This study focuses on mechanized process of mixing and sieving variety of flour (such as yam, plantain, cassava, etc.) with ease and good finished quality, especially when large quantity is required. This is achieved by a combination of a channel fitted with a conveyor blade which is set in a spiral manner on a shaft to produce thorough mixing, and a net in a wooden frame driven by pulley and connecting rod to perform the sieving action. The designed machine is to be driven by a compound belt drive from an electric motor of 1h.p at 1400rpm and its throughput capacity is 13.4 kg/hour. The availability of both mixing and sieving compartment in the design has distinguished the machine from the regular sieving or mixing machine. The machine is affordable and simple to maintain and therefore, it is recommended for small holders, local processors and home use.

It has become critical to build a de-stoning machine that can be used in our homes whenever we need it. As a result, the goal of this research was to develop and build a wet-method household rice destoning equipment. The design was built utilizing locally accessible materials and was based on the notion of material separation using water as a medium of separation. A reservoir, hopper, de-stoning chamber, washing chamber, impeller, water filter, and brush drum make up the machine. The produced machine was powered by a 1 horsepower variable electric motor that communicated the rotating motion of the driving pulley to the driven pulley, which was supported by bearings, through a V-belt. The machine was built and tested, and it was discovered that 2kg/10minutes and 20.04kg/hour of processed rice were destoned at a de-stoning speed of 400rpm, which is the optimal speed for maximum speed separation. The destoning machine's effectiveness in terms of stone removal is approximately approaching 100 percent free of impurities, making it ideal for residential usage. This discovery elucidates the potential to deal with the challenges of stone removal from locally produced rice using hand and manual method, which are inefficient, time and energy wastage, it acts as a rice processing industry innovation.

Due to loss of structural strengthening at temperatures beyond 250°C, heat-treated aluminium alloys (e.g. AA 6061-T6) weldments are usually characterized with poor mechanical properties including hardness, tensile and impact strengths. In this work, friction stir weldments of AA 6061-T6 reinforced with the additions of SiC, B4C and Al2O3 particles at the joints were produced and investigated for improved hardness, tensile strength and impact strength over the unreinforced weldment. The results showed that the entire reinforced welded joint exhibited improved hardness because of the enhanced metal matrix grain refinement and inherent high hardness of the reinforcement particles. B4C particle addition produced hardest joint of about 81% of the base metal hardness (∼114 HV0.3). The impact energies of the SiC (16.9 J), B4C (16.5) and Al2O3 (12.2 J) reinforced weldments are closer to that of the base metal (18.6 J) compared with the unreinforced weldment (9.6 J). The reinforced weldments showed no significant improvement over the tensile strength of the unreinforced weldment. B4C and SiC reinforcements produced the highest improvements in the hardness (at the joint) and impact strength of the AA 6061-T6 friction stir weldments, respectively.

The current research trend for excellent miscibility in polymer mixing is the use of plasticizers. The use of most plasticizers usually has some negative effects on the mechanical properties of the resulting composite and can sometimes make it toxic, which makes such polymers unsuitable for biomedical applications. This research focuses on the improvement of the miscibility of polymer composites using two-step mixing with a rheomixer and a mix extruder. Polylactic acid (PLA), chitin, and starch were produced after two-step mixing, using a compression molding method with decreasing composition variation (between 8% to 2%) of chitin and increasing starch content. A dynamic mechanical analysis (DMA) was used to study the mechanical behavior of the composite at various temperatures. The tensile strength, yield, elastic modulus, impact, morphology, and compatibility properties were also studied. The DMA results showed a glass transition temperature range of 50 °C to 100 °C for all samples, with a distinct peak value for the loss modulus and factor. The single distinct peak value meant the polymer blend was compatible. The storage and loss modulus increased with an increase in blending, while the loss factor decreased, indicating excellent compatibility and miscibility of the composite components. The mechanical properties of the samples improved compared to neat PLA. Small voids and immiscibility were noticed in the scanning electron microscopy images, and this was corroborated by X-ray diffraction graphs that showed an improvement in the crystalline nature of PLA with starch. Bioabsorption and toxicity tests showed compatibility with the rat system, which is similar to the human system.

