CHAPTER 2
1. Casting process basically involves 3 steps:
oPouring molten metal into a mold
oAllow it to solidify
oRemoving the part from the mold
2. Three important considerations in casting operation:
oFlow of the molten metal into the mold cavity
oSolidification and cooling of the metal in the mold
oInfluence on the type of mold material
3. Basic gravity casting system as follows:
Pouring cup gating system (sprue, runner, gate)
mold cavity
4. Fluidity is the term to describe the ability of the molten metal to fill mold cavities.
5.Fluidity influence by two basic factors:
Characteristics of the molten metal
Casting parameters.
6. Two basic principles of fluid flow are relevant to gating design: Bernoulli’s theoremand the law of mass continuity.
7.Shrinkagewill cause dimensional changes and (sometimes) cracking.
8. Hot tears in castings occur because the casting cannot shrink freely during cooling, owing to constraints in various portions of the
molds and cores.
9. Porosity caused by shrinkage can be reduced or eliminated by using internal or external chill. Chill must be the same material as
casting.
1. Casting processes generally are classified as expendable-mold or permanent-mold casting.
2. In expendable mold processes, the mold is destroyed after each using.
3. Most sand-casting operations use silica sand as mold material.
4. Sand is suitable as mold material in sand casting because of its high-temperature characteristics and high melting point.
5.
Sprue–through which molten metal flows
Flask –support the mold
Risers –supply additional molten metal as it shrinks.
6. Casting process where its mold and a pattern must be produced for every casting. Evaporative-pattern casting.
7. There are two types of design issues in casting:
Geometric features
Mold features
8. The evaporative-pattern casting process uses a polystyrene pattern, which evaporates upon contact with molten metal to form a
cavity for the casting
Chapter 4
1. Rollingis the process of reducing the thickness or changing the cross-section of a long work piece by compressive forces
applied through a set of rolls.
2. Roll forces can cause significant deflection & flattening of the rolls and this will affect rolling operation. One way to
reduce it by increasing friction at the roll-work piece interface. False
3. Compared with hot rolling, Cold rolling produces sheets and strips with a much better surface finish. True
4. The basic requirements for roll materials are strength and resistance to high temperature. False
5. Rolling can be carried out only at room temperature (cold rolling). False
Chapter 4 part 2
1. Forging is a basic process in which the work piece is shaped by compressive forces applied through various dies and
tooling.
2. Which forging process (cold or hot forging) is suitable for making a component for Ferrari F1 car.
Ans: Cold forging (good dimensional accuracy).
3. Cogging is the phenomenon that cause by frictional forces at the die-work piece interfaces. False
4. Cogging is basically an open-die forging operation in which the thickness of a bar is reduced by successive forging steps
(bites) at specific intervals.
5. Impression-die forging process can be defined as hot forging process. Ans: True
6. Flash is an excess material that forms from impression-die process.
7. Open-die forging operation is the most suitable forging operations for net-shape forming process.
Ans: False (Closed-die forming –flash fless forging)
8. The most suitable forging process for making coins is
closed-die forging process.
9. Forgeability generally is defined as the capability of a material to undergo elastic deformation without cracking.
Ans: False (plastic deformation)
10. One of the reasons that cause internal defect is undersized billet. In this defect, die cavities are filled prematurely, and the
material at the center flows past the filled regions as the dies close.
Ans: False (oversized billet)
11. The mechanical performance of forged or wrought parts is usually better because of the microstructure change sand the
directional grain flow imparted during the forging process.
12. List the necessary tools that can be used during open-die forging according to the video on forging.
Ans: Accessory tools that can be used during open-die forging are (1) saddles, (2) blocks, (3) rings, (4) mandrels, and (5)
punches.
13. List the performing operations discussed in the forming video
Ans: The preforming operations discussed in the forming video are (1) edging –to increase the cross section of the work
and (2) blocking –to refine the shape. Then,
(3) finish forging is used to complete the shape.
Chapter 4 part 3
14. Extrusion process which is done at room temperature is known as cold extrusion.
15. Why Hot extrusion is an important manufacturing process?
For metals and alloys that do not have sufficient ductility at room temperature (or in order to reduce the forces required),
extrusion is carried out at elevated temperatures
16. A cross-section of a long rod or wire typically is reduced or changed by pulling it through a die. Drawing process
17. Process of pushing a billet through a die to reduce its cross section or to produce various solid or hollow cross sections :
Extrusion process
18. Proper lubrication is essential in drawing in order to improve die life and product surface finish and to reduce drawing
forces and temperature.
19. The die angle, reduction in cross section, extrusion speed, billet temperature, and lubrication all affect the extrusion
pressure.
20. What is the purpose of dummy block : To avoid the formation of oxide films on the hot extruded product.
21. What is the difference between drawing & extrusion: The difference between drawing and extrusion is that in extrusion the
material is pushed through a die, whereas in drawing it is pulled through it
Chapter 5
1. Die material is one of the processing parameters in extrusion in order to ensure product integrity and uniform dimensional
accuracy. Ans: False (Die design)
2. In extrusion , raw materials in the form of thermoplastic pellets , granules , or , or powder are placed into a hopper and fed
into the barrel of a screw extruder.
3. Screws have three distinct sections:
Feed sectionFeed section Feed section
Melt section
Metering Metering or or pumping section
4. In Injection molding, the pellets or granules are fed into the heated cylinder heated and the melt is forced into the mold
either by a the mold either by a hydraulic plunger or by the or by the or by the rotating screw system of an extruder.
Why tooling in thermoforming is relatively inexpensive.
Ans: Molds for thermoforming usually are made of aluminum because high strength is not required, hence tooling is relatively
inexpensive.
