Palm kernel oil refining requires efficient degumming to remove phospholipids that negatively impact oil quality and stability. The optimization of phospholipids removal and oil quality parameters with three factors: FCW concentration (0.05 – 0.15 w/w), temperature (80 – 100 °C), and reaction time (10 – 20 min) was studied using Central Composite Design (CCD) of Response Surface Methodology. The phosphorus content, of FCW-assisted deacidification, after degumming ranged from 8.58 – 42.62 mg/g, while acid value, free fatty acid content, iodine value, and saponification value also showed variations across experiments. Linear models were obtained for all responses and a significant lack of fit for phospholipids content and limited predictive power for most quality parameters were obtained. Experimental optimization identified optimal conditions at phosphoric acid concentration of 0.15 w/w, temperature of 80 °C, and time of 10 min, achieving a validated phosphorus content of 7.73 mg/g (59.3

Wire arc additively manufactured (WAAMed) parts often require some degree of post-processing operations to improve their quality and then enhance their lifetime performances in service conditions. In this work, wire arc additive manufacturing (WAAM) was used to fabricate AISI 308LSi wall structures, and then, post-processing treatments including annealing, cold forging, and a combination of cold forging and annealing were applied to enhance the quality of the fabricated walls. Thereafter, the microstructure, density, percentage porosity, hardness, tensile, wear, and corrosion properties of the walls (as-deposited and post-processed) were examined. The effects of the annealing, cold forging, and a combination of the cold forging and annealing processes on the quality of the WAAMed AISI 308LSi walls were determined and then compared. Highly dense walls were deposited via WAAM. The density increased to within 99.6% of the as-received AISI 308LSi, and the porosity was estimated to be < 0.5% after forging and a combination of forging and annealing post-processing. The hardness of the as-deposited wall (approximate to 153 HV) was found to increase by 14.1% and 8.5% after the cold forging and a combination of cold forging and annealing, respectively. The post-annealing process resulted in the highest increase in ductility (approximate to 31%), but the highest improvement in tensile strength (approximate to 7.5%) was produced by the combination of the cold forging and annealing post-processing. Post-cold forging processing followed by a combination of cold forging and annealing processing yielded improvements in wear and corrosion resistances of the WAAMed AISI 308LSi wall structures. This work has established the suitable post-processing methods for enhancing the quality of WAAMed structures.

The global demand for effective utilization of both humans and machinery is increasing due to wastage incurred during product manufacturing. Excessive waste generation has made entrepreneurs find it difficult to breakeven. The development of dynamic error-proof Overall Equipment Effectiveness (OEE) model for optimizing a complex production process is targeted at minimizing/eradicating operational wastes/losses. In this study, the error-proof sigma metric was integrated into the extended traditional OEE factors (availability, performance, quality) to include losses due to waste and man-machine relationships. Error-proof sigma statistics enabled continuous corrective measures on unsatisfactory or low-level OEE resulted from process output variations (quantity delivered or expected), which were mapped into sigma statistical standards (one- to six-sigma). Application of the model in a processing company showed that errors of the process were reduced by 78% and 42% respectively for traditional OEE and the new Error-Proof OEE (OEE-EP). The results revealed that the OEE-EP model is better than the other existing schemes in terms of losses elimination in the production process.

High strength 7xxx series aluminium alloys are widely utilized in the aerospace, automotive and other manufacturing industries due to their low cost, high specific strength, high stiffness strength and fracture toughness. Additive manufacturing presents new opportunities in producing 7xxx series aluminium alloys such as reduced material waste, shorter lead time, and increased design freedom. This paper reviews the current progress in Wire Arc Additive Manufacturing (WAAM) of 7xxx series aluminium alloys, a technology that offers benefits such as better energy absorption than alternative laser-based processes, high deposition rates, and unrestricted build size. A classification of the AM processes utilized to fabricate aluminium alloys and WAAM process variants for fabricating aluminium alloys are introduced. Also, some common defects including porosity, solidification cracking and volatile elements loss encountered during the WAAM process of 7xxx series aluminium alloys are discussed. Whilst porosity remains a major issue in 7xxx series aluminium alloys produced via WAAM, several opportunities to minimize or eliminate the defects through process selection and alloy development are presented.

