Thermal expansion is a phenomenon which occurs when a body (liquid, gaseous or solid) increases in volume as a result of an increase in temperature. This increase is caused by oscillation variation of the atoms around the equilibrium point.
In case of solid body, the thermal expansion concerns length, surface area and volume.
Thermal expansion with temperature variation and thermal expansion coefficient presents errors in measuring machines.
The exact behavior of different materials used in the construction must be understood. At Elbo Controlli NIKKEN, we dedicate time and resource to test and approve the use of granite for our presetters and optical scales.
In a normal working environment, the internal temperature may vary, depending on the conditions (outside temperature, seasons, air conditioning), by around ten degrees: for example, from 20°C to 30°C from 8 A.m. To 5 P.m. (over 9/10 hours).
When combining different materials (natural granite/ carbon steel), it is important to consider the masses: a considerable amount of NATURAL GRANITE, to which the slides and the spindle (made of STEEL) are mounted, takes much longer to reach the same temperature than an assembly composed of STEEL/STEEL (for example CAST IRON/STEEL or ALUMINUIM/STEEL).
For example, after 3/4 hours, starting from 20 ° C, the CAST IRON / STEEL combination will have reached 30 ° C, while the GRANITE / STEEL combination will take much longer to reach the same temperature.
From here, one can sense that over the same elapsed time, the heating and expansions are much more sensitive when using a metal mass rather than one composed of NATURAL GRANITE and STEEL.
This is due to the higher thermal conductivity of metals compared to granite.
GRANITE is a material with a low coefficient of thermal conductivity (excellent insulator) therefore its temperature varies very slowly as the temperature of the surrounding environment changes (high thermal stability): in conclusion, NATURAL GRANITE is the material par excellence in construction of measuring machines for its chemical / physical and mechanical characteristics.
For years now, NATURAL GRANITE has been the preferred choice of manufacturers who produce three-dimensional measuring machines to guarantee more precise measurements and stability over time.
Temperature variations the presets undergo during the day can alter measurements and negatively affect the final result. Having a stable presetter is paramount.
All Elbo Controlli NIKKEN presetting machines use NATURAL GRANITE for both the base and for the column.
No need for geometric compensation through software, Elbo Controlli NIKKEN presetters will amaze you with their precision and consistency. Seeing is believing.
