The V-Process was invented in Japan in 1971 as an
improvement on conventional sand casting. In this process, a thin
preheated sheet of plastic film material is placed over a pattern and a
vacuum is applied to draw the sheet to the pattern contours. The flask
containing the mould is then filled with dry unbonded silica sand which
is compacted by vibration. A second plastic sheet is placed at the back
of the flask and the mould is further compacted under vacuum. With the
vacuum maintained, the pattern is then removed and the two halves of the
mold are joined and secured for pouring. After the metal has solidified,
the vacuum is removed and the casting is released.
The original inventors of this proprietary process have established
working agreements on a worldwide basis so that today individually
licensed foundries using the V-process are producing castings of all
sizes and shapes. These range from thin-sectioned curtain walls in
aluminum to cast iron pressure pipe fittings, stainless steel valve
bodies and massive 8-tonne ship anchors. Other components being
routinely cast include bathtubs, railroad bolsters and side frames,
machine tools, engine parts and agricultural castings. Any metal (Grey,
ductile, malleable iron, various grades of steel, or aluminum and
copper-base alloys) may be poured in a V-process mold, with the possible
exception of magnesium.

Gives
good dimensional accuracy and surface finish with generally twice the

accuracy of sand
castings.

Eliminates
gas hole defects.

Pattern
life is longer because there is no contact between the sand and the
pattern.

Eliminates
the use of binders and minimizes sand waste.

Is
suitable for a wide range of casting sizes from grams to tonnes.

The
process can be used for complex geometries and can be automated to
achieve

greater consistency and
productivity.

It
can be highly cost competitive with other casting processes.

Requires
plated pattern equipment.

Close
synchronization of mould and metal readiness is essential in foundry
practice.

Is
not typically suitable for high rates of production.

Is
not suitable for some casting geometries due to flexibility limitations
of the plastic