Which type of marking tool is recommended for marking fastener locations on parts?

The recommendation for using a non-graphite pencil for marking fastener locations on parts is based on several important factors that align with best practices in aerospace assembly. Non-graphite pencils are preferable because they do not contain metal or graphite, which could potentially contaminate sensitive components or surfaces, leading to failure or safety issues. They provide a clear and precise mark that is easy to read during the assembly and inspection processes.

In addition, the marks made by non-graphite pencils can also be easily erased or cleaned off without leaving residue that could interfere with other processes, such as painting or coating. This is critical in aerospace applications where the integrity of surfaces and the finish of parts are vital for performance and safety.

Other marking tools, such as chalk or fine tip markers, may not provide the necessary precision or could leave marks that are difficult to remove or might smudge. Permanent markers, while bold and easily visible, could introduce unwanted materials onto the surface that may affect the part's properties or violate specific aerospace standards regarding contamination. Thus, non-graphite pencils represent a safe and practical choice for marking fastener locations in an aerospace context.