Grinding heads

Today's market for small abrasive tools offers a vast selection of grinding heads from various manufacturers. Based on specific application conditions and situations, it's easy to select a grinding head with the required size, shape, grit size, and hardness.

Types and designations of grinding heads

According to DIN69170, grinding heads are produced in the following shapes:

Cylindrical	ZY
Cylindrospherical	WR
Pointed conical	WK
Conical (with a rounded top)	KE
Centrospherical	SP
Spherical	KU
Cup-shaped	TO

Grinding head mandrels are made of structural carbon or alloy steel and, depending on the head size, come in 3mm diameter and a standard 30mm length; 6mm and 8mm diameter and a standard 40mm length; or extended. In the latter case, the shank length varies by manufacturer.

Material of grinding heads

A grinding head consists of a pre-sized abrasive powder bonded with a binder and a steel shank. They are made from the same abrasives and have the same designation characteristics as all other bonded abrasive tools. Grinding heads are typically made from various types of fused alumina (normal fused alumina, white fused alumina, chromium fused alumina, chromium-titanium fused alumina, etc.) or mixtures thereof. Silicon carbide (black and green) and ceramic grain are also used. A ceramic bond is most commonly used for grinding heads, while bakelite is less common. The choice of head material depends on the workpiece being processed.

The choice of grinding head grit is influenced not only by the type of grinding (coarse or fine), but also by the head diameter. For example, you won't find small-diameter grinding heads (e.g., 4-5 mm) made of coarse F36-F46 grit.

The hardness of an abrasive tool characterizes the ability of the bond to retain the abrasive grains during machining. The higher the hardness, the more firmly the grains are held in the abrasive head. At the same time, a hard bond increases the temperature in the cutting zone and requires higher pressure on the tool during machining.

How to choose the optimal grinding head?

The grinding head's bond, hardness, and grain mixture all have varying effects on grinding performance, tool life, and aggressiveness. Therefore, when selecting a grinding head's characteristics, consider the following criteria:

When processing planes, softer heads should be selected, since they are subject to less specific pressure and a soft head will obviously provide higher removal productivity;
When processing edges or shaped surfaces, heads with a harder bond should be selected, as long-term tool shape retention is paramount in this case. Furthermore, the specific pressure during edge processing is significantly higher than when processing flat surfaces;
for harder grinding material, a head with a softer bond is selected, which will provide productivity with less pressure on the tool;
For grinding materials that are sensitive to temperature changes, a head with a softer bond is also selected.
The higher the actual cutting speed of the tool, the lower the head hardness should be used, and, conversely, for low machining speeds, harder heads are used.