Metal Casting Process | Interview Question and Answers

Metal Casting Process | Interview , VIVA , Oral Question and Answers

1. What is draft allowance? How is it provided for patterns?

It the vertical faces of pattern are perpendicular to parting line, the edges of mould may damaged when the pattern is removed from the sand. Hence the vertical faces are mode taper for easy removal of pattern. This slight taper given on the vertical sides of pattern in caused draft allowance.

2. Name four different casting defects.

Shifts – Two halves mismatching or casting
Hot tear – Internal or external cracks
Fins – Thin projection of parting line
Inclusions – Foreign material present in casting

3. What are the common allowances provided on pattern?

The various types of pattern allowances normally given are;
1. Shrinkage allowance
2. Machining or finish allowance
3. Draft or taper allowance
4. Distortion or camber allowance
5. Rapping or shake allowance

4. What are the functions or riser?

The main function of the riser is to supply excess molten metal to the solidifying casting it allows the escape of air.

5. How pattern differ from casting?

Pattern is slightly larger in size as compared to the casting. Pattern may be in two or three pieces where as a casting is in one piece.

6. What are the tests carried out to determine the quality of casting?

Destructive test: Tensile, Impact, Hardness etc.
Non Destructive: Visual, sound, magnetic particles, dye penetration, ultrasonic etc.

7. Define foundry.

A plant where the castings are made is called a foundry.

8. Define casting.

The Process of producing metal parts by pouring molten metal in to the mould cavity of the required shape and allowing the metal to solidify. The solidified metal piece is called as casting.

9. Define mould.

Mould is the cavity of the required casting made in wood, metal or plastics.

10. Define pattern.

The Model of the required casting made in wood, metal or plastics.

11. Name the various pattern materials.

Wood – Teak wood, white pine etc.
Metal – cast iron, brass, aluminium etc.
Plaster
Plastic
Wax

12. What are the different types of patterns used in foundries?

Solid or single piece pattern, match plate pattern, split pattern, sweep pattern, skeleton Pattern, segmental pattern, loose piece pattern, shell pattern.

13. When do you made core (or) what is function of core in moulding sand?

To provide a hollow surface or recess on the casting, the core is made.

14. What is core print and what is its purpose?

A core print is an extra projection on the pattern. It supports the core.

15. What do you understand by core setting?

Caring or heating the cores to obtain enough hardness is called as core setting.

16. What are requirements of core sand?

Permeability, refractoriness, strength collapsibility, stability.

17. Mention the specific advantages of CO2 process.

Give strength and hardness to core
Process cost is less
It saves time on heating
It can be stored for long use

18. What is the properties good moulding sand?

Porosity or permeability, plasticity or flowability, strength or cohesiveness, adhesiveness, Refractoriness, collapsibility.

19. What are the different types of moulding sand?

Green sand, Dry sand, Synthetic sand, Loam sand, Special sand, parting sand.

20. Write the composition of good moulding sand.

Green sand: It contains 5 to 8% water and 15 to 20% clay.

Loam Sand: Loam sand is a mixture of fine sands, fine refractoriness, clay, graphite fiber and water. It contains more clay (50%)

21. List out any five moulding tools.

Shovel, Riddle, Rammer, Trowel, Slick, Strike off bar, lifter

22. What are the uses of runner and riser?

Runner:

It is used to make a sprue a hole in the cope.
It receives the molten metal from the pouring basin and passes to the cavity.

Riser:

It supplies excess molten metal to the solidifying casting.
It allows the escape of air.

23. What are chaplets?

Some times it is not possible to provide sufficient support for a core in the mould being poured, if the cores are bigger in size. In such cases the core is supported with rigid metal pieces called chaplets.

24. Mention any 2 difference between green sand mould and dry sand mould.