Papers by Keyword: Roughness

Abstract: Machining of tool steels is often an important used technology. Products made from these materials are often used in mechanical engineering, and quality of workpiece surface roughness after machining respective grinding is one of the important parameters that to us speak about the quality of the machining process. The paper deals with the influence of cutting conditions when grinding bearing steel 100Cr (EN ISO) on machined surface roughness. This steel belongs to a group of bearing steels.

Abstract: The influences of laser processing parameters on the symbol contrast and surface roughness of Data Matrix barcodes were studied by single factor experiments using a Q-switched lamp pumped Nd:YAG laser. The orthogonal experiments were carried out to further study the relationship between laser parameters and surface roughness. Multivariate nonlinear regression analyses were performed based on the orthogonal experimental results and a mathematical relationship between parameters and surface roughness was established. The results show that the change trend of surface roughness is similar to symbol contrast with the increase of laser parameters. Both the average power and two different overlaps are important factors affecting the surface roughness and symbol contrast. But the current intensity has an insignificant impact on the surface roughness. The developed regression model can be used to predict the roughness of Data Matrix barcodes. This study can improve industrial application of laser direct part marking technology on titanium alloy substrates.

Abstract: It was difficult to prepare micro-hole with large aspect ratio by traditional processing technologies. In order to solve the problem, a preparation was proposed. It was carried out by casting method. Carbon fiber and metal wire coated graphite paint were used as hole core respectively. And morphology and geometrical characteristic of micro-hole were observed and analyzed by scanning electron microscope and laser scanning confocal microscope. The results showed that average diameter and aspect ratio of micro-hole obtained by the group of carbon fiber hole core were about 0.2 mm and above 1700, respectively. For the other group, about 0.5 mm and 700, respectively. The micro-hole obtained by the metal wire coated graphite paint hole core was more close to circle. Its shape factor was about 0.72. The roughness of micro-hole value obtained by carbon fiber hole core was close to 3.2 μm, smaller than that of the metal wire coated graphite paint.

Abstract: This study deals with the electrical characterization of PiN diodes fabricated on a 4°off-axis 4H-SiC n⁺ substrate with a n^- epilayer (1×10¹⁶ cm^-3 / 10 µm). Optimized p⁺⁺ epitaxial areas were grown by Vapour-Liquid-Solid (VLS) transport to form p⁺ emitters localized in etched wells with 1 µm depth. Incorporated Al level in the VLS p⁺⁺ zones was checked by SIMS (Secondary Ion Mass Spectroscopy), and the doping level was found in the range of 1-3×10²⁰ at.cm^-3. Electrical characterizations were performed on these PiN diodes, with 800 nm deposit of aluminium as ohmic contact on p-type SiC. Electrical measurements show a bipolar behaviour, and very high sustainable forward current densities ≥ 3 kA.cm^-2, preserving a low leakage current density in reverse bias. These measurements were obtained on structures without any passivation and no edge termination.

Abstract: The main objective of this work was to study the influence of the injection moulding process on the tribological behaviour of ABS polymers and nylon PA6.6+15% of glass fibres. The article also describes the structure of wear maps. Its topic is the preservation of the initial surface roughness at the bottom of the track in tribotesting. Testing and measurement methodologies and data processing techniques are described. ABS and PA6.6+15%GF are polymers. Their specifications state that they are both thermoplastics with very similar characteristics. Tribotesting was employed to find whether or not this is the case. The pin-on-disc method was used to obtain the data. As a summary of the experiment was created wear map that describes the behavior of the material with various input test conditions. During subsequent analysis of this map were discovered not correlating areas that were undergone to further investigation. During this investigation an unknown inclusions in the structure were revealed which are now subjected to further investigation.

