Which tool is necessary for cleaning cutting grooves of a file?

The tool essential for cleaning the cutting grooves of a file is a file card. A file card is designed specifically for this purpose, featuring bristles that can effectively remove metal shavings and debris that accumulate in the grooves during the filing process. Keeping the file clean is crucial to maintain its effectiveness and extend its life, as clogged grooves lead to poorer performance and potential damage over time.

Other tools mentioned, such as a flaring tool, flare wrench, and gate valve, are used in different applications and do not serve the function of cleaning files. Flaring tools are typically used for creating flared ends on pipes, flare wrenches are designed for tightening or loosening flare fittings, and gate valves are used to control fluid flow in piping systems. None of these tools are appropriate for maintaining a file's cutting efficiency.