The natural hard rock granite is a basic deep rock that has formed over hundreds of thousands of years from molten material from the earth's crust. Due to its history of formation, it is high-strength, extremely homogeneous and fine-pored and has a dense structure. As a result, granite has low thermal expansion and thermal conductivity. It is virtually stress-free and retains its shape over a long period of time. The material also has high abrasion resistance.
These specifications make the material a perfect base material for precise measuring instruments and machine parts. The crystalline structure results in very good grinding and lapping properties. Compared to metallic materials, the coefficient of thermal expansion is very low. In addition, stone is naturally corrosion-free, so that no time is required for maintenance work and degreasing.
How is granite formed?
Granites in a wide variety of shapes and compositions were formed millions of years ago by the very slow solidification of molten rock (magma) in the earth's lower crust. They were found at a depth of more than 2 kilometers below the earth's surface. Granite is therefore a basic deep rock and is also known technically as "PLUTONITE".
Tectonic movements and erosion of the rock above bring the solidified granite to the surface, where it can be mined in large quarries around the world.
These formation processes are still taking place today. However, it takes another 10 to 15 million years for the solidified and naturally hard rock to become granite.
Origin, quarrying, quality assurance
Stones that meet our requirements are mainly quarried in Europe, Asia and Africa. We work closely with quarries in France, Asia and South Africa. The supply can therefore be classified as relatively crisis-proof.
For our products, we select granites that are as uniformly structured as possible. All blanks undergo strict selection processes in which actual defects are consistently sorted out.
Nevertheless, the blanks may show differences in color. Like all natural materials, our stone is subject to a variety of influences, such as immense pressures and temperatures. They change, shape and ultimately turn it into the material that we refine today. These processes do not take place under "clean room conditions", but in nature. This can result in color deviations, but these do not affect the physical properties and do not impair accuracy.
How sustainable is granite?
Natural hard stone and sustainability go together perfectly. The material has grown over millions of years and can be found in nature almost ready-made. This means that no energy is required for its production today, only for extraction, transportation and processing. However, compared to other materials, such as steel, plastic or ceramics, which are assembled from various raw materials, this energy requirement is also very low. In terms of the global warming potential of the primary energy requirement, the CO2 emissions of granite are significantly lower than the CO2 emissions of other materials.
Granite also performs excellently in terms of durability and disposal. There is hardly any other material that has a longer service life than natural hard stone. Many measuring tools and assemblies made of natural hard stone, such as machine beds and measuring tools, can be easily refurbished time and time again. Signs of wear can simply be ground off and lapped, making the component as good as new. PLANOLITH offers this calibration service both directly at the customer's premises and as a retrofit in the factory.
Finally, unusable products made of natural hard stone/granite can still be processed into gravel and chippings. The material does not contain any harmful substances, so that nothing stands in the way of a new, completely different use.
Technical data granite
| Property | Value |
|---|---|
| Bulk density | 2.99 kg/dm³ |
| E-modulus | 100,000 - 120,000 N/mm² |
| Compressive strength | 280 N/mm² |
| Bending tensile strength | 13 - 22 N/mm² |
| Thermal expansion | 0.69 mm/m/100°C |
| Linear expansion coefficient | 5 - 7.5 x 10 ↑-6 /K |
| Abrasion resistance | 4 - 10 cm³ / 50 cm² |
| Water absorption | 0,1 % - 1 % |
| Available dimensions | max. 7 m³ |
| Resistant to frost | resistant |
| Resistant to aggression | resistant |
| Polish | durable |
| Poisson's ratio | 0,11 - 0,25 |
| Thermal conductivity | 2.8 W/(m*K) |
