Effect of Peak Current and Pulse On Time on the Coating Layer Thickness using Electrical Discharge Coating

The present study focused on the surface modification of aluminum 6061 by using electrical discharge coating (EDC) with powder suspension. The effects of peak current (Ip) and pulse on time (Ton) on the coating layer thickness were investigated. This study used Tungsten powder as an additive and mixed it with the kerosene oil and surfactant Span 83. The results indicated that peak current and pulse on-time significantly affected the coating layer thickness. The thinnest coating layer was observed at 3A, 150 µs, while the thickest coating layer with an average value of 17.239 µm was obtained at parameter 4A and 250 µs. In conclusion, the high value of peak current and longer pulse duration on time increased the thickness of the coating layer.

Analysis of Carbon Fiber-Reinforced Polymer Composites Delamination during Vibration Assisted Trimming using Historical Data Design

Delamination is one of the main issues during the CFRP cutting process. This problem attracts researchers to investigate to meet the stringent quality need. This paper evaluates the influence of Rotary Ultrasonic Assisted Trimming (RUAT) when slotting carbon fiber reinforced plastic (CFRP). The study investigates rotation speed, vibration amplitude, and frequency particularly. The correlation effect of these parameters is to be evaluated by response surface methodology (RSM) to identify the minimum delamination. Seventeen trials were conducted with 38 plies of multi-directional CFRP panel. The trimming quality was determined by the minimum delamination damage of the slotting area analyzed by the ImageJ software. The best slotting quality can be achieved by applying spindle speed, amplitude, and frequency of 5305 rpm, 2.75 µm, and 26.79 kHz.

Morphological Characteristics and Wear Mechanism of Recycled Carbon Fibre Prepreg reinforced Polypropylene Composites

The polypropylene (PP) reinforced with recycled carbon fibres (rCF) was successfully produced using a Haake internal mixer via melt compounding. The compounding was performed at 180°C, rotor speed of 50 rpm and compounding period of 10 minutes. The standard samples for the pin on disc testing were prepared using injection moulding. The effect of rCF filler loadings of 0.5, 1, 3, 5, 7, 10, 13, 15 and 20 wt% was studied for the tribological properties. The results were compared with 100% PP. The morphological behaviours for the effect of low and high fibre loadings were observed using scanning electron microscopy analyses. The composites with low carbon fibre loading of up to 3 wt% imposed higher resistance to dry sliding friction. In contrast, the increment of fibre loading at 5 wt% to 20 wt% decreased the wear rate of the composites due to patch film and transfer film formation. The wear mechanism of the composites for different fibre loading was graphically sketched from morphological observation. As the conclusions, the composites showed promising self-lubricating properties, capable of wear reduction with significant physical and mechanical properties.

Impact, Hardness and Fracture Morphology of Aluminium Alloy (Al-Si) filled Cobalt Oxide Nanoparticles at Various Stir Casting Temperatures

The automotive and aviation fields require engineering materials that can save and optimise fuel consumption. Unique characteristics of lightweight, higher strength to weight ratio, good corrosion resistance, and good castability are indispensable for castable metal such as Silicon Aluminium (Al-Si). The mechanical properties of Al-Si could be further improved through the addition of Cobalt Oxide (CoO) nanoparticles during the casting process. The importance and purpose of this study were to determine the impact toughness, hardness and fracture morphology of Al-Si metal alloy filled with 0.015 wt.% CoO nanofiller at the various melting temperature of 750 °C, 800 °C and 850 °C. The stir casting method was utilised considering the most appropriate method for mixing nanoparticles powder into the Al-Si matrix. Three test specimens were prepared for each temperature variation. Impact testing using the Charpy method (ASTM E23-56 T) and hardness testing using Rockwell Superficial HR15T and fracture morphology obtained from impact testing fractures were performed accordingly. The impact test results showed that the Al-Si added with 0.015% CoO at 800 °C of melting temperature possessed the highest impact toughness value of 25.111 x 10-3 Joule mm-2 than the other variations. The hardness test results showed that Al-Si added 0.015% CoO with a melting temperature of 850 °C had the highest hardness value of 79.52 HR15T. The fracture morphology of the impact test in all specimens shows uniform brittle fracture characteristics. It is found that the melting temperature during the stir-casting process of Al-Si has played a significant role in influencing the resulted properties of Al-Si filled CoO nanoparticles metal matrix composites. The selection of an accurate melting temperature for the stir casting process will affect the resulted properties of produced metal composites.

