Construction and working of Gear finishing process

 TABLE OF CONTENTS

    1. Gear burnishing

    2. Gear shaving

    3. Gear lapping

    4. Gear grinding

There are various gear finishing processes available. They are as follows

1. Gear burnishing
2. Gear shaving
3. Gear lapping
4. Gear grinding

In this article students may able to understand about the various gear finishing processes

1. Gear burnishing

• This is a method of finishing of gear teeth which are not hardened. 
• This is a cold working process. 
• This method is used to improve the surface finish of the gear teeth. 
• This also increases the hardened at the teeth surface. 
• In burnishing, the gear to be finished is rolled between three burnishing gear. 
• They are arranged at 120° position around the work gear.
•  Power drive is given to one of the burnishing gears. 
•  The teeth are finished on both the faces uniformly. 
• A lubricant is applied between the teeth to get smooth surface finish. 
• They also reduce friction and heat.

2. Gear shaving

 

• This is the most common method of gear finishing.
• In this method, a very hard gear shaving cutter is used to remove fine chips from the gear teeth. 
• The work gear is held between centres and is free to rotate. 
• The shaving cutter meshes with the work gear. 
• The axis of the cutter is inclined to the gear axis at an angle equal to the helix angle of the cutter (θ). 
• When the gear and the cutter rotate, the cutter reciprocates in a direction parallel to the gear axis. 
• The cutting edges of the shaving cutter remove burns, nicks and high points on the surface of the work gear. 

3. Gear lapping

 

• The  hardened   gears   are  finishing  accurately  by  lapping  process
• .Lapping removes very small amount of metal (not more than 0.05 mm). 
• The work gear is rolled between three lapping gears. 
• The lapping gears are made of cast iron. 
• The lapping gears are arranged at 120° position around the work gear.
• The axis of the two lapping gears (2&3) are inclined at about 4° to the work gear axis. 
• The axis of the other lapping gear (1) is parallel to the work gear axis. 
• The drive is given through this gear.
•  When gear rotate, a lapping compound is applied between them. 
• The compound is a mixture of a very fine abrasive powder and kerosene. 
• The lapping process improves the tooth contact.

4. Gear grinding

• Gear grinding is used for finishing gears after hardening. Gear grinding is done for
• Increasing the accuracy of gears also Improving the surface finish.
• There are two method of gear grinding. 
• They are Formed wheel grinding , Generation gear grinding

Formed wheel grinding

• In formed wheel grinding, the grinding wheel is dressed to the form of tooth space of the gear.
• The grinding wheel is moved parallel to the work gear axis. 
• After grinding one tooth space, the work gear is indexed to the next tooth space. 
• About three passes are required to finish the tooth space. 
• Proper coolant should be used while finishing by grinding.