The demands on decreased environmental impact from vehicles are resulting in a strong push for decreased engine oil and fuel consumption.

Recent engine tests have shown a promising reduction in oil consumption when using cylinder liners with a smoother finish than the current plateau honing.

One approach to produce smoother liner surfaces is to replace SiC ceramic honing stones with diamond tools. However, even though the diamond honing process results in higher productivity, improved quality control is needed to monitor the degree of cold worked material - “blechmantel” (German), and the resulting risk of increased wear and scuffing.

A number of petrol and diesel engine cylinder liners have been mapped to be able to verify the quality and consequences, in terms of wear and function, of the honing process. A new mapping method, combining SEM images and quantitative image analysis with traditional 2D profilometry has been developed and tested in this study. The surface mapping method developed was employed before and after the test to study effect of running-in wear on the surface, features characterized with the SEM- and the 2D profilometer.

The results show that combining SEM- and profilometric methods gives a good picture of the effects of varying the cylinder liner pressure and roughness. The core roughness decreases more for diesel liners than for petrol liners.. A probable cause is that the more severe diesel high pressure run-in conditions are able to effectively “truncate” the plateaux and remove residing plastically deformed un-cut honing residues while the less severe petrol liner conditions do not manage to remove the blechmantel and irregularities to an important extent.

The demands on decreased environmental impact from vehicles are resulting in a strong push for decreased engine oil and fuel consumption. Engine oil and fuel consumption are to a great extent controlled by the topography of the cylinder liner surface.

Recent engine tests have shown a promising reduction in oil consumption when using cylinder liners with a smoother finish than the current plateau honing.

One approach to produce smoother liner surfaces is to replace SiC ceramic honing stones with diamond tools. However, event though the diamond honing process results in higher productivity, improved demands of quality control is needed to monitor the degree of cold worked material - “blechmantel” (German), and the resulting risk of increased wear and scuffing.

A number of petrol and diesel engine cylinder liners have been mapped to be able to verify the quality and consequences, in terms of wear and function, of the honing process. A new mapping method, combining SEM images and quantitative image analysis with traditional 2D profilometry has been developed and tested in this study. The liners where tested in a reciprocating rig of 8 mm stroke and with a frequency of 10 Hz, simulating the top-dead center conditions in a running engine.

The tests where carried out in high- and low pressure conditions with smooth respectively rough liner roughnesses against PVD coated piston rings. The developed surface mapping method was employed before and after the test to study effect of running-in wear on the surface, features characterized with the SEM- and the 2D profilometer.

The results show that combining SEM- and profilometric methods gives a good picture of the effects of varying the cylinder liner pressure and roughness. The core roughness decrease more for diesel liners than for petrol liners. In average (rough and smooth liners) the diesel core roughness decrease 265% while the petrol liners average on a 60% decrease. Blechmantel- and Irregularities ratio show a high sensitivity to varying conditions and decrease 1180% to 100% for the diesel liners while the parameters increase between 106% to 18% for all the petrol liners. A probable cause is the more severe diesel high pressure run-in conditions are able to effectively “truncate” the plateaux and remove residing plastically deformed un-cut honing residues while the less severe petrol liner conditions not manage to remove the blechmantel and irregularities in an important extent.

