Gear Making

Workshop Technology

Mansoor Ghazi, Department of Mechanical EngineeringCollege of E&ME, NUST Pakistan

Contents

• Functions of Gears• Gear Types• Gear Nomenclature• Conventional Manufacturing Processes

GEAR FUNDAMENTALS

What Is A Gear ?

• A rotating machine part/element with teeth cut into it which is used to:– Transmit torque or– Alter velocity or– Change direction of motion or– Perform any combination of above functions

• A gear meshes with another gear(s) to form a transmission system.

• Relative motion between gears take place due to meshing of gear teeth.

Gear Types - Illustrated

Gear Nomenclature

CHECK WHAT IS GEAR MODULE !

GEAR MANUFACTURING OVERVIEW

Conventional Manufacturing ProcessesConventional Manufacturing Processes

Gear Cutting

Hobbing

Shaping

Planning

Milling

Gear Forming

Casting

Forging

Gear Finishing

Grinding

Shaving

Overview of Gear Manufacturing

• Gear cutting processes involve cutting the teeth onto a blank gear with help of shaped cutters.

• Gear forming processes are employed to produce gears without material removal. Used for mass production of low criticality gears.

• Gear finishing processes are employed after gear forming or cutting. These processes are used to impart required finishing before gear assembly.

• Majority of gears are made of carbon and low-alloy steels.

GEAR CUTTING

Gear Hobbing

• Relatively inexpensive yet fairly accurate, hobbing employs helical cutters to cut teeth into a blank gear.

• The helical cutter called ‘hob’ rotates on an axis perpendicular to the axis of blank gear.

• The hob moves radially to the depth of teeth and is then fed axially along the width of the gear teeth.

• The hob and blank gear rotate in constant timed relation with each other that determines the number of teeth being cut into the gear.

Gear Hobbing - Illustrated

Gear Shaping

• A gear of desired teeth profile is used to cut similar shaped teeth into the blank gear.

• The cutting gear rotates along with the blank gear while simultaneously reciprocating parallel to the cut teeth.

• Unlike hobbing, shaping is capable of producing internal gears.

• Worm gears cannot be produced with shaping.

Gear Shaping - Illustrated

Pinon Type Cutter Rack Type Cutter

Gear Milling - Illustrated

GEAR FORMING & FINISHING

Fundamentals

• Gear forming processes include:– Casting– Forging– Roll Forming– Stamping– Powder Metallurgy– Extrusion

• Gear forming processes are employed to mass produce relatively smaller size gears with appreciable accuracy and mechanical properties.

• Gear finishing processes are used to impart surface finishing to generated and formed gears.

THE END