# 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