Comminution of minerals and stones in Nigeria is laden with myriads of resource challenges associated with other developing nations. A typical challenge is the need to import costly mining and mineral processing machineries or replace their components. To address this challenge, economic consideration was prominent in the development of components for the single toggle jaw crusher. Geometric modeling and structural/stress analysis of the components were achieved using Pro/Engineer® and Autodesk Inventor® computer applications. Designed eccentricity of 7 mm resulted in 5 mm throw and 0.01° angle of twist in the eccentric shaft. The designed base frame was statically stable, having yielded a maximum displacement of 0.008066 mm. Analysis of the compression spring indicated design compliance. Also, hardfaced crusher jaws and large diameter pulley and flywheel were developed. Selection of a three-phase, 3730 W electric motor resulted in a 0.24 ton/hr capacity jaw crusher in service. Optimal and maximum feed of the crusher were found to be 0.5 kg and 1 kg, respectively. Average eccentric shaft speed decreased with increased mass of granite lumps undergoing crushing. Therefore, the methods presented can be adopted in developing affordable and easily maintainable jaw crushers for artisanal miners and stone workers in Nigeria.

Photovoltaic panels are less efficient when fixed only to a particular angle of inclination with the sun. However, its efficiency improves with the application of a solar tracker which changes the panel orientation automatically in accordance with the sun’s position. In this work an automated solar tracking device was developed, whose control was from either predictive models or sensors signal. The data collected on field were analyzed and the graphical representation was used to determine the most suitable trend. The trends were of Fourier series, linear regression, hyperbolic and exponential function which stands as basis for the predictive models formulated. The most appropriate azimuth and altitude panel orientation were achieved by the developed solar tracking device with the aid of microcontroller and two linear actuators. A programmable intelligent computer (PIC) was used for controlling the linear actuators during cloudy and sunny condition with input signals from the predictive models developed and solar sensors respectively. The correlation coefficient of the models was found to be above 0.95 and 0.92 for azimuth and altitude respectively, indicating high degree of agreement of both predicted and actual angle data. The maximum percentage errors were 4.72% for azimuth and 11% for altitude of the models developed showing an appreciable level of accuracy. The tracker developed has an efficiency of 72.25%. The stationary panel generated a total of 1.458 kW of power stored per day while the average power stored by the tracking panel is 1.916 kW per day. The tracking percentage power gain was estimated to be 46.15% at peak period above the fixed panel from the analysis of the data collected. Keywords— Efficiency: Energy: Models: Optimize: Sensor: Solar: Tracking.

The recurrent failure of jaw-type crushing machine was traced to an inappropriate external shaft ratio and frequent wear of the jaw of the machine. Current jaw-type crushing machines are designed and constructed with spring steel was improvised with spring steel because of the scarcity of the required material to cast the jaw, which has to be imported whenever there is a failure. The analysis of the relationship between the life span of the jaw of the rock crushing machine to the shaft eccentricity was carried out to determine the external shaft ratio of the machine. The eccentric lobe to impact motion at various positions were analyzed and plotted out for both angular and linear displacements. The analysis and evaluation involved data collection from existing quarries. The results show that an external diameter/offset ratio within the average of 10:1 can be considered for the offset calculation of a jaw-type crusher shaft. The outcome of the result was used to redesign and develop a prototype crushing machine with better output crushing pressure of 13.1x10(5) kN/m(2) and capable of crushing 425-569 kg of rock per hour, depending on the type of rock to be crushed. The machine performed exceptionally well with an efficiency of 95% and is relatively durable compared to high grade imported rock crushing machine.

This paper presents a comparison on the effects of blending chitin and/or starch with poly(lactic acid) (PLA). Three sets of composites (PLA–chitin, PLA–starch and PLA–chitin–starch) with 92%, 94%, 96% and 98% PLA by weight were prepared. The percentage weight (wt.%) amount of the chitin and starch incorporated ranges from 2% to 8%. The mechanical, dynamic mechanical, thermal and microstructural properties were analyzed. The results from the tensile strength, yield strength, Young's modulus, and impact showed that the PLA–chitin–starch blend has the best mechanical properties compared to PLA–chitin and PLA–starch blends. The dynamic mechanical analysis result shows a better damping property for PLA–chitin than PLA–chitin–starch and PLA–starch. On the other hand, the thermal property analysis from thermogravimetry analysis (TGA) shows no significant improvement in a specific order, but the glass transition temperature of the composite increased compared to that of neat PLA. However, the degradation process was found to start with PLA–chitin for all composites, which suggests an improvement in PLA degradation. Significantly, the morphological analysis revealed a uniform mix with an obvious blend network in the three composites. Interestingly, the network was more significant in the PLA–chitin–starch blend, which may be responsible for its significantly enhanced mechanical properties compared with PLA–chitin and PLA–starch samples.

