Macro Porosity Formation: A Study in High Pressure Die Casting

David Blondheim Jr. & Alex Monroe

Abstract

Porosity formation in high pressure die casting (HPDC) impacts mechanical properties and casting quality. Much is published regarding micro porosity and its impact on mechanical properties, but there is limited research on the actual formation of macro porosity. In production applications, macro porosity plays a critically important role in casting quality and acceptance by the customer. This paper argues that the most useful definition of macro porosity is the limits of visual detectability. With this definition, it will be shown macro porosity presents stochastically within a controlled HPDC process. This means macro porosity has a random probability distribution or pattern that should be analyzed statistically and cannot be predicted precisely. The general region where macro porosity forms is predictable with simulation, but its actual size and distribution of the voids are random. These results challenge the industry accepted practices for inspections and process controls. This also underscores the importance of up-front design for manufacturability to avoid macro porosity-related quality issues.

고압 다이캐스팅(HPDC)의 다공성 형성은 기계적 특성과 주조 품질에 영향을 미칩니다. 미세 기공과 기계적 특성에 미치는 영향에 대해 많이 발표되었지만 매크로 기공의 실제 형성에 대한 연구는 제한적입니다. 생산 응용 분야에서 매크로 다공성은 주조 품질과 고객의 수용에 매우 중요한 역할을 합니다. 이 논문은 매크로 다공성의 가장 유용한 정의가 시각적 탐지 가능성의 한계라고 주장합니다. 이 정의를 통해 매크로 다공성이 제어된 HPDC 프로세스 내에서 확률적으로 나타납니다. 이것은 매크로 다공성이 통계적으로 분석되어야 하고 정확하게 예측할 수 없는 무작위 확률 분포 또는 패턴을 가지고 있음을 의미합니다. 매크로 다공성 형성이 시뮬레이션으로 예측 가능한 일반적인 영역, 그러나 공극의 실제 크기와 분포는 무작위입니다. 이러한 결과는 검사 및 공정 제어에 대해 업계에서 인정하는 관행에 도전합니다. 이것은 또한 매크로 다공성 관련 품질 문제를 피하기 위해 제조 가능성에 대한 선행 설계의 중요성을 강조합니다.

Keywords

  • high pressure die casting
  • porosity
  • casting defects
  • defect classification
  • macro porosity
  • micro porosity

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