What is the difference between chemical milling and chemical etching?

Chemical milling and chemical etching are related processes that involve selectively removing material from the surface of a material using chemical etchants. While they share similarities, there are distinct differences between chemical milling and chemical etching:

Chemical Milling:
1. Purpose: Chemical milling is primarily used to remove specific amounts of material from large, relatively thick metal sheets or plates. It is commonly used in aerospace, automotive, and other industries to produce complex parts with precise thickness requirements.

2. Depth Control: Chemical milling focuses on achieving precise material removal depths. The etchant is applied for a controlled period to remove material uniformly from the entire surface, resulting in a consistent thickness reduction.

3. Tolerances and Specifications: Chemical milling is often employed when tight tolerances and precise specifications for thickness, flatness, and dimensional accuracy are required. It allows for the removal of uniform thickness across the entire surface of the metal sheet.

4. Masking: In chemical milling, masking techniques are used to protect certain areas of the metal sheet from the etchant. Masking materials like photoresist films or tapes are applied to define the areas that should not be milled, ensuring accuracy and preventing over-etching.

5. Industrial Scale: Chemical milling is typically performed on an industrial scale, often using large tanks or immersion systems. The process is commonly used for mass production of parts or components.

Chemical Etching:
1. Purpose: Chemical etching is employed to create intricate designs, patterns, or markings on the surface of metals. It is utilized in various industries for decorative, functional, or identification purposes.

2. Design and Detail: Chemical etching focuses on achieving precise and detailed designs on the surface of the material. It allows for the creation of complex patterns, logos, text, or other desired artwork with high accuracy and fine details.

3. Masking: In chemical etching, masking materials or techniques are used to protect certain areas of the metal surface that should not be etched. The masking materials are applied to define the areas where the design or pattern will be preserved.

4. Small-Scale Production: Chemical etching can be performed on a smaller scale, making it suitable for custom or low-volume production. It is often used for prototyping, customization, or one-off designs.

5. Material Thickness: Chemical etching can be applied to various material thicknesses, ranging from thin foils to thicker sheets. It allows for selective material removal and does not focus on achieving uniform thickness reduction like chemical milling.

Overall, the key difference between chemical milling and chemical etching lies in their primary purposes and applications. Chemical milling is primarily used to achieve controlled material thickness reduction, while chemical etching is focused on creating precise designs and patterns on the surface of the material.