Jawaharlal Nehru Technological University Hyderabad B.Tech III UNCONVENTIONAL MACHINING PROCESSES Previous Question Paper (February - 2023 - R16)

Non-traditional metal cutting offers several key advantages over conventional machining: it allows for the machining of extremely hard, brittle, or difficult-to-cut materials that would be impractical for standard tools. Additionally, it enables the creation of complex, intricate geometries, deep holes, and thin-walled sections without inducing significant mechanical stresses or thermal damage to the workpiece.

In Ultrasonic Machining (USM), the slurry acts as the primary medium for material removal and tool cooling. It consists of a mixture of abrasive grains suspended in a liquid carrier, typically water or a light oil.

The nature of the slurry is defined by three critical characteristics:

• Abrasive Material: Hard particles such as boron carbide, silicon carbide, or aluminum oxide are used. The grit size is carefully selected, with finer grains providing better surface finish and coarser grains increasing the material removal rate.
• Concentration: The ratio of abrasive to liquid is typically maintained between 20% and 50% by volume. This concentration ensures an optimal balance between the number of active cutting particles and the fluidity required for circulation.
• Functionality: The slurry serves to carry the abrasive particles into the machining zone, where they are accelerated by the vibrating tool to impact the workpiece. Simultaneously, it flushes away the eroded debris and heat generated during the process, preventing tool clogging and maintaining machining efficiency.