Abstract:
Metal Matrix Composites (MMC) belong to a new generation
of engineering materials that have desirable qualities such as
high strength-to-weight ratio, high toughness, low value of coefficient
of thermal expansion, high wear resistance, and thermal stability.
They are therefore increasingly finding applications in the areas of
aerospace, automotive, defense, biological and nuclear energy fields.
Due to the nature of their application, these materials require to be
machined to a high accuracy and to have a good surface finish. This
requirement poses a challenge due to hard and abrasive nature of
the materials. Mostly, grinding is the process used but the process
is expensive and slow. Electrical Discharge Machining (EDM) can
be used to address these challenges since it can be used to machine
electrically conducting materials irrespective of their hardness.
This paper investigates the effect of using oil and deionised
water as the dielectric fluids as well as the effect of introducing
low frequency vibration in EDM machining of Aluminium Silicon
Carbide (AlSiC) MMC. Experiments were carried out on AlSiC
(AMC225XE) material using Sarix-100 high precision micro-erosion
machine. A series of experiments were carried out with and without
workpiece vibrations. For the experiments with vibrations a vibration
frequency of 900Hz was used. The results of this study indicate that
introduction of vibration raises the material removal rate but results
to an inferior surface quality. Using deionised water as the dielectric
results in lower machining time as opposed to Oil. However, this also
results in an inferior surface quality and geometry of bore.
