What is the purpose of a tool holder?

The primary purpose of a tool holder is to securely hold the cutting tool in place during machining operations. This function is essential for ensuring precision and stability while the cutting tool interacts with the workpiece. A tool holder must be robust and precise to maintain the alignment and position of the cutting tool, which directly impacts the quality of the machining process. When a cutting tool is firmly held, it can effectively cut through materials without unnecessary vibration or movement, leading to better surface finish and accuracy in the final product.

The other options relate to different functions that are not the primary purpose of a tool holder. For instance, while drilling holes in materials is a task performed by the cutting tool itself, it does not reflect the tool holder's role. Measuring the dimensions of a workpiece is performed by measuring tools like calipers and micrometers, not the tool holder. Lubrication of the cutting tool typically involves separate systems designed specifically for cooling and reducing friction during machining, rather than being a function of the tool holder.