Abstract: The feasibility study of the face-milling performance of hard-facing weld metal on JIS-S50C carbon steel was investigated on microstructure, chip characteristics, wear properties, and surface roughness. Discontinuous chips were found in all machining conditions. No buffering weld metal (No buffering layer, NBL) produces longer and thicker chips than that of the buffering weld metal (Buffering layer, BL). The flank wear of the cutting tool edge increases with the cutting length of the test specimen. The maximum wear of 850 mm was found in a wet condition of the NBL weld metal which is about 4 times higher than that of the base metal. High hardness value of the NBL weld metal produces a higher flank wear of the cutting tool edge than that of the BL weld metal. After comparing the wear of the cutting tool edge in wet and dry conditions, it was found that the dry condition exhibits a smaller flank wear than that of the wet condition. In the wet condition, more amount of coolant oil droplets cannot penetrate into the chip-tool interface and then provides an insufficient amount of lubricant in order to decrease the cutting temperature. Therefore wet condition produces severe wear of the cutting.

Abstract: This paper aims documentary research of theoretical and experimental statistical process control in industrial engineering. The most effective means to reduce process variations against the customer requirements is to implement a quality management system based on statistical process control tools. Cutting regime changes in turning processes are based on careful monitoring of vibration. As soon as it is found in the milling excessive noise or vibration the measure to which it resort is to reduce one or more parameters (speed, feed and depth of cut) to remove the effect. Finally, the measure has a negative impact on performance.

Abstract: The evolution of the CVD diamond coatings morphology after perpendicular direction reactive ion etching was investigated. During the surface treatment, the average surface roughness was reduced. The efficiency of the etching decreases with the increasing of the processing time, until the surface roughness has been reduced by 30±5%. The height points spread over the surface were measured. The quality of the obtained films was investigated using the Raman spectroscopy.

Abstract: A company recently reported, the unexpected and sudden failure of several containers, fabricated from aluminium 8006 and sealed using a polymeric film. The failure resulted when there was a loss of adhesion at the metal/polymeric lid interface, making the containers unusable. Some preliminary adhesion tests have highlighted that, containers, coming from various production batches and sealed using the same kind of lid, exhibited different adhesion strengths. To investigate the cause of the detachment of the lid from the edge of the container, the following parameters has been considered: (i) the iron content of the Al alloy, (ii) the effect of lubricant oil at the polymeric film/substrate interface, (iii) the topography of the contact surface between the lid and the container. The electrochemical behaviour of Al8006 was investigated by means of potentiodynamic polarization tests, both in an aerated aqueous solution of Na₂SO₄ (0.5 M) and in an aerated aqueous solution of NaCl (0.6 M). The results revealed a significant increase in corrosion rate for the samples with higher iron content, as well as the negative influence of oil on the surface. Roughness measurements have confirmed the importance of the surface profile: a surface showing Sku>3, provides better adhesion. Metallographic measurements demonstrated that high iron content in the alloy results in the development of numerous corrosion spots and prevents good adhesion between the sealant polymeric film and the aluminium foil.

Abstract: The scheme for the wave strain strengthening of inner cylindrical surfaces diameter up to 100 – 120 mm is offered. One-ring and multi-ring drifts, bolls of various diameters are used as a tool. The effectiveness of a dynamic influence upon the center of deformation is considerably higher than that of the static one used during common burninshing. At the same time the share of power spent for the plastic deformation increases and power intensity drops, and technological possibilities of the process become wider. The experimental research of wave deformation strengthening at different diameters of openings in bushes with different wall thickness revealed that the process is realized in a wide range of tightnesses from 0.5 to 3 mm which is necessary to choose taking into account the wall thickness, and strengthening embraces the whole wall thickness (up to 20 mm) under certain conditions. A considerable decrease of roughness height parameters of the strengthened surface and profile bearing length increase are established. The formation of oil pockets takes place on a surface worked as a consequence of kinematic peculiarities of the wave strain strengthening that contributes to wear resistance increase of friction couples. The productivity of wave strain strengthening exceeds the productivity of common burnishing more than twice, and there appears a possibility to exclude the operations of finishing abrasion with unfavorable technological heredity from the engineering procedure.