The study sought to investigate the effect of pulverized glass waste (PGW) particle size as reinforcement for AA6061-T6 joints produced by Friction Stir Welding (FSW). The study utilized three particle sizes of 15 microns, 45 microns and 75 microns of the PGW as reinforcement alongside established process parameters of 900 rpm, 1120 rpm, and 1400 rpm for rotational speed, 25 mm /mi n, 40 mm min-1 and 63 mm/min for traverse speed and 1 degrees, 1.5 degrees and 2.5 degrees for tilt angle in a Taguchi L9 orthogonal array experimental design for the welding process. The welding experiments were repeated for each reinforcement particle size utilized in this work. Parallel-hole reinforcement strategy was used on all joints for the application of the PGW. Microstructural analysis, tensile strength and hardness tests were carried out on the welded joints. The volume percentage of the PGW in the aluminum alloy matrix at the welded joint were determined using Image J Processing software. A processing condition of 900 rpm rotational speed, 25 mm/min traverse speed and 1 degrees tilt angle was found to produce the weldment (sample 4) that has a favourable combination of high tensile strength (77.3 MPa) and high hardness (87.3 BHN). The tensile strength was established to increase as the PGW size decreased. This correlation was found to be statistically significant. The hardness of the welded joint did not show any particular trend with the size of the PGW. However, the hardness of the welded joint increased with the increase in the volume percentage of the pulverized glass waste in the welded joint. A moderate Pearson correlation (0.615) between hardness and PGW volume percentage was found.

Wire arc additive manufacturing (WAAM) has been established to be an efficient and cost-effective additive manufacturing technique for fabricating functional metallic parts from scratch. However, there is need to determine optimal processing condition for each material system to produce high-quality parts. In this work, a parametric study of WAAM of AISI 308LSi was performed to determine the processing condition(s) at which single tracks of high dimensional accuracy, excellent geometry, no visible crack and pore, and high hardness required for high-quality multi-track deposition can be achieved. The track geometries were investigated using a combination of optical microscopy and image processing software. The microstructure and hardness of the deposited single tracks were examined using optical microscopy and Vickers hardness tester respectively. A process map predicting the process stability of WAAM of AISI 308LSi was developed within a process window. Continuous single tracks of high dimensional accuracy were produced from a stable deposition process. The process becomes unstable whenever the wire deposition volume per unit length of track is in excess of the available heat energy per unit length of track. The wire feed rate and traverse speed significantly influence the stability and geometry of the single tracks. The processing conditions at which single tracks of low wetting angle (<90◦), high aspect ratio (>1.5), high surface quality, and high hardness (close to the as-received material) can be deposited were determined. These processing conditions were considered suitable for the fabrication, surface modification and repair of functional engineering parts made of 308LSi stainless steel.

Wire arc additive manufacturing (WAAM) has gained significant attention in recent years as a cost-effective and efficient method for fabricating complex geometries. This study investigates the effects of cold forging and annealing on mechanical properties of AISI 308LSi wall fabricated using an automatically controlled gas metal arc welding on a CNC machine. The multilayer WAAM wall manufactured at an optimized parameters was first machined to a fairly smooth surface. Thereafter, the wall samples were differently subjected to annealing at 930°C and cold forging processes to improve the mechanical properties. Microstructural characterization of the post-processed and as-deposited samples were performed using optical and scanning electron microscopy while the tensile and hardness properties were investigated using Instron universal testing machine and Vickers hardness tester respectively. Annealing process was found to improve the tensile properties while the cold forging improved hardness of the deposited WAAM wall. These findings offer valuable insights into optimizing post-processing techniques for WAAM parts, especially 308LSi stainless steel and contribute to the advancement of this technology for industrial applications.

