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Manufacturing Processes

Subject : engineering
Instructions:
  • Answer 26 questions in 15 minutes.
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  • Match each statement with the correct term.
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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. 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






2. Or short local solidification times - the structure becomes finer with smaller dendrite arm spacing.






3. 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






4. Avoid turbulence in gating system - the flow is highly chaotic and can lead to aspiration. Laminar flow is ideal






5. Defects such as folds - laps - scars - adhering sand layers.






6. Premature solidification - not enough metal poured.






7. 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






8. The portion of the runner through which the molten metal enters the mold cavity.






9. 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






10. Atapered vertical channel through which the molten metal flows downward in the mold.






11. 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






12. 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






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.






14. 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.






15. 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






16. 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.






17. A function of the volume of a casting and it surface area (Chvorinov's rule) = C(volume/surface area)






18. The capability of molten metal to fill mold cavaties. Consists of two basic factors: 1.) Characteristics of the molten metal 2.) Casting parameters






19. 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)






20. Porous area of a casting caused by shrinkage - or dissolved gases - or both.






21. Or long local solidification times result in coarse dendritic structures with large spacing between dendrite arms.






22. Serve as reservoirs of molten metal to supply any molten metal necessary to prevent porosity due to shrinkage during solidification.






23. Are the channels that carry the molten metal from the sprue into the mold cavity or connect the sprue to the gate.






24. 1. Pouring basin or cup - where the molten metal is poured. 2. Gating system - molten metal flows through gating system






25. 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






26. Defects consisting of fins - flash - or projections.