Abstract

Square blind holes have certain qualities that make them useful in fields where accuracy and efficiency
are crucial, like aerospace, automotive, molding, and general manufacturing industries where
structural integration is required in precise assembly. It is challenging to machine square blind holes
with traditional machining due to geometrical complexity as precision is required for sharp corners
which is difficult to get at the corners due to tool wear. Electrical discharge machining is an advanced
machining technique used for machining electrically conductive and difficult to cut materials. The
primary goal of present work is to evaluate and quantify the output and input parameters during
Electric Discharge Machining of square blind holes with varying depths at each level. Here, the
experiments were conducted on Maraging steel MDN 250 material which is widely used in aerospace
and allied industries because of its unique properties. The material is known for its good malleability
while having exceptional strength and hardness. During experimentation, the depth of the hole was
varied while maintaining the input parameters Current, Pulse on Time and duty cycle constant. The
output responses that were taken into consideration were the Electrode Wear Rate, machining time,
squareness, taperness, and surface roughness. It was noted that the Tool Wear decreased as the hole
depth was increased. Squareness values are significant which affects the relative motion between
machined parts, which is critical for their functionality. The taperness remains relatively low,
suggesting effective control over the machining process. A non-linear relationship where specific
depths significantly affect surface finish was noted. The achieved results can be useful in defense,
aerospace and EDM industries to increase the productivity with precision.

Keyword: Electrical discharge machining (EDM), electrode wear rate, square blind hole, squareness, taperness, surface roughness

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