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Gear Cutting

Gears are used extensively for power transmission. They can be manufactured through forming or machining processes. Gear cutting involves roughing and finishing operations using tools like milling cutters, hobbing cutters, and grinders. Gear milling uses end mill cutters or disc cutters to cut the tooth spaces one at a time by indexing between cuts. Gear hobbing uses a helical cutting tool called a hob to progressively generate all the teeth in one rotation by meshing the hob and gear blank like gears. Hobbing provides high accuracy and can cut both internal and external gears.

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muhammad umar
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804 views13 pages

Gear Cutting

Gears are used extensively for power transmission. They can be manufactured through forming or machining processes. Gear cutting involves roughing and finishing operations using tools like milling cutters, hobbing cutters, and grinders. Gear milling uses end mill cutters or disc cutters to cut the tooth spaces one at a time by indexing between cuts. Gear hobbing uses a helical cutting tool called a hob to progressively generate all the teeth in one rotation by meshing the hob and gear blank like gears. Hobbing provides high accuracy and can cut both internal and external gears.

Uploaded by

muhammad umar
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© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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• Gear Cutting:

• Gears: Gears are used extensively for transmission of power. They find application
in automobiles, gear boxes, oil engines, machine tools, industrial machinery,
agricultural machinery, geared motors etc.
• Manufacturing of Gears:
They consists of two categories: Forming and Machining.
• Forming means forming of shape by plastic deformation in which volume remains
constant approximately before and after the process. It consists of direct casting,
rolling, powder metallurgy, injection molding, drawing, extrusion, stamping,
forging etc. of tooth forms in molten, powdered, or heat softened materials.
• Machining involves roughing and finishing operations involving material removal.
Cutting, Shaping, planning, slotting, broaching, Milling, Grinding, Hobbing etc.
• Machining Methods for Gear Manufacturing:
1) Forming & Generation
• Form Cutting or Forming – where the profile of the teeth are obtained as the
replica of the form of the cutting tool (edge); e.g., milling, broaching etc.
• Generating – where the complicated tooth profile are provided by much
simpler form cutting tool (edges) through rolling type, tool – work motions,
e.g., hobbing, gear shaping etc.
1.1 Gear Milling:
Forming is sub-divided into milling by disc cutters and milling by end mill cutter which
are having the shape of tooth space.
• Form milling by end mill cutter: The end mill cutter shape
conforms to tooth spacing. Each tooth is cut at a time and then
indexed for next tooth space for cutting. It is suited for a
Small volume production of low precision gears.

• Form milling by disc cutter: The disc cutter shape conforms to the
gear tooth space. Each gear needs a separate cutter. To reduce costs,
form milling method is the least accurate for all the roughing methods.

2) Shaping, Planning and Slotting


3) Broaching
• Gear Hobbing:
• Gear hobbing is a machining process in which gear teeth are progressively generated by
a series of cuts with a helical cutting tool (hob). All motions in hobbing are rotary, and
the hob and gear blank rotate continuously as in two gears meshing until all teeth are cut.

• Each hob tooth cuts its own profile depending on the shape of cutter. One rotation of the
work completes the cutting up to certain depth.
• Excellent surface finish is achieved by this method and it is widely used for production
of gears
• Advantages:
• High accuracy.
• Both internal & external gears can be cut
• Feed Directions in Gear Hobbing
• The direction of feed during hobbing operation depends, upon the type of gear to be cut.
1. Axial Feeding (for cutting spur or helical gears).
2. Radial Feeding (for cutting bevel gears).
3. Tangential Feeding (for cutting worm gears).

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