| 1. |
- Reddy, Vijeth Venkataram, 1990-, et al.
(författare)
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Surface characterization and analysis of textured injection moulded PC-ABS automotive interior components
- 2023
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Ingår i: Surface Topography: Metrology and Properties. - Bristol : Institute of Physics (IOP). - 2051-672X. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Automotive interior components are produced by injection moulding due to its cost effectiveness in mass production. The surfaces of these components are textured to control the appearance and other surface functional properties such as wear and scratch resistance. Key challenges lie in replicating the features of mould tool with high aspect ratio which are influenced by the polymer and large number of process variables. Hence, to control the aesthetic properties, it is important to improve the understanding of the replication of textured surfaces and its relationship with measured gloss. In this study, the surface topography of PC-ABS samples is investigated using coherence scanning interferometry. Replication of two types- coarse and fine grain surface texture are investigated to identify the effects of tool temperature, injection speed and holding pressure. Areal surface parameters are scrutinized for the quantitative characterization and discrimination of study samples surface topographies. The correlations between process parameters, measured gloss and areal surface parameters are discussed. The results show significant influence of process variables on the replication of surface topography and measured gloss. The grain pattern governed the set of surface parameters selected and the variation in gloss. The process variables are observed to influence different region or distribution of specific surface features represented by surface parameters. © 2023 IOP Publishing Ltd.
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| 2. |
- Reddy, Vijeth Venkataram, 1990-, et al.
(författare)
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Surface topography characterization of brass alloys : lead brass (CuZn39Pb3) and lead free brass (CuZn21Si3P)
- 2017
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Ingår i: Surface Topography: Metrology and Properties. - Bristol : Institute of Physics Publishing (IOPP). - 2051-672X. ; 5:2
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Tidskriftsartikel (refereegranskat)abstract
- Manufactured surfaces usually consist of topographical features which include both those put forth by the manufacturing process, and micro-features caused by disturbances during this process. Surface characterization basically involves study of these features which influence the functionality of the surface. This article focuses on characterization of the surface topography of machined lead brass and lead free brass. The adverse effect of lead on human health and the environment has led the manufacturing sector to focus on sustainable manufacturing of lead free brass, as well as how to maintain control of the surface integrity when substituting the lead content in the brass with silicon. The investigation includes defined areal surface parameters measured on the turned samples of lead- and lead free brass using an optical coherence scanning interferometer, CSI. This paper deals with the study of surface topography of turned samples of lead-and lead free brass. It is important to study the topographical characteristics of the brass samples which are the intermediate link between the manufacturing process variables and the functional behaviour of the surface. To numerically evaluate the sample's surface topography and to validate the measurements for a significant study, a general statistical methodology is implemented. The results indicate higher surface roughness in turned samples of lead brass compared to lead free brass. © 2017 IOP Publishing Ltd
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| 3. |
- Dimkovski, Zlate, 1974-, et al.
(författare)
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Effect of the measurement size on the robustness of the assessment of the features specific for cylinder liner surfaces
- 2014
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Ingår i: Surface Topography: Metrology and Properties. - Bristol : Institute of Physics Publishing (IOPP). - 2051-672X. ; 2:1
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Tidskriftsartikel (refereegranskat)abstract
- The quality of the cylinder liner surface is of great importance due to its impact on the fuel/oil consumption and emissions of the internal combustion engine. A good liner function depends on the size and distribution of the deep honing grooves and the amount of the cold work material (Blechmantel) left inside the grooves after finishing. A fast evaluation of these features requires optical three-dimensional measurements with a large area and good resolution, but many interferometers used today have limited resolution when measuring larger areas. To find out how the measurement size and resolution would affect the quantification and the variation of the parameters, two objectives, 2.5 × and 10 × , were used for measuring a cylinder liner from a truck engine. The Blechmantel was of special interest as it first comes into contact with piston/rings, detaches as particles and wears the running surfaces. The 2.5 × objective showed more robust assessment than the 10 × one, manifested by a lower coefficient of variation for the parameters describing the features: Blechmantel, groove width and height, groove balance and number of grooves. This means that fewer measurements are required if a 2.5 × objective is used in production and hence the time and cost of the liner would be decreased. © 2014 IOP Publishing Ltd.
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| 4. |
- Bartkowiak, T., et al.
