How can you accurately represent surface treatments in a mechanical drawing?

1 Surface treatment symbols

One of the most common methods to represent surface treatments in a mechanical drawing is to use surface treatment symbols. These are graphical elements that indicate the type, location, and extent of the surface treatment applied to a part or a feature. Surface treatment symbols consist of a circle with a letter or a number inside, and sometimes a line or a leader connecting the symbol to the part or the feature. The letter or the number inside the circle corresponds to a specific surface treatment code, which can be found in various standards, such as ISO 1302, ANSI Y14.36, and ASME Y14.6.

2 Surface treatment notes

Another method to represent surface treatments in a mechanical drawing is to use surface treatment notes. These are textual descriptions that specify the details of the surface treatment, such as the material, the thickness, the method, the color, and the quality. Surface treatment notes can be placed directly on the drawing, near the part or the feature that requires the treatment, or in a general notes section, where they apply to the whole drawing or a group of parts or features. Surface treatment notes should be clear, concise, and consistent, and follow the conventions of the standard or the specification used.

3 Surface texture symbols

A special type of surface treatment that requires its own representation method is surface texture. Surface texture is the variation of the surface geometry, which affects the friction, wear, and appearance of a part or a feature. Surface texture can be created intentionally by machining, grinding, honing, or other processes, or unintentionally by casting, forging, or welding. To represent surface texture in a mechanical drawing, surface texture symbols are used. These are complex symbols that consist of several elements, such as a basic symbol, a modifier, a value, and a datum reference. Surface texture symbols indicate the roughness, waviness, lay, and direction of the surface texture, as well as the sampling length and the evaluation method.

4 Surface treatment views

Sometimes, surface treatment symbols and notes are not enough to represent surface treatments in a mechanical drawing, especially when the surface treatment affects the shape, size, or contour of a part or a feature. In such cases, surface treatment views are used. These are additional views that show the part or the feature before and after the surface treatment, using dashed lines or different line types to indicate the difference. Surface treatment views can also show cross-sections or details of the surface treatment, such as the coating thickness or the pattern. Surface treatment views should be labeled and referenced properly, and aligned with the main views of the drawing.

5 Surface treatment layers

Another way to represent surface treatments in a mechanical drawing, especially when using computer-aided design (CAD) software, is to use surface treatment layers. These are virtual layers that can be added, removed, or modified on the drawing, without affecting the geometry of the part or the feature. Surface treatment layers can have different colors, line types, line weights, and visibility, to distinguish them from the base layer of the drawing. Surface treatment layers can also have attributes, such as names, codes, or notes, to describe the surface treatment details. Surface treatment layers can help to organize, edit, and print the drawing, as well as to export it to other formats or applications.

6 Surface treatment best practices

To represent surface treatments in a mechanical drawing accurately, it is not enough to know the methods and the symbols, but also to follow some best practices. When deciding on a method and symbol for the surface treatment, consider the type, location, extent, and purpose of the treatment. Additionally, adhere to the standards and specifications that apply to the surface treatment, such as ISO, ANSI, ASME, ASTM, or MIL-STD. Avoid ambiguity, redundancy, or contradiction in the surface treatment representation and make sure it is consistent with the rest of the drawing and design intent. Ensure that fonts, sizes, and styles for symbols and notes are clear and legible without overlapping or crowding them on the drawing. Finally, check and verify the surface treatment representation before finalizing the drawing. Utilize appropriate tools and methods to measure and inspect the quality of the surface treatment.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?