Development of a multi-roller abrasive Cassava peeling machine

A simple to operate, maintain and affordable multi-roller abrasive cassava peeling machine comprising a feed section, peeling chamber, abrasive surface, tuber discharge chute and waste peel chute was designed, fabricated and evaluated. The machine development was based on engineering standards and specification while considering crop, machine and operational factors to include the physical and mechanical properties of cassava tubers, abrasive property of peeling surface, material and speed of the machine. The machine was evaluated for performance with commonly used varieties NR 8082, 8083, 8208, 09/0581 and UMUCAS 38 having moisture content of 63.33%, 64.50%, 65.40%, 63.50% and 84.33% respectively. The performance evaluation results at a roller speed of 360rpm showed peeling efficiency of 91%, throughput capacity of 2.17kg/min, and a proportion by weight of peel of 0.9%. The cassava peeling machine fabricated, eliminated the drudgery, loss of time and tuber flesh encountered in manual peeling with better product quality when compared with the existing machines.

Comparison of the abrasive properties of two different systems for interproximal enamel reduction: oscillating versus manual strips

Background The aim of the present investigation was to evaluate enamel reduction efficiency, abrasive property decay, and enamel effects between oscillating mechanical and manual systems for interproximal enamel reduction (IPR). Methods Three oscillating strips and three manual strips were tested on twelve freshly extracted premolars blocked in an acrylic cylinder pot by means of a material testing machine. Each strip underwent one test of 8 cycles (30 s each). Both abrasive tracks and teeth surfaces were qualitative evaluated before and after IPR by means of SEM analysis. Efficiency and abrasive property decay of both IPR systems were investigated by the amount of enamel reduction within the eight-cycle testing. Independent t-test was used to evaluate differences in variables between the two systems. Results Mechanical IPR system showed higher efficiency in terms of enamel reduction (p < 0.005) when compared with manual IPR system (0.16 mm and 0.09 mm, respectively). Quantity of removed enamel decreased throughout the 8 cycles for both systems. Less presence of enamel debris and detachment of abrasive grains were observed on mechanical strips rather than manual strips. SEM analysis revealed more regular surface of teeth undergone mechanical IPR procedures. Conclusion Oscillating diamond strips showed more controlled efficiency when compared with the manual IPR system leading to a more regular enamel surface.

Design of a Magnetorheological Finishing Tool Manipulated by a Mechanical Magnetic Switch for Magnetic Field Assisted Finishing

In this study we proposed a finishing tool where a slurry composited of magnetorheological (MR) fluid and abrasive particle was utilized as the polishing medium such that the rheological property and corresponding abrasive property could be controlled by changing the magnetic field. The MR abrasive fluid is magnetized by a permanent magnet. With a design of a steel C-shape structure (C-Structure) the magnetic field generated by the magnet can be directed to the tool tip. With a movable slider as a gate of the C-Structure the magnetic field directed to the tip can be adjusted continuously. The slurry was supplied from the tail and reached the tip through a fluid channel in the center of the tool. While the tool rotates with its tip near a workpiece filled with the magnetized slurry, the finishing machining process can be achieved. The usage of this finishing tool was designed to be similar as a conventional milling cutter’s tool allowing for handling surfaces of complex 3D geometries.

Numerical Investigation on the Effect of Abrasive Property for Abrasive Flow Machining

Numerical investigations of the abrasive influence on material removal efficiency of the micro-hole for AFM process is conducted in this paper. A three-dimensional model is constructed for this process. The abrasive with various particles volume fraction and different micro-holes with various diameters are selected in this study. The simulation results show that the lower particle volume fraction may be in favour of the metal removal uniformity, but the processing time will be too long if too low fraction is selected.

Experimental Research on Deep Hole Honing of Difficult-to-Cut Materials Based on Mixture-Abrasive Honing Stones

The deep hole honing is an effective and precise method in deep hole processing. It can remove the machining allowance to ensure the hole size and the shape accuracy, and have better surface quality of a hole. The difficult-to-cut materials such as precipitation-hardening stainless steel, stainless steel (1Cr18Ni9Ti) and titanium alloy have the properties of high hardness, wear resistance, heat resistance, and corrosion resistance. The conventional single-abrasive honing stones can not handle the difficult-to-cut materials effectively because of their single-abrasive property. For higher efficiency, more than ten of mixture-abrasive honing stones with different proportion of different abrasives have been designed and the contrast experiments have been done for different mixture-abrasive honing stones to grind precipitation-hardening stainless steel, stainless steel (1Cr18Ni9Ti) and titanium alloy. According to several comprehensive evaluation factors of the grinding ratio, the specific grinding energy and the area that the honed chips stick the oilstones surface, the optimum proportion of different abrasives have been found for honing difficult-to-cut materials. It can be observed that the mixture-abrasive honing stones have better performance than that of single-abrasive stones when honing certain kind of difficult-to-cut materials.

Fluid Flow and Pressure in the Grinding Wheel-Workpiece Interface

A model is presented for flow of grinding fluid through the grinding zone. It was found that the flow rate through the contact zone between the wheel and the workpiece is a function of fluid pressure in the grinding zone, delivery flow rate, fluid density, and wheel velocity. An empirical coefficient of value less than 1 is introduced. The coefficient depends on wheel geometry, jet velocity, abrasive property, and fluid property. Air flow interfering with the delivery grinding fluid is also analyzed. A relationship was found between atmospheric pressure and the retention of fluid particles in the boundary layer on the wheel periphery. The model was tested for both porous and impervious wheels.

Noise-related roughness of railway wheel treads-full-scale testing of brake blocks

Results from full-scale tread braking experiments on an inertia dynamometer (brake testing machine) are presented. Eighteen prototypes of brake blocks are investigated. Two braking characteristics relating to the influence of the blocks on the wheel tread are studied: generation of hot spots and generation of roughness (corrugation, waviness). Wheel tread temperatures are measured during braking using an infrared (IR) technique. The wheel roughness is measured after each brake cycle when the wheel has cooled down. A roughness indicator, RλCA, relates measured roughness to expected rolling noise as generated by the wheel in operation. A correlation between the spatial distributions of temperatures and roughnesses is normally found: stronger for cast iron blocks and composition blocks and weaker for sinter blocks. The cast iron blocks are found to produce high tread roughness levels, partly owing to material transfer from brake block to wheel tread. The composition blocks are found to result in lower roughness levels than the cast iron blocks. Finally, the sinter metal blocks are found to lead to the lowest roughness levels, a fact which is probably due to the abrasive property of these blocks. Friction coefficients during braking are also measured.

A NEW FORM OF ABRASION TESTER

A machine for testing the abrasive property of textile material is described. This abrasion tester differs from others in the method of renewing the wearing surface. This offers certain advantages.