Shrinkage cavities

Lunker, n. Metal.) shrinkage cavity, shrink-hole, pipe, -bildtmg, /, Metal.) formation of cavities, piping. 

SchwindungS fahigkeit, /. tendency to shrink, property of shrinking, -loch, n. shrinkage cavity, -riss, m. shrinkage crack. 

A crane holding a bucket of scrap aluminum and sows (10,000 kg) was loading into a holding furnace which contained some 12,000 kg of molten aluminum. Upon opening the clam shells, an immediate explosion occurred. The furnace was cooled and most sows were recovered intact. There was no evidence of foreign material in the charge. It was considered likely that one sow had a shrinkage cavity which contained some water... 

This method consists of high-frequency sound waves (0.1-25 MHz) incident upon the test sample and measuring the energy of the reflected beam. Because of the flaws in the sample there will be loss in energy of the beam, known as attenuation. Cracks, laminations, shrinkage cavities, bursts, flakes, disbonds and other discontinuities can be detected by this method. 

Principal advantages of gas-pressure infiltration over other mechanically driven pressure infiltration processes are that infiltration parameters are controlled with precision and that weak molds can be used, which can be used to minimise impurities in the composite. It is thus an attractive method for academic research however, it is also used industrially, to produce electronic substrates for example. After infiltration, the metal is solidified. We use directional solidification, induced by lowering the mold onto a chill (Fig. 1), to avoid shrinkage cavity formation in the composite. The applied... 

RO Fusion-cast Refractory. A fusion-cast refractory made in an inclined mould designed to concentrate the shrinkage cavity in one comer of the block such blocks are made in France (RO = Retassure Orient6e, i.e. oriented cavity cf. DCL, RT and SR). 

Schrumpfung, Schwund Abnahme, Einlaufen Nachschrumpftmg shrinkage cavity/ shrinkhoie Lunker, Hohlraum, Vakuole (Fehler) shrinkproof... 

Other applications examine shrinkage cavities in metal castings [191], thermal isolation of aluminum rivets [ 192], and thermal gradients on the surface of heating coils [193]. 

Fig. 3.23 Macro-shrinkage cavity observed in ductile cast iron (courtesy of SACMI, Imola)...

Fig. 9.19 A large. shrinkage cavity in the interior of an ainmininm-bronze sand...

Shrinkage cavities Lack of sufficient feed metal (i) Promote directional solidification by control of heat flow (ii) Raise pouring temperature Relocate risers and ingates... 

Il jSL Uld be noted that contraction cracks often have an external wi(i ,.ii,iiii e very similar to a shrinkage cavity (see Section 9.6). ruify can lie dill ercntiated from the latter because there is no cavity... 

I 0. 20 Dispersed shrinkage cavities in a section of a sand-cast tin-bronze. A surface hot fear can also be seen. 

It should be noted that contraction cracks often have an external appearance very similar to a shrinkage cavity see Section 9.6). They can be differentiated from the latter because there is no cavity or porous area beneath the surface. Furthermore, contraction cracks arc normally located in positions clearly related to the geometry of the casting and to the restriction of free contraction by parts of the mould. A good example of this is shown in Fig. 9.14, where cracking has occurred in the fillet region between two parts of the casting. 

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