The development of engine components in the automotive industry is governed by several constraints such as environmental legislation and customer expectations. About a half of the frictional losses in an internal combustion engine come from the interactions between the piston assembly and cylinder liner surface. The tribological considerations in the contact between the piston ring and cylinder liner have attracted much attention over the past few decades. Many non-conventional cylinder liner finishes have been, and are being, developed with the aim to reduce friction losses and oil consumption, but the effects of the surface finish on piston ring pack performance is not well understood. One way of reducing friction in the cylinder system is to reduce the tangential load from the piston ring pack, focusing on the oil control ring. However, the side-effect of this is a disappointingly increased oil consumption. In this study a number of different cylinder liner surface specifications were developed and implemented in test engines with the aim of maintaining the level for oil consumption when decreasing the tangential load for the piston ring pack. To improve our understanding of the result, the same surfaces were evaluated in elastic and elasto-plastic rough contact and hydrodynamic flow simulation models. It is shown that oil consumption is strongly related to surface texture on the cylinder liners and at lower speeds (900–1200 rpm), a 'rougher surface' with a high core (e.g. Sk) and valley roughness (e.g. Svk) results in higher oil consumption. At the medium speed range (1200–3600 rpm), oil consumption continues to dominate for the 'rough' surfaces but with a visible influence of a lower oil consumption for a decreased roughness within the 'rough' surface group. 'Smooth' surfaces with a 'smooth' core (Sk), irrespective of the valley component (Svk), show similar oil consumption. For engine speeds above 3600 rpms, an increase in plateau roughness results in higher oil consumption. Throughout the study, standard roughness parameters were computed to compare with the results from engine testing and simulation. Future work will be directed to continuous optimization between oil consumption and friction. Improving the understanding of the functional cylinder system surfaces' ability to form oil films in the cylinder system opens up opportunities, not only in reducing the tangential load of piston ring packs but also in optimizing oil viscosity in order to reduce friction.

The roughness of stratified surfaces such as cylinder liners, produced by plateau honing, is functionally important in their tribology but is notoriously difficult to characterise. An issue in manufacturing quality control related to their tribological function is the comparative ability of various roughness characterisation systems. In this paper the Rk family of parameters is compared with the Rq family as regards stability and discrimination. When coefficients of variation of the two parameter families are compared as a measure of stability, CVs of individual parameters vary between 8% and 20% but do not seem to indicate a clear advantage to either family. When the correlation of parameters within and between the two groups is computed as a measure of relative discriminative ability, many parameters are found to be highly correlated, to the point where values of Rpk and Rpq are effectively indistinguishable. The relative robustness of the parameters is also established by simulation of surface or measurement artefacts: outlying peaks and valleys, high-frequency noise, changes in stylus or skid radius, changes in high-pass filter and in assessment length. Outlying peaks cause a large increase in Rpk, while outlying valleys have little effect. The Rq parameters are more sensitive to high-frequency noise than the Rk parameters. Increasing the stylus radius reduced the valley parameters, while adding a 25 mm radius skid increased Rk and Rpq by as much as 15%. Increasing the short-wavelength cut-off from 2.5 m to 8 m reduced most parameters, particularly the peak parameters, while replacing the robust Gaussian filter used throughout by a valley-suppression filter had little effect. Finally reducing the assessment length from 17 mm to 4 mm decreased the values of many parameters by up to 11%. Increasing plateau honing time decreased plateau roughness, while increasing pressure during coarse honing increased valley roughness, but these changes could not be correlated with roughness parameters. This suggests that the optimum parameter set has not yet been found. 2008 Elsevier B.V. All rights reserved.

The paper analyses changes in user activities and behaviour across different types of actors following the introduction of 3D printers. 3D printing, or additive manufacturing, has been claimed to disrupt manufacturing, allowing firms to move from prototyping to full-scale end-part production and replacement part production in a one-step process. 3D printing has many different uses, for example, the manufacturing of toys, shoes, lamps and fashion accessories, and by implication many different types of users and buyers. There are few empirical studies on the types of uses and users of 3D, hampering our understanding in what ways the 3D printers may change the behaviour of users, and whether 3D printers affect the likelihood and the nature of entrepreneurship or business model innovation. To investigate this, a model was created based on the 3DP literature. The model is applied on a distributor customer database and four interview-based illustrative case studies. The empirical findings show that the use of 3DP a) lowers the knowledge and resource barriers for experimentation and entrepreneurial entry, b) increases product and concept prototyping in product development, c) provides a potential for business model innovation by expanding the boundaries of the firm upstream and downstream, and d) becomes a ticket for entrepreneurial entry. Based on our results, the paper suggests that the potential of 3D printers alter user innovative activities is high but most of the potential is latent.

