What is the primary function of a work holding device in CNC milling?

The primary function of a work holding device in CNC milling is to securely fasten the workpiece to the machine table. This is essential for maintaining stability and precision during the milling process. When the workpiece is securely held in place, it reduces the risk of movement or vibration, which can lead to inaccuracies in the machining operation. Proper work holding ensures that the tool can effectively cut into the material at the correct depth and angle, resulting in a high-quality final product.

The other options represent functions that are not directly related to the purpose of work holding devices. Manual adjustments, while important for setup and operation, do not pertain to the primary function of securely holding the workpiece. Increasing the speed of the milling process is more about the machine's controls and settings rather than how the workpiece is held. Similarly, regulating the temperature of the workpiece is generally managed through machining parameters such as feed rate and cutting fluid use, rather than through the work holding itself. Thus, the function of a work holding device is specifically focused on providing a firm hold on the workpiece to ensure accuracy and consistency in machining.