The Hitchiner casting process is a variation of
chemically bonded sand moulding processes. It uses a counter-gravity
(vacuum) system to fill the mould cavity with molten metal. The flask is
partially submerged in a metal bath. Small diameter feeders in the drag
(bottom) half of the flask are used to draw metal under vacuum into the
mould cavity. Filling moulds by gravity (i.e. by pouring into a sprue)
can introduce air into the mould cavity and result in defects.
Introduced air can constitute up to 30% of the total volume of metal
poured. The Hitchener process achieves better filling consistency and
virtually eliminates air ingress and the resulting inclusions and
porosity defects. This has been shown to reduce casting repair costs by
50-65%. Such cost savings can compensate for the higher up-front costs.
Produces
light section castings in a variety of alloys normally not castable by
other processes.
Gives
higher casting definition than conventional sand moulding and similar
definition to investment
casting.
Requires
less metal cleaning.
Higher
metal yields are achieved than by conventional sand moulding due to
smaller gating systems
and
greater precision.
Decomposition
gases are removed by the vacuum, making emission control easier,
reducing
emissions and
reducing gas inclusions.
|
Limitations of The Hitchiner Process |
The
process is more expensive than conventional sand casting.
Production
volumes are limited to low to medium throughput.
Requires
less metal cleaning.
The
size of the casting is limited to a maximum of 45 kg.
The
Hitchiner Process
