Most aluminum casting disputes start at the alloy line of the drawing. Buyers often write the alloy their last supplier used, without knowing that a different alloy can cut cost, improve anodizing or survive a tougher environment.
The four alloys below cover the overwhelming majority of gravity, low-pressure and sand casting orders we run. Matching alloy to function is the single biggest lever after process selection.
Key Points
- ADC12 / A380 (Al-Si-Cu): the workhorse — excellent castability and machinability, lowest cost. Best for housings, brackets and covers not exposed to heavy corrosion.
- A356 / A357 (Al-Si-Mg): higher strength and elongation after T6 heat treatment, better for structural, safety and pressure-tight parts (motor housings, suspension, rail transit).
- AC4B: a Japanese-spec alloy between the two — good heat resistance and machinability, common in automotive.
- When corrosion resistance or a bright anodized finish matters, we recommend a lower-copper alloy — tell us the application, not just the grade.