. What are the limitations of casting?
Casting is a laborious and time consuming process and the objects produced via casting do not have good surface finish.
5. What are the applications of casting?
Casting is used for production of heavy equipment in construction sites, farming, mining, machining industries, steel and thermal power plants. It can also be used for producing art objects and household appliances.
6. What is forming?
In a forming process, the metal is heated to a temperature, which is slightly below the solidus temperature and then a large force is applied such that the material flows and takes the desired shape.
7. What are the applications of forming?
Forming processes are used for producing seamless tubes, rods, turbine rings, cement kilns, bearings, plates, steel sheets, and various components of an automotive car. Along with that, missiles, aircraft components, hinges, bolts, nails, agricultural tools and military products are also produced with the help of this process.
8. What are the different types of forming processes that are based on temperature?
By applying heat, the property of the forged material can be changed. So, if temperature is considered then the three types of forming processes are hot forming, warm forming and cold forming.
9. What is a hot forming process?
In the hot forming process, the metal is heated above the recrystallization temperature. The recrystallisation temperature generally varies between one-third to half the melting point of most of the metals. During the hot forming of the sheet metal, the material recovers and softens.
10. What is a cold forming process?
In a cold forming process, the metal is heated below the recrystallization temperature of the metal. During cold forming, the strength and hardness of the material increases.
11. What is a warm forming process?
In a warm forming process, the metal is deformed above the room temperature but below the recrystallization temperature.
12. What is welding?
It is a process in which localized permanent joints can be produced with or without application of heat, with or without application of pressure, with or without application of filler material for joining of similar or dissimilar materials.
13. What are the different types of welding processes?
Welding is classified into three processes, they are: Homogeneous welding, Heterogeneous welding and Autogenous welding.
14. How dangerous is welding?
Due to high electric arc temperatures in welding, there can be a risk of electrocution, fire and explosion, burns, electric shock, vision damage, inhalation of poisonous gases and fumes, and exposure to intense ultraviolet radiation.
15. What are the five essentials for a good weld?
The five essentials for a good weld are correct electrode size, correct current, correct arc length, correct travel speed and correct electrode angle.
16. What are the applications of welding?
Welding is commonly used in aerospace, automotive, energy and construction industries. It is used to join metals, thermoplastics or wood for a variety of applications and it is also used to create artwork by a growing community of artists.
17. What are the advantages of welding?
Welding helps in the formation of a permanent joint and the strength of the joint will be equal to or more than the strength of base material. By this process, a leak proof joint can also be possible.
18. What are the limitations of welding?
Welding requires a skilled operator and the setup cost is more. Also, internal stress can be developed in the joint that is being welded, and due to this, cracks can be formed.
19. What is the major difference among Homogenous, Heterogeneous and Autogenous welding processes?
In heterogeneous welding, a fusion weld made with filler material which is different from the parent material. Coming to homogeneous welding, filler material has the same composition as that of the base metal. In autogenous welding, two or more metals are joined without the addition of filler metal.
20. Is welding a permanent joint?
Welding is a permanent joint and therefore it is not possible to dismantle the welded parts without partially destroying them.
Intermediate Casting Forming & Welding Interview Questions with Answers
21. What is permeability?
Some gases get dissolved in molten metal and when this molten metal starts to solidify, these dissolved gases come out of the molten metal and try to escape out of the moulding sand. The ability of sand to allow the gases to pass through it easily is called permeability.
22. What is flowability?
The ability of the sand to flow over and around the pattern when the mould is rammed is called flowability. Flowability helps the sand in easily occupying the space in the moulding box and in taking up its shape. This also allows the sand to compress to a compact density and lets it pack around the pattern.
23. What does a Grain Fineness Number indicate?
Grain Fineness Number will indicate the average grain size distribution of a given moulding. Greater the Grain Fineness Number, lower is the grain size.
24. What are the different properties of moulding sand?
The different moulding sand properties are: Refractoriness, Green strength, Dry strength, Hot strength, Permeability, Flowability, Adhesiveness, Cohesiveness, Toughness and Collapsibility.
25. What are the different types of patterns used in casting?
The different types of patterns used in casting are: Single piece pattern, Split pattern, Gated pattern, Cope and drag pattern, Match plate pattern, Loose piece pattern, Sweep pattern, Follow board pattern, Skeleton pattern and Shell pattern.
26. Why is wood flour added to moulding sand?
When a metal of high melting temperature is poured into the mould cavity, the sand grains in the moulding sand expand and convert into ash. Due to this expansion, the volume of the core or mould increases. To control this expansion of sand, wood flour is added. Wood flour increases the collapsibility and porosity of both mould and core and in turn reduces the expansion defects.
