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# System prepended metadata

title: CH13 Multiple use mold casting processes

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# CH13 Multiple use mold casting processes
## Summary
- 優點
    - 產率較高
    - 有利於自動化
    - good surface finish 
    - consistent dimensions
    - directional solidification 
- 缺點
    - mold是用金屬做的，因此鑄造的金屬或合金材料須為低熔點
    - 模具成本較高 要耐高溫 耐疲勞(反覆收縮膨脹)
    - molds are not permeable
    - limited mold complexity
- Permanent Mold Casting
    - Vacuum casting
    - Die casting
    - Squeeze casting
    - Semisolid casting
    - Centrifugal casting
- Die casting
    - types
        - Hot chamber castings
            - fast cycling times
            - zinc, tin, lead-based alloys
            - 設備比較貴
        - Cold chamber castings
            - longer operating cycle than hot chamber
            - high productivity
            - aluminum, magnesium, copper, and high-aluminum zinc
            - 尺度廣泛
    - 優點
        - High production rates
        - good strength
        - intricate shapes
        - dimensional precision
        - execellent surface qualities
        - small medium sized castings
- Die complexity can be improved through the use of 
    - water cooled passages
    - retractable cores
    - moving pins to eject castings
- Die life 
    - limited by erosion and usage temperature
    - surface cracking
    - heat checking
    - thremal fatigue
- Summary of Die casting
    - dies fill so fast with metal that there is little time for the air in the runner and die to escape
    - molds offer no permeability
    - air can become trapped and cause defects
    - risers not used because of the high pressures used
    - sand cores can not be used due to high pressure
    - cast-in inserts can be used
    - high production rate
    - little post casting finishing necessary
## Problems
### 考古
1. Please describe the process advantages of permanent-mold casting
    - 產率較高
    - 有利於自動化
    - good surface finish 
    - consistent dimensions
    - directional solidification 

2. What are some of the attractive features of die casting compared to alternative casting methods?
    - High production rates
    - good strength
    - intricate shapes
    - dimensional precision
    - execellent surface qualities
    - small medium sized castings

3. 針對砂模鑄造、永久模鑄造進行優缺點及特性評述(包括 適用鑄造的對象材料、鑄件品質控制性、尺寸精度、表面光度、製程掌控、稱產性、成本、適用生產量)
    - 砂模
        - 優點
            - 適用高熔點材料
            - 低成本
            - 可製作高複雜性產品
            - 氣體穿透性佳
        - 缺點
            - 品質控制性不好
            - 精度相對差
            - 表面光度相對差
            - 製程掌控相對差
            - 產量相對小
    - 永久模
        - 優點
            - 適合自動化 量產
            - 品質控制佳
            - 尺寸精度高
            - 表面光度佳
            - 製程掌控好
            - 成品一致性高
        - 缺點
            - 低熔點材料
            - 高成本
            - 氣體穿透性差
            - mold複雜性較小