(författare)
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Establishing functional correlations between multiscale areal curvatures and coefficients of friction for machined surfaces
- 2018
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Ingår i: Surface Topography: Metrology and Properties. - 2051-672X. ; 6:3
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this research is to determine the strengths of correlation, and their variation with scale, between friction coefficients and topographic characterization parameters, calculated using statistical representations of multiscale areal curvatures. The surfaces are created by milling and manual polishing. Coefficients of friction were measured during bending under tension tests. Surfaces were measured with a white light interferometer. Curvature tensors were calculated using a normal based method adapted for multiscale analysis. Three different regions were analyzed from each of eight samples. Curvature tensor parameters: principal, mean, and Gaussian curvatures were calculated for scales between 0.78 and 47.08 μm. These statistical measures of the curvatures were regressed against the coefficient of friction. Three different analyses were performed, taking into account entire curvature distributions, only negative or positive values and curvatures of top heights. Strong correlations (R2 > 0.85 for many and as large as 0.96) were found for the standard deviations for all four curvature measures when entire distributions were considered. These results suggest that the frictional responses of surfaces could be related to the variance of their topographic curvatures. Average curvature parameters correlate strongly with coefficients of friction for negative values. Curvatures calculated from top regions present strong correlations for both mean and standard deviation of maximal, mean and Gaussian curvatures. This supports the use of multiscale curvature tensor methods for characterizing interactions between surface topography and tribological performance.
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| 5. |
- Bergman, Martin, 1985-, et al.
(författare)
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Material & Surface design methodology-the user study framework
- 2020
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Ingår i: Surface Topography-Metrology and Properties. - Bristol : Institute of Physics Publishing (IOPP). - 2051-672X. ; 8:4
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Tidskriftsartikel (refereegranskat)abstract
- A material and surface selection within the car industry is usually based on a comprehensive study based on sensation and perception, focusing on particular perceived qualities and impressions (emotional functions) through visual and tactile interaction of plastic surfaces. On top of that 'emotional function', the 'technical function' such as surface roughness or gloss for a certain matter in symbiosis, will result in a number of material and surface proposals. The range of materials fitting into the window of these requirements varies depending on the industry's ability to hit the target specified in regard to the 'emotional functions', usually defined by the designer's intention. Thus, to be able to get a deeper understanding of how to frame the 'emotional functions' and link them to the 'technical functions', two user studies were made in this paper. The user studies were made with two different designs however with the same main research target to be able to understand the varieties of these two. The aim of doing so was to be able to find the user study design that was the most time efficient and providing the most significant data linked to the 'technical functions' and process control/traceability. However also finding the user study design with the least strains for the participating users in regard to uninterrupted brain activity. By designing the user study in relevant subsets in a certain sequence, user study design nr 2 has proven to be more time efficient and provide more data regarding the soft metrology. Future work will focus on deeper knowledge about how these surfaces different material- and surface properties correlate to the participants responses regarding perceived quality of a car interior design. The development of a new non-contact measurement is also discussed, enabling the possibility to complement and improve the hard metrology set up.
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| 6. |
- Dimkovski, Zlate, 1974-, et al.
(författare)
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Functional parameter screening for predicting durability of rolling sliding contacts with different surface finishes
- 2018
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Ingår i: Surface Topography: Metrology and Properties. - Bristol : Institute of Physics Publishing (IOPP). - 2051-672X. ; 6:2
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Tidskriftsartikel (refereegranskat)abstract
- The reliability and lifetime of machine elements such as gears and rolling bearings depend on their wear and fatigue resistance. In order to screen the wear and surface damage, three finishing processes: (i) brushing, (ii) manganese phosphating and (iii) shot peening were applied on three disc pairs and long-term tested on a twin-disc tribometer. In this paper, the elastic contact of the disc surfaces (measured after only few revolutions) was simulated and a number of functional and roughness parameters were correlated. The functional parameters consisted of subsurface stresses at different depths and a new parameter called 'pressure spikes' factor'. The new parameter is derived from the pressure distribution and takes into account the proximity and magnitude of the pressure spikes. Strong correlations were found among the pressure spikes' factor and surface peak/height parameters. The orthogonal shear stresses and Von Mises stresses at the shallowest depths under the surface have shown the highest correlations but no good correlations were found when the statistics of the whole stress fields was analyzed. The use of the new parameter offers a fast way to screen the durability of the contacting surfaces operating at similar conditions. © 2018 IOP Publishing Ltd.
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| 7. |
- Dimkovski, Zlate, 1974-, et al.
(författare)
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Novel testing methods for screening the tribological performance of ring-liner surfaces
- 2018
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Ingår i: Surface Topography: Metrology and Properties. - Bristol : Institute of Physics Publishing (IOPP). - 2051-672X. ; 6:3
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Tidskriftsartikel (refereegranskat)abstract
- The piston system accounts for about the half of the frictional losses of internal combustion engines and requires special testing methods to understand and improve its function. The most common way to screen the surface performance is to rub ring/liner segments against each other in a reciprocating manner. However, short reciprocating tests have intrinsic low sliding speeds, unable to reach the mixed/hydrodynamic regimes found in the engine, especially at the mid-stroke. This paper presents a rotating test for the oil control ring, which has the largest frictional losses of all other rings. Both reciprocating and rotating tests were conducted using different in-house developed modules and fixtures. Twin land oil control rings against liners with two different finishes commonly used in heavy duty diesel truck engines were tested under similar loads and speeds as in a real engine. Engine oil 5W-30 and room temperature was used for all the tests. Sliding speed, load, friction force and electrical resistance were recorded during the tests. The results show a clear discrimination of the different liner finishes depending on the lubrication regime present.
