Experimental investigation on magnetorheological fine finishing of EN-8 steel alloy mold surface for cylindrical plastic bottle caps

The cylindrical mold is a key element utilized in the manufacture of different cylindrical components for a wide range of applications in industries like automotive, aerospace, medical, and among others. Fine finishing of the cylindric mold with high surface integrity has several benefits such as good fits and tolerance, increased product quality, and high load-bearing capability for components. Recently, a cutting-edge rotating magnetorheological honing (RMRH) method based on permanent magnet tools was developed for the fine finishing of interior cylindrical surfaces with great productivity. Furthermore, many industrial real-time cylindrical molds need to be fine-finished with high productivity to enhance their functionality. To meet these requirements, the RMRH procedure could be the better option. Therefore, the RMRH process is investigated in the current study to finely finish the inner surface of the real-time EN-8 steel mold for plastic bottle caps. To determine how well the real-time EN-8 steel cylindrical mold could be fine-finished using the current process, the response surface technique was used to know the best finishing parameters. The significant % drop in parameters of the surface roughness profile ( Ra, Rz, and Rq) of the MR finished real-time EN8 mold surface is achieved as 86.05, 82.17, and 84.62, respectively, after 40 minutes of the RMRH process with the optimal parameters. Also, a considerable improvement in straightness is obtained as the final surface waviness on the inside cylindrical surface of the real-time EN8 mold for plastic bottle caps is decreased from an initial value of 120 nm to 40 nm. Further, circularity and surface morphology tests are carried out over the mold's finished inner surface. After providing the efficient MR finishing using the current process, results indicate that surface properties and functional efficacy of the internal surface of the real-time mold for producing plastic bottle caps have improved.