Adjoint Method for the Optimisation of Conformal Cooling Channels of 3-D Printed High-Pressure Tools for Aluminium Casting

The emergence of additive manufacturing (AM) technology has
enabled the internal cooling channel layout for high pressure
aluminium die casting (HPADC) tools to be designed and modified
without topological constraint. Optimisation studies of a full industrial
HPADC mould for extending the tool service life has received limited
attention due to the high geometrical complexity and the various
physics with multi time- and length- scales in addition to the
manufacturability limitations. In this work, a new computationally
efficient algorithm that employs the adjoint optimisation method has
been developed to optimise the coolant channels layout in a complete
mould with various 3D printed inserts. The algorithms significantly
reduced the computational time and resources by decoupling the fluid
flow in the coolant channels from the tool and simulating them
separately. The channel’s heat transfer coefficient values are then
interpolated and mapped into the thermal model that implements the
adjoint optimisation approach to automatically push/pull the pipes
toward the cavity based on the gradient of the optimisation function
with respect to the pipe surface location. Using the adjoint method,
with a customised multi-objective function, an improvement of 15 %
for the cooling uniformity between the mould/cast interface was
achieved. Because of the simplified mapping approach, a significant
reduction in computational cost was achieved by adopting this
strategy. The spatial distribution of the tool temperature and cavity are
presented for the baseline and optimised channels. The results showed
that the optimised channels not only have variations in layout but also
in their cross-sectional shape at different locations to satisfy the
objective function. The optimised insert designs have been applied in
production, yielding a significant increase in tool service lifespan,
reaching approximately of 130,000 shots.