Prediction of die casting process parameters by using an artificial neural network model for zinc alloys

Abstract

Pressure die casting is an important production process. In pressure die casting,
the ® rst setting of process parameters is established through guess work. Experts
use their previous experience and knowledge to develop a solution for a new
application. Due to rapid expansion in the die casting process to produce
better quality products in a short period of time, there is ever increasing
demand to replace the time-consuming and expert-reliant traditional trial and
error methods of establishing process parameters. A neural network system is
developed to generate the process parameters for the pressure die casting process.
The system aims to replace the existing high-cost, time-consuming and expertdependent
trial and error approach for determining the process parameters. The
scope of this work includes analysing a physical model of the pressure die casting
® lling stage based on governing equations of die cavity ® lling and the collection of
feasible casting data for the training of the network. The training data were
generated by using ZN-DA3 material on a hot chamber die casting machine
with a plunger diameter of 60 mm. The present network was developed using
the MATLAB application toolbox. In this work, the neural network was developed
by comparing three di€ erent training algorithms: i.e. error backpropagation
algorithm; momentum and adaptive learning algorithm; and Levenberg±
Marquardt approximation algorithm. It was found that the Levenberg±
Marquardt approximation algorithm was the preferred method for this application
as it reduced the sum-squared error to a small value. The accuracy of the
developed network was tested by comparing the data generated fromthe network
with those of an expert froma local die casting industry. It was established that by
using this network the selection of process parameters becomes much easier, so
that it can be used by a novice user without prior knowledge of the die casting
process or optimization techniques.
1. Introduction
Pressure die casting is an important production process that is extensively used to
produce castings for the electrical, electronic and automobile industries. The process
has its origins in type casting machines developed in 1822. The process showed its
production potential as early as the mid 1800s when it had reached a high level of
automation and mechanical efficiency.
In 1894, the ® rst die casting machine was developed, in which molten metal was
forced through an inclined port and out of the nozzle into the die by the central ram
actuated by a lever. During the past two decades, the pressure die casting process has
become an essential casting production process for the engineering industry. High
production rate, excellent surface ® nish and good mechanical properties of the ® n-
Revision received March 1999.