Hardness of grinding wheels

The hardness denotes the strength by which each particle of grain is retained by the bonding within the grinding wheel. An alphabetical letter identifies the hardness whereby A represents very soft and Z very hard.

Structure

The structure of a grinding wheel is denoted by a number from 1 to 18 which relates to the spacing between each individual grain particle. Low numbers mean small spacing, higher numbers mean large spacing.

Pore inducers

The volume of pores is dictated by the percentages of grain and bonding used. More coolant is present in the grinding zone by using an open structured wheel; this reduces the risk of burning. The structure of a grinding wheel can be controlled by the use of pore inducers i.e. type, size and amount to suit the individual application.