Application of AHP and FAHP Algorithm for Supplier Development Evaluation

Implementation of supplier development (SD) is appropriate for a firm that intends to reduce costs and streamline its operations while minimising defective products. However, the number of practices involved in the SD program is too large, making them difficult to manage. Conventionally, the selection of decisions is based on multicriteria and is often complex and unstructured. Thus, this paper proposed the Analytic Hierarchy Process (AHP) and Fuzzy Analytic Hierarchy Process (FAHP) methodologies to evaluate and select SD practices. Both methods produced the same result. The results obtained can be indicated by the production professionals as guidelines to look for the opportunity to implement the SD program to improve the capabilities of their suppliers.

Critical Factors Influencing Project on Effective Maintenance, Repair and Overhaul (MRO) in Aircraft Aviation Industry

This study aims to identify the critical factor influencing the project as regards successful aircraft maintenance, repair, and overhaul (MRO) in the aviation industry. Furthermore, this research also aims to investigate whether regulation of project changes plays a role in moderating the relationship between the independent variables and dependent variables described in this research. Through the literature review process, it was found that top management support, stakeholders, key factors competency, acceptance, risk management, project plan monitoring, and effective communication are among the critical factors identified. Referring to a completed project, this research showed that project progress was in two dimensions in a maintenance context, which this research classifies as a successful micro and macro project. The macro viewpoints of project success mean the organizational stage of the project must be recognized and accomplishment relies on the consumer or collaborators to share. The micro perspective of project success can help to manage a project in small levels and is normally alluded to at the finishing line of the project. The summary result for the 4 hypotheses tested, all of them were significant. The result obtained clearly expressed all of the dependent variables have positive influences on project success in MRO aircraft in the Malaysian aviation industry. This research also demonstrates through trial and error that project key factors’ competency and project mission are critical factors in influencing the micro-project success and as well for macro project success, top management support and project mission are two main critical factors.

Electrical Conductivity and Antenna Properties of Polyaniline filled GNPs Nanocomposites

This study was conducted to investigate the potential of utilizing conductive polymer nanocomposite for flexible type antenna application. The polyaniline (PANI) filled with graphene nanoplatelets (GNPs) nanocomposites were synthesized by an oxidative aniline polymerization in an acidic medium. The PANI/GNPs nanocomposites were then characterized by using various spectroscopy and imaging tools. It was found that the strong interaction between PANI macromolecules and GNPs flakes is caused by the strong ?-? conjugation between them, as validated by an increase of Id/Ig ratio of PANI/GNPs nanocomposites. As a result, it established a three-fold improvement for the electrical conductivity of PANI/GNPs nanocomposites, due to the larger amount of charge carrier transport at higher GNPs nanofiller loadings (1.00 wt.%). Later, the PANI/GNPs nanocomposites powder was applied to the cotton fabric by integrating it with a rubber paint slurry. Electrical conductivity, antenna gain, return loss, and radiation pattern of the antenna were reported. It was found that PANI/GNPs flexible textile antenna possessed a constant gain of 4.1809 dB, return loss at -13.154 dB, and radiation pattern which operated at 10.36 GHz for 100% improvement of electrical conductivity, in comparison with unfilled PANI. From these findings, it can be said that the development of wearable textile antenna utilizing PANI/GNPs nanocomposites on the cotton fabric as flexible radiation patch, has great potential for wireless communication purposes.

Fill Time Optimization Analysis In Flow Simulation Of Injection Molding Using Response Surface Method

This study focuses on the analysis of fill time by optimizing the injection molding parameters to reduce the defects that are always found on the plastics part such as poor weld line and part not completely filling which can contribute to mechanical properties of the plastic part. The parameters selected for this study are melting temperature, mold temperature, injection time, and the number of gate positions. Response Surface Method (RSM) was used to determine the most significant and optimum parameters on the fill time. From the result analysis, it is found that the injection time is the most significant parameter that affected the fill time with a 99% contribution. The result shows that there is no interaction between process parameters toward fill time which the injection time is the only major factor that affects the fill time. The improvement increases by 0.07% after the optimization process from 4.278s to 4.281s. The most optimum parameters to longer the injection time are mold temperature at 60°C, injection time at 4s, and the number of the gate with two gates position. Thus, the longer the injection time, it can reduce the defect of molded part in the injection molding process.