Abstract:
investment casting is the process well known for achieving excellent finishing of surface,
accuracy of dimensions and intricate shapes development. The process parameters behind the
preparation of wax blends and ceramic slurry make the investment casting process laborious
and troublesome. Due to the thermal expansion, shrinkage of material of pattern, material of
mould and solidification of alloy being casted, there are changes that occur between pattern
and its corresponding part of casting. Composition of the wax plays a vital role to optimization
of the expansion, shrinkage and maximization of hardness of pattern. The ceramic slurry,
composition also plays an important role to improve and stabilize the ceramic slurry. The most
crucial step in investment casting is the 'dewaxing' of investment shells. It describes the
nature of casting because the surface and dimensional traits of the wax are transferred to the
shell of ceramic and it leads to the final stage of casting. In the present work, experiments
were conducted with different type of waxes namely paraffin wax, microcrystalline wax and
carnauba wax, varying their proportion.
The dewaxing of wax from shell was done in microwave and infrared ovens. Using the data
obtained from the experiments an attempt has been made to find out the set of input
parameters, which could offer a set of ideal properties of wax blend and ceramic slurry.
Taguchi method was used to optimize the process parameters. The Orthogonal Array which
represents the matrix of number of parameters those are to be varied gives the number of tests
to be conducted. Taguchi method has successfully suggested the set of input parameters which
could offer the desired properties. The changes in properties like linear shrinkage, volumetric
shrinkage, surface roughness and hardness have been calculated by dewaxing the shell in
microwave and infrared ovens
