1. A
DISSERTATION REPORT
ON
Effect of Vacuum on reduction in porosity of A380 alloy for
high pressure die casting
Submitted in partial fulfillment of the requirements
Of the degree of
Master of Technology
(Physical Metallurgy)
By
SHINGADE ROHIT ASHOK
(121326016)
Under the Guidance of
Prof. M.J. Rathod
DEPARTMENT OF METALLURGY AND MATERIALS SCIENCE
College of Engineering, Pune
(An Autonomous Institute of Govt. of Maharashtra)
July-2015

2. ABSTRACT
Porosity is one of the major defects in aluminum castings, which results in a decrease of the
mechanical properties. It is induced by several mechanisms (solidification shrinkage and gas
segregation). High pressure die castings usually contain gas porosity due mainly to the entrapment
of air or gas in the melt during the very high speed injection of the molten metal into the cavity.
The effect of vacuum assistance on the porosity distribution and mechanical properties of the
produced castings were studied in detail. The examinations were held by means of the Buhler high
pressure die casting machine equipped with a vacuum system. Castings were produced for the
parameters selected on the basis of design of experiments i.e. for the plunger travelled in fist stage,
first phase and second stage velocity, vacuum start point and vacuum end point.
It was found that the volume of gas porosity and the pore sizes in the castings were significantly
reduced by using vacuum assistance during die casting. As a result, the density was improved. An
optimum injection speed was also identified for producing high performance castings. The
experimental results from the MINI - TAB were used to map the relationship between process
parameters and porosity formation of the die cast part and to study the effect vacuum pressure on
various level of porosity formation in HPDC process. Lowest Porosity noted after process
parameter optimization.