Zlate Dimkovski

Influence of Minimum Quantity Lubrication on Friction Characterizing Tool–Aluminum Alloy Contact

The possibility to reduce the amount of cutting fluids from machining processes is actively studied by the industrials and researchers. Minimum Quantity Lubrication (MQL) is a solution towards cutting fluids reduction. This article investigates the consequences on friction coefficient induced by the use of MQL. A tribometer is used in order to simulate experimentally the tribological conditions encountered during machining. As the cutting speed increases a lower amount of oil is deposited on the rough surfaces. Depending on the MQL operating conditions and sliding velocities it is plausible to reach starvation by leaving the real rough contact partly dry. A model computing a starvation percentage by filling an estimated oil amount in a deformed topography correlates with the experimental results.

Characterisation of Cylinder Liner Honing Textures for Production Control

It is of common interest to reduce oil consumption and frictional losses in internal combustion engines, which are heavily influenced by the quality of the cylinder liner surface. The plateau cross-hatch topography of a cylinder liner consists of a system of grooves of different density, width and depth, some parts covered by folded metal, and some parts totally interrupted and unbalanced as a result of imperfection in the honing process. These grooves are critical for good liner function, and need to be quickly and objectively quantified for an efficient surface finish development. A suitable way to do this is to use 3D interference measurements and to combine profile and image analysis. Thus, the features/parameters, such as honing angle, balance of honing texture, groove interrupts, width, height, and distance between grooves, are successively quantified. Here, these parameters, along with areal surface texture parameters in the published ISO specification standard were used in two case studies. The first case study is on the effect of the folded metal on the surfaces of run truck liners and the second is an evaluation of the improvements of the surface quality introduced by the diamond honing in production of car liners. In addition, based on the significant parameters of the surface, a general characterisation tool for qualifying the surface quality and determination of the required number of measurements is presented.