When characterizing surfaces and searching for correlations to functional properties, such as friction, finding the right scale of roughness for evaluation can improve correlations. However, in traditional roughness parameter analysis, a wide range of scales, or all scales of topography in the surface roughness measurements are evaluated together. In this study a multi-scale method using a series of band-pass filters is employed for finding scales of topography with strong correlations to friction.

In die and mould manufacturing, the method used for quality control of finished surfaces is usually visual and tactile inspection of the finish, which is not easily quantifiable. In the present study, an evaluation of the connection between surface finish appearance and measured surface roughness was carried out using scale-sensitive fractal analysis to find functional correlations and to determine suitable cut-off limits for functional data filtration. A selection of ball-nose end-mills in combination with two different tool steels (hardness 39 and 47 HRC) were used to manufacture surfaces that were inspected and measured. It was found that the method developed in the present study for evaluating functional correlations and designing filters worked well. It was also found that there is a correlation between the surface roughness parameter Sq and the surface finish appearance and that this correlation is stronger in certain wavelengths on the surface.

This work investigates correlations between the surface topography of milled steel dies and friction with steel sheet. Several die surfaces were prepared by milling. Friction was measured in bending under tension testing. Linear regression coefficients (R²) between the friction and texture characterization parameters were tested. None of the height, spacing, material volume, void or segmentation parameters showed good correlations. Developed area, rms surface gradient, relative area and complexity showed strong correlations (R² > 0.7). For area-scale fractal complexity the correlation increases markedly at scales below 200 μm², with a maximum R² of 0.9 at 50 μm².

Comparisons between different measuring strategies were made on three types of smooth tool steel surfaces. Three replica materials were tested to study possibilities within replication techniques. An optical interferometer as well as a mechanical stylus was used to evaluate the surfaces. The results showed that the tested replica materials generated good representations of both the form and the surface roughness (Sq > 300 nm). The evaluated surfaces were quite homogeneous, thus, few measurements are needed to get representative results. However, it was found that caution must be taken regarding manually polished surfaces which can be less homogenous and therefore require more measurements to get representative results.

This study was an evaluation of measuring strategies using a handheld 2D profiler for quality control of finish milled tool steel with regard to surface roughness. A selection of ball nose end mills in combination with two different tool steels (hardness 39 and 47 HRC) were used to manufacture the surfaces that were to be measured. It was found that using an appropriate measuring strategy it is possible to measure the roughness of these relatively smooth surfaces (0.1<1µm) with satisfactory accuracy using a handheld profiler. However, it was also found that, in contrast to what is common practice, Ra is not a suitable parameter to use for evaluation. Instead, using Rz or Rp is suggested. To be able to control quality, the machining process (selection of cutting tool, cutting data, workpiece material etc) as well as limits for the evaluated parameters first have to be established.

In die and mould manufacturing, the method used for quality control of finished surfaces is usually visual and tactile inspection of the finish, which is not easily quantifiable. In this study, an evaluation of the connection between surface finish appearance and measured surface roughness was carried out using scale-sensitive fractal analysis to find functional correlations and to determine suitable cut-off limits for functional data filtration. A selection of ball nose end mills in combination with two different tool steels (hardness 39 and 47 HRC) were used to manufacture surfaces that were measured. It was found that the method employed in this study for evaluating functional correlations and designing filters worked well. It was also found that there is a correlation between the surface roughness parameter Sq and the surface finish appearance and that this correlation is stronger in certain wavelengths on the surface.

Anisotropy of functional surfaces can in many practical cases significantly influence the surface function. Tribological contacts in sheet forming and engine applications are good examples. This article introduces and exemplifies a method for visualization of anisotropy. In a single graph, surface texture properties related to the anisotropy as a function of scale are plotted. The anisotropy graph can be used to explain anisotropy properties of a studied surface such as texture direction and texture strength at different scales of observation. Examples of milled steel surfaces and a textured steel sheet surface are presented to support the proposed methodology. Different aspects of the studied surfaces could clearly be seen at different scales. Future steps to improve filtering techniques and an introduction of length-scale analysis are discussed.

