A Novel Approach to Reduction of Frictional Losses in a Heavy-Duty Diesel Engine by Reducing the Hydrodynamic Frictional Losses

An important parameter in the reduction of fuel consumption of heavy-duty diesel engines is the Power Cylinder Unit (PCU); the PCU is the single largest contributor to engine frictional losses. Much attention, from both academia and industry, has been paid to reducing the frictional losses of the PCU in the boundary and mixed lubrication regime. However, previous studies have shown that a large portion of frictional losses in the PCU occur in the hydrodynamic lubrication regime. A novel texturing design with large types of surface features was experimentally analyzed using a tribometer setup. The experimental result shows a significant reduction of friction loss for the textured surfaces. Additionally, the textured surface did not exhibit wear. On the contrary, it was shown that the textured surfaces exhibited a smaller amount of abrasive scratches on the plateaus (compared to the reference plateau honed surface) due to entrapment of wear particles within the textures. The decrease in hydrodynamic friction for the textured surfaces relates to the relative increase of oil film thickness within the textures. A tentative example is given which describes a method of decreasing hydrodynamic frictional losses in the full-scale application

From Traditional Manufacturing to Digital Manufacturing: Two Swedish Case Studies

Digital manufacturing can produce new and advanced tools more rapidly and at lower cost than traditional manufacturing. This new technology means manufacturers need to develop innovative business models adapted to this change in the manufacturing landscape. With digital manufacturing, companies have both an opportunity and a challenge. They can enter new markets where large-scale production provides competitive advantage. They can enter niche markets that become more attractive as old boundaries and structures lose relevance. Yet their additive manufactured components must meet the same standards set for conventional manufactured components. However, we know little about how companies manage this change as they make the transition from traditional manufacturing to digital manufacturing. This chapter presents two co-creation digital manufacturing projects between university researchers and Swedish companies. In each project, the goal was to develop sustainable and efficient digital production methods that offer tailor-made product solutions. Various technical methods used in the projects are described as materials, and prototypes are developed, tested, and analyzed

Towards New Interferometer Technology for Surface Metrology

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

High gloss polishing of tool steels – step by step

The surface preparation of moulds for high gloss applications, e.g. tools for injection moulding of plastic parts, is still a relatively unknown area. Most knowledge is accumulated by individual polishers with long experience in the field. Literature covering the polishing process/mechanisms is rare and it becomes harder and harder to recruit new skilled polishers. Today it is also a matter of time, and cost; how long time is needed to prepare a new mould? How many steps are needed? Which tools? Is it possible to replace the manual polishers by robots? This article is part of a study where equivalent steel samples were prepared in different polishing shops to investigate the surface quality achieved in every step of the process. The polishers have documented their processes and comment on the final results. The main goal was to study how different proceedings affect the final surface quality; which are the crucial factors in order to achieve a high gloss polished surface with low defect levels? The sample analysis is based on visual estimations as well as interferometer measurements and belonging surface parameters; e.g. seems the number of preparation steps be crucial to the final surface quality

A Step-by-Step Analysis of Manual Polishing Sequences

Polishing of tool steels for e.g. injection moulding of plastic parts or direct polishing of products is perhaps the most important industrial finishing process today. Polishing is often made manually to ensure the highest quality and nanometre roughness. This study compare steel samples prepared in different companies to study how different polishing sequences affect final surface qualities, i.e. trying to find crucial factors controlling high gloss appearance and defect levels. The samples were prepared in a way that every step of the polishing process could be studied quantitatively at nanometre level using phase shifting- and coherence scanning interferometry. In addition, all samples were qualitatively documented and judged visually by the polishers themselves. It could be concluded that a ‘several-step’ strategy in combination with short polishing time was advantageous. Also, guidelines for tool and abrasive selection is presented suggesting cotton as carrier and diamonds of 1 µm size for more time efficient final polishing.Funding: Uddeholms AB, The Swedish Foundation for Strategic Research Fund and ProViking as well as the European Commission Seventh Framework and the poliMATIC projectpoliMATI

Evaluation of a robot assisted polishing equipment

This study is based on several tests of a robot assisted polishing equipment, the Strecon RAP-200, which was recently developed by Strecon A/S in purpose to polish punches and dies for metal forming. The main part of the study was a 4-factor 2-level design of experiment, where the influence of pressure, pulse, repetitions and linear speed on the final surfaces were studied with help of both a mechanical stylus and an interferometer. The number of repetitions seemed to be the main factor affecting the final surface quality, but also the rotation speed seemed to affect the surface roughness. Further evaluations will be performed in the forthcoming three years

Uncertainties and optimized sampling in surface roughness characterization

Usage of 3D roughness parameters measurements requires knowledge of uncertainty causes in order to design proper measurement procedures. Even on apparently homogeneous machined surfaces, large local variations in 3D roughness parameters have previously been reported. This paper introduces and tests a concept for optimized sampling based on local-, and global topography analysis, using measurements of the Sa parameter on a large machined component as a practical example. It is shown that more than 40 measurements of Sa may be needed to attain a stable value, but that choice of an appropriate sampling strategy may reduce this requirement considerably. The results point to a possible route to minimize required measurements and contribute to the development of the "best-practice" when using 3D surface structure metrology

Robust and Easy to Use Quality Control of Roughness on Milled Tool Steel Surfaces

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

Surface Finish and Roughness Measurement in Die and Mould Manufacturing

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

Tool steel polishing and topography characterization

Manual polishing is a common method to accomplish a mirror-like mould surface, although it is a cumbersome and time-consuming process. It is, thus, of great interest within the industry to find faster and better polishing techniques to decrease the costs and lead times. A key factor towards improved polishing techniques is to find ways to characterize polished surfaces; which parameters and instruments can be used and what is the definition of polishability? This paper summarises a study where three steel grades were analysed with five different measuring devices. The results showed that mechanical stylus instrumentations are not enough to describe very smooth surfaces, but measurement devices with better resolution are needed, such as interferometers