An empirical model for predicting the required compaction pressure of heterogeneous briquettes was developed in this study. The study was based on low-pressure compaction, where the used of binders is paramount. Three agricultural wastes: sawdust, rice husk, and palm kernel shell were used in the study. The material type was a key factor of influence on the briquette samples produced. The optimum compaction pressures of the homogeneous briquettes were 686.5, 981, and 981 N/cm(2), for sawdust, rice husk, and palm kernel shell, respectively. The predicted required compaction pressures of the heterogeneous briquettes, as predicted from the model, ranged from 715 N/cm(2) to 950 N/cm(2) for sawdust/palm kernel shell briquettes, 710 N/cm(2) to 906 N/cm(2) for sawdust/rice husk briquettes, and 936 N/cm(2) to 975 N/cm(2) for palm kernel shell/rice husk briquettes. The heterogeneous briquette samples compacted at the predicted required compaction pressures offered better quality briquettes in terms of density and calorific value than those compacted at a fixed compaction pressure of 1177 N/cm(2). It was established that the developed model offered ease of compaction and effective utilization of materials and will be of great use in the design of variable pressure briquetting machines.

Procedures for producing hardfaced jaws using ferro-alloy hardfacing inserts and low carbon steel substrate have been established. This research was prompted by the need to provide an economical substitute to the high manganese austenitic steel that has dominated the mining and minerals industries since its invention by Sir Robert Hadfield in 1882. In this research, ferro-alloy hardfacing inserts of composition 72.80 %Fe. 12.32 %Mn, 7.38 %Cr were produced by sand casting. The inserts were welded to low carbon steel substrate by manual metal arc-welding to form the hardfaced jaws. Welding was carried out intermittently using E6013 gauge 10 oerlikon electrode and a current of 100 A. The fixed and movable jaws lost 0.3 and 0.1 kg, respectively, after crushing 400 kg of granite in the jaw crusher. Hardness values and wear volumes of the hardfacing insert and workhardened Hadfield steel were 653 HV, 0.0069 cm3 and 517 HV, 0.017 cm3, respectively. Cost of producing the hardfaced jaws was five times cheaper than the estimated cost of producing Hadfield steel jaws. Consequently, the hardfaced jaws can economically substitute the Hadfield steel jaws in jaw crushers.

The integration of information management into spare parts planning for Automobile maintenance cannot be overemphasized. Information on automobile spare parts under service condition from three selected automobile maintenance jobshops in South-western Nigeria was garnered in order to identify their levels of important and criticality. The known state of the spare parts condition with prior probability was used to determine conditional probability of failure based on the criticality conditions. The posterior failure probability spare parts was obtained for a future maintenance cycle time using the modified Bayesian probability model by integrating levels of spare parts criticality into the system. The computer software package was developed using Visual Basic (V.B) computer language and applied in the Automobile Industries for rapid information management as regards spare parts planning, to failure analyses and grouping and effective choice of maintenance policy. The system model was implemented on three jobshops that were responsible for the maintenance of three brands of vehicles selected for this study. The practical implication of the results showed that the developed computer software package is more efficient in term of effectiveness in maintenance operation planning and cost savings than the traditional methods being used in the jobshops.

A review on hardfacing is presented. Hardfacing involves applying a consumable with desired wear properties over a soft base metal surface to enhance resistance to different wear mechanisms. Substrate materials used for hardfacing are mainly steel, while the alloys of carbide forming elements dominate the surfacing consumables. Powder metallurgy, atomisation and granulation are methods of producing hardfacing alloy powder. Most welding methods were identified to be successfully used in applying consumable on substrate surfaces. Dilution decreases with increase in the number of hardfacing layers. Buffers, butters and build-up metals are used to compensate for composition differences to prevent spalling, overcome welding difficulties and make up for badly worn surfaces, respectively. Waffle, stringer and dot patterns are the existing hardfacing deposit patterns. Benefits of hardfacing include: reduced downtime, inventory and maintenance cost, increased plant availability and productivity, and a good number of service life extensions through timely reparation.Keywords: Hardfacing, wear, substrate, consumable, service life extension, composition compensation

Extension of service lives of critical machine components subjected to wear is possible through application of hardfacing alloys. In this work, two hardfacing alloys were produced based on the mass ratios of 2: 1: 1 and 7: 1.5: 1.5 for Fe: Mn: Cr by sand and open permanent mold casting processes, respectively. XRD analysis of both samples showed the prominent presence of (Mn, Cr)23C6, (Fe, Mn, Cr)7C3, Cr3C2, Fe3C2 and Fe4C carbides. Hӓgg carbide was prevalent in the SEM microstructural analysis of the sand cast sample, while cementite dominated the permanent mold cast sample. The average hardness values, impact energies absorbed and wear volumes of the samples produced with their respective charge mass ratios are 567 HV, 30 J and 0.131 cm3 for 2: 1: 1 ratio and 592 HV, 29.5 J and 0.085 cm3 for the 7: 1.5: 1.5 ratio. For service life applications as jaws, rolls, mantles, and concaves in crushers, the latter was recommended for manual metal arc welding to low carbon steel substrate because of its higher hardness, lower wear volume and cheaper alloy cost.

