Porosity is very common in casting. How can we calculate safety factor by considering the effect of porosity on the design?
Really this is an excelent question. I need time to reflect an answer.
Normally, casting parts have porosity. This type of defect reduce the mechanical resistance of the piece, because the part have minus material to support the loads.
Feodosiev said that for materials with plastic behaviour (1,5 - 2) may be a normal security coefficient, but for other materials that show fragile behaviour the securityt coefficient may be from 2 to 5.
Dear Prasath,
The occurrence of porosity definitely has its impact on design factor of safety. It mainly depends on the functional use of the component cast and also the material used.
Depends on application you use for. For critical applications, cast parts are not used where safety of the product against failure is requirement.
Porosity definitely has an impact on the design factors. Porosity tends to form around the gates so from a design point of view it is important to consider the areas around the gates i.e. try not to design areas of thin wall near the gates i.e. in the separation of two materials in cylinder heads with oil and water galleries for instance.
If you have areas where porosity is an issue you can use design to increase the wall thickness in that particular area or utilise a cooling pin system to disperse the porosity in that area possibly combining it with thickening of the area. It all comes down to the individual component.
From a design point of view you can simulate the casting process using one of a number of different casting simulation software solutions such as MagmaSoft for instance.
Hope this is of some use.
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