The plain end milling process requires ________ machine toolQuestion 5Select one:horizontaluniversalCNCverticalstiff

The plain end milling process can be performed on various types of machine tools. However, without specific context or additional information, it's difficult to definitively answer this question. Here's a brief overview of the options:

1. Horizontal: This type of machine tool has a horizontally oriented spindle. End mills are often used on these machines to perform milling operations.

2. Universal: Universal machines have a swivel table, which gives them the ability to mill at various angles. End mills can also be used on these machines.

3. CNC: CNC stands for Computer Numerical Control. This type of machine tool is controlled by a computer, which allows for high precision. End mills are commonly used on CNC machines.

4. Vertical: This type of machine tool has a vertically oriented spindle. End mills are often used on these machines to perform milling operations.

5. Stiff: This isn't a type of machine tool, but rather a characteristic. A stiff machine tool would have less vibration and could potentially provide more accurate results.

Without more context, it's difficult to definitively say which machine tool is required for the plain end milling process. It could potentially be any of the first four options, depending on the specific requirements of the process.