Pyrolysis is a method used for the thermochemical conversion of biomass and agro wastes into three major by-products namely, biochar, bio-oil, and biogas in the absence of oxygen. Global waste generation is increasing at an alarming rate. Palm kernel shell (PKS) is among the palm wastes accumulating in many palm oil mills around the globe with the attendant problems in waste management. The utilization of coal for energy generation is more expensive and not environmentally friendly. Bio-oil refineries and industries require the utilization of minimum resources (input) to achieve optimal response (output) in the production process. However, more than 30% of the energy content derivation from the pyrolysis process is wasted due to nonoptimization of the process parameters. This study investigated the optimization of the product yields of the pyrolysis of PKS in a fixed-bed batch reactor using response surface methodology (RSM). Masses of 1 kg, 2 kg, and 3 kg were pyrolyzed in batches at process temperature variations of 200 OC, 300 OC, 400 OC, and 500 OC. Design Expert 12 software (Version 12.0.3.0 Stat-Ease Inc. MN, USA) and Analysis of Variance (ANOVA) were used for the statistical analysis. Lack-of-fit, adjusted, and predicted multiple correlation coefficients and coefficient of variation of the different polynomial models were compared to select the best-fitting polynomial model. The optimal feedstock parameters were 2.66 kg of PKS and 410.0 OC process temperature. The predicted results were 0.986 kg of biochar, 1.205 kg of bio-oil, 0.481 kg of biogas, 1116.5 cm3 of bio-oil, and 140.6 minutes. The experimental results were 0.894 kg of biochar, 1.316 kg of bio-oil, 0.498 kg of biogas, 1208.9 cm3 of bio-oil, and at 162.8 minutes through validation. The validated quadratic model was suitable for the optimization and RSM is a numerical, statistical, and mathematical tool for modeling and optimization of the pyrolysis process in a fixed-bed batch reactor.

In this study, the optimum process parameters for the manufacture of brake friction linings (BFLs) from palm kernel shells (PKS), periwinkle shells (PWS), and coconut shell (CNS) composites were established using signal–to–noise ratio based on the Taguchi technique. The L 9 (3 4 ) orthogonal array was set up for the investigation of the performance metrics (coefficient of friction, wear rate, and hardness) synergized by multiple criteria evaluation. The manufacturing parameters considered were molding pressure, molding temperature, curing time, and heat treatment time. Consequently, the optimized parameters were utilized for the production of different BFL composites of the PKS/PWS/CNS mix. Finally, entropy and TOPSIS techniques were employed to isolate the best composite for comparative analysis. The results show that the optimum process parameters are 29 MPa (molding pressure), 120 °C (molding temperature), 6 min (curing time), and 2 h (heat treatment time). ANOVA using Minitab 21.1.0.0 shows that the effects of the molding pressure and curing time are statistically significant at α = 0.05, with a total contribution of 94.45%. The entropy-TOPSIS analysis gave sample S2 pkpc with a composition of 12% PKS, 15% PWS, and 18% CNS as the best composite. Compared to the asbestos BFL, the composite shows an improvement in friction coefficient (45.7%), wear rate (66%), density (60.2%), and oil and water absorption (233%) (542.8%) respectively. The live test on a Peugeot 301 using S2 pkpc BFL confirms the satisfactory performance of the composite. However, an increased wear rate was observed at vehicle speeds above 90 km/h.

The present paper reviews the concept of wire arc additive manufacturing (WAAM), its associated defects, and the existing post-processing methods for product quality enhancement. The application of friction stir processing (a surface modification technique) for enhancing the microstructure and mechanical properties of wire arc additively manufactured parts was considered as a new horizon in this field of research. Finally, the article concludes that the widespread usage of WAAM is still challenged by some obstacles, which may need to be targeted and addressed in unique ways for different materials in order to generate functional systems in a reasonable amount of time. Unifying materials and manufacturing techniques to produce defect-free and structurally robust deposited parts will become increasingly important in the future.

