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Full text of "Metallurgy Of Cast Iron"

CHAPTER LXVIII.
MOULDING,  SWABBING AND POURING TEST BARS.
In moulding test bars, every precaution should be taken to insure a uniform treatment at all times. The sand should always be of the same '' temper,'' as far as practical, rammed regularly, and of the same degree of hardness. The best way to attain this is to select some one intelligent man, who will make it his business to do all the moulding and casting of test bars which shall be required for any one department. The end to be sought in obtaining test bars is that they should be as near as possible the size of the pattern from which they are moulded. There are two factors affecting these results. The first is in the ramming and '' temper'' of sand, the second, in drawing the patterns. Practice, with . some, is such as to require more or less jarring or rapping of the patterns before they were removed from the mould, and while one moulder might not do so to a perceptible degree, another might go to the extremes. A system to be favored in making comparisons in one's own shop, or in the case of one firm with another, should be arranged so as to remove any semblance of the necessity of rapping or jarring patterns. For moulding test bars, some space as near the cupola as practicalters LVL, LIX. and LXV.