Generalization of mathematical representation for tool path based on boundary representation (BREPS) data structure

A generic representation of linear and curvilinear entities with embedded motion attributes is possible via the integration of a Hermite curve and dynamic of motion. A Hermite curve will form the curve, while a dynamic of motion will position the vertices on the curves with the introduction of a delta distance (Δs). A three-phase algorithm is introduced to examine the applicability of generic representation in tool-path generation. The preprocessing stage will examine the input model prior to Phase I. Phase I will extract the BReps data, and these BReps data will be used in Phase II to develop the generalized mathematical representation of the tool path. Finally, the tool path is drawn in Phase III

Mobile application dictionary for hearing impaired students

Mobile applications have been acknowledged by societies as a support tool that can be accessed everywhere via smartphone or any handheld device. The use of technology nowadays is not only limited to normal people; it can also be used by the disable community. Hearing-impaired people usually receive education via sign language and the dictionary is one tool used in schools to teach hearing-impaired students. There are several issues related to sign language dictionary such as the thickness of dictionary which makes it difficult to bring anywhere. Besides, teachers and students need to take longer time to access the targeted information. This research is conducted based on two main aspects: development of mobile application for the dictionary for the hearing-impaired and evaluation involving experts in the related research. This mobile application has been developed based on the Software Development Model of Mobile Application Dictionary. This model consists of five phases, which are analysis, design, development, prototyping and evaluation. The evaluation on mobile application for the dictionary involved four experts who have evaluated the interface design and learning design. The human computer interaction for mobile principles, dual coding theory, cognitive load theory, and multimedia theory have been used in the development of the dictionary. Based on the experts’ review, it is found that the value of content validity index is 0.91 for the features of interface design and 0.83 for learning design. Hence, this shows the value of content validity index is acceptable. The research aim is to improve the quality of sign language learning for hearing-impaired students and community related to them

Effect of combined Ce and Er Addition on Solidification, Microstructure of the Al-7Si-alloy

This paper highlights the effects of the additions of two rare earth elements (REEs) (Ce and Er) on microstructure and to investigate the characteristic temperatures during solidification of the modified alloy. Five changes of Al-7Si alloys with xEr+xCe additions (x=0.15, 0.25, 0.4, 0.5 and 0.75) were produced by casting technique via the solidification parameters examined using computer-aided cooling curve thermal analysis (CA-CCTA). The thermal analysis tests were carried out for each one by using a thermal analysis system that includes (K-type Thermocouple, EPAD-TH8-K, EPAD-Baes2 and Laptop with Dewesoft-7.5-Lt). To estimate the change in microstructure and solidification as a result of adding (Ce+Er) additions, the obtained result showed that the growth TG Al-Phase and nucleation TN Al-Phase temperatures decreased to lower temperatures 614.7°C and 615.5°C respectively as the amount Ce, Er increased

Enhancement of thermo-physical and lubricating properties of sic nanolubricants for machining operation

Vegetable oils have been adjudged a suitable replacement for conventional cutting fluid in metal cutting process because of its biodegradability, less toxic, high lubricity and environmental friendly. However, efficient performance of vegetable oil has been limited when machining at higher cutting speed or elevated temperature as the cutting fluid evaporates when in contact with cutting tools already heated to high cutting temperature. Thus, nanoparticles are introduced into base lubricating oils to improve their thermal and lubricating properties. The present work is to investigate the thermal and lubricating properties of coconut oil-based Silicon Carbide (SiC) nanofluid at varying concentration of 0.35wt.%, 0.7wt.% and 1.05wt.%. Thermal conductivity and viscosity of the nanofluid was measured with the aid of KD2 Pro thermal analyser and LVDV-III Rheometer respectively while the four-ball wear and friction tester will be used to measure anti-wear property of the nanofluid. Thermal conductivity and viscosity of nanofluid improved with increase of nanoparticle concentration but decrease with increase of temperature. The highest ratio of enhancement of thermal conductivity of is 1.038 while increase of viscosity of nanofluid at temperatures of 30°C and 70°C are 1.277 and 1.397 respectively. The nanofluid was deficient in performance of tribological properties

