Production of grinding wheels in vitrified bond and resin bond
Our abrasives are manufactured from the so-called conventional abrasives corundum / aluminium oxide or silicon carbide in vitrified bond or resin bond. Below you will find a brief overview of the manufacturing process for grinding wheels. This can be applied to all our grinding tools also, e.g. sharpening stones.
The process of manufacturing grinding wheels can be divided into 5 steps:
- Mixing
- Pressing
- Drying and Firing
- Finishing
- Quality Control
1. Mixing of grain and bond
Before the first step, the mixing of grain and bond, the bond must first be prepared. The bond components are mixed and ground. Vitrified bonds (abbreviation “V”) usually contain natural (clay, kaolin, feldspar) and artificial mineral raw materials (glass-like frits).
After this is done, the abrasive grain and bond are mixed in mixing machines. It is important to maintain the ratio of components specified in the recipe in order to ensure consistent quality. The mixture is then transported to the 2nd working step, “pressing”.
2. Pressing of grinding wheels
For pressing, the required mould is built into the press. Then the mixed material is filled into the press mould as evenly as possible. Steady filling is crucial in order to produce a homogeneous, uniform grinding wheel. Then the wheel is pressed and the so-called “Grünling” (pressed, not yet fired grinding wheel) comes out. This is carefully transferred from the press to a trolley.
3. Drying and firing of wheels
Upon pressing, the not yet fired grinding wheels are transported to the drying oven. Here the grinding wheels are dried before firing.
For firing, the wheels are placed on fireproof exchange carts and driven into the kilns. Firing process takes its time and must be scheduled. The firing takes up to a week, depending on the dimensions of the grinding wheels. For vitrified bonded grinding wheels, the kiln is first heated for several days to a firing temperature of approx. 1000-1300 °C (resin bonded grinding wheels are fired or hardened at approx. 180 °C). This firing temperature is held for a certain time and the kiln is then slowly cooled down again. Only after a determined cooling phase the grinding wheels can be removed from the kiln. However, these fired grinding wheels cannot usually be used in their present form, but require some finishing operations.
4. Finishing
Depending on the shape, the finishing or post-processing of grinding wheels can be very time-consuming and labour-intensive. The reworking of grinding wheels takes place at several work stations. In any case, the grinding wheel is planed, the bore is drilled to the required inner diameter and the grinding wheel is ground at the circumference to the required outer diameter. Grinding wheels with special geometries such as cup wheels or worm wheels for gear grinding are profiled on special dressing machines/profiling machines
5. Quality control
In the last step, the quality of the grinding wheels is checked as part of our quality control. In addition to checking the dimensions, we also check the unbalance and the break resistance / strength at increased speed (higher than working speed). Hardness is tested using various methods (see Services). The grinding wheels tested in this way are then securely packed and shipped to you.
