Effect of Scraper Geometry on Scraping HAP/ZrO2 Slurry in Digital Light Processing

Digital light processing (DLP) can be used to form HAP/ZrO2 mixed ceramic slurry. In the printing technology, the scraper geometry has an important effect on the scraping process; thus, it is necessary to conduct analysis. A modified lattice Boltzmann method (LBM) is proposed to conduct the numerical simulations according to the non-Newtonian behavior of the slurry. The Cross behavior of the slurry is viewed as a special external force; then, the traditional LBM including the true external force can be utilized effectively. The triangle, rectangle, trapezium, and rounded rectangle are the main considered section geometries of the scraper. When the flow velocity is set to 0.1 m/s, the results show that the maximum velocity occurs near the bottom surface of the scraper. In four situations, the velocity peak of the triangle case is 0.6270 m/s, which is the maximum, and much larger than the flow velocity of 0.1 m/s. The velocity peak of the rectangle case is 0.0466 m/s, which is the minimum. Although the velocity peak of the rounded rectangle case is 0.0556 m/s, the second velocity peak is 0.0465 m/s; the difference is smaller than that of the rectangle case. In addition, the streamlines figures show that the sharp corner leads to the obvious velocity change. In summary, the rounded rectangle is considered to be more suitable for scraping the HAP/ZrO2 mixed slurry.

Analysis of the compromise between cutting tool life, productivity and roughness during turning of C45 hardened steel

Tool wear and surface roughness as performance indexes are considered to be the most important in terms of hardened materials’ machinability. The best combination of cutting parameters which enhances the compromise between tool life, productivity and machined surface quality contribute to benefice on production cost, which makes manufacturing industry interested in it. The aim of this research is to investigate the life of ceramic cutting tool and machining productivity together with surface roughness during turning of hardened steel C45, with focus on the selection of the optimal cutting parameter combination. The experiments are carried out based on uni-factorial planning methodology of cutting speeds and feed rates. The results show that the mixed ceramic tool is suitable for turning hardened steel C45 (40 HRC) and the conclusion is that it performed well in terms of tool life, productivity and surface quality at a combination of cutting speed (200 m/min), feed (0.08 mm/rev) and depth of cut (0.3 mm). Additionally, a tool life model has been proposed which is presented very high coefficient of determination.

An experimental study on the effect of tool geometry on tool wear and surface roughness in hard turning

The main purpose of this study is to investigate the influence of tool geometry (cutting edge angle, rake angle, and inclination angle) and to optimize tool wear and surface roughness in hard turning of AISI 1055 (52HRC) hardened steel by using TiN coated mixed ceramic inserts. The results show that the inclination angle is the major factor affecting the tool wear and the surface roughness in hard turning. With the increase in negative rake and inclination angles, the tool wear decreases, and the surface roughness increases. However, the surface roughness will decrease when the inclination angle increases to overpass a certain limit. This is a new and significant point in the research of the hard turning process. From this result, the large negative inclination angle (λ = −10°) should be applied to reduce the surface roughness and the tool wear simultaneously. With the optimal cutting tool angles in the research, the hard machining process is improved remarkably with decreases of surface roughness and tool wear 8.3% and 41.3%, respectively in comparison with the standard tool angles. And the proposed tool-post design approach brings an effective method to change the tool insert angles using standard tool-holders to improve hard or other difficult-to-cut materials turning quality.

Relationship between surface roughness and chip morphology when turning hardened steel

Hard machining is a process which has become highly recommended in manufacturing industry to replace grinding and perform production. The important technological parameters that determine this process are tool wear, machined surface roughness, cutting force and morphology of the removed chip. In this work, an attempt has been made to analyse the morphology and form of chip removed during turning of hardened steel AISI 1045 (40HRC) with mixed ceramic tool type CC650. Using a Taguchi plan L9, whose factors are cutting speed and feed rate with three levels for each. Macroscopic and microscopic results of chip morphology were correlated with these two cutting parameters additional to surface roughness. Sufficient experimental results were obtained using the mixed ceramic tool when turning of hardened steel AISI 1045 (40HRC) at high cutting speeds. Roughness of machined surface confirmed that it is influenced by feed rate. Chips show a sawtooth shape for all combinations of the experimental plan used. The chip form changed with cutting parameters variation and given an important indicator of suraface quality for industriel. Having the indicators on the surface quality from simple control of chip without stopping machining give an important advantage in order to maximize production and reduce costs.

Use of Recycled Aggregates Made from Construction and Demolition Waste in Sustainable Road Base Layers

Research has been carried out on recycled aggregates from the exclusive crushing of structural concrete waste (CDWRCon) and mixed ceramic materials (CDWRCer) in selective demolitions. This study analyses the use of these recycled aggregates as wet mix macadam (GARCon, GARCer) and in cement soil (CSRCon, CSRCer). The materials comply with the requirements of a road base; although, due to the low values of resistance to fragmentation, these materials are adequate for use in sensitive road systems and other places, such as urban roads and car parks, that have a low intensity of heavy traffic. As soluble salt contents were detected, additional waterproofing or drainage measures must be adopted to prevent water infiltration into the layers made up of CDWRCon or CDWRCer. Finally, the high initial values of unconfined compressive strength (UCS) allow the temporary passage of light vehicles over CSRCon or CSRCer after three days.

Dry turning of AISI D3 steel using a mixed ceramic insert: A study

AISI D3 steel is a new kind of hardened tool steel with excellent wear resistance. This hard material receives wide promotion, investigation, and application in the die manufacturing industries. In the machining of AISI D3 steel, tool wear has a close relationship with the presence of different constituent elements in the workpiece material and cutting conditions. This study reports an improved experimental investigation approach to the analysis of effect of cutting speed, feed rate, and depth of cut on cutting forces, surface roughness, tool wear, and chip morphology in high-speed turning of AISI D3 steel using a hybrid TiN-coated Al2O3 + TiCN mixed ceramic insert. The range of each parameter is set at different levels for the analysis purpose. The experimental observations show that the cutting force is predominantly influenced by the feed rate accompanied by the depth of cut. The predominant factor influencing flank wear is the feed rate accompanied by the depth of cut and cutting speed. Feed rate is one of the dominating factors that influences the surface finish characteristics. The characterization of tool wear and chip morphology was performed by a scanning electron microscope supplied with energy-dispersive X-ray spectroscopy pattern. The results demonstrated that the predominant wear mechanism of the multilayered hybrid-coated tool was flank wear, crater wear, adhesion wear, and abrasive wear.