There is an increasing requirement from manufacturing industries for improved technologies to measure surface topography. New instruments have to be accurate; robust to be used on the industry floor; non-invasive; automatic; and sufficiently fast to be used in real time as well as to simultaneously measure over a large area. The industrial applications are plenty:

• On-line quality control of machined parts,
• Direct feed back to the manufacturing process,
• Analysis and selection of surface texture/structure.

This paper presents new developments in interferometer techniques for new robust area-based topographic instruments.

The manufacturing and finishing (honing) of cylinder liners for the automotive industry is a constant challenge in order to reduce friction losses and oil consumption. A better knowledge of surfaces generated during plateau honing is then required for optimization of the process. Despite a well-known and controlled honing process, variations in surface roughness appear at both global (due to honing tool wear) and local (TDC, middle stroke, BDC) scales and need to be mapped and analysed. The following paper proposes to map the global and local variations in roughness by using a confocal 3D measuring equipment able to measure and scan any area of a cylinder liner. Six motor blocks (five liners each) are evaluated with twenty topography measurements per liner. In total, six hundred 3D measurements of size 1×1 mm are performed and roughness parameters are computed. The results show that some parameters do correlate with the honing tool wear specific to each cylinder. Experimental models could be built. Furthermore surface roughness varies significantly over the axial length of the liners due to waviness deviations combined with a lack of flexibility of the honing tool in axial direction. © Published under licence by IOP Publishing Ltd.

The automotive industry and the design of engines are strongly ruled by performance and legislation demands. In the valve train, mechanical components such as camshafts and rollers are defined by specifications including more and more constraints concerning their ability to face wear thus prolonging lifetime.

The aim of the thesis is to develop tools facilitating the choice between different manufacturing processes for wear optimization purposes of cam and roller components for IC engine valve trains. Tools are both experimental and theoretical.

For the experimental part, statistical and relocated studies of wear have been performed. It is shown that measuring the very same surface before and after experiments is preferable to understand wear mechanisms of cams and rollers. A set of analysis tools for describing changes between unworn and relocated worn surfaces is developed. As results, it is found that the predominant mechanism of wear for cams and rollers is a flattening of asperities: surfaces are pressed and plastic deformations occur.

In parallel, simulations have been developed to explain theoretically the wear observed. Micro and macro simulations are developed to predict the ability of a given manufacturing process to resist wear. For the microscopic simulation, a rough contact model including elasto-plastic behavior of materials is used and shows good correlations with experiments. Concerning the macroscopic simulation, a model including form deviations due to manufacturing is developed and computes oil film thicknesses and deformations. The different parameters computed by both simulations are indicators of the wear performance of different surfaces. It is shown that such simulation can rank different manufacturing processes in terms of ability to face wear.

The automotive industry and the design of engines are strongly ruled by performance and legislation demands. First order aspects defining the main functions of a component are well known and new challenges appear at a lower scale. Wear reduction is defined as a second order problem and requires decreasing the scale of observation of components down to roughness. This thesis work and its aim lie within the scope of wear improvements and are focused on the injection cam/roller contact of heavy duty diesel engines. In order to reach the aim several material and methods are used: a valve train rig test, roughness characterisation and different manufacturing processes. It is shown by experiments that the flank and nose of injection cams are specific areas with specific roughness (higher density of summits Sds) compared to the rest of the cam. The wear is characterized by rounded-off of summits (Ssc). From those results and since wear processes are strongly linked to the pressure generated between the mating surfaces, the development of a rough contact model is of great interest. An elastic rough contact model is implemented and improved later on by an elasto-plastic description of materials. The simulations are validated by a wear test and are used to rank the ability of surfaces (both cam and roller) to face wear problems. The ratio of plastically deformed peaks shows that the flank and nose of the cam are reacting badly to pressures. Additionally the rough contact allows ranking/optimization of different machining processes with respect to their expected functional contact performance. Future work will be to use such a model to choose a good combination of surfaces (cam and roller) in order to reduce wear.

