What is the definition of "G ratio"?
Cubic volume of stock removed divided by the cubic volume of wheel wear. In conventional grinding, the ratio ranges from 20:1 to 80:1.

Learn more about G ratio in the class Grinding Variables 200 below.


Abrasives Training


Class Information
Tooling U-SME classes are offered at the beginner, intermediate, and advanced levels. The typical class consists of 12 to 25 lessons and will take approximately one hour to complete.
Class Name:Grinding Variables 200
Description:This class identifies the most common variables that occur during grinding, with an emphasis on speeds and feeds. Includes an Interactive Lab.
Prerequisites: 250110  250120 
Difficulty:Intermediate
Number of Lessons:13
Language:English, Spanish
 
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Class Outline
  • Objectives
  • Managing Grinding Variables
  • Material Removal and Surface Finish
  • G Ratio
  • Feed
  • Infeed
  • Speed vs. Feed
  • Wheel Speed
  • Wheel Behavior
  • Heat
  • Grinding Fluid
  • Workpiece Material Characteristics
  • Summary
  
Class Objectives
  • List examples of common grinding variables.
  • Describe the balance between material removal and surface finish.
  • Define G ratio.
  • Identify the different types of feed.
  • Explain the relationship between infeed and the arc of cut.
  • Distinguish between speed and feed.
  • Understand the limitations of changing wheel speeds.
  • Explain how operational changes can affect wheel behavior.
  • Describe the negative results heat can produce.
  • Identify the purposes of grinding fluid.
  • Explain how workpiece material characteristics influence grinding.

Class Vocabulary

Vocabulary TermDefinition
arc of cut The area of contact between the wheel and the workpiece. Also called the cutting zone.
chemical resistance The ability to resist chemical changes. Chemically resistant materials do not react with abrasives or their bonds.
creep feed grinding A grinding method in which the depth of cut is increased while the feed rate is decreased compared with normal grinding practices. It is used for large amounts of material removal.
cross feed The lateral feed of the grinding wheel or table.
cutting zone The area of contact between the wheel and the workpiece. Also called the arc of cut.
feed The rate of movement of a workpiece, table, wheelhead or other grinding component. Feeds often involve linear movement from one point to another and are measured in inches per minute.
finish passes Movement of a grinding wheel across a workpiece that improves surface finish with minimal removal of material.
G ratio Cubic volume of stock removed divided by the cubic volume of wheel wear. In conventional grinding, the ratio ranges from 20:1 to 80:1.
glazing The unwanted formation of a smooth surface on a grinding wheel. Glazing occurs when the heat from grinding reacts with a loaded wheel.
grinding The use of an abrasive to wear away at the surface of a workpiece and change its shape.
grinding fluid A liquid used during grinding to clean, cool, and lubricate the site.
horsepower A unit of power used to describe machine strength. One horsepower equals 746 watts.
inches per minute The number of linear inches that a component travels in one minute. Inches per minute (ipm) is a measurement of feed.
infeed The feed of the grinding wheel into the workpiece.
oxidation Deposits that form on the surface of a workpiece when grinding heat and/or pressures combine with fluids to create a chemical reaction.
regulating wheel A wheel, usually made of plastic or rubber bond, used during centerless grinding to rotate the workpiece and pull it through the operation.
revolutions per minute The number of times a component rotates 360 degrees, or in a complete circle, in one minute. Revolutions per minute (rpm) is a measurement of speed.
rotary table A rotating, cylindrical surface on which the workpiece rests during grinding.
rough passes Movement of a grinding wheel across a workpiece that removes material without regard to surface finish.
speed The rate of rotational movement of the grinding wheel, rotary table, or regulating wheel. Speeds are measured in revolutions per minute or surface feet per minute.
surface feet per minute The number of linear feet that a location on a rotating component travels in one minute. Though surface feet per minute (sfm or fpm) represents a linear distance, it is a measurement of speed.
through feed The feed of a workpiece as it travels through an operation. Often used to describe workpiece motion in centerless grinding.
tolerance The unwanted but acceptable deviation from the desired dimension.
wheel head The part of the grinding machine on which the wheel is mounted.
work feed The feed of the workpiece past the grinding wheel.