Effect of cryogenic machining for titanium alloy based on indirect, internal and external spray system

Due to the excellent properties of Ti-6Al-4V titanium alloy such as lightweight, high wear and corrosion resistance and able to maintain high strength at high elevated temperature, this material has been used mostly in aerospace and biomedical industries. However, titanium alloy being considered as a hard-to-cut material with poor machinability due to its low thermal conductivity which leads to the excessive tool wear during machining and requires high machining cost. To overcome these problems, cryogenic machining has been taken place as a promising method for machinability improvement in terms of tool wear reduction, lower energy consumption and low machining cost. Even though this method has been implemented for titanium alloy machining, it is difficult to handle the excessive extremely low-temperature coolant (up to -150) that exposed directly to the workpiece. As a result, the workpiece hardness will be increased, hence will increase the required cutting force for the machining process. In concern with the problem, this paper presents a novel cryogenic cooling mechanism (indirect cryogenic cooling) that will be used as one of the cooling and lubrication strategy. The performance of the indirect cryogenic cooling will be compared with flood cooling, Minimum Quantity Lubrication (MQL) and conventional cryogenic cooling method by using the external and internal spray system. Liquid nitrogen (LN2) being selected as the cooling medium in this work since its temperature can reach lower -196, odorless and more environmentally friendly. A specially designed tooling kit that able to supply the liquid nitrogen to the cutting tool internally is used in this method. The developed indirect cryogenic supply method able to improve the machinability of Ti-6Al-4V. The cutting force is reduced by 54% and the tool life is improved by 90% compared to the conventional flood coolant strategy

Irregular Shape Effect of Brass and Copper Filler on the Properties of Metal Epoxy Composite (MEC) for Rapid Tooling Application

Due to their low shrinkage and easy moldability, metal epoxy composites (MEC) are recognized as an alternative material that can be applied as hybrid mold inserts manufactured with rapid tooling (RT) technologies. Although many studies have been conducted on MEC or reinforced composite, research on the material properties, especially on thermal conductivity and compressive strength, that contribute to the overall mold insert performance and molded part quality are still lacking. The purpose of this research is to investigate the effect of the cooling efficiency using MEC materials. Thus, this research aims to appraise a new formulation of MEC materials as mold inserts by further improving the mold insert performance. The effects of the thermal, physical, and mechanical properties of MEC mold inserts were examined using particles of brass (EB), copper (EC), and a combination of brass + copper (EBC) in irregular shapes. These particles were weighed at percentages ranging from 10% to 60% when mixed with epoxy resin to produce specimens according to related ASTM standards. A microstructure analysis was made using a scanning electron microscope (SEM) to investigate brass and copper particle distribution. When filler composition was increased from 10% to 60%, the values of density (g/cm3), hardness (Hv), and thermal conductivity (W/mK) showed a linear upward trend, with the highest value occurring at the highest filler composition percentage. The addition of filler composition increased the compressive strength, with the highest average compressive strength value occurring between 20% and 30% filler composition. Compressive strength indicated a nonlinear uptrend and decreased with increasing composition by more than 30%. The maximum value of compressive strength for EB, EC, and EBC was within the range of 90–104 MPa, with EB having the highest value (104 MPa). The ANSYS simulation software was used to conduct a transient thermal analysis in order to evaluate the cooling performance of the mold inserts. EC outperformed the EB and EBC in terms of cooling efficiency based on the results of thermal transient analysis at high compressive strength and high thermal conductivity conditions

Improving thermal and tribological properties of enhanced biolubricant with graphene and maghemite nano-additives

