Machine tools with high thermal stability

highest stability with Hydropol®

Machine tool with high thermal stability

Machine tools that are completely non-responsive to changes in temperature are desirable, yet not feasible due to varying thermal expansion rates of the used materials depending on the actual temperature range and shape of the parts.

Experience tells us that up to 80 % of accuracy deviations of state-of-the-art machine tools are caused by thermoelastic deformations of the structure of the machine.

A highly thermally stable machine bed is the basic requirement for high accuracy machining and therefore for the production of precision workpieces.

 

PCM-temperature

Hydropol® - special material compound with high thermal stability

The material characteristics and compound construction of Hydropol® machine beds and structures offer the best prerequisites for achieving the best possible thermal stability. Thermal stability goes hand in hand with thermal capacity which compensates short-term temperature fluctuations immediately.

Steel, as a commonly used material in machine construction, has almost the same thermal expansion coefficient as the Hydropol® filling materials. Accuracy defining machine parts like guide rails are directly mounted on the machine bed and show the same heat expansion in order to achieve the highest machining precision.

 

Latent thermal storage

By using “Phase Change Materials” (PCM), the thermal mass can be increased significantly without altering the actual weight of the part. In case of special requirements where the standard material compositions are limited we use PCM-materials. The part with this special material mix is able to absorb thermal energy without changing its temperature or shape.

Newsletter 01

Tempered machine beds

A further option to systematically counter negative temperature effects is the integration of heating or cooling circuits into the Hydropol® machine bed. This can be done with little extra effort due to the special construction and design of Hydropol® parts. Depending on the use case the machine bed can be tempered large-scale or only in particular areas. The cooling lubricant of the machine can be used as tempering fluid, separate circuits or components like electric heating pipes are also possible.

Long-time experience

Our development team is constantly researching new and innovative solutions to optimize product performance. We are able to rely on the extensive experience and know-how from years of practice and technological leadership. Collaborations with renowned research institutes and universities allow us to permanently stay up-to-date with technological developments and incorporate them into our products to continuously set new standards.

Material-Related Machine Structure Deformation

A machine bed thermally as stable as possible is a basic requirement for the production of high-precision workpieces.

Machine beds for machine tools can be produced from a variety of different materials. The thermal properties of these materials result in various deformations under the influence of heat.

Deformation Under Force

fixed beams

FEM model with four beams fixed on one side having equal outside dimensions (500 x 500 x 1200 mm) and equal bending strength with four different materials:

  • solid cast mineral composite
  • grey cast iron with 38 mm wall thickness
  • aluminium with 67 mm wall thickness
  • Hydropol® with 5 mm steel wall thickness

Material Characteristics

Development Of Ambient Temperature

  • start at 22 °C
  • jump to 32 °C, sustain for 24 h, then
  • jump back to 22 °C, sustain for 24 h

The position of the front surfaces as a function of time is evaluated in each case (average over the entire surface)

Zellweger Ingenieurgesellschaft mbH creates models for very fast calculation of the thermal growth of larger systems. The present comparison of designs originates from the preparatory work for a project with a large machine tool manufacturer. The exchange with framag on this topic took place at a later point in time.