Considering its origin, processing, material properties and design rules dimension stone can be a technical and economical alternative to conventional materials such as cast or polymer concrete used in mechanical engineering.
Products made of dimension stone used in the fields of high-precision mechanics - measurement standards, basic bodies of measuring machines - are the measure of all things. This natural material is characterized by low density, high dimensional (free of residual stress) and long-term stability, homogeneous structure, thermal inertia, as well as low thermal coefficient of expansion.
Typically, machining such as milling, drilling or grinding with statically undeterminate edges gives the stone its final shape. After tranches have been delivered and the goods have been inspected, the usual work routine comprises grinding, edge breaking, milling / drilling, cleaning, gluing of insert parts, finishing (lapping) in air conditioned measuring rooms (stability of temperature +/- 0,1 degree Celsius; +/- 0,2 degree Celsius 24 hours).
Basic requirement to reach the desired, reproducable accuracy is to define identical mounting points during the entire manufacturing process up to the installation at the customer’s premises. Installation is possible on adjustable supports, cabinets or frames designed to carry the weights (see OELZE-Katalog PDF). The component is leveled tension-free on three defined (bearing) points. All other adjusting elements are manually installed as a tilt protection.
In practice all kinds of dimension stones can be put to use. Typically, these are abyssal stones as they possess a dense and homogeneous structure.
South African Gabbro Impala is predominantly used for measuring and precision tools.
Raw blocks, blasted out of mountain massifs in open-cast mines, are semi-finished parts for manufacturing which are often plate-shaped components. The explosion crust is removed from the raw blocks and afterwards they are cut in slices (also called tranches).
We further process these tranches according to your wishes and requirements. If you have never worked with hard rock and do not have any knowledge about its construction do not hesitate to ask us. We will advise you on how to produce an efficient construction that is also appropriate to the material.
Our engineering know-how is not only limited to hard rock. We will advise you and help you with the installation of a complete machining system and machine tools. We can process monolithic components with a length of up to 10 m or a width of 2.20 m. Component groups which weigh up to 16 tons can be mounted easily at our plant.
Other dimension stones which are commonly used are e.g. Silverstar, Tarngranit, Diabas, Kuru Grey (by their trade names). We will gladly advise you on choosing the ideal material for your specific application.
In order to use a material most efficiently - both technically and economically - the construction has to be appropriate to the material. Not only the material’s physical characteristics are of great importance, but most of all also its origin and its original form. In contrast to the often thin-walled or ribbed steel and cast constructions, dimension stone is loosened from a whole piece.
The raw block, as well as the tranches usually have a cubic shape. By producing economically and resource-friendly we try to minimize subsequent takeoff. Our modern tool park makes the production of thin-walled components possible, nevertheless a detailed power flux analysis is necessary so that materials are used efficiently and the risk of cracking is prevented.Lapping makes reproducable deviations of evenness of 0,001mm on one square meter possible. Beside installation conditions extreme thermal conditions must be adhered to.
There are two different connection technologies for hard rock components:
a) quick release screw connection
There are different types of screw connections.
Threaded inserts which are glued into hard rock have to be glued in accordance to a defined edge distance (see table below) to be able to withstand the permissible torque. In case of falling below clearance, cracking is possible.
b) indissoluble (only resoluble after destruction) adhesive connection
Adhesive connections are an easy and quick solution for force-locked connections. According to the specific application required, you can choose between full-surface gluing or gluing by filling of adhesive gaps.
In practice mixed forms of both connection types have become common. Components are aligned and fixed with a screw connection; glue is applied afterwards in adhesive gaps or joints. This additional fixing is often used for dynamically stressed assemblies.