Laser metal deposition using wire feeding system is increasingly becoming known as a process for making engineering components from the scratch. The process quality determines the end properties of the components hence, their lifetime performances in the service environments. In this study, single tracks and multiple tracks (walls) of AISI 308LSi on AISI 304 substrate were laser deposited using lateral wire feeding system. The microstructures of the deposited tracks were examined using optical microscopy and scanning electron microscopy. The macrohardness at different stages of the built walls was determined using Vickers hardness tester, while the ultimate tensile strength of the walls was investigated according to ASTM E8M-13 standard. The microstructure of the walls revealed nearly vertical columnar dendrites growing perpendicularly to the horizontal. The macrohardness of the deposited walls is within 167-194HV but decreased from the bottom layer to the top layer. The tensile strength of the walls which ranges between 474 and 525MPa depends on the wall building directions.

A review on the design and operations challenges of a single toggle jaw crusher is presented. Strength and fracture toughness of the material to be crushed are intrinsic properties that determine the time and energy required to crush the material. Economy of the crushing process is partly dependent on the angle of nip. Productivity of the crusher can be improved upon by increasing the eccentricity of the eccentric shaft, use of reversible jaws, bush bearing and easily adjustable toggle plate. Vibrations and fatigue cracks in the crusher frame will be nipped in the bud through structural analysis at design stage. Determination of the optimal angle of inclination of the toggle plate, development of jaws with varying wear rate along the crushing chamber, and development of comminution energy models that take into cognizance relevant crushing parameters for simulation and optimization of the crushing process are some areas that require close attention. http://dx.doi.org/10.4314/njt.v36i3.22

High manganese austenitic steel, popularly called “Hadfield steel” has dominated and played significant role in wear applications, especially in the mines and minerals industries since its invention over a century ago. A review on the researches on this steel revealed that its prominence in these fields is mainly due to its good combination of impact and abrasion wear resistance arising from its high toughness and high hardness respectively. Its strain hardening ability under impact loading is evidenced by increase in hardness as the material work hardens; this lowers the amount of wear in service. The work hardening property of the steel has been linked to governing mechanisms such as dislocation, deformation twinning, and dynamic strain ageing; also, it is enhanced by increase in carbon, ageing temperature and reduction in manganese content. Carbide precipitation along the grain boundaries and within the grains is the major cause of embrittlement of the steel. These carbides together with voids and porosities during casting solidification, improper heat treatment, overheating during welding, use of unsorted scrap metal and wrong wear application have been identified as the causes of premature failure in service. Hardfacing method has been proposed as a means of substituting the steel in wear applications, as alternative wear materials such as white cast iron and austempered ductile iron lack the combination of impact and abrasion resistance being offered by the Hadfield steel.

In this work, a simple efficient and economical plantain slicing machine was designed and constructed. The entire machine is a slider-crank mechanism driven by an electric motor via a v-belt, with the driven pulley borne on a shaft supported by two bearings. The slider comprises of the hopper (which houses the plantains), guide and stanchion. The mechanism consists of two cranks, each on either side. They are linked to the slider with the aid of a connecting rod through which motion is transmitted to the hopper (slider). The to and fro motion of the slider along the bed of the guide (which houses the cutting blade) achieves the desired chip formation. The machine has average efficiency of 93%, compared with 87% and 63% of chip cutter and domestic knife respectively, at tremendous reduction of time, cost of production, labour and operating capacity of 0.1124 /s (a plantain for 9s).The efficiency of this machine is far more than the existing ones. From the results obtained during performance evaluation, the average time required slicing 30 pieces of plantain of average length of 260mm, weight of 0.3kg and diameter of 65mm using domestic knife, chip cutter and the plantain slicer were approximately 1986s, 1487s and 267s respectively. Though this plantain slicing machine produces chips of uniform thickness like chip cutter but with higher efficiency and minimal human input. This improved machine is simple, hygienic, portable, detachable, easy to operate and maintain. It is suitable for both small and large scale productions of plantain chips .