Snmek 1
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