Polymer concrete - properties
There is constant pressure to innovate in the field of processing and machine tools. Ever-increasing demands on precision and productivity are constantly presenting machine manufacturers with new problems. As a result, machine manufacturers need a material that not only fulfills the desired technological properties but can also be used flexibly and thus offers the designer sufficient leeway to be able to develop both stable and complex components.The use of polymer concrete allows a great deal of design freedom, for example by allowing media lines, cooling ducts and fastening elements to be cast directly into the material.
Compared to traditional construction materials, polymer concrete offers high dynamic stability due to its high degree of damping. Due to the low thermal conductivity and high thermal capacity, components made of polymer concrete are less sensitive to deformations caused by short-term temperature fluctuations. The good thermal stability is essential for achieving high precision, especially in machine tool construction.
Polymer concrete - also known as mineral cast or reaction resin concrete - essentially consists of mineral fillers and a reaction resin as a binder. Due to its excellent properties, polymer concrete is being used more and more in mechanical engineering. Polymer concrete is used in machine tool construction in particular due to its good thermal properties compared to conventional construction materials and its excellent material damping properties.Mechanical properties of polymer concrete
The mechanical properties of polymer concrete are listed in the following table
| Characteristic values of polymer concrete | |||||||
|---|---|---|---|---|---|---|---|
| Modulus of elasticity | 25-35 | N/mm2 | |||||
| Compressive strength | 140-160 | N/mm2 | |||||
| Flexural strength | 25-32 | N/mm2 | |||||
| Tensile strength | 9-14 | N/mm2 | |||||
| Density | 2,3-2,5 | g/cm3 | |||||
| Vaporization (log. decr.) | 0,032 | 103kg/ms | |||||
| Poisson's ratio | 0,29 | ||||||
The low strength and stiffness values of polymer concrete compared to gray cast iron and steel are compensated by a correspondingly larger dimensioning. The most important property of polymer concrete is its excellent damping behavior. Compared to gray cast iron, this is approximately 16 times better. The decay curve of the polymer concrete and that of a test specimen made of gray cast iron are shown in the following figure.
Processing of polymer concrete
Components made of polymer concrete are manufactured using the casting process, whereby the resin-hardener system is stirred into the mineral filler to produce a castable mass. The casting molds are made of aluminum, steel, coated wood or plastic, which are previously sealed with a release agent in a multi-layer process. However, wooden molds can only be used for a few castings due to the high stresses involved in demolding.To ensure demoldability, the molds must be designed in several parts and undercuts must be avoided. In terms of design, care must be taken to ensure that the minimum wall thickness of the component is not less than five times the diameter of the largest aggregate grain.
Pouring compound for hollow cross-sections (steel and aluminum profiles)
For many applications, it is too expensive to manufacture machines entirely from polymer concrete, as large and complex molds have to be produced.Machine frames and fixtures are therefore often constructed from hollow profiles.
Unfortunately, in addition to their many advantages, these profiles have one major disadvantage - poor vibration behavior.
As many applications require a high degree of vibration damping and the associated smooth running, we have developed a casting compound for hollow profiles based on our polymer concrete. For example, the advantages of aluminum profiles or welded constructions can be combined with the excellent damping properties of polymer concrete.
In addition to its good mechanical properties, the casting compound has also been optimized in terms of its workability. This enables easy casting without special equipment in almost any environment. For best results, we recommend vibrating the compound during casting to achieve maximum compaction. You can find more information about our potting compound here:
