Penetration and lubrication evaluation of vegetable oil with nanographite particles for broaching process

With increasing environmental concerns, the substitution of mineral oil-based cutting fluid has become an urgent issue. Using vegetable soybean oil as base fluid, nanofluid cutting fluids (NFCFs) were prepared by adding different weight concentrations of nanographite particles (NGPs), and their penetration and lubrication performances were studied. A novel simulated tool-chip slit with micrometer-sized geometry was manufactured to evaluate and quantify the penetration rate of the NFCFs by image analysis approach. Moreover, a large number of comparative experiments on the closed-type broaching machine were carried out to compare the performance of the proposed NFCFs and a commercial cutting fluid in terms of cutting force, workpiece surface roughness, and metal chip. It is found that there is an optimal NGP concentration in NFCF for practical cutting applications. When the concentration of NGP is 0.4 wt%, the broaching process lubrication exhibits an ideal mixed lubricate state, resulting in minimal friction resistance, and thus, both the cutting force and chip curling angle reach their corresponding best values. Moreover, the proposed NGP-based vegetable-oil cutting fluid exhibits excellent environment-friendliness and low-cost consumption in the minimal quantity lubrication (MQL) method; this demonstrates its potential for replacing the traditional broaching cutting fluid.

Thermal Efficiency of a Solar Air-Heating Collector with a Metal Chip Absorber

It is known that one of the main issues of heat transfer in complex designs of solar air-heating collectors is the problem of determining the coefficient of convective heat transfer in some parts of absorbers. The article studies the processes of heat transfer occurring in a solar air-heating collector with an absorber, which is a system of metal flow chips and a V-shaped surface. A description of the design of a solar air-heating collector with a metal chip absorber is given. The absorber allows us to increase the contact surface between the coolant and the absorber. The experimental procedure and the results are presented. The experiments have shown that within the range of 850 – 950 W / m2 of direct incident solar radiation density, the average heating of coolant is 17.5 °C; within the range of 650 – 750 W / m2, it is 14.1 °C; within the range of 450 – 550 W / m2, it measures 10.1 °C. The maximum coolant heating is 27 °C which is equal to the output collector temperature 60 °C. The average heating of the coolant is 14 °C, which corresponds to the average output temperature of 45 °C. According to the data obtained in the experiment, empirical formulas are concluded. They are presented in the form of the dependence Nu = f (Re), it is aimed at determining the heat transfer coefficient of flow metal chips and V-shaped absorbers of a solar air-heating collector. The dependence of the absorbers heat transfer from metal flow chips and the V-shaped surface of the solar air-heating collector on the Re numbers within the range of 103÷104 is shown. A formula is derived that allows us to compare the effectiveness of absorbers of various types with a flat absorber of a solar air-heating collector

Mechanical and structural properties of composites made from recycled and virgin polyethylene terephthalate (PET) and metal chip or mesh wire

Although polyethylene terephthalate (PET) is a champion of recycling, intense research is being done to find new solutions for using recycled plastic. This study aims to characterize the mechanical andstructural properties (SEM- scanning electron microscopy) of products made from recycled metal swarf or mesh wire with recycled plastic (PET) in comparison with virgin plastic. Samples manufactured from virgin and recycled PET are made by pressing and high temperature. The loss of mechanical properties ofproducts made from recycled plastic is a major drawback that influences their use. SEM images confirm that the dispersion and distribution of the PET phase is not very uniform. By addition of virgin plastic in various compositions with recycled plastic, processing parameters and mechanical properties can be optimized.