Quantification of Blechmantel Effect on Wear of Cylinder Bore Microtopography
Paper in proceedings, 2008
The presence of cold work material (blechmantel) smeared out on cylinder liners by faulty honing is undesirable as it seals the oil-bearing honing grooves. It is also believed to correlate with increased bore wear, presumably due to its loosening and together with the carbon build-up from the piston’s top land form an increased quantity of abrasive particles. An attempt has been made to estimate the extent of removal of blechmantel for different wear regimes present at the middle and top region (near the top dead centre) of the liner surface using the unworn bottom region as a reference for comparison. A number of truck cylinder liners were axially sectioned after varying periods of engine running under similar conditions of load, engine speed and lubrication. 3D surface measurements were taken at the three regions and a range of standard parameters was extracted. Combining the profile and image analysis, an algorithm was developed to identify and quantify the blechmantel covering the grooves that is most likely to break and act as abrasive wear particles and at the same time it represents the part of blechmantel which covers the most of the surface. It was found out that a mere portion of the blechmantel from the middle and bottom section was removed, while the blechmantel from the top section was greatly removed and thereby it represents one of the possible causes for wear. Axial wear scratches more emphasized on the thrust side of the liner were observed not only through the whole stroke area, but also in the bottom region. The fact that the most of the blechmantel is not removed from the running surface of the liner (except for the very small portion of the polished areas at the dead centres), points out that the blechmantel plays only a minor role on wear of the cylinder liner surfaces.