This paper presents a study conducted to examine the effect of cutting parameters, namely standoff distance, nozzle traverse speed (TS), abrasive flow rate (AFR), and material type on cutting performance for two types of marble workpieces, Carrara white and Indian green. Statistical analysis was undertaken to assess the influence of the cutting parameters on the process performances in terms of surface roughness, surface waviness, and Kerf taper ratio. The results showed that the TS and material type were the most significant factors that affected surface roughness and Kerf taper ratio. Also, although AFR was found to have significant effect on surface waviness, it had no noticeable influence on surface roughness nor Kerf taper ratio. Subjects: Manufacturing Engineering; Manufacturing Technology; Mechanical EngineeringKeywords: abrasive water jet machining (AWJM); surface roughness (Ra); surface waviness (Wa); Kerf taper ratio (TR)

The effect of heat treatment on microstructure and tensile properties as well as wear behavior on TC21 (Ti-6Al-2Sn-2Zr-3Mo-1Cr-2Nb-Si, wt.%) Ti-alloy was investigated. The samples were solution treated at 900˚C for 15 min followed by furnace cooling to 800˚C with a cooling rate 1˚C/min and holding for 20 min, then the samples cooled down to room temperature either using water quenching (WQ) or air cooling (AC). Consequently, aging treatment was applied at 575˚C for 4 hr. The microstructure feature showed a secondary α phase (α s ) precipitated in residual β phase due to the step cooling from 900˚C to 800˚C inside furnace as well as the aging treatment. The highest wear rate was obtained for WQ samples due to increasing in volume fraction of α p (58%). However, the lowest wear rate was reported for WQ + Aging samples due to the high hardness. Optimum mechanical properties of the studied TC21 Ti-alloy were obtained for AC + Aging condition. A better combination of hardness, tensile properties, and wear resistance was achieved for AC + Aging samples, although their wear resistance was found to be slightly lower than that of WQ + Aging samples.

This article presents the results of an experimental investigation into the machinability of Ti6Al4V alloy during hard turning, including both conventional and high-speed machining, using polycrystalline diamond (PCD) inserts. A central composite design of experiment procedure was followed to examine the effects of variable process parameters; feed rate, cutting speed and depth of cut (each at five levels) and their interaction effects on surface roughness and cutting temperature as process responses. The results revealed that cutting temperature increased with increasing cutting speed and decreasing feed rate in both conventional and high-speed machining. It was found that high-speed machining showed an average increase in cutting temperature of 65% compared with conventional machining. Nevertheless, high-speed machining showed better performance in terms of lower surface roughness despite using higher feed rates compared to conventional machining. High-speed machining of Ti6Al4V showed an improvement in surface roughness of 11% compared with conventional machining, with a 207% increase in metal removal rate (MRR) which offered the opportunity to increase productivity. Finally, an inverse relationship was verified between generated cutting temperature and surface roughness. This was attributed mainly to the high cutting temperature generated, softening, and decreasing strength of the material in the vicinity of the cutting zone which in turn enabled smoother machining and reduced surface roughness.

Jigs and fixtures is a branch of science including many of mechanical design and production engineering rules. The traditional concepts of jigs and fixtures have famous applications until now in the Egyptian industries. There are many CAD applications found in the worldwide literature, but all of them related to modular fixtures and other applications of flexible fixtures. Most of the modular fixture CAD systems ignore the relation between clamp force and the machining cutting force. In this paper, a new system framework discusses a CAD in traditional jigs and fixture. The proposed system package includes visual basic and AutoCAD. It extracts and recognizes the machined part features (cylindrical or prismatic shapes) and starts the jigs design automatically. The system classifies the machined parts into groups and for each group suggests the optimum jigs design.

Characteristics of cutting insert are key factors for the reliability of machining of difficult-to-cut materials such as Ti6Al4V alloy. Therefore, in this paper a comparison between the performance of two different materials, ceramic insert coated by (Al2O3+TiNC) and CBN, when turning Ti6Al4V alloy in dry environment. Effect of process parameters, feed rate, cutting speed and depth of cut, and their interactions on measured cutting temperature were examined for both inserts. Taguchi method was utilized to design of experiments (L9) and the results were analyzed by analysis of variance (ANOVA). From the results, CBN insert showed a good behavior for heat dissipation during machining compared with coated ceramic insert with a reduction in cutting temperature by 28%. Moreover, it was found that cutting temperature increased by increase in cutting speed and depth of cut and decrease in feed rate when using the two types of insert. In addition, it was observed that cutting temperature was affected by varying process parameters when machining by CBN insert more than the case of coated ceramic tool. The significant parameter affected cutting temperature in the case of CBN was feed rate followed by cutting speed. While at coated ceramic insert, the most significant parameters effect on cutting temperature was cutting speed.