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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. 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
Incomplete casting
Even higher cooling rates (10^6 to 10^8 K/s)
Mushy Zone
Basic Gravity Casting System
2. 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
Basic Steps of Casting
Reynolds Number
Sprue Design
Incomplete casting
3. Serve as reservoirs of molten metal to supply any molten metal necessary to prevent porosity due to shrinkage during solidification.
Reynolds Number
Even higher cooling rates (10^6 to 10^8 K/s)
Risers (or feeders)
Re Range
4. 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
Fluidity
Eutectics
Solidification Time
Important considerations in casting operations
5. 1. Pouring basin or cup - where the molten metal is poured. 2. Gating system - molten metal flows through gating system
Defective surface
Basic Steps of Casting
Shrinkage
Basic Gravity Casting System
6. Premature solidification - not enough metal poured.
Incomplete casting
Mass Continuity
Fluidity
Slow cooling rates (10^2 K/s)
7. The portion of the runner through which the molten metal enters the mold cavity.
Flow Characteristics
Gate
Important considerations in casting operations
Risers (or feeders)
8. 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.
Characteristics of molten metal
Mass Continuity
Re Range
Latent Heat
9. Are the channels that carry the molten metal from the sprue into the mold cavity or connect the sprue to the gate.
Sprue
Eutectics
Runners
Slow cooling rates (10^2 K/s)
10. The capability of molten metal to fill mold cavaties. Consists of two basic factors: 1.) Characteristics of the molten metal 2.) Casting parameters
Basic Steps of Casting
Fluidity
Higher cooling rates (10^4 K/s)
Even higher cooling rates (10^6 to 10^8 K/s)
11. Or long local solidification times result in coarse dendritic structures with large spacing between dendrite arms.
Gate
Fluidity
Slow cooling rates (10^2 K/s)
Basic Steps of Casting
12. Defects consisting of fins - flash - or projections.
Gate
Metallic projections
Latent Heat
Defective surface
13. 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
Higher cooling rates (10^4 K/s)
Porosity
Gate
14. 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.
Porosity
Flow Characteristics
Mass Continuity
Shrinkage
15. 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
Defective surface
Incomplete casting
Basic Gravity Casting System
16. 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
Fluidity
Incomplete casting
Latent Heat
17. Or short local solidification times - the structure becomes finer with smaller dendrite arm spacing.
Gate
Shrinkage
Higher cooling rates (10^4 K/s)
Basic Steps of Casting
18. A function of the volume of a casting and it surface area (Chvorinov's rule) = C(volume/surface area)
Porosity
Solidification Time
Basic Gravity Casting System
Sprue Design
19. Defects such as folds - laps - scars - adhering sand layers.
Re Range
Mushy Zone
Fluidity
Defective surface
20. Atapered vertical channel through which the molten metal flows downward in the mold.
Solidification Time
Defective surface
Higher cooling rates (10^4 K/s)
Sprue
21. 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
Solidification Time
Eutectics
Re Range
Sprue
22. Porous area of a casting caused by shrinkage - or dissolved gases - or both.
Porosity
Defective surface
Reynolds Number
Even higher cooling rates (10^6 to 10^8 K/s)
23. 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
Mass Continuity
Sprue
Slow cooling rates (10^2 K/s)
Flow Characteristics
24. 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)
Reynolds Number
Sprue Design
Sprue
Latent Heat
25. Avoid turbulence in gating system - the flow is highly chaotic and can lead to aspiration. Laminar flow is ideal
Flow Characteristics
Even higher cooling rates (10^6 to 10^8 K/s)
Basic Gravity Casting System
Mass Continuity
26. 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
Re Range
Sprue Design
Characteristics of molten metal
Basic Gravity Casting System