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HELICAL GEAR
Elements of teeth are twisted or helical.
Used for connecting shaft at an angle in same or different planes.
Smooth acting gearing.
MITRE GEARING
When the shafts are at 90º and two bevel gears are of same size, known as “miter gears”.
SPUR GEAR
Teeth element parallel to rotating shafts are known as spur gear.
Used to transmit power and motion through parallel shafts.
HERRINGBONE GEAR
It’s equivalent to two helical gears,one having a right hand and other a left hand helix.
It’s used in heavy duty machines like steel roll mills.
BEVEL GEAR
When two shafts are in same plane but at another,bevel gears an angle with one are used.
It’s a frustum of a cone having all elements of teeth intersecting at a point.
DIRECTION OF ROTATION OF CUTTER
Down milling Direction of rotation
of cutter and work piece feed in same direction.
METHOD OF MOUNTING THE CUTTER
Arbor type cutter. Cutter mounted on
arbor and arbor size selected as per cutter bore size.
DIRECTION OF HELIX OF CUTTER
Cutter axis is held vertically and the helix is towards the right side is called a right hand helix cutter.
DIRECTION OF HELIX OF
CUTTER
Helix is towards the left side ,it is called a left hand helix cutter.
DIRECTION OF HELIX OF CUTTER
When a cutter has a helix and a cut of the same hand,this force will pull the cutter away form the spindle.
HYPOID GEARS
Modification of a bevel gear where the shaft are at right angle but they don’t intersect as do the shaft for bevel gears.
RACK GEARS
Rack gears are straight and have no curvature.
Used for feeding mechanism and reciprocating drives.
BASIC ELEMENTS OF SPUR GEAR
Pitch circle. Circular pitch. Pitch circle diameter. Addendum circle. Root circle. Addendum. Dedendum . Hand. Clearance. Working depth. Flank of tooth.
BASIC ELEMENTS OF SPURGEAR
Diametral pitch. Pressure angle
WORM GEAR
When a large speed reduction is desired worm gear are used.
Worm will always be the driver & used for teeth mechanism.s
ANNULAR GEAR
A gear with internal teeth is known as annular gear are used in automobiles.
CLERANCE ANGLE
This is the clearance or relief provided behind the cutting edge.
It prevents rubbing as well, thus reducing cutting force.
RAKE ANGLE
Angle given in front of the leading edge of tool.
It’s reduce the pressure of the chip on the tool face.
Positive rake angles produce better finish at low speeds.
RAKE ANGLE
Zero and negative rake angle tools are stronger and have a long tool life.