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