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What Are the Different Types of Milling Tools?

T. L. Childree
T. L. Childree

Milling machines utilize several different types of milling tools for particular applications. The most common types of milling tools are end mills and slot drills which perform similar actions. Roughing end mills create irregular cuts and slab mills produce wide cuts. Hollow mills are used to smooth cylinders while ball nose cutters produce three dimensional shapes. A woodruff cutter creates keyways and an involute gear cutter is shaped like a circular saw blade.

A milling machine is designed to shape a surface by feeding the workpiece against various types of milling tools. These milling tools are equipped with cutting teeth and rotate against the workpiece. Most of these tools are constructed of a heat resistant, high-speed steel material. Each tool is designed to quickly and efficiently perform a specific application. Several different milling tools may be needed to shape and finish a single workpiece.


An end mill is one of the most commonly used milling tools. It has cutting teeth at one end and along the sides. Its appearance is similar to a drill bit and it is typically utilized with vertical milling machines. A slot drill has two fluted cutters with a single tooth in the center and is typically employed for making slotted openings. This milling tool is able to drill directly into a workpiece.

A roughing end mill is also referred to as a ripping cutter. It is useful for cutting out large pieces of material. A roughing end mill is fitted with a series of wavy cutting teeth and typically leaves a rough finished surface. Its wavy teeth are designed to minimize vibrations during use. This tool is known for its quiet operation and zigzag cutting pattern.

Slab mills are utilized for making cuts along the outside edge of a workpiece. This cylinder-shaped milling tool has its cutting teeth mounted at a helix angle. This mounting angle allows the tool to distribute its cutting force slowly. A slab mill is typically used with a horizontal milling machine to quickly cut large, flat surfaces.

A hollow mill tool is pipe-shaped with interior cutting teeth. It is primarily used to finish the exterior of cylindrical workpieces. A ball nose milling tool creates three-dimensional shapes and forms. It is similar to a slot drill and is often referred to as a ball mill. A woodruff milling tool is used for making keyways in a workpiece.

Involute gear cutters are versatile milling tools shaped like a circular saw blade. They are available in a variety of different sizes for various milling applications. This tool has a total of 12 cutting teeth arranged around its circumference. An involute gear cutter’s size options make it suitable for a variety of milling tasks.

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