Failure of biolubricants at elevated temperature hinder their efficient performance. These challenges are ameliorated using nano-additives to enhance the thermal and anti-wear properties of lubricants. In this study, coconut oil as base fluid was dispersed with 0.1% volume concentration of maghemite (γFe2O3) and exfoliated graphene (XGnP) nano-additives. Thermogravimetric analysis (TGA) was performed using thermal analyser to evaluate thermal degradation of nanolubricants and the base oil. In addition, anti-wear properties and viscosity of base coconut oil and the enhanced nanolubricants were evaluated. The TGA results indicates that oxidation onset temperature was retarded by 9 ℃ and 31.82 ℃ for maghemite (MGCO) and graphene (XGCO) enhanced nanolubricants respectively in comparison with base coconut oil (CCO). Friction reduction and anti-wear property of the nanolubricants showed better performance over the base oil. For graphene enhanced nanolubricant, a reduction of 10.4% and 5.6% in terms of COF and WSD respectively was observed while 3.3% and 4.3% reduction in COF and WSD respectively for maghemite enhanced nanolubricant when compared with the base oil (CCO). The excellent property improvement of thermal stability and tribological properties makes the enhanced lubricants a suitable candidate for consideration as machining lubricants

Enhanced performance of bio-lubricant properties with nano-additives for sustainable lubrication

Purpose: The purpose of this study is to evaluate the potentials of nano-additives in enhancement of oxidation and thermal stability of biolubricants thereby, improving the resistance of dispersed nanolubricants to thermal degradation under elevated temperature. Design/methodology/approach: This study evaluates the oxidation stability and tribological performance of nano-enhanced biolubricants. Graphene and maghemite nanoparticles at 0.1% volume concentration were dispersed into coconut oil. Oxidation stability was analysed using a thermal analyser to understand the effect of nano-additives on thermal degradation of lubricants under increasing temperature. In addition, tribological performance and viscosity of the tested lubricants were evaluated using a four-ball friction tester and viscometer according to American Society for Testing and Materials standards. Findings: The results reveal that the oxidation stability of biolubricants dispersed with nano-additives improves due to delayed thermal degradation. The nano-enhanced biolubricants’ oxidation onset temperature was delayed by 18.75 °C and 37.5 °C, respectively, for maghemite (MGCO) and graphene (XGCO) nanolubricants. This improvement imparts the performance viscosity and tribological performance positively. For graphene-enhanced nanolubricant, 10.4% and 5.6% were reduced, respectively, in coefficient of friction (COF)and wear scar diameter (WSD), whereas 3.43% and 4.3% reduction in COF and WSD, respectively, for maghemite-enhanced nanolubricant compared with coconut oil. The viscosity index of nanolubricants was augmented by 7.36% and 13.85%, respectively, for maghemite and graphene nanolubricants. Research limitations/implications: The excellent performance of nanolubricants makes them suitable candidate as sustainable lubricants for machining with regard to environmental benefits and energy saving. Originality/value: The effect of graphene and maghemite nanoparticles on the oxidation stability and tribological performance of biolubricants has been investigated. It is an original work and yet to be published elsewhere

Trade-off analysis between machining time and energy consumption in impeller NC machining

Electrical energy is directly linked to society's prosperity across the globe; much of this due to the diverse innovations on manufacturing processes. Keeping pace with the high energy demand growth will require constant efforts in terms of investment and research in order to bring new alternatives of usage. This paper outlines the application of multiple response optimization in order to analyze the trade-off between machining time and energy consumption in 5-axis impeller rough machining to find a possible balance between them. It is well known that a higher speed reduces machining time but increases energy consumption, and vice versa. A quantitative form of the relationship between the involved factors was obtained by utilizing response surface methodology (RSM) together with the desirability function method. Four independent factors were selected, namely, spindle speed, feed rate, depth and width of cut. The responses are the consumed energy and the machining time. The results showed that selecting an appropriate feed rate is crucial to balance the trade-offs between energy and time. Spindle speed is the major factor for energy consumption, while width of cut is the most influential factor for machining time