The manufacturing and finishing (honing) of cylinder liners for the automotive industry is a constant challenge in order to reduce friction losses and oil consumption. A better knowledge of surfaces generated during plateau honing is then required for optimization of the process. Despite a well-known and controlled honing process, variations in surface roughness appear due to honing tool wear and need to be mapped and analyzed. The following paper proposes to map the variations in roughness by using confocal 3D measuring equipment able to inspect any area of a cylinder liner. Six motor blocks, each with five cylinder liners, were evaluated with 20 topography measurements per liner (giving six hundred 3D measurements in total). In addition to standard 3D roughness parameters, tailor made parameters extracting honing texture information are computed. The results show that only a few parameters (Spk, Ssc and Sk) do correlate with the honing tool wear specific to each cylinder. Tailor made parameters indicate similar results. Indeed, as the honing tool wears down, the cylinder liner surface gets rougher plateau or peaks and sharper asperities indicating that ploughing occurs instead of cutting. In future, experimental models could be built in order to perform production and functional optimizations. © 2015 Elsevier Inc. All rights reserved.

Friction and wear are constant problems encountered in camshaft development. The contact between roller and cam is a mix of sliding and rolling which leads to a wide range of failure modes. The uniqueness of this contact is also due to variations all around the cam of a multitude of parameters such as load and radius. A previous study described surface topography as a function of cam shape. The different types of wear mechanisms are strongly linked to contact pressures which are also dependent on roughness. The aim of the paper is to develop a rough contact model which will be utilized as a tool to rank surfaces and their ability to face wear problems. In order to verify the tool, rough contact results are compared to roughness parameter variations due to wear produced in a cam roller rig test. The surface measurements used for this study are made by a non-contact light interferometer. The Greenwood-Williamson contact model has been developed in a deterministic way and the elasto-plastic behaviour of the material has been integrated to the model. The outputs of the simulation give a ranking of surfaces which is compared to their roughness variations due to wear. The study shows that the model developed is a reliable tool to rank and define surface quality since the results are correlated to wear. However, the results show as well some discrepancies which could be corrected in the future by integrating to the model two new features: a rough to rough contact including sliding between surfaces. This new model should be verified by an accurate experimentation using relocation between unworn and worn surfaces.

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. © 2015 by ASME

There is a variety of engineering surfaces having linear scratches/grooves of different density, width and depth, some parts covered by folded metal, and some parts totally interrupted and unbalanced as a result of the machining or wear process. These grooves are critical for good function of the surface, and need to be quickly and objectively quantified for an efficient surface finish development. A suitable way to do this is to use optical 3D measurements and to combine the profile and image analysis. In this tutorial extraction and quantification of grooves/wear scratches of machined (honed and polished) and worn (honed) surfaces will be presented. In particular, it will be shown how the features, such as width, height, and distance between grooves, honing angle, balance of honing texture, and groove interrupts can be successively characterized.

The frictional losses, oil consumption and emissions in internal combustion engines are in great extent controlled by the cylinder liner surface topography. This emphasises the importance of: investigating the liner’s topography by objectively characterising it, investigating its effects on the tribological function to gain a better understanding and improving its manufacturing. As a first attempt in this study to objectively characterise the liner surface, a traditional combination of Scanning Electron Microscope (SEM) images and roughness profiles was used. The groove and image parameters characteristic for liner topographies were extracted by applying specially developed algorithms and together with the standard parameters served to study wear on liners of diesel and petrol engines. An experiment was designed to improve the liners’ manufacturing by varying of the honing process parameters and oil flow simulations were run to study the influence of the characteristics of the manufactured surfaces on their function. The results suggested that reducing the base honing pressure and increasing the plateau honing time gave the best surface with smoother plateaux, summits of higher density and milder slopes, more but smaller islands and shallower valleys. The potentials of fast acquiring and containing 3D data of the interference measurements were utilised to overcome the encountered problems in the usage of the combination of profile and SEM measurements and to enable automatic quality control of the cylinder liner surfaces. In the efforts to examine the influence of the surface properties on liner’s function, the extent of blechmantel (cold work material) removal was estimated from 3D measurements of run liners in engine tests. For characterising this feature, algorithms were developed and implemented and it was found that the most of the blechmantel is still left on the liner pointing that it plays a minor role on wear.

