Selective surface functionalization generating site-isolated Ir on a MnO: X/N-doped carbon composite for robust electrocatalytic water oxidation

Water oxidation catalysis plays a pivotal role in the context of the worldwide interest for sustainable energy. Finding cost-effective and robust catalysts to replace the state-of-the-art noble metal materials is hence urgent. In this work, we develop a molecular iridium complex that selectively and uniformly anchors on the surface of manganese...

Environmental responsibility for sulfur dioxide emissions and associated biodiversity loss across Chinese provinces

Recent years have witnessed a growing volume in Chinese interregional trade, along with the increasing disparities in environmental pressures. This has prompted an increased attention on where the responsibilities for environmental impacts should be placed. In this paper, we quantify the environmental responsibility of SO2 emissions and...

A protocol for evaluating the accuracy of 3D body scanners

Scan-derived landmarks locations and surface shapes are more and more used, but there is no commonly accepted protocol for evaluating the accuracy of these measurements. Therefore we propose a protocol for evaluating the accuracy of surface shape and the repeatability of scan-derived landmark locations. According to existing Japanese and German...

Design of micro square endmills for hard milling applications

In experiments of machining hardened tool steels (such as AISI H11, H13, and D2, up to 56 HRC) by commercial Ø 0.5 mm square endmills, it is observed that the tested micro endmills showed severe wear at an early stage of the process due to chipping off around cutting edge corners, resulting in unsatisfactory tool life and product appearance ...

MIMO-OFDM performance in relation to wideband channel properties

In this paper, the sensitivity of the error rate performance of MIMO-OFDM-based practical systems (WiMAX and LTE) to wide band channel properties is investigated. The behavior of the wideband channel is characterized in terms of delay spread (DS) and angular spread (AS). The impacts of DS and AS on the system performance are addressed with both...

Micromilling of thin ribs with high aspect ratios

Micro features with high aspect ratios are one of the commonly encountered geometries found in micro products. In the literature, these structures are often used in demonstrator products machined by a micromilling process. In this paper, the challenges in micromilling thin ribs with high aspect ratios have been studied. Due to the scaling effect...

A study of factors affecting the performance of micro square endmills in milling of hardened tool steels

Proper setting of cutting conditions is critical for the performance of micro endmills in micro milling of hardened tool steels. In this paper, the influence of the cutting parameters on the wear behaviour of micro square endmills is presented. The selected parameters are cutting speed, depth of cut, and feed per tooth; Central Composite...

Experimental study of the surface roughness of hardened tool steel Böhler W300 milled by micro square endmills

Surface roughness is a key parameter in evaluation of engineering surface in macro scale; in case of micromilling, it is of even greater importance because the magnitude of the roughness can be comparable with the workpiece tolerance, and will have a direct impact on the quality of the microproducts. This paper presents the preliminary results...

Tool Neck Geometry Design to Improve Stiffness of Micro Endmills

Due to the scaling effect, micro endmills have low stiffness in nature, which will result in lose of form accuracy in workpiece and vibration of micro tools during micromilling process. Through analytical modeling, it is found that the neck geometry of the micro endmill has a big influence on the tool stiffness; therefore it is important to...

Experimental validation of micro endmill design for hard milling application

Abstract: In experimental investigations of micro milling of hardened tool steel SAE H11, with a hardness of 56 HRC, with commercially available micro square endmills of Ø 0.5mm, it was observed that the endmills suffered from severe tool wear/failure. Because of these problems, the quality of the machined workpiece was not satisfying, in terms...

Improvement of micro endmill geometry for micro hard milling application

One of the applications of the micromilling technology is to machine micro features on moulds by direct machining of hardened tool steels. However at this moment, this process is not industrial applicable because of the encountered problems, such as the big tool deflection, severe tool wear, and pre-mature tool breakage. A detailed examination...

Improved method for the cutting coefficients calculation in micromilling force modeling

This paper discusses the influence of runout on the calculation of the coefficients of mechanistic force models in micromilling. A runout mode is used to study the change of chip thickness, tool angles, and immersion period of two cutting edges of micro endmills due to runout. A new method to find the cutting coefficients was proposed based on...