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Common Metals for CNC Machining: A Guide to Corrosion Resistance and Thermal Expansion Properties

模型製作, 模型生產, 治具製作廠商, 模具製作廠商, 測試治具製作, 產品模型製作, 模型製作公司, 塑膠模型製作, 模型 翻模, 公仔模型製作, 公仔生產, 客 製 化模型 公仔, 樹脂公仔製作, 矽膠模具製作, pvc模型製作, 金屬模具製作, 模具製作廠商, 簡易模具製作, 塑膠模具製作流程, 矽膠模具製作, 模具開發流程, 模具設計, 塑膠模具製作流程, 模具加工流程, 汐紫模型, 3d列印代工推薦, 3d列印矽膠模具, 橡膠3d列印, 3d列印翻模, 矽膠 翻模 代 工, 3D 列印 代工 學生, 光固化代印價格, 3d列印模型, 3d列印模型製作, 3d列印公仔, 3d列印圖檔製作, 3d列印廠商, 大型3d列印代工

Common Metals for CNC Machining: A Guide to Corrosion Resistance and Thermal Expansion Properties

Introduction

The long-term stability of metal parts is closely linked to their environmental resistance. Understanding the corrosion resistance of different metals and their expansion and contraction characteristics under temperature fluctuations is crucial to ensuring part precision and longevity in various environments. This article will explain these two key properties of commonly used CNC machining metals.

Detailed Explanation of Metal Material Properties

Stainless Steel (e.g., SUS304, SUS316)

Corrosion Resistance: Stainless steel, due to its chromium content, forms a dense passive film on its surface, imparting excellent resistance to oxidation and corrosion. It offers excellent resistance to atmospheric, freshwater, and mild acid attack. SUS316, in particular, boasts superior chloride corrosion resistance to SUS304 due to the addition of molybdenum, making it more suitable for use in coastal or saline environments.

Thermal Expansion: Stainless steel has a medium coefficient of thermal expansion among metals (approximately 17 x 10⁻⁶ K⁻¹). This means that dimensional changes are relatively stable in environments with drastic temperature fluctuations, helping to maintain tight tolerances.

Aluminum Alloy (e.g., AL6061, AL6063)

Corrosion Resistance: Aluminum alloys also form a protective oxide film in the atmosphere, providing excellent corrosion resistance, including resistance to atmospheric and freshwater attack. Surface treatments such as anodizing can significantly enhance their corrosion resistance and surface hardness.

Thermal Expansion: Aluminum alloys have a relatively high coefficient of thermal expansion (approximately 23 x 10⁻⁶ K⁻¹), approximately 1.5 times that of stainless steel. When designing precision-fitting parts for environments subject to large temperature fluctuations, this dimensional change must be taken into account to avoid seizure or loosening caused by thermal expansion and contraction.

Magnesium Alloy (e.g., AZ91D, AZ31B)

Corrosion Resistance: Magnesium alloys are chemically more reactive, making them less corrosion-resistant than stainless steel and aluminum alloys, especially in humid or acidic environments. Therefore, magnesium alloy parts typically require effective surface protection through coating, electroplating, or painting.

Thermal Expansion Properties: Magnesium alloy has the highest coefficient of thermal expansion of the three alloys (approximately 26-27 x 10⁻⁶ K⁻¹), approximately 1.7 times higher than stainless steel. This means it is most sensitive to temperature changes, and in applications requiring stringent dimensional accuracy, operating temperatures must be strictly controlled.

Key Terms

  • Corrosion Resistance: This refers to a metal’s ability to resist chemical or electrochemical attack by surrounding media (such as air, water, acids, alkalis, and salts). Excellent corrosion resistance is essential for long-term reliable component operation.
  • Coefficient of Thermal Expansion (CTE): This measures the degree to which a material’s dimensions change with temperature. The change in length per 1°C increase is its CTE. This value is crucial for the design of precision components operating in high-temperature environments.

Conclusion

When selecting a metal, it is important to fully consider its end-use environment. For applications requiring high corrosion resistance, stainless steel is undoubtedly the preferred choice. Aluminum alloys strike a good balance between corrosion resistance and cost. While magnesium alloys offer significant advantages in lightweighting, their corrosion resistance is relatively weak and their thermal expansion and contraction are more pronounced, requiring additional consideration during design.