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Anglicky v odbornch pedmtech"Support of teaching technical subjects in EnglishTutorial: Engineering technology

Topic: Castings defects

Prepared by: Ing. Elena Nov

Projekt Anglicky v odbornch pedmtech, CZ.1.07/1.3.09/04.0002je spolufinancovn Evropskm socilnm fondem a sttnm rozpotem esk republiky.

Castings defects

Defects are divided according to activity where they originated:Defects at casting and solidifying Forming defects

Castings defects

Defects at casting and solidification

Slag inclusions At casting slag has not been retained -> surface faults, inner defects

Castings defects

Structure precipitation Casted material does not solidify equally (solidification goes from outside to inside) -> on a thicker walls maybe created cavities, -> called shrinkages (these will not happen if the casting walls are of equal thickness).

Babbles in casting structure Wet forming sand releases hydrogen and oxygen at the cast temperature and if not properly removed the gasses will enter the structure of the castingCastings defects

Cast tearing Diameter of transitions have been constructed too short (solidification of thicker parts have been slower) -> a bigger metal cooler parts are inserted into moulds with bigger diameter -> managing of cooling process Segregation Starts segregating of casted parts at solidification and uneven distribution of alloying parts -> different properties of material inside and outside of the cast. Castings defects

Residual stress Shrinkage cavity is hollow parts initiated at the cooling process.

Castings defects

Faults initiated at forming

Offset, reject casting Is caused if forms dont matched exactly Edge or oval thickening if the form is not sufficiently rammed -> hydrogen and oxygen recede under the casted material pressure. Castings defects

strojirenstvi.studentske.cz/2008/10/kontrola-vady-odlitk.htmlUsed literature