Grinding wheels in CBN and ceramic-bounded diamond

Mole Abrasive Ermoli Srl, present on the abrasives market for over 125 years, produces grinding wheels in CBN and ceramic-bounded diamond.

CBN GRINDING WHEELS

CBN (cubic boron nitride) is produced by synthesis with technology similar to diamond.
It is less hard but more resistant to the temperature of the diamond and it does not contain carbon.
Considered the best abrasive for working hard steels and cast irons, the ceramic binder is the best way to fully exploit its characteristics. These grindstones, unlike resin, metal or electrolyte, can be easily revived or profiled during processing, thus allowing continuous cycles that would otherwise be impossible.

The structure is rather open, with controlled porosity and consequent better refrigeration, which translates into increased removal capacity and reduced grinding consumption.
These characteristics, together with the properties of the CBN abrasive, allow to obtain very high performances, with savings on the processing times that largely compensate the greater cost of the product.

The optimal application is internal grinding of steels with hardness higher than 58-60 HRC.
In this case, excellent removal is obtained, far superior to conventional abrasives but also to CBN resinoid and metal bonding wheels.

DIAMOND GRINDING WHEELS

Even the diamond is suitable, for some processes, to be agglomerated with ceramic binders.
Here too, the resulting porous structure allows the optimization of refrigeration, which is very important for these grinding wheels because the diamond above 700 ° C turns into graphite and completely loses its abrasive properties.
The use of exclusive ceramic binders does not allow to obtain very hard wheels suitable for example to sharpen tools.
The company instead produces very suitable wheels for machining with a large contact surface, for example for vertical axis, continuous-rim or grinding or for grinding with pads or segments. Excellent results have been obtained with pad-based wheels in grinding spherical valves with a hard metal surface used in the oil industry.

MARKING OF GRINDING WHEELS

The company's marking system accurately classifies all the characteristics and specifications of their wheels.
For example, the code 100x20x25 - F20x5 - 1A1 - 2B 91 C100 N5 VB indicates:

 PARAMETERS OF USE, DRESSING COOLANTS

Ermoli Srl can recommend suitable operating parameters (such as cutting depth per pass, workpiece rotation, increment and peripheral speed of the grinding wheel), which can effect their machining performance. With ceramic bond, the wheels can be repaired or re-profiled directly on the machine, using small diamond wheels that rotate at high speed, diamond rollers or crushers, dressers based on pads or brake-controlled machines.
These kind of operations usually require a large amounts of coolant, especially after the use of dressing tools controlled by brakes or machines, to reset the grinding wheel with corundum abrasive sticks to restore full grinding capacity.
The company suggest the use of light and low viscosity straight oil that acts as a lubricant to reduce friction, to extend the life of the grinding wheel and to improve the grade of finish. It is possible to use various types of emulsifiable oils, but always in relatively high concentrations (at least 5-6%). Dry processing must be avoided.