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Test your basic knowledge |
Manufacturing Processes
Start Test
Study First
Subject
:
engineering
Instructions:
Answer 26 questions in 15 minutes.
If you are not ready to take this test, you can
study here
.
Match each statement with the correct term.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.
This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.
1. 1.) Contraction of molten metal as it cools prior to solidification. 2.) Contraction of the metal during phase change from liquid to solid (latent heat of fusion). 3.) Contraction of the solidified metal (casting) as its temp. drops to ambient temp.
Risers (or feeders)
Shrinkage
Sprue
Sprue Design
2. Atapered vertical channel through which the molten metal flows downward in the mold.
Sprue
Porosity
Incomplete casting
Fluidity
3. Defects such as folds - laps - scars - adhering sand layers.
Defective surface
Basic Steps of Casting
Fluidity
Shrinkage
4. The capability of molten metal to fill mold cavaties. Consists of two basic factors: 1.) Characteristics of the molten metal 2.) Casting parameters
Shrinkage
Fluidity
Higher cooling rates (10^4 K/s)
Risers (or feeders)
5. 1. Pouring basin or cup - where the molten metal is poured. 2. Gating system - molten metal flows through gating system
Defective surface
Basic Gravity Casting System
Reynolds Number
Latent Heat
6. 1. Flow of molten metal into the mold cavity 2. Solidification and cooling of the metal in the mold 3. Influence of the type of mold material
Eutectics
Porosity
Fluidity
Important considerations in casting operations
7. Or long local solidification times result in coarse dendritic structures with large spacing between dendrite arms.
Important considerations in casting operations
Runners
Mass Continuity
Slow cooling rates (10^2 K/s)
8. The structures developed are amorphous ('without shape' - or non - crystalline solid is a solid that lacks the long- range order characteristic of a crystal). As the structures develop - the resulting grain sizes influence the properties of the casti
Even higher cooling rates (10^6 to 10^8 K/s)
Mushy Zone
Reynolds Number
Mass Continuity
9. The design of a sprue must be tapered from top to bottom as long as the pressures are the same - Asub1/Asub2 = sqrt(hsub2/hsub1)
Flow Characteristics
Sprue Design
Slow cooling rates (10^2 K/s)
Porosity
10. The portion of the runner through which the molten metal enters the mold cavity.
Important considerations in casting operations
Latent Heat
Basic Steps of Casting
Gate
11. The width of the mushy zone - in which both liquid and solid phases are present - is described in the terms of a temperature difference - known as the: freezing range = (TL - TS) - which is a time not a temp.
Mushy Zone
Metallic projections
Sprue Design
Incomplete casting
12. Or short local solidification times - the structure becomes finer with smaller dendrite arm spacing.
Solidification Time
Mushy Zone
Higher cooling rates (10^4 K/s)
Re Range
13. Defects consisting of fins - flash - or projections.
Sprue
Mushy Zone
Metallic projections
Basic Steps of Casting
14. Serve as reservoirs of molten metal to supply any molten metal necessary to prevent porosity due to shrinkage during solidification.
Solidification Time
Risers (or feeders)
Gate
Sprue Design
15. Re- it is used to quantify flow characteristics. It represents the ratio of the inertia to the viscous forces in fluid flow. Re= vDp/n v= velocity D= diameter of the channel p and n= viscosity and density of the liquid
Reynolds Number
Mushy Zone
Shrinkage
Porosity
16. The higher the Reynolds Number the greater the tendency for turbulent flow to occur. In a gating system Re ranges from 2 -000 to 20 -000. A value of up to 2 -000 represents Laminar flow.
Reynolds Number
Shrinkage
Re Range
Important considerations in casting operations
17. The law of mass continuity states that - for incompressible liquids and in a system with impermeable walls the rate of flow is constant. Q=Asub1vsub1 = Asub2vsub2 - Q= volume rate of flow (such as m^3/s) - A= cross sectional area of the liquid strea
Higher cooling rates (10^4 K/s)
Mass Continuity
Gate
Latent Heat
18. Avoid turbulence in gating system - the flow is highly chaotic and can lead to aspiration. Laminar flow is ideal
Higher cooling rates (10^4 K/s)
Sprue
Basic Steps of Casting
Flow Characteristics
19. Are the channels that carry the molten metal from the sprue into the mold cavity or connect the sprue to the gate.
Metallic projections
Runners
Risers (or feeders)
Slow cooling rates (10^2 K/s)
20. Porous area of a casting caused by shrinkage - or dissolved gases - or both.
Porosity
Sprue Design
Important considerations in casting operations
Flow Characteristics
21. 1.) Viscosity- varies by temp. 2.) Surface Tension - high surface tension reduces fluidity 3.) Inclusions - can have an adverse effect on fluidity 4.) Mold Design - design - dimensions of the sprue - runners - and risers all affect fluidity. 5.) Heat
Gate
Characteristics of molten metal
Basic Gravity Casting System
Sprue
22. Solidify in similar manner as pure metals; as pure metals freezing range approaches zero - the solidification front moves as a plane without forming a mushy zone. The type of structure developed after solidification depends on the composition of the
Shrinkage
Higher cooling rates (10^4 K/s)
Eutectics
Flow Characteristics
23. A function of the volume of a casting and it surface area (Chvorinov's rule) = C(volume/surface area)
Porosity
Incomplete casting
Re Range
Solidification Time
24. 1. Pouring molten metal into a mold patterned after the part to be manufactured. 2. Allowing it to solidify 3. Removing the part from the mold
Basic Steps of Casting
Runners
Important considerations in casting operations
Latent Heat
25. The heat released or absorbed by a body during a change of state without change of temperature. The term most often refers to a phase transition - such as melting of ice or the boiling of water. Pure metals solidify at constant temperatures - After t
Latent Heat
Shrinkage
Incomplete casting
Gate
26. Premature solidification - not enough metal poured.
Sprue Design
Important considerations in casting operations
Sprue
Incomplete casting