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Influence of cooling lubricants on the surface roughness and energy efficiency of the cutting machine tools

Jersák J., Simon S.

International Journal of Applied Mechanics and Engineering

2017

Vol. 22, no. 3

779--787

The Technical University of Liberec and Brandenburg University of Technology Cottbus-Senftenberg investigated the influence of cooling lubricants on the surface roughness and energy efficiency of cutting machine tools. After summarizing the achieved experimental results, the authors conclude that cooling lubricants extensively influence the cutting temperature, cutting forces and energy consumption. Also, it is recognizable that cooling lubricants affect the cutting tools lifetime and the workpiece surface quality as well. Furthermore, costs of these cooling lubricants and the related environmental burden need to be considered. A current trend is to reduce the amount of lubricants that are used, e.g., when the Minimum Quantity Lubrication (MQL) technique is applied. The lubricant or process liquid is thereby transported by the compressed air in the form of an aerosol to the contact area between the tool and workpiece. The cutting process was monitored during testing by the three following techniques: lubricant-free cutting, cutting with the use of a lubricant with the MQL technique, and only utilizing finish-turning and finish-face milling. The research allowed the authors to monitor the cutting power and mark the achieved surface quality in relation to the electrical power consumption of the cutting machine. In conclusions, the coherence between energy efficiency of the cutting machine and the workpiece surface quality regarding the used cooling lubricant is described.

X-ray diffraction study of distribution of macroscopic residual stresses in surface layers of bearing steel after grinding

Pala Z., Ganev N., Jersák J.

Inżynieria Materiałowa

2007

Vol. 28, nr 3-4

455-458

The focus of this contribution is analysis of the state of residual stress in surface layers of ground bearing steel of grade DIN 17210-86 (ĆSN 14 220). The influence of various coolants on macroscopic residual stress was investigated. Three forms of cooling were applied: dry grinding, liquid coolant and flow of cold air from a Ranque- Hilsch vortex tube. The surfaces of the samples were analysed by X- ray diffraction technique in six azimuths in order to acquire complete strain tensors. Since -vs.-sin y/ dependances in grinding direction are non-linear and exhibit psi splitting, the method proposed by Dólle and Hauk [1] was used to evaluate tensors of anisotropic trialxial state of residual stress. The effective penetration depth of CrKa X-ray radiation into ferrous materials for sin2 y/= 0,4 is approximately 4 um and therefore removal of surface layers is a necessity in order to pinpoint the distribution of residual stresses beneath the surface. The impact of material removal should cause minimal or neglecting mechanical and thermal distortions to the investigated state of stress. Electro-chemical polishing, which was used, is acknowledged as the most appropriate tool [2].