**Author details**

H. Allmaier, C. Priestner, D.E. Sander and F.M. Reich *Virtual Vehicle Competence Center, Austria*

#### **5. References**

34 Will-be-set-by-IN-TECH

occurs for a lubricant temperature of 100◦C already significant metal-metal contact at 2000rpm which leads to a significant rise in friction for this engine and potentially to problems in the operating reliability. However, with an enlarged bearing width even lower viscosity oil can be used; for the case presented the optimum is a low viscosity 0W20 oil combined with a broader bearing shell, in this case 21mm. Thereby, in comparison to the original configuration with 18mm bearings and 10W40 oil, the journal bearing losses can be reduced by 10% at 2000rpm

The results show that small changes in the bearing geometry bear no significant impact on the friction losses in the journal bearings. However, the use of a low viscosity lubricant holds obvious advantages in regards to a reduction of these losses, despite the need of wider bearings to retain the bearing load capacity. In the presented example this combination of low viscosity lubricants with wider bearings revealed itself as optimal and proves approximately 10-30% decreased losses in comparison to the initial situation. Alternatively, if more complex in design, the increase in size of the journal bearing diameter and the therefore necessary larger journal diameter brings advantages also in regards to the NVH performance due to the increased stiffness of the crankshaft. Further measures for friction reduction like an on-demand oil supply could potentially also attain significant savings and be analysed

While this basic example of friction reduction in engines displays the efficiency of various measures, it is important to emphasise that the choice of the optimum lubricant affects the whole engine and the other major source of mechanical losses, namely the piston assembly, challenges with (partly) opposing requirements to the lubricant. In this sense, the optimum choice of the lubricant in terms of friction reduction shall only be taken under consideration

The authors would like to acknowledge several very interesting discussions on friction related topics and want to express their gratitude in particular to C. Forstner (MIBA Bearing Group), F. Novotny-Farkas (OMV Refining & Marketing GmbH), A. Skiadas (K & S Gleitlager GmbH)

Further, the authors acknowledge the kind permission of the MIBA Bearing Group and the OMV Refining & Marketing GmbH to publish the results and the financial support of the 'COMET K2 - Competence Centers for Excellent Technologies Program' of the Austrian Federal Ministry for Transport, Innovation and Technology (BMVIT), the Austrian Federal Ministry of Economy, Family and Youth (BMWFJ), the Austrian Research Promotion Agency

(FFG), the Province of Styria and the Styrian Business Promotion Agency (SFG).

H. Allmaier, C. Priestner, D.E. Sander and F.M. Reich

*Virtual Vehicle Competence Center, Austria*

and by approximately 30% at 4600rpm despite the significantly wider bearing shells.

**4.2. Conclusion**

through the presented model.

of the complete system.

**Acknowledgment**

**Author details**

and O. Knaus (AVL List GmbH).


*of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering* 223(10): 1311–1325.


© 2013 Engin, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

distribution, and reproduction in any medium, provided the original work is properly cited.

© 2013 Engin, licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**Theories on Rock Cutting, Grinding and** 

Tribological research studies including cutting, abrading and polishing mechanisms have firstly started with metals, metal cutting theories and formulas have been developed and then applications on rock material have started. In this part of the book, natural stone cutting, abrasion and polishing mechanisms are compiled and presented as a summary.

Processes of cutting, grinding and polishing natural stones are made as a result of grindingabrading mechanism developed on the use of different abrasive grains (mostly diamond and SiC). Wear intensity is named as cutting, abrading or polishing according to the speed,

No matter which cutting machine is used, generally cutting process of natural stones are done with the use of segments that are obtained through sintering of diamond grains and metal powders. Industrial diamond grains in these segments rubbed against the material to be cut with a certain force and material is removed, and as a result, the material is cut along

In the stage of abrading and polishing of natural stones, products called grinding stone containing SiC grains are generally used. Intenseness of material removal from natural stone surfaces can be arranged by changing grain size of this abrasive and magnitude of pressure intensity. When relatively coarser grains and higher pressures are chosen, coarse abrading process is obtained while slight abrading and polishing is obtained when slighter grains and

Wear is described in the literature as the loss of material as a result of the change in the shape of friction surfaces. Many researchers have stated that there are 4 main wear

**Polishing Mechanisms** 

Additional information is available at the end of the chapter

chip size and situation of obtained surfaces.

lower pressures are chosen.

this surface as the material is removed as much as segment width.

**2. The basic wear mechanisms emerging all types of materials** 

Irfan Celal Engin

**1. Introduction** 

http://dx.doi.org/10.5772/56046
