Thread inserts are glued into the granite
Very large granite measuring plate
Steel insets can be glued into precision granite parts as required
Round granite measuring plate - Ideal for use as round table top
High-precision components can be ideally manufactured in granite. The reasons for this are primarily the extremely good properties of this material. Natural hard stone is the ideal basis for the manufacture of precision products due to its fine crystalline structure, low coefficient of expansion, high abrasion resistance, optimum vibration damping and freedom from unwanted internal stresses. Very fine surface quality can be achieved when machining hard stone. This makes granite parts particularly suitable for air-bearing guides. The air consumption is reduced to a minimum due to the high surface quality. In any case, the use of granite is always worthwhile when the quantities of parts, such as machine beds or high-precision base plates for guides, are relatively small. If the quantities are over 50 per year, the use of polymer concrete can be considered. We can also make you an offer for polymer concrete. However, please note the high initial costs due to the production of the mould.
|Property||Unit||Granite||Polymer concrete||Steel||Cast Iron|
|density||kg/dm³||2,9||2,1 - 2,4||7,85||7,15|
|Bending Strength||N/mm²||13||25 - 35||300 - 600||290|
|Compressive strength||N/mm²||250||100 - 180||260 - 1200||720 - 1150|
|Linear expansion||µm/(m°K)||5 - 7||12 - 20||12||10|
|Thermal conductivity||W/(m°K)||3,0||1,3 - 2,0||50||50|
|Special heat capacity||J/(kg°K)||845||900 - 1100||500||500|
|Modulus of elasticity||kN/mm²||60 - 90||30 - 40||210||88 - 113|
In addition to the properties shown in Table 1, there are other advantages to using hard stone:
Magmatic rocks are formed by cooling hot molten material from the earth's interior, the so-called magma. If the cooling takes place underground, one speaks of plutonites or intrusive rocks. Due to the relatively good thermal insulation of the overlying rocks, the molten magma cools down only slowly so that large mineral crystals can be formed. Examples of plutonic rocks are granite or gabbro. The magma can form huge rock masses, the so-called plutons, which often contain several thousand cubic kilometers of rock Granites (from Ital. granito, "granulated") are massive, relatively coarse-crystalline, magmatic deep rocks (plutonites), which are rich in quartz and feldspars, but also contain dark minerals, for example mica. The phrase feldspar, quartz and mica, the three I never forget, gives a somewhat simplified description of the composition of granite. Translated with www.DeepL.com/Translator (free version)
Today, high-precision granite parts are widely used. They can be found in circuit board drilling machines, measuring machines, grinding machines, milling machines and other applications. Granite can be machined particularly accurately. Up to under 0.001 mm/m is possible. The surface quality is extremely good. This makes it possible to realize very precise guides in combination with air bearings. But granite is also frequently used as a basis for recirculating ball bearing guides. The execution in hard stone is especially worthwhile if only small quantities with high precision are needed. The granite components are finished in very precisely air-conditioned rooms. When machining, it is very important that you give us the support points on which the part is supported during installation. This is the only way to achieve the highest, repeatable accuracy. Translated with www.DeepL.com/Translator (free version)
The final inspection is carried out with laser interferometers, autocollimation telescopes and electronic inclination scales of highest precision. According to your specifications, we insert appropriate threaded holes, T-slots or various metal parts into the granite body. We work with a high-strength two-component adhesive specially designed for bonding steel / granite. Below you will find a table with the dimensions and the maximum permissible tightening torques for the standard threaded inserts. The positioning accuracy of the threaded hole is +/-0.1 mm. The inserts are inserted approx. 0.5 - 1 mm below the surface.
With the measuring bars made of granite, the main focus is on the parallelism of the longitudinal surfaces to each other. They serve as straightness standards. The underlying standard for the granite measuring bars is DIN 874 for parallelism. Mainly granite measuring bars are used for straightness and parallelism control of guides and for alignment purposes. The granite measuring bars are designed as follows:
Dark hard stone, the two narrow longitudinal surfaces are lapped parallel to each other, all other surfaces of the measuring bars are cleanly ground, two handling holes are drilled at each of the besselsche contact points. The delivery takes place in a wooden case.
We can also produce higher accuracies on request. Here you see only an extract of our delivery program. Also handling drillings and other special requests can be realized. In special design THOME Präzision can also supply measuring bars with 4 longitudinal surfaces lapped parallel and at right angles to each other. Please ask for all special requests individually.
Hard rock angle standards are primarily used to control the 90° angle. Angle standards are ideally suited for quick alignment of angles (for example for measuring machines or machine tools). The granite angle standards are made of dark hard stone. Four narrow surfaces of the angle standards are parallel to each other and lapped at right angles. The specification of the angular accuracy is related to the long leg. The two large surfaces of the granite angle standards are ground. Through-holes are provided for weight reduction and better handling. Threaded inserts for eyebolts can also be provided on request. The underlying standard of our granite angle standards is DIN 875 for rectangularity. A wooden case and a test report are included in the delivery.
These granite angle standards are used to control 90° angles. They are made of dark hard stone. The two narrow leg surfaces of the granite angle standards are lapped at right angles to each other, the remaining surfaces are cleanly ground. The angular accuracy is related to the longer leg. Through holes are drilled to reduce weight and for better handling. The underlying standard for our granite angles is DIN 875 for rectangularity. A wooden case and a test report are included in the delivery.
These hard stone cubes are used as angle standards. The angle check is time-saving and extremely accurate. Granite cubes are used in machine tools and measuring machines for fast geometry checking. The granite cubes are made of dark hard stone. All 6 sides are lapped at right angles to each other, the opposite sides are parallel. The angular accuracy is related to the longer leg. To reduce weight and for better handling, through holes or threaded inserts can be inserted according to customer requirements. The underlying standard for the granite cubes is DIN 875 for rectangularity. A wooden case and a test report are included in the delivery.
Measuring plates made of granite serve as a basis for control, assembly and laboratory purposes. The granite measuring plates are made of black hard stone (granite). The surface of the granite measuring plates is first finely ground and then lapped. The sides of the granite measuring plates are cleanly ground. The granite measuring plates are chamfered on the reverse side. The flatness of the measuring plates is classified according to DIN 876. The granite measuring plates serve as measuring tables in combination with a base frame.
The flatness of a granite measuring plate is only guaranteed if it is installed correctly. Please proceed as follows:
All standard measuring plates from THOME Präzision have the same support points as besselsche support points. The support points with the lowest deflection are located about 22% from the edge.
Manual measuring machine for quick and easy measurement.
CNC measuring machine for quick and easy measuring.
Fast measurement results through simple operation.
Flexible clamping system for fast clamping of your workpieces.
Tested used coordinate measuring machines with 6 months warranty.