Explain Rake angle - Angles of a drill

It is also known as helix angle .It is the angle formed between a plane containing the drill axis and the leading edge of the land. It can have a positive, negative or zero value. For a right hand flute its value is positive, for a left flute negative and for parallel flutes it is zero. For most drill the value of rake angle varies from 0 to as high as 48.However, 16 to 32 ranges is quite common for normal materials. Higher values are suitable for softer materials and lower values for harder materials. The power or torque required to rotate the drill is greatly influenced by this angle. Larger the value of this angle, lesser will be the torque required and vice-versa