CASTING
Figure 4 . Example of a 24 ’’ gate valve body ’; ‘ as cast ’ weight 2,600 kg .
• Air traps ,
• Flow tracer . We can also visualise solidification results , such as :
• Thermal behaviour
• Material status ( solid , liquid )
• Hot Spots
• Cooling rate
• Possible remaining defects : porosity , shrinkage , Niyama ( micro porosity )
Tips to achieve good results
To obtain sustainable results , you must correctly define various elements . These include :
The materials and the heat exchange within the mould . The foundry ‘ s experience of the considered alloys and the casting technique will significantly influence the final result . The meshing part . Too rough mesh size will lead to poor results , but using a very fine mesh size will increase the calculation time . It can , therefore , be interesting to use different mesh sizes depending upon the areas you wish to analyse . The casting process . To ensure that the simulatation process reflects reality as closely as possible , the casting process must be modelled by setting detailed experiment plans to identify the various parameters .
Conclusion
To underline the importance of casting simulation tools , it is essential to realise that there is no room for a ‘ trial and error ’ approach to large-size castings . For example , when manufacturing a DN 2800 valve with a finished weight of 5700 kg , we need to melt and pour at least 12500 kg of melted alloy . Both the cost of the alloy and the melting cost have a significant impact on the global manufacturing cost .
Figure 5 . Solidification time . Figure 6 . Viusation of last solidification .
38 Valve World November 2022 www . valve-world . net