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| 8. |
- Flys, Olena, 1971-, et al.
(författare)
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Applicability of characterization techniques on fine scale surfaces
- 2018
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Ingår i: Surface Topography: Metrology and Properties. - Bristol : Institute of Physics Publishing (IOPP). - 2051-672X. ; 6:3
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Tidskriftsartikel (refereegranskat)abstract
- In this study, several surface topographies typical for dental implants were evaluated by different measurement techniques. The samples were prepared by machine turning, wet chemical etching and electrochemical polishing of titanium discs. The measurement techniques included an atomic force microscope (AFM), coherence scanning interferometer (CSI) and a 3D stereo scanning electron microscope (SEM). The aim was to demonstrate and discuss similarities and differences in the results provided by these techniques when analyzing submicron surface topographies. The estimated surface roughness parameters were not directly comparable since the techniques had different surface spatial wavelength band limits. However, the comparison was made possible by applying a 2D power spectral density (PSD) function. Furthermore, to simplify the comparison, all measurements were characterized using the ISO 25178 standard parameters. Additionally, a Fourier transform was applied to calculate the instrument transfer function in order to investigate the behavior of CSI at different wavelength ranges. The study showed that 3D stereo SEM results agreed well with AFM measurements for the studied surfaces. Analyzed surface parameter values were in general higher when measured by CSI in comparison to both AFM and 3D stereo SEM results. In addition, the PSD analysis showed a higher power spectrum density in the lower frequency range 10-2-10-1 μm-1 for the CSI compared with the other techniques.
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| 9. |
- Flys, Olena, 1971-, et al.
(författare)
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Using confocal fusion for measurement of metal AM surface texture
- 2020
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Ingår i: Surface Topography: Metrology and Properties. - Bristol : IOP Publishing Ltd. - 2051-672X. ; 8:2
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Tidskriftsartikel (refereegranskat)abstract
- The highly complex nature of as printed metal AM surfaces pose other challenges for making measurements compared to surfaces made with many conventional processing methods. The high complexity is caused by high aspect ratios, a mix of high and low reflexivity, steep angles etc. It is not clear which method is the most suitable for measuring these surfaces. The objective of this study was to compare four different measurement modes available in one instrument to evaluate the advantages and drawbacks of the respective techniques regarding measurements of metal AM surfaces. The evaluated measurement modes are Confocal Microscopy, Coherence Scanning Interferometry, Focus Variation and Confocal Fusion. The effect of advantages and drawbacks of studied techniques was tested on typical surfaces produced by L-PBF process. Surfaces printed at 0° and 90° inclinations were compared regarding the measurement results achieved from the different methods. The Power Spectral Density analysis and visual comparison were used for the examination of studied measurements methods. Besides the comparison of areal measurements acquired by different modes available in the instrument also extracted profile measurements were compared with profile images acquired using an Optical Microscope. This study reveals that confocal fusion is a promising technique for AM surface characterisation, due to the highest amount of valid data points in the typical measurement. The new approach developed in the study showed that PSD analysis can be used for evaluation of fill in algorithms incorporated in different software. Results of the profile comparisons help to illustrate features that can be depicted by surface measurements, applying different measurement principles, as well as enables comparison of raw profile data between different types of measurements. Further investigation of measurements on AM surfaces in the frequency domain will bring more understanding about the limitations of measurement techniques.
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| 10. |
- John, Shobin, 1991-, et al.
(författare)
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Friction between pin and roller of a truck's valvetrain
- 2019
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Ingår i: Surface Topography: Metrology and Properties. - Bristol : Institute of Physics Publishing (IOPP). - 2051-672X. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- In order to minimize the fuel consumption in internal combustion engines, the frictional losses must be minimized between the moving parts such as the sliding bearings. In this study, the sliding friction between the pin and roller in a heavy duty truck engine's valvetrain has been investigated. Three combinations of production components with different surface treatment were used: steel pin with steel roller, steel pin with WS2 coating inside the roller and PVD coated steel pin with steel roller. In-house test rig was used, enabling controlled conditions close to the real engine. A new method for alignment using a laser scanner was introduced together with high resolution tactile measurements of radial displacement during test. Surface topography of pins and rollers was measured before test with a mechanical stylus instrument. The WS2 showed 3.1 times and the PVD showed 2.5 times lower friction than the steel type at low speeds. Even though the friction reduction of WS2 over the PVD is not large, the important advantage is that the WS2 can be manufactured at lower costs than the PVD one. Good correlations among the friction, initial roughness and radial displacements were also found.
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