# CH12 Expendable-Mold Casting Process
## Summary
- Expendable-Mold Casting Process
- 模只會一次性的使用，鑄造完後把他破壞，拿出裡面鑄件
- Sand casting
- Vacuum molding
- Shell molding
- Ceramic molding casting
- Plaster molding casting
- Investment casting
- Evaporative pattern molding

- Three categories of molds
- sinle-use molds with multipule-use patterns
- single-use molds with single-use patterns
- multiple-use molds

- Sand casting is the most common and versatile form of casting
- 沙模種類
- Green-sand, Dry-sand, Skin-Dried molds
- 最便宜
- No bake, Air-set, Chemically Bonded Sands
- 樹脂(synthetic liquid resin) 當作黏著劑的模。好處是不用加到高溫，模也可以硬化
- high dimensional precision and good surface finish
- 成本較green sand molding高

- Gravity flow is the most common method fo inserting the liquid metal into the mold

- Different types of pattern
- Wood
- cheap but not dimensionally stable
- Metal
- expensive but stable and durable
- Pattern selection is determined by
- the number, size and shape of the castings
- desired dimensional precision
- molding process
- Sand casting
- Vacuum molding
- 把 Pattern 用熱固型塑膠包覆，加熱使塑膠固化。接著把砂倒入，並抽真空，使沙子可以和覆蓋熱固型塑膠的pattern 貼齊，藉此製成模
- 優點
- no moisture-related defects
- no binder cost
- sand is reuseable
- better surface finish
- no fume during pouring operation
- 缺點
- relative slow process
- low to medium volume parts
- Shell molding
- 使用permenant pattern(different from sand casting)
- 精細度和光滑度皆比沙模高 可以製作較複雜的零件
- 過程方便自動化 人力成本也較低
- Plaster molding casting
- 石膏
- Ceramic molding casting
- 用陶瓷做模，這樣就可以鑄造高溫的金屬（比如說不鏽鋼）
- Investment casting
- 脫蠟法 脫蠟鑄造
- single use pattern
- 優點
- 可製造複雜形狀
- 可製作較細的結構
- machining can be eliminated or reduced
- 缺點
- 步驟複雜
- 成本較高
- investment : 環繞
- Rubber mold casting
- Evaporative pattern molding (full mold and lost foam)
- 消失模鑄造法
- pattern是用保麗龍(Polystyrene)做的 受熱揮發
- 優點
- sand can be reused
- castings of almost any size
- ferrous(亞鐵) abd nonferrous metals
- not require draft
- complex pattern
- 高光滑度
- no parting lines
- [各種molding的過程](https://hackmd.io/@0xff07/H1Wlgto2U/https%3A%2F%2Fhackmd.io%2F%400xff07%2FByOdwdmje#Expendable-Mold-Casting)
## Problems

### From昌峻 (他修淦哥的課)
1. What is the most common method of inserting/introducing the liquid metal into the mold in sand casting?

2. Please draw a schematic of the dump-box version of shell molding and describe corresponding processes.

3. Please draw an illustration (with a brief description) to show/describe the Investment-casting steps for the flask-cast method.

4. Please draw an illustration (with a brief description) to show/describe the investment-casting steps for the shell-casting procedure.

5. Please draw a schematic (with a brief description) of the lost-foam casting process.

~~懶得找答案ㄌ~~
### 考古
1. Please describe the four primary requirements of molding sand ==(手頭上有的考古都有出)==

- Refractoriness, ability withstand high temperatures
- 耐火性
- Cohesiveness, ability to retain shape
- 黏固性
- Permeability, ability of a gases to escape through the sand
- 氣體穿透性
- Collapsibility, ability to accommodate shrinkage and part removal
- 潰散性
2. What types of geometric features might require the use of cores
- cylinders
### Quizlet
[flash card](https://quizlet.com/124300204/materials-chapter-12-review-questions-flash-cards/)
## Nouns
- Expandable
- 可擴展的
- binder
- 黏合劑
- fume
- 煙
- machining
- (因為沙子是凹凸不平的，而且又會收縮等等，所以做出來的東西需要進一步做處理)