Grinding Science and Parameters

GRINDING SCIENCE

An early device for dressing a sandstone grinding wheel was patented by Altzschner in 1860 .
Seminal publications by Alden and Guest started the process of bringing the art of grinding into a scientific basis [Alden1914, Guest 1915].

Grinding is a machining process that employs an abrasive grinding wheel rotating at high speed
to remove material from a softer material. In modern industry, grinding technology is highly
developed according to particular product and process requirements. Many grinding machines combine computer-controlled feed-drives and slide-way motions, allowing complex shapes to be manufactured free from manual intervention. Modern systems will usually incorporate algorithms to compensate for wheel and dressing tool wear processes. Programmable controls may also allow fast push-button set-up. Monitoring sensors and intelligent control introduce the potential for a degree of self-optimization.

Faster grinding wheel speeds and improved grinding wheel technology have allowed greatly
increased removal rates. Grinding wheel speeds have increased by two to ten times over the last century. Removal rates have increased by a similar factor and in some cases by even more. Removal rates of 30 mm3/mm/s were considered fast 50 years ago, whereas today, specific removal rates of 300 mm3/mm/s are increasingly reported for easy-to-grind materials. In some cases, removal rates exceed 1,000 mm3/mm/s. Depths of cut have increased by up to 1,000 times values possible 50 years ago. This was achieved through the introduction of creep-feed and high-efficiency deep grinding technology.

Advances in productivity have relied on increasing sophistication in the application of abrasives.
The range of abrasives employed in grinding wheels has increased with the introduction of new
ceramic abrasives based on sol gel technology, the development of superabrasive cubic boron nitride
(CBN), and diamond abrasives based on natural and synthetic diamond.

New grinding fluids and methods of delivering grinding fluid have also contributed in achieving higher removal rates while maintaining quality. Developments include high-velocity
jets, shoe nozzles, factory-centralized delivery systems, neat mineral oils, synthetic oils, vegetable
ester oils, and new additives. Minimum quantity lubrication provides an alternative to flood and
jet delivery aimed at environment-friendly manufacturing.

The problems experienced in grinding include thermal damage, rough surfaces, vibrations, chatter, wheel glazing, and rapid wheel wear. Overcoming these problems quickly and efficiently is helped by a correct understanding of the interplay of factors in grinding.

Evaluation of grinding system costs including labor, equipment, and nonproductive time is taking place now.

Grinding  Parameters

Grinding Process Parameters

2.1.1 Wheel Life
2.1.2 Redress Life
2.1.3 Cycle Time
2.2 Process Parameters
2.2.1 Uncut Chip Thickness or Grain Penetration Depth
2.2.2 Wheel Speed
2.2.3 Work Speed
2.2.4 Depth of Cut
2.2.5 Equivalent Wheel Diameter
2.2.6 Active Grit Density
2.2.7 Grit Shape Factor
2.2.8 Force per Grit
2.2.9 Specific Grinding Energy
2.2.10 Specific Removal Rate
2.2.11 Grinding Power
2.2.12 Tangential Grinding Force
2.2.13 Normal Grinding Force
2.2.14 Coefficient of Grinding
2.2.15 Surface Roughness
2.2.16 RT Roughness
2.2.17 RA Roughness
2.2.18 Rz Roughness
2.2.19 Material or Bearing Ratio
2.2.20 Peak Count
2.2.21 Comparison of Roughness Classes
2.2.22 Factors That Affect Roughness Measurements
2.2.23 Roughness Specifications on Drawings
2.2.24 Stock Removal Parameter
2.2.25 Decay Constant τ
2.2.26 G-Ratio
2.2.27 P-Ratio
2.2.28 Contact Length
2.2.29 Geometric Contact Length
2.2.30 Real Contact Length

Grinding Temperatures Related Parameters
2.3.1 Surface Temperature
2.3.2 Maximum Workpiece Surface Temperature
2.3.3 The Cmax Factor
2.3.4 The Transient Thermal Property βw
2.3.5 Workpiece Partition Ratio Rw
2.3.6 Effect of Grinding Variables on Temperature
2.3.7 Heat Convection by Coolant and Chips
2.3.8 Control of Thermal Damage