machining Machining is a manufacturing process where a desired shape or part is created using the controlled removal of material, most often metal, from a larger piece of raw material by cutting. Machining is a form of subtractive manufacturing, which util ...

, the rake angle is a parameter used in various

cutting Cutting is the separation or opening of a physical object, into two or more portions, through the application of an acutely directed force. Implements commonly used for wikt:cut, cutting are the knife and saw, or in medicine and science the sca ...

processes, describing the

angle In Euclidean geometry, an angle can refer to a number of concepts relating to the intersection of two straight Line (geometry), lines at a Point (geometry), point. Formally, an angle is a figure lying in a Euclidean plane, plane formed by two R ...

of the cutting face relative to the workpiece. There are three types of rake angles: ''positive'', ''zero'' or ''neutral'', and ''negative''. * Positive rake: A

tool A tool is an Physical object, object that can extend an individual's ability to modify features of the surrounding environment or help them accomplish a particular task. Although many Tool use by animals, animals use simple tools, only human bei ...

has a positive rake when the face of the cutting tool slopes away from the cutting edge at inner side. * Zero rake: A tool has a zero (or neutral) rake when the face of the cutting tool is perpendicular to the cutting edge at inner side. * Negative rake: A tool has a negative rake angle when the face of the cutting tool slopes away from the cutting edge at outer side. Positive rake angles generally: * Make the tool more sharp and pointed. This reduces the strength of the tool, as the small included angle in the tip may cause it to chip away. * Reduce cutting forces and power requirements. * Helps in the formation of continuous chips in

ductile Ductility refers to the ability of a material to sustain significant plastic deformation before fracture. Plastic deformation is the permanent distortion of a material under applied stress, as opposed to elastic deformation, which is reversi ...

materials. * Can help avoid the formation of a built-up edge. Negative rake angles generally: * Increase the strength of the cutting edge. The tool is more blunt. * Increases the cutting force. * Increases the power required for a cut. * Can increase

friction Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. Types of friction include dry, fluid, lubricated, skin, and internal -- an incomplete list. The study of t ...

, resulting in higher temperatures. * Can improve

surface finish Surface finish, also known as surface texture or surface topography, is the nature of a interface (matter), surface as defined by the three characteristics of lay, surface roughness, and waviness.. It comprises the small, local deviations of a ...

. Zero rake angles: * Easier to manufacture. * Easier to resharpen. * Less power and cutting forces than a negative raked tool. * Chip will wear and 'crater' the rake face.

Recommended rake angles

Recommended rake angles can vary depending on the material being cut, tool material, depth of cut, cutting speed, machine, setup and process. This table summarizes recommended rake angles for: single-point turning on a lathe, drilling,

milling Milling may refer to: * Milling (minting), forming narrow ridges around the edge of a coin * Milling (grinding), breaking solid materials into smaller pieces by grinding, crushing, or cutting in a mill * Milling (machining), a process of using ro ...

, and sawing.

References

Cutting tools Metalworking terminology {{Metalworking-stub