Rake angle is a parameter used in various
cutting and machining processes, describing the angle of the cutting face relative to the work. There are three types of rake angles: ''positive'', ''zero'' or ''neutral'', and ''negative''.
* Positive rake: A tool 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 is a mechanical property commonly described as a material's amenability to drawing (e.g. into wire). In materials science, ductility is defined by the degree to which a material can sustain plastic deformation under tensile stres ...
materials.
* Can help avoid the formation of a
built-up edge.
Negative rake angles generally:
* Increasing 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, resulting in higher temperatures.
* Can improve surface finish.
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
The phrase speeds and feeds or feeds and speeds refers to two separate velocities in machine tool practice, cutting speed and feed rate. They are often considered as a pair because of their combined effect on the cutting process. Each, however, ...
, machine, setup and process. This table summarizes recommended rake angles for: single-point
turning
Turning is a machining process in which a cutting tool, typically a non-rotary tool bit, describes a helix toolpath by moving more or less linearly while the workpiece rotates.
Usually the term "turning" is reserved for the generation ...
on a
lathe
A lathe () is a machine tool that rotates a workpiece about an axis of rotation to perform various operations such as cutting, sanding, knurling, drilling, deformation, facing, and turning, with tools that are applied to the workpiece to c ...
, drilling,
milling, and sawing.
References
Cutting tools
Metalworking terminology
{{Metalworking-stub