Mechanical characterization and creep strengthening of AZ91 magnesium alloy by addition of yttrium oxide nanoparticles

In the current research, the authors have attempted to improve the mechanical properties and creep behavior of the magnesium alloy Mg–9Al–1Zn (AZ91) in three different stress levels. To this end, the present study investigated experimentally the addition effects of different values of yttrium oxide nanoparticles to the AZ91. In this regard, weight percentages of 0.5%, 1%, 1.5%, and 2% nanoparticles were added to the material using the vortex casting method. Then, various test specimens were fabricated based on the ASTM standards by utilizing a Computer Numerical Control lathe machine. Different experiments were performed, and the results of different groups were compared with each other. The results revealed that the addition of yttrium oxide (Y2O3) nanoparticles increases the strength of AZ91 magnesium alloy until the nanoparticles do not clump in the microstructure. In other words, the tensile strength of the nanocomposite increased by adding nanoparticles up to 1.5%, but by adding 2% of nanoparticles, we found that the tensile strength is lower than that of pure magnesium. Moreover, one of the most important achievements of this study is that if the nanoparticles do not clump in the material microstructure, the addition of Y2O3 increases the rate of stable creep (the secondary creep stage). Also, the experimental results indicated that the highest stable creep rate is related to the nanocomposite with 1.5% yttrium oxide nanoparticles. Furthermore, the maximum hardness of the material was obtained in the same case.

Effect of Post-Deposition Solution Treatment and Ageing on Improving Interfacial Adhesion Strength of Cold Sprayed Ti6Al4V Coatings

This study aims at investigating the effect of post-deposition solution treatment and ageing (STA) on improving the interfacial adhesion strength in cold spray (CS) Ti6Al4V coatings deposited on Ti6Al4V substrates, measured by the adhesive-free collar-pin pull-off (CPP) test. Solution treatment was performed at 940 °C for 1 h and ageing was carried out at 480 °C for 8 h. Investigations were carried out for specimens with three different pre-treatments of the substrate surface, namely grit-blasted, as-machined (faced on lathe machine), and ground. Additionally, the effect of post-deposition STA was studied in terms of phase analysis, microstructure, and porosity level. It was observed that STA led to complete interfacial mixing resulting in significantly improved adhesion strength (by more than 520%) with the maximum measured value of greater than 766 MPa for ground substrates, reaching 81% of the ultimate tensile strength of mill annealed Ti6Al4V.

Experimental Investigation on the Advantages of Dry Machining over Wet Machining during Turning of AISI 1020 Steel

In this study, the experiment was conducted to investigate the advantage of dry machining over wet machining during turning of AISI 1020 steel using cemented carbide tool on a CNC lathe machine. Surface roughness and cutting temperature were measured by VOGEL surface roughness tester and infrared thermometer respectively. The experiments were conducted based on Taguchi L9 orthogonal array design. Surface roughness, cutting temperature, tool life, and machining cost were analyzed graphically. The average surface roughness and cutting temperature achieved with wet machining was 2.01 μm and 26.540C, which was 17.41% and 44.86% respectively, lower than dry machining. The high cutting temperature in dry turning result in short tool life, which was 41.15% shorter than wet turning. The machining cost of wet turning was about 56% greater than the cost of dry turning. The cost of coolant in wet turning is 42.88% greater than that of the cutting tools. The highest cost was shared by tool cost, which was 81.33% of the total cost for dry turning, while 70.00% of the total cost was shared by coolant cost for wet turning. Results revealed that dry turning is more economical than wet turning.

Development of a Low Cost Eco-Friendly Minimum Quantity Lubrication System for Machining Processes

Recently all environmental worries are calling for reducing the usage of fluids in machining operations. One of the promising solutions that appeared lately is minimum quantity lubrication (MQL). This research aimed to develop an eco-friendly cooling system for a lathe machine and assess its performance. After considering the customer needs, the needs were translated into engineering specifications in the conceptual design phase, and then the quality function deployment was developed. Three concepts were generated and evaluated considering the selection criteria, and a final concept was selected using the decision matrix method. Following this, a detailed design and fabrication of the subsystems such as the oil tank and a structure accommodate all the components. The developed system was tested on six different workpiece samples to compare the MQL system with the conventional one. In general, the MQL system resulted in lower surface roughness values as well as lower tool wear.

Effects of Occupational Hazards on Pulmonary Health among Lathe Machine Workers: A Cross-Sectional Study in Tangail, Bangladesh

Background: Occupational exposure to metal dust particles leads to irritation and initiation of inflammatory responses in the respiratory system that subsequently onsets lung diseases. Lathe machine workers have a greater risk of having lung diseases due to continuously conducting metal dust particles. This study aimed to explore the pulmonary health status of lathe machine workers. Methods: In this cross-sectional study, 80 individuals (lathe workers) were adopted from a different area of the Tangail district in Bangladesh. A questionnaire’s survey was accomplished along with oximetry and spirometry. After that, blood was drawn for measuring Erythrocyte Sedimentation Rate (ESR), C-reactive protein (CRP), and Immunoglobulin E (IgE) test to the lung function abnormalities. Results: Among 80 lathe machine workers, 12% had breathing problems, 13.8% had coughing, 16.2% had to sneeze and 8.7% had a chest. In addition, spirometry results including, FVC, FEV1, FEV1%, PEF, PEF%, FEF25, FEF75, and FEF2575 were significantly lower in lathe workers compared to control. Moreover, higher levels of IgE (264.93±141) and ESR (11.5±4.77) were reported in lathe machine workers than in the control group. Not using protective masks and smoking were considered as risk factors for having respiratory diseases in lathe machine workers. Conclusion: This study concludes that exposure to metal dust particles can cause respiratory disease symptoms and lower pulmonary function in lathe machine workers. Furthermore, metal dust might also augment the blood IgE and ESR level.

Studies and Practice of Geometrical Test Procedures & Reconditioning of CNC Lathe Machine Tool

Machining Centres have been major production units for many decades with desired levels of accuracy, economy in costs of production and ease of control. Though new disruptive technologies such as rapid manufacturing, near net shape manufacturing technologies are replacing these machining units, still small and medium Indian Industries go with the conventional ways of large-scale production using conventional and classical machining approaches. With huge setups in place, such machines with high productivity demands, require stringent parts alignment tests frequently from time to time, referred to as Geometrical or Alignment tests to enable accurate finishing and machining of parts and smooth and uninterrupted production. This paper puts forth some basic Geometrical Tests performed on SB CNC 60 Lathe Machine Tool unit, identifying major deviations measurements and reconditioning the machine parts. The main objective of running such tests is to prevent breakdown of the machine and ensure safety working when handling older and heavier conventional machines.

Study on Heat Sources of Horizontal Lathe Machine by Using Inverse Method

Thermal has significantly effect on high speed machine tools. When temperature growing up, it often causes processing errors and further reduces product quality. This paper aims to investigate magnitude of heat sources and temperature distribution in a horizontal lathe based on inverse method. In present thermal model, there is not only consideration of spindle but also analyzing relative structures. Simulated and experimental temperatures are used as input data to predict heat sources and temperature field. Effects of speed, number measured points, measurement errors and measured distance on predicted results are analyzed. Results indicate that this inverse method can accurately estimate the heat sources based on two measured temperatures at front and rear outer rings. The trend of estimated heat sources is then compared to measured load rate. Results herein are useful information for designing horizontal lathe spindle and reducing thermal errors.