Investment castings are easy to be deformed during production
process. We can divide the deformation into self
micro-deformation, flaring deformation and warping deformation.
*Self micro-deformation: gray iron investment castings
are most easy to trace the deformation in alloy materials. Grey
iron castings shake out after cleaning, existing residual stress
is mainly residual thermal stress. In addition to make castings
cold cracked, the residual stress is also the main reason
causing self micro-deformation. Even if no more than yield
strength of material, but in the role of residual stress, gray
iron castings will slowly produce micro-plastic deformation by
*Flaring deformation: Forming reason is that sand core or
sand mould in the opening size hinders the contraction of
investment castings, thus free structural part of castings
produce plastic deformation, resulting in a flaring deformation
*Warping deformation: Investment castings after sand
removal occurred warping deformation at one end, both ends and
even outer edges. Therefore the middle of investment castings
was dent, leading to uneven castings. We call such deformation
as warping deformation. Its forming reason is because when the
casting is cooling, the wall thickness of investment castings is
uneven and for temperature difference, so each part of the
casting cooling speed is different, producing uneven plastic
deformation. Then warping deformation is formed.
Below are our suggestions to solve investment casting
1. Before inject wax into mould, put the mould in wax injection
room to keep the mould temperature is the same as that of wax
injection room. After that we start to do wax injection.
2. Test the wax pattern ourselves after wax patterns are
finished to check whether there is any problem. Wax pattern
should be unified laid and avoid overlapping and dangling.
3. Coming out from furnace, when the temperature of module is
still high, we should avoid overlapping and do it regularly so
that the deformation is in the same direction, which will be
convenient for us to reform.
4. The material of collection fixture for castings should be
hard material and wear resistance.
Investment castings will have great influence on the deformation
of mechanical products. So the investment castings with bad
quality will seriously affect the service life of mechanical
products. So once find any deformation, we should carry on
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