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, then exsiting residual stress is mainly residual thermal stress.In addition to make castings cold craked,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 mirco-plastic deformation by time flies.
*Flaring deformation:Forming reason is that sand core or sand mould in the opening size hinder the contraction of investment castings,thus free structural part of castings produce plastic deformation,resulting in a flaring deformation defect.
*Warping deformation:Investment castings after sand removal occur warping deformation at one end,both ends or even outer edges.Therefore,the middle of investment castings 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 colling speed is different,producing uneven plastic deformation.Then warping deformation is formed. Below are our suggestions to solve investment casting deformation:
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 deformance of mechanical products.So the investment castings with bad quality will seriously affect the service life of mechanical products.So once find any performation,we should carry on timely correction.