Reducing friction in the Piston-Cylinder Unit - PCU is one of the priorities in the automotive industry as it is the largest contributor to the frictional losses and hence the fuel consumption of the internal combustion engines. Not only fuel consumption, but also the oil consumption and emissions are largely affected by the piston-ring-liner interactions. Therefore, from an optimized PCU, competitive, economic and environmental benefits would be gained.  In this project, fuel/oil consumption and emissions of car and truck engines were reduced by using different cylinder liner finishes and different ring designs/loads. Experimental and theoretical studies have been performed by simulating and testing the behaviour of various oil control rings and cylinder liner surfaces in reciprocating tribotesters. Several full-scale engine tests were performed to verify the improvements. The engine tests showed up to 1.8% reduction of the fuel consumption while keeping low oil consumption by using smoothly honed liner surfaces and low ring loads/widths. Further reduction of the oil consumption was shown in the tribotests and simulations when textured liner surfaces were used. To accomplish this, a cost-effective texturing process has to be found and to be confirmed in the engine tests.

Cylinder liner surfaces are often on the agenda of engine developers because of their large influence on the frictional losses, oil consumption and emissions of internal combustion engines. Improving the liner function involves not only manufacturing new surfaces and checking their function but also characterising them as a necessary intermediate step for better understanding of the changes made. In the manufacturing of the liners, honing is a well adapted and widely used finishing process and along with the characterisation and function has been the subject of studies in this thesis. Regarding the liner’s function, three phenomena were monitored: wear, friction and oil passage rate (correlated with engine’s oil consumption). The first one was studied experimentally while the other two were simulated. Only the interactions with the twin land oil control ring were simulated as it has the greatest influence on the control of friction and oil consumption of all other rings. In the mid-stroke region of truck engine liners, the presence of axial wear scratches was observed and their relation with the removal of the cold worked material (“Blechmantel”) folded inside the deep honing grooves was investigated. Algorithms were developed for estimating the extent of Blechmantel, revealing that most of it remained on the surface whereas the engines still performed well. Other algorithms for characterising honing angle, balance of honing texture, width, height, distance between honing grooves/axial wear scratches, etc were developed for quicker and more objective inspection of unworn and worn surfaces from 3D interference measurements. Based on such 3D measurements, the algorithms were incorporated in a characterisation tool enabling rating of the surfaces and determining the number of measurements necessary to achieve stable roughness parameter values. In addition, it was found that interference measurements are more suitable for quantification of the deposits on the worn truck liner surfaces compared with scanning electron microscope measurements. The lubrication and friction of flat oil control ring lands and differently slide honed surfaces of truck liners were simulated. Friction mean effective pressure and oil passage rate were calculated for each surface showing in each case a reduction for the surfaces with smoother plateaus and smaller valleys. Such a liner surface was finished by using a low base honing pressure and a longer plateau honing time. In a car engine, the influence of different liner surfaces, ring land widths and tensions was examined by running simulations. The results suggest that a considerably improved function can be achieved if the ring land width and tension are reduced whereby the differences between the liner surfaces would reduce.

