![]() ![]() A roughing cutter may have serrated teeth for breaking the chips of material into smaller pieces. These teeth leave a rough surface behind. A finishing cutter may have a large number (four or more) teeth for removing material carefully. Coatings: The right tool coatings can have a great influence on the cutting process by increasing cutting speed and tool life, and improving the surface finish.However, the large number of flutes leaves little room for efficient swarf removal, so they are less appropriate for removing large amounts of material. Polycrystalline diamond (PCD) is an exceptionally hard coating used on cutters that must withstand high abrasive wear. A PCD coated tool may last up to 100 times longer than an uncoated tool. ![]() However, the coating cannot be used at temperatures above 600 degrees C, or on ferrous metals. Tools for machining aluminium are sometimes given a coating of TiAlN. Aluminium is a relatively sticky metal, and can weld itself to the teeth of tools, causing them to appear blunt. Shank: The shank is the cylindrical (non-fluted) part of the tool which is used to hold and locate it in the tool holder.However, it tends not to stick to TiAlN, allowing the tool to be used for much longer in aluminium. A shank may be perfectly round, and held by friction, or it may have a Weldon Flat, where a set screw, also known as a grub screw, makes contact for increased torque without the tool slipping. The diameter may be different from the diameter of the cutting part of the tool, so that it can be held by a standard tool holder.§ The length of the shank might also be available in different sizes, with relatively short shanks (about 1.5x diameter) called "stub", long (5x diameter), extra long (8x diameter) and extra extra long (12x diameter).Įnd mills (middle row in image) are those tools that have cutting teeth at one end, as well as on the sides. The words end mill are generally used to refer to flat bottomed cutters, but also include rounded cutters (referred to as ball nosed) and radiused cutters (referred to as bull nose, or torus). They are usually made from high speed steel or cemented carbide, and have one or more flutes. They are the most common tool used in a vertical mill. Roughing end mills quickly remove large amounts of material. This kind of end mill utilizes a wavy tooth form cut on the periphery. These wavy teeth act as many successive cutting edges producing many small chips. This results in a relatively rough surface finish, but the swarf takes the form of short thin sections and is more manageable than a thicker more ribbon-like section, resulting in smaller chips that are easier to clear. During cutting, multiple teeth are in simultaneous contact with the workpiece, reducing chatter and vibration. Rapid stock removal with heavy milling cuts is sometimes called hogging. ![]()
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