This study established the optimum process parameters for manufacturing brake friction lining (BFL) from coconut shells (CNS), palm kernel shell (PKS) , periwinkle shells (PWS) composites. Optimization was achieved in respect of the performance metrics (coefficient of friction, wear rate and hardness) using Signal-to-Noise (SN) ratio and Entropy and Technique for the Ordered Preference by Similarity to the Ideal Solution (Entropy-TOPSIS). The optimum parameters obtained using SN ratio and Entropy-TOPSIS method were compared and are respectively 29 MPa and 29 MPa (molding -pressure), 120? and 140? (molding-temperature), 6 and 6 minutes (curing-time) and 2 hr. and 3 hr. (heat-treatment-time). ANOVA using Minitab 21.1.0.0 reveals the effect of the molding pressure and the curing time on the synergized performance metric as statistically significant at a = 0.05 with total contribution of 94.44%. Comparatively, the significant parameters values were unaltered in both methods of optimization. Therefore, it is concluded that any of the optimum parameter values obtained using either the SN ratio approach or the Entropy-TOPSIS method can safely be used for producing BFL of different composition of CNS, PKS and PWS.

AA6061-T6 is becoming a material of choice in the automobile, marine and aerospace industries because of its combination of relatively favourable and superior properties including high toughness, strength and excellent corrosion resistance. The major issue of concern about this material is the deterioration of these properties in the welded joint which has been established to improve through the additions of synthetic reinforcements such as SiC, WC, Al2O3, B4C and SiO2. This study seeks to investigate the quality of pulverised glass waste-reinforced friction stir welded joints of AA6061-T6 within a process window (rotational speed: 900-1400 rpm; traverse speed: 25-63 mm/min; tilt angle: 1° - 2.5°) as well as developing a regression model predicting the tensile strength of the pulverised waste glass-reinforced AA6061-T6 friction stir welded joints at varying process parameters. The tensile strength of the weldment was determined using Instron universal testing machine while the model was developed using a new statistical method (analysis of variance and hierarchy rule). The effects of the interaction of the parameters on the joint quality were also determined. Optimum tensile strength of ~185 MPa was achieved at rotational speed of 1120 rpm, traverse speed of 40 mm/min and tilt angle of 1.5°. There is an improvement of about 37% over the unreinforced joint with tensile strength of ~135 MPa. A model with a prediction accuracy of 92% was developed. The analysis of variance revealed that tool rotational speed, traverse speed and tilt angle had significant effects on the tensile strength of the weldments while the factors’ interactions do not show any significant contribution to the tensile strength. The model finds technical applications where timely selection of optimum process parameters is required for producing particulate-reinforced AA6061-T6 friction stir welded joints.

The purpose of this study is to investigate the effect of different reinforcement strategies on the mechanical properties of pulverized glass waste (PGW) reinforced AA6061-T6 friction stir welded joint. Friction stir welding of PGW reinforced AA6061-T6 was carried out at an optimized processing parameters by using different reinforcement strategies including centre groove, parallel holes, centre holes, zig-zag holes and side holes arrangements. Thereafter, the microstructure and mechanical properties of weldments produced using each strategy were investigated. The results showed that all the reinforcement strategies utilized in this work produced harder joints than the unreinforced joint. The parallel holes (PH) strategy followed by the centre holes (CH) exhibited the highest hardness of 72 HRC B and 66 HRC B respectively. Only the joints produced using PH, CH and SH strategies exhibited higher or improved impact energy than the unreinforced. Though the joints produced using PH and CH reinforcement strategies have tensile properties that are close to that of the unreinforced joints, the unreinforced joints show higher tensile properties than the entire reinforced joints. Compared with other reinforcement strategies, better particle distribution was achieved through the use of PH and CH reinforcement strategies. Parallel holes and centre holes arrangements have been established as the most appropriate reinforcement strategies for producing high quality aluminium alloy composite welded joints.