Proceedings on CD-ROM

The presence of the honing scratches/grooves in cylinder liner surfaces is intended and desired as they improve the lubrication and retain the debris reducing the piston assembly/liner friction and consequently improve the fuel economy and longevity of the internal combustion (IC) engines. Axial scratches caused by the abrasive wear between the tribological partners and/or entrained wear particles are undesired since they are correlated with increased oil consumption and noxious emissions of the IC engines. Due to the imperfection of the manufacturing process, the honing grooves, especially the deep ones, are smeared and interrupted by folds. A portion of the folds would eventually detach during the running process and act as abrasive particles increasing the wear in the cylinder. To closely examine the influence of all these features on the liner's function, it emerges a need to objectively quantify the axial wear scratches, plateau honing grooves, deep honing grooves and their interrupts. The existing techniques fail to segment a groove containing interrupts as they usually appear as summits at several locations in the course of the groove. Combining the profile and image analyses, the deep grooves and their interrupts were successfully identified and quantified in earlier works of the authors. In this paper those algorithms are extended, so that the deep honing grooves, plateau honing grooves and axial scratches crossing different depth levels are sequentially segmented in three levels/steps in an immersing way. A number of parameters derived from this method were utilised to compare 3D interference measurements from the top dead centre, middle and bottom region of a liner run in a truck engine test whereas the three regions represent different wear regimes due to the different running conditions. The results show that: (i) the axial scratches are densest in the top dead centre and about the same size as the plateau grooves in all three regions, while in the bottom region there are only few scratches; (ii) the presence of plateau grooves in the top region clearly decreases, (iii) the deep groove interrupt and coverage are lowest in the top region, and (iv) the groove height and distance between grooves spread mostly.

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. © 2013 Springer-Verlag Berlin Heidelberg. All rights are reserved.

The presence of the honing scratches/grooves in cylinder liner surfaces is intended and desired as they improve the lubrication and retain the debris reducing the piston assembly/liner friction and consequently improve the fuel economy and longevity of the internal combustion (IC) engines. Axial scratches caused by the abrasive wear between the tribological partners and/or entrained wear particles are undesired since they are correlated with increased oil consumption and noxious emissions of the IC engines. Due to the imperfection of the manufacturing process, the honing grooves, especially the deep ones, are smeared and interrupted by folds. A portion of the folds would eventually detach during the running process and act as abrasive particles increasing the wear in the cylinder. To closely examine the influence of all these features on the liner's function, it emerges a need to objectively quantify the axial wear scratches, plateau honing grooves, deep honing grooves and their interrupts. The existing techniques fail to segment a groove containing interrupts as they usually appear as summits at several locations in the course of the groove. Combining the profile and image analyses, the deep grooves and their interrupts were successfully identified and quantified in earlier works of the authors. In this paper those algorithms are extended, so that the deep honing grooves, plateau honing grooves and axial scratches crossing different depth levels are sequentially segmented in three levels/steps in an immersing way. A number of parameters derived from this method were utilised to compare 3D interference measurements from the top dead centre, middle and bottom region of a liner run in a truck engine test whereas the three regions represent different wear regimes due to the different running conditions. The results show that: (i) the axial scratches are densest in the top dead centre and about the same size as the plateau grooves in all three regions, while in the bottom region there are only few scratches; (ii) the presence of plateau grooves in the top region clearly decreases, (iii) the deep groove interrupt and coverage are lowest in the top region, and (iv) the groove height and distance between grooves spread mostly. © 2010 Elsevier B.V. All rights reserved.

It is of common interest to reduce the oil consumption and frictional losses in the internal combustion engines which are in a great deal influenced by the quality of the cylinder liner surface. Its criss-cross patterned topography consists of a communicating system of grooves of different density, width, and depth, somewhere covered by folded metal, and somewhere totally interrupted and unbalanced as a result of the honing process imperfections. These features are crucial for a good liner’s function and are inspected from scanning electron microscope images by experts, which is subjective and time consuming process. Today, a fast automatic quality control is possible by using optical instruments to measure the liner’s topography, and a computer to calculate and check if the standard roughness and groove parameters are in tolerance. Therefore, combining the profile and image analysis, algorithms were developed to compute liner’s groove parameters from 3D interference measurements taken from three different types of cylinder bore surfaces of passenger cars. One of the surface types was a result of a test of an improved honing and the other two being currently in use. Then, the standard and new parameters (groove interruption, number of grooves, holes, etc) were incorporated in a characterisation tool to objectively and quickly evaluate the improvement of the liner’s quality for an updated monitoring in production.

