Anglicky v odborných předmětech "Support of teaching technical subjects in English “

1. Anglicky v odborných předmětech"Support ofteachingtechnicalsubjects in English“ Tutorial: Engineering technology Topic: Castingsdefects Prepared by: Ing. Elena Nová Projekt Anglicky v odborných předmětech, CZ.1.07/1.3.09/04.0002 je spolufinancován Evropským sociálním fondem a státním rozpočtem České republiky.

2. Castings defects

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

4. Castings defects Defects at casting and solidification • Slag inclusions – At casting slag has not been retained -> surface faults, inner defects

5. 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 casting

6. Castings 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.

7. Castings defects • • Residual stress– Shrinkage cavity is hollow parts initiated at the cooling process.

8. Castings defects • Faults initiated at forming • Offset, reject casting – Is caused if forms don’t matched exactly • Edge or oval thickening – if the form is not sufficiently rammed -> hydrogen and oxygen recede under the casted material pressure.

9. Used literature • strojirenstvi.studentske.cz/2008/10/kontrola-vady-odlitk.html