In an attempt to provide a more flexible means of achieving friction stir welding (FSW) of Aluminum without the use of expensive FSW machine tool, which are not readily available, this study developed a mobile fixture system (MFS) for FSW on Vertical milling Machine Tool (VMMT) and Pillar drilling machine Tool (PDMT). A conceptual design of the fixture system with a moving work table, which provides for transverse feed (movement) of the workpieces during FSW, was generated. The detailed design of the components of the MFS was done using existing mechanical design formulae. Subsequently, the design was fabricated and evaluated. An ATmega 328P Arduino Uno microcontroller was used to design a control system to automate the MFS worktable movement. Results revealed that the MFS worked smoothly during FSW of AA 1100 materials. The MFS performed well during the FSW of the Aluminum materials on the VMMT as well as the PDMT. The efficiency of its motion accuracy was estimated as 87.2%. Also, the trend of the tensile strength and the hardness value as well as the joint efficiencies of the AA 1100 weldments produced using the developed MFS agreed with existing studies.

In this work, gas metal arc welding of AISI 304 stainless steel at varying compositions of argon-CO2 shielding environment was performed using an established optimum parametric combination. Thereafter, investigations on the microstructure of the welded joints and mechanical properties of the weldments were carried out. Weldments of excellent surface quality that are void of spatters and pores were obtained when the shielding gas composition (wt.%) range is between 100% argon and 75% argon - 25% CO2. Increasing percentage composition of CO2 beyond 25% resulted in irregular bead formation characterized with spatters and pores. The hardness of the welded joint became significantly high as the CO2 composition in the shielding gas increased. The highest value of 310 HV was obtained when the shielding gas composition was 5% argon- 95% CO2. The least (220 HV) was obtained when the shielding gas was 100% argon. High ultimate tensile strength (596 - 378 MPa) was achieved when the shielding gas composition range is between 100% argon and 75% argon-25% CO2. The UTS dropped significantly as the CO2 composition in the shielding gas increased beyond 25%. It decreased from 336 MPa at 70% argon-30% CO2 shielding gas composition to 133 MPa when 100% CO2 was utilized as the shielding gas. At the end, the effects of the CO2 addition and suitable composition of CO2 addition to argon shielding environment during GMAW of AISI 304 stainless steel have been established.

Aluminium alloys are one of the choice materials with ever-increasing demands in manufacturing industries. The aluminium alloy 6 xx series such as AA6061-T6, has emerged as one of the promising materials utilized owing to its combination of favourable properties which include high strength to weight ratio, good ductility, excellent corrosion resistance and relatively low cost. These superior properties are responsible for its emergence and usage in the fabrication of aircraft wings and fuselages, yacht/ship construction, automotive rims and wheel spacers. However, joining of AA6061-T6 including the use of friction stir welding (FSW) has serious concerns because the mechanical and tribological properties of the AA6061-T6 welded joints deteriorate significantly compared with the base metal. This phenomenon has been attributed to the severe softening encountered at the stir zone (SZ) of the aluminium matrix during FSW. Other inherent challenges of FSW such as weld thinning, kissing bond and keyhole formation also contribute to the reduction in the weld joint quality. The softening phenomenon has been linked to the dissolution of the strengthening precipitates (B″-Mg5Si6) as a result of high heat input during the welding process. Hence, this paper attempts to review the various improvement strategies adopted in the existing studies to improve the quality of AA 6061-T6 welded joint. These include parametric optimization, selection of appropriate tool design, pre and post heat treatments, adoption of different groove/hole designs for particle addition as well as the addition of reinforcement particles to the weld joint. The variants of FSW recently developed will also be considered. The findings from the review will generally be useful for future work on FSW of heat treated aluminium alloys. The evolution of FSW and its associated challenges are briefly discussed while the research areas yet to be harnessed are suggested for future works.

