# CH11 Fundamentals of casting
## Summary
- Shape-Producing Process
- casting
- material-removal
- deformation processes
- consolidation processes
- Casting Process
- material melt
- heat
- modify chemical makeup
- poured into mold
- solidify

- Advantages of casting
- complex shapes
- can have hollow sections or cavities
- can produce large parts
- different mold materials can be used
- sand
- metal
- ceramics
- different pouring methods

- Steps
- produce mold
- melt
- pour
- solidify
- remove mold
- finishing

- molten metal is poured into the mold at a proper rate to ensure that erosion and defects are minimized.
- mold should should be designed so that shrinkage is controlled.
- 比較
- Casting processes can produce extremely ==complex shapes==, but may have defects related to shrinkage and porosity.
- Material removal processes can have outstanding ==precision==, but generate scrap as the material is cut away.
- Deformation processes can offer ==high rates of production==, but require powerful equipment and dedicated tools or dies.
- Consolidation processes can produce large or complex shapes, but the joints may possess properties that are different from the base material.
- Two casting defects occuring solidification
- gas porosity, 氣孔
- prevent: to melt in a vacuum
- shrinkage, 收縮
- Two stages of solidification
- nucleation 成核, 形成結晶微顆粒
- growth 生長, 結晶微顆粒的表面逐漸沉積更多的固體, 最後生長成為大型的晶體顆粒
- (冷卻速度越快, 晶粒越小, 機械性質越好)

- When metal flows into mold cavity
- fluidity is the ability of a metal to flow and fill
- most important controlling factor is pouring temperature
- Gating sys
- deliver the molten metal to the mold cavity
- control the speed of molten metal and cooling during flow

- Cavities and voids can be prevented by directional solidification

- Hot tears can occur when there is significant tensile stress on the surface of the casting material

- Pattern must be slightly larger than the desired part, because when the cast solidifies, it shrinks at some limit due to metal shrinkage property at the time of cooling.

## Problems
### From昌峻 (他修淦哥的課)

1. Please list 5 basic groups (family categories) of Shape-Producing Processes

- casting
- material-removal
- deformation processes
- consolidation processes
- additive processes

2. Excluding the consolidation processes and additive processes, please describe the other 3 materials processing families with subgroups and typical processes.


3. Please write down six basic steps of casting.

- produce the mold
- heat the molten material to proper temperature
- pour the molten material into the mold
- solidification
- remove mold
- cleaning, finishing, inspection

4. Given 12 terminologies (Pouring Cup, Sprue, Runner, etc), please draw a typical cross section of a mold for casting (hint: two-part sand mold).

- Pouring cup : 把金屬倒進去的地方
- Sprue：Pouring Cup下面那段
- Runner：流道, 給金屬流的空間
- Riser：冒口, 預留金屬來補足鑄件冷卻收縮時多出來的空間的構造
- Core：砂心, 做中空鑄件的時候放在中間不讓金屬流過去的東西
- Parting Line：分模線, 區分上下模的界線
- Cope/Drag：砂模是上下兩片蓋起來的，上面那片膜叫Cope, 下面那片模叫Drag
- Flask：砂箱
- Pattern : 一開始要把模做出來時，作為基準的小模型
<!-- - [Source](https://hackmd.io/@0xff07/H1Wlgto2U/https%3A%2F%2Fhackmd.io%2F%400xff07%2FByOdwdmje#E-Sand-Casting) -->

5. Please list two casting defects occur during solidification.

- Gas porosity
- Shrinkage

6. Please draw a typical curve/figure (temperature vs height of metal column; or volume) showing shrinkage occurs upon solidification


### 考古
1. Why might directional solidification be desirable in the production of a cast product?

- Because cavities and voids can be prevented by directional solidification.

2. What types of modifications or allowances are generally incroporated into a casting pattern?
- Dimensional modification are incorporated
- the pattern must be slightly larger than the desired part.

3. 鑄件內部殘留氣孔的原因為何?
- 氣體在金屬融化成液態後沒有排出，導致固化時形成氣孔

4. 如何避免氣孔?
- 在低溶解度的氣體 or 真空中融化金屬

5. 鑄造程序的六個基本步驟為 1.產生模穴 2. 熔解金屬 3.澆注金屬到模內 4. 固化 5. 移除模具 6.清潔與檢測，請說明1到4個步驟中的重要注意點
- 產生模穴:
- take shrinkage into account
- determine single use or permanent mold
- 熔解金屬:
- 適當溫度
- 澆注金屬:
- to pour at a proper rate to ensure that erosion and defects are minized
- 固化:
- 控制冷卻方向性
- 固化的速度影響結晶大小，進而影響成品的機械性質
### Quizlet
[flash card](https://quizlet.com/124328768/materials-chapter-11-review-questions-flash-cards/?funnelUUID=eb5f28db-14f4-46cb-a320-dfc06c3d2a8f)
## Nouns
- casting
- 鑄造
- deformation
- 形變
- consolidation
- 合併
- solidification
- 凝固
- ceramics
- 陶瓷
- pour
- 倒
- erosion
- 侵蝕
- defect
- 缺點
- shrinkage
- 收縮
- porosity
- 孔隙度
- nucleation
- 成核
- pattern allowance
- 模具允許誤差
- incorporated
- 包含