Cutting tools
🛠️ Cutting Tools | Sakkary Machinery
Overview of Metal Cutting and Tool Materials
Classification and Properties of Industrial Cutting Tools
Metal-cutting tools are classified as single point or multiple point. A single-point cutting tool can be used for increasing the size of holes, or boring. Turning and boring are performed on lathes and boring mills. Multiple-point cutting tools have two or more cutting edges and include milling cutters, drills, and broaches.
There are two types of operation; either the tool is moving on a straight path against the stationary workpiece, as on a shaper, or the workpiece is moving against the stationary tool, as on a planer. Relief or clearance angles must be provided to prevent the tool surface below the cutting edge from rubbing against the workpiece. Rake angles are often provided on cutting tools to cause a wedging action in the formation of chips and to reduce friction and heat.
Tool Materials
In order to remove chips from a workpiece, a cutting tool must be harder than the workpiece and must maintain a cutting edge at the temperature produced by the friction of the cutting action.
- Carbon Steel: The earliest material used, with a carbon content ranging from 1 to 1.2 percent. It is comparatively inexpensive but loses cutting ability at temperatures around $400^\circ \text{F}$ ($205^\circ \text{C}$).
- High-Speed Steel (HSS): Introduced in 1900, it allowed operation at two or three times the speeds of carbon steel. A common type contains $18\%$ tungsten, $4\%$ chromium, $1\%$ vanadium, and $0.5–0.8\%$ carbon.
- Cast Alloys: Nonferrous alloys containing cobalt, chromium, and tungsten. They are effective in penetrating the hard skin on cast iron and retain their cutting ability even when red hot.
- Cemented Tungsten Carbide: First used in 1926. Its principal ingredient is finely divided tungsten carbide held in a binder of cobalt. Its hardness approaches that of a diamond, and it operates at cutting speeds many times higher than HSS.
- Oxides: Ceramic or oxide tool tips, one of the newest developments. They consist primarily of fine aluminum oxide grains bonded together.
- Diamonds: Used for taking light finishing cuts at high speed on hard or abrasive materials, and for finish-boring bronze and babbitt-metal bearings.
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