The increased presence of cold work material on cylinder liners due to the introduction of the diamond honing is undesirable as it seals the oil-bearing honing grooves. The most of it is a smeared metal inside the deep honing grooves (blechmantel) that may break and act as abrasive wear particles increasing the bore wear. 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 least worn bottom region as a reference for comparison. A number of truck grey iron 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. The algorithm has successfully identified/quantified the blechmantel and can be used for automatic surface quality and process control. It was found that the amount of the blechmantel in the middle section was approximately the same (though slightly lower) as that in the bottom section, while there was a considerable dislocation and removal of blechmantel in the top section and thereby it represents one of the possible causes for wear. Axial wear scratches of different size and distribution were observed not only through the whole stroke area, but also in the bottom region. All engines and liners performed well throughout the tests, and the observed quantities of blechmantel and axial scratches are acceptable for the time being.

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.

Cylinder liner surface has a direct impact on the oil consumption and frictional losses in the internal combustion engines which are in common interest to be as lower as possible. Thus, the optimisation of the liner surface, its function and manufacture is often on the agenda of the automotive industry. Since the liner surface finish is a subject of improving, there is a need of improving and facilitating of its 3D characterisation preliminary when the parameter control limits are unknown, as well as later when it is experimentally verified and the limits are better determined. For that purpose a method for quality control in 3D of cylinder liners is proposed here. A tool was developed and implemented for rating of cylinder liner surfaces, computing of 3D groove parameters (groove width, height and distance between grooves) and determination of a needed number of measurements.

The accumulation of deposits in the honing grooves of the cylinder liner surfaces of internal combustion engines is undesirable as they seal the grooves (reducing their oil retention capability) and increase engine's oil consumption. As part of a long-term programme of truck engine development, after different running times and under similar conditions of load, engine speed and lubrication, a number of grey iron cylinder liners were axially sectioned, measured, inspected and a presence of deposits was discovered. These deposits were characterised in order to gain knowledge about their origin and quantities. The X-ray energy dispersive analysis revealed elements stemming from the oil/fuel (C, O and S), from the detergent (Ca and Mg), from the anti-wear additive (Zn and P), and from some contaminants (K and Si). Higher concentration of S and Ca were mostly found in the honing grooves covered with deposits suggesting a domination of the detergent additive. Deposit thickness measurements obtained by a white light interferometer revealed patchy deposit topographies concentrated at the top region reducing towards the bottom of the liner which was also confirmed by scanning electron microscope measurements. Despite the limitations of the interferometer, it has been shown that the interference measurements are sufficiently reliable for a quick and objective quantification of the overall deposit accumulation.

Cylinder liner surface finish controls the frictional losses, oil consumption, and emissions of internal combustion engines to a large extent. In order to minimize such losses, it is important to optimize the liner surface topography by a consistent and more productive finishing process such as slide honing. This process employs diamond abrasives and has been recently introduced in the automotive industry. In this study, its potentials are explored, especially the winning combination of its key process parameters: the base honing pressure and plateau honing time that would yield an optimal liner surface finish. A number of truck engine liners were slide-honed by using different process parameters, samples of the liners were cut, and three-dimensional (3D) surface measurements were taken on a white light interferometer. Then, among others, the (deep honing) groove parameters, specific for liner surfaces, were computed from the measurements for building a large database for comparison and correlation. By simulating the contact and fluid mechanics between the measured liner topographies and a twin land oil control ring under mixed lubrication conditions, the friction mean effective pressure and oil passage rate for a range of engine speeds were calculated. These two parameters represent the liner's function associated with the engine's friction and oil consumption respectively. The results show that the lowest friction and oil flow are highly correlated with surfaces having smoother plateaus and smaller valleys, finished by using lower base honing pressure and longer plateau honing time. High correlations between the 3D roughness parameters were also found, enabling the selection and use of more stable and robust parameters in the quality control of the liner's surface finish. © IMechE 2012.