PurposeThe purpose of this study is to determine the effects of post-annealing and post-tempering processes on the microstructure, mechanical properties and corrosion resistance of the AISI 304 stainless steel gas metal arc weldment.Design/methodology/approachGas metal arc welding of AISI 304 stainless steel was carried out at an optimized processing condition. Thereafter, post-annealing and post-tempering processes were performed on the weldment. The microstructure, mechanical and electrochemical corrosion properties of the post-weld heat treated samples, as compared with the as-welded, were investigated.FindingsThe as-welded joint was characterized with sub-granular grain structure, martensite formation and Cr-rich carbides precipitates. This made it harder than the post-annealed and post-tempered joints. Because of slower cooling in the furnace, the post-annealed joint contained Cr-rich carbides precipitates. However, the microstructure of the post-tempered joint is more refined and significantly devoid of the carbide precipitates. Post-tempering process improved the elongation (∼23%), tensile (∼10%) and impact (∼31%) strengths of the gas metal arc AISI 304 stainless steel weldment, while post-annealing process improved the elongation (∼20%) and impact strength (∼72%). Owing to the refined grain structure and significant elimination of the Cr-rich carbide precipitates at the joint, the post-tempered joint exhibited better corrosion resistance in 3.5 Wt.% NaCl solution than the post-annealed and the as-welded joints.Originality/valueThe appropriate post-weld heat treatment that enhances microstructural homogeneity and quality of the AISI 304 gas metal arc welded joint was determined.

The correlation and prediction of optimum process parameters in biodiesel production is useful in obtaining high rate of conversion of vegetable oil to biodiesel as well as in process control. In this study, the correlation of the operating parameters such as reaction time, reaction temperature, stir speed, catalyst concentration and methanol-oil ratio at a pressure of 400 kPa for the production and prediction of the optimum biodiesel yield during biodiesel production was carried out using the Central Composite Design (CCD) and Artificial Neural Network (ANN). By adjusting networks and initializing weights, the neural network was iteratively trained with the aid of the Levenberg Marquardt algorithm in MATLAB R2018b environment using experimental results from the central composite design. From the analysis of results obtained, the correlation coefficients, adjusted and predicted R as well as R squared were close to1. In addition, predicted values from the central composite design and neural network show good correlation results when compared to the experimental data. The validation of the neural network was done with arbitrary values and random selection of process parameters. The observed output in terms of percentage yield of biodiesel from the trained network fell within the range of experimental results, thus, indicating that the network is an efficient tool for correlating and predicting process parameters for biodiesel production.

Steels are majorly used for diverse structural applications; however, they suffer severe degradation in a corrosive environment which necessitates the need for a protective surface coating. In this paper, the electrochemical study of MgZnCa alloy thin film coating on an AISI 304 stainless steel was reported. The study intends to investigate the influence of coating thickness on the electrochemical performance of the ternary MgZnCa alloy thin film. The polarization results indicated that better corrosion resistance is achieved when the MgZnCa coating is applied on the steel substrate, as the corrosion current density of the 4 mu m coating (0.28 mA/cm(2)) is lower than for the uncoated substrate (0.44 mA/cm(2)). As the MgZnCa coating thickness increases from 4 to 6 mu m, a decrease in the corrosion density with a resultant increase in the corrosion potential was observed. The microstructural characterization revealed fewer corrosion attacks for the coated substrates as compared with the uncoated material with the presence of more degradation products. The corrosion resistance of the steel substrate is enhanced by the application of MgZnCa coating and increasing coating thickness is significantly beneficial.

Water availability is a critical variable for virtually every economic activity, including agriculture and industry, the energy sector and public use. Specifically, Farmers could waste thousands of cubic meters of water daily through Irrigation. This project developed a smart irrigation system capable of making autonomous decision of irrigating the soil with an appropriate amount of water required through monitoring of soil irrigation factors. The soil moisture level and the rainfall status were the soil irrigation factors considered. The threshold values of the irrigation factors required for soil to be irrigated were established. Subsequently, a system was developed to sense the soil irrigation factors and monitor when the threshold values are reached so that necessary information is communicated to switch on or off a water pump designed for irrigation purpose. The system is implemented with a PIC16f876A microcontroller. The results of performance evaluation conducted on the system revealed that the system is able to monitor and estimate the soil irrigation factors with good accuracy. Also, the system is able to start the water pump to irrigate soil and stop it as appropriate depending on whether the soil irrigation factors value indicates need for irrigation or not. Keywords: Irrigation; Autonomous; System; Microcontroller; Threshold.