Analysis of Triangular WEDM Cut Corner Inaccuracy of Aluminium Composite Mold Material

Abstract

Aluminium Composite mold has been used exclusively in industries such as Aerospace, Automobile, Medical Equipment, Transportation, and Marine. They are preferred due to efficient heat transfer and strength. These molds are used to produce seat foams, urethane panels, silicone patterns, MRI instrument covers. Leakage in any of the products due to machining inaccuracy in corners will lead to serious problems. Therefore, the corner inaccuracy has been investigated. Composite mold material is made of Al-TiB2. Wire EDM can be used for machining Al-TiB2 composite efficiently and the optimization of the parameters in WEDM such as MRR, surface roughness, and corner inaccuracy. Triangular profile of 60° angle with sides 30 mm was cut from the composites. Composites machining done with wire electric discharge technique by varying control factors wire tension, spark voltage, pulse on duration, and pulse off duration. Machining experimentation was done using a brass tool electrode wire and size of 0.25 mm in diameter. The surface roughness (Ra) of the cut was evaluated through a surf-tester with a sampling length of 0.8 mm. To examine a corner inaccuracy of the machined surface, OM pictures were taken on the machined surface of Al-TiB2 composites. Calculation of inaccuracy in the corner was done using ImageJ software. The corner inaccuracy can be estimated by subtracting a machined area from actual area. By calculating the inaccuracies of machined composites, it was found that the minimum deviation in corner area was observed in the machining conditions of maximum wire tension (WT) and maximum Pulse on time (Ton). Wire Tension provided less deflection during the machining. The less deflection in wire provided stable sparks and constant inter-electrode gap providing the least corner inaccuracy during machining. In order to increase corner accuracy, the wire tension can be increased to a certain limit and above that which the wire tends to break due to the presence of non-conductive ceramic particles in the aluminium matrix.