27. What is the composition of green sand?
The sand contains 2-6% of moisture content. It is a mixture of silica and 15 to 30% clay with about 8% water. Clay and water act as a bonding material to give strength. Green sand is used only for simple and rough casting products. It is used for both ferrous and non-ferrous metals.
28. What is the function of a sprue in casting?
Sprue is nothing but a large diameter passage through which the molten metal from the pouring basin reaches the mould cavity. In many cases, it controls the flow of metal into the mould.
29. How does a riser work?
Riser is used as a reservoir in the casting so that hot metal can flow back into the mould cavity when there is a reduction in volume of metal due to solidification.
30. What is the use of a chaplet?
Chaplets are metallic pin stands which support the cores in a mold box that is used in casting processes. Cores are nothing but devices that are used to produce internal cavities.
31. What are the factors that govern the selection of pattern material?
The factors that govern the selection of pattern material are shape, size of component, surface finish of components to be produced, number of components used, type of moulding method and cost of the pattern material.
32. What are the limitations of shell moulding?
The size of the casting obtained by shell moulding is limited and highly complicated shapes cannot be obtained. Also, the patterns are very expensive. More sophisticated equipment is needed for handling the shell mouldings such as those required for heated metal patterns.
33. What are the limitations of Investment casting?
Investment casting is an expensive process because of large manual labour involved in the preparation of pattern and the mould. Also, the process is limited to only small sized castings. Apart from that, cores are also required and their holes cannot be smaller than 1.6mm and should be no deeper than about 1.5 times the diameter.
34. What is the difference between a hot tear and a hot spot?
Hot tear is the crack that occurs due to variation in solidification rate while hot spot is due to high temperature point.
35. What is the use of chill in casting?
Chills are metallic objects which are placed in the mould to increase the cooling rate of castings to provide uniform or desired cooling rate. Also, chills are metals of high thermal conductivity.
36. What is the composition of an effective moulding sand in general?
The main constituents of moulding sand are silica sand, binder, moisture content and additives.
37. What is refractoriness of a moulding?
The ability of material to withstand the high temperature of molten metals is called refractoriness.
38. When is follow board pattern used?
A follow board pattern is used when thin or overhanging sections in castings are required. This pattern is used for castings that have few structurally weak portions and if not supported correctly are possible to break under force of ramming.
39. When is a gated pattern used?
When there is a need for small components in mass production, Gated patterns are used. In such patterns, gates and runners are already attached beforehand.
40. What is the use of runner?
A small diameter channel in the parting plane through which the flow of the molten metal is regulated before they reach the mould cavity is called runner.
41. When is a butt joint formed in welding?
A butt joint is formed when two pieces of metal are placed together in the same plane, and the side of each metal is joined by welding. It is used in the fabrication of structures and piping systems.
42. What is a heat affected zone?
A part of the parent metal which is metallurgically affected by the weld or thermal cutting heat is called a heat affected zone.
43. What is a fusion weld?
The boundary between the weld metal and the heat affected zone is a fusion weld. This is a non-standard term for weld junction.
44. How does Impact extrusion work?
A cold working process in which required shapes are made by striking slugs of metal at high pressure and speed is called Impact extrusion. It is used for making toothpaste, shaving cream and collapsible medicine tubes.
45. How does deep drawing work?
Deep drawing uses the mechanical action of a punch to produce a hollow body with a smaller cross-section. It is used for making cup shaped parts from sheet metal blanks, where the depth of the cup is greater than that of the diameter of the cup.
46. What is wire drawing?
Drawing of metal through a small aperture die and wounding in the form of coil is called wire drawing. The aperture is generally below 16mm diameter.
47. What is the difference between Hot spinning and Cold spinning?
Hot spinning is the process of making a circular cross section or a dish or head from circular, heavy plates by spinning sheet metal. Cold spinning is the process of shaping very thin metals by pressing against a form while it is rotating. It is carried out at room temperature.
48. What are the basic welding joints?
The five basic welding joints are Butt joint, Corner joint, Lap joint, Tee joint and Edge joint.
49. Why is pure CO2 used in welding?
Pure CO2 provides very deep weld penetration, which is useful for welding thick material. However, it produces a less stable arc and more spatter.
50. Why is DC welding preferred over AC welding?
DC welding has smoother and more stable arcs, easier starts, fewer arc outages, less spatter and easier vertical up and overhead welding.
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