What are common casting defects and how do you prevent them?

Common casting defects include: Porosity (caused by trapped gases - prevent with proper venting and degassing), Shrinkage cavities (due to inadequate feeding - use risers and chills), Hot tears (from restrained contraction - modify design and use proper allowances), Cold shuts (incomplete filling - increase pouring temperature and speed), and Misruns (premature solidification - optimize gating and fluidity). Prevention requires proper mold design, process parameter control, and material quality.