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Advancement in Magnetic Field Assisted Finishing Processes
Published in Yashvir Singh, Nishant K. Singh, Mangey Ram, Advanced Manufacturing Processes, 2023
Girish C. Verma, Dayanidhi K. Pathak, Pawan Sharma, Aviral Misra, Pulak M. Pandey
In the present era, dimensional accuracy and surface quality are the two most stringent requirements of manufacturing industries. Many of these products have freeform surfaces due to their functional and aesthetic requirements, like metallic mirrors, medical implants, etc. Additionally, due to the dependency of fatigue strength on surface roughness, it also becomes a major concern for the product’s life. For improving the surface finish, different conventional finishing techniques like grinding and lapping are available; however, most of these processes cannot finish freeform surfaces. Also, applying these conventional finishing processes induces residual stresses in the finished surface, resulting in variation in its mechanical properties. Due to these limitations, non-conventional finishing processes are used, such as chemical polishing, magnetic field assisted finishing (MFAF), etc. Among these, MFAF processes are considered versatile because of their ability to finish non-conductive material [1–2]. Additionally, the polishing pressure in MFAF processes can be regulated precisely, resulting in a smoother and more accurately finished surface.
Synthesis of polishing fluid and novel approach for nanofinishing of copper using ball-end magnetorheological finishing process
Published in Materials and Manufacturing Processes, 2018
Single-point diamond turning (SPDT) is also an option to finish soft materials like copper, aluminum, etc., but it leaves concentric tool marks at the surface, which are not desirable in high-precision optics. Moreover, by this process only axisymmetric surfaces can be finished [14, 15]. Magnetic-assisted finishing processes such as magnetic abrasive finishing (MAF) [6, 16], magnetorheological finishing (MRF) [17] and MR abrasive flow finishing (MRAFF) [18] also have shape limitations and are suitable for either flat or less-complex surfaces. These magnetic field-assisted finishing processes are not preferred for more complex surfaces.
Post-processing treatments to enhance additively manufactured polymeric parts: a review
Published in Virtual and Physical Prototyping, 2021
F. Tamburrino, S. Barone, A. Paoli, A. V. Razionale
A magnetic field is used in magnetic-field-assisted finishing (MFAF) to control and manipulate a magnetic abrasive medium for the material removal process. The magnetic polishing medium is employed as a flexible tool capable of accessing complex geometries. MFAF must be considered as a secondary finishing technique because primary finishing of the part is usually required to reduce the roughness values to approximately 1–2 μm. In (Guo et al. 2018), MFAF following a precision grinding process was used to improve the surface quality of polyamide (PA)-SLS parts. The results showed that Ra was reduced from 15 to 2.85 μm by means of primary finishing and further to 0.89 μm by MFAF. Ball-end magnetorheological finishing (BEMRF) is a recently developed MFAF process that uses a tool to flow pressurised magnetorheological fluid, containing abrasive particles (e.g. iron particles), through the centre of a spindle surrounded by an electromagnetic coil (Figure 4-c). A magnetic flux density gradient occurs between the workpiece and the tool tip when the electromagnet is energised, and the fluid stiffens into the form of a magnetically controlled ball-end shape at the spindle tip. This process forms a polishing spot with a controlled size and shape, which is used as a finishing tool on the part’s surface. BEMRF is an unconventional technique that imparts a good surface finish on magnetic as well as nonmagnetic parts, which can have either flat or freeform shapes (Singh, Jha, and Pandey 2011, 2013). This process was tested with good results in (Kumar et al. 2019) for poly (lactic acid) (PLA)-FDM parts. An Ra of 81 nm was obtained after 75 min of treatment. In general, this process is suitable when high-quality surfaces are required. However, the higher equipment cost with respect to traditional processes, the strict control requirements for process parameters (e.g. spindle speed, feed, and gap between tool tip and workpiece), and the composition of the magnetorheological fluid are factors to be considered.