PSI - Issue 71

Sameer S. Gajmal et al. / Procedia Structural Integrity 71 (2025) 430–437

431

most commonly 2.45 GHz frequency is used. With several benefits like short processing times, energy savings, economic effectiveness, clean and environmentally friendly processing, many such microwave processing techniques are best suited for industrial usage Bajakke et al. (2021). Materials have the ability to reflect, transmit, and absorb microwaves. When microwaves are absorbed by a material, it’s transformed to heat inside the material and temperature raises. Energy is provided to material directly during microwave processing through chemical interactions with electromagnetic fields. In material processing using thermal energy, energy is delivered to the material through convection, conduction, and radiation. The process of energy conversion in microwave processing is different compared to conventional heat transfer method. In this process, the microwaves are absorbed by the material, where the molecules vibrate rapidly causing rise in temperature. This results in internal heat development of the material. As a result, heat is produced throughout the material's volume, where thick materials can be heated rapidly and uniformly Mishra and Sharma (2018) developed Al 7039 and copper castings with microwaves operating at 2.45 GHz at a power of 1.4 W. The interrelationship of microstructure, hardness, and porosity of the cast specimens was studied by Mishra and Sharma (2015) (2018). Kumara et al. (2015) reports on cold shut defects in case of grey CI FG200 using response surface methodology. Pouring temperature, pouring time and phosphorus content were the important parameters chosen for optimization. It was found that pouring temperature between 1430 °C – 1470 °C, pouring time of 06-09 seconds and phosphorus content as 0.15 % to 0.25 % as the optimum parameters, yielding rejection from 27.64% to 2.5%. Dabade and Bhedasgaonkar (2013) used two methods like Taguchi and casting simulation to optimize the parameters. The parameters considered are green compression strength, moisture content, mold hardness and mold sand permeability. Porosity was reduced by 15% and casting yield was improved by 5%. In the present work, pin castings were produced using microwave aided casting technique. The molten metal was heated, melted, and poured using microwave energy. Additionally, the process of solidification was allowed to occur under a microwave environment. The material used is ASTM B-23 Tin Based Babbitt alloy and its reaction to microwave processing in melting, pouring and solidification are investigated. Measurements were made of defects namely solid shrinkage and porosity portion. 2. Experimental Setup 2.1 Material specifications Charge refers to the raw material used to make casting. Babbitt alloy made of tin, ASTM B-23 Grade 3, was used as charge. Babbitt alloys are of two types: Pb and Sn based alloys. Tin-based alloys are typically chosen in applications requiring strong wear resistance, while lead based are typically used in corrosion-resistant applications. In this study, Tin-based Babbitt alloy is used. ASTM B-23 Tin Based Babbitt alloy is selected due to its application in heat resistance, strong wear resistance and durability. The cam shaft bush manufacturing with this alloy is the final target of the research. The chemical composition of the selected alloy is given in Table 1.

Table 1 Chemical constituents of Babbitt Gajmal and Raut (2022) Element Sn Sb Cu Pb

Bi Ni Amount % 89.39 7.11 3.19 0.23 0.022 0.002 0.05 0.034 0.003 0.008 0.006 Zn Al As Cd Fe

2.2 Specimens details A cylindrical pin of 12 mm dia. and 30 mm length, shown in Fig. 1 are prepared for the study.

Fig.1. Cylindrical Pin Gajmal and Raut (2022)