The greater portion of all moulding can be done with flasks consisting of a cope and drag as described. These are called two-part flasks. Sometimes, however, a casting is required of such shape that the pattern cannot be made of two pieces and drawn out of the sand of the cope and drag. When this occurs flasks of three, four or more parts are used. Fig. 53 illustrates the use of 11 three-part flask for the moulding of a flanged pulley. The pattern is made in two parts separated along the dotted line E F. It is evident that it could not be drawn from the sand if rammed in a two-part flask. The pariing line would then he on the line E F. The flanges would be buried in the sand and could not be drawn. The use of a three-part flask makes the moulding possible. One half the pattern C E F D' is laid upon the moulding board. The drag is set over it hut raised by a frame the height D G. The Band is then rammed and the drag turned. The frame used for raising the drag is removed and the sand cut away and sleeked down to the parting lines C C and D D'. The middle section or cheek of the flask A C, B D is then put on the drag, the other half of the pattern set on its mate and the sand rammed outside the pattern in the spaces a a. This sand is sleeked off on the parting lines A A' and B B'. The cope is then put on and rammed. The sand of the cope tills in the hollow b b on top of the pattern. The cope is then lifted off leaving the pattern in the sand. In drawing the pattern its upper half is first drawn out of the sand of the middle section : the middle section or cheeki is then lifted from the pattern, and the bottom half is finally drawn from the sand of the drag. In lifting the middle section from the pattern, the latter should be gently rapped. Other and more complicated patterns may require the use of flasks of a greater number of parts, but the principle upon which they are made and used is the same as that here given. The middle sections are provided with bars in the same way as the cope or better with the lifting plates d d. Usually flasks are especially fitted for this work. The bars should be so arranged as to conform to the contour of the pattern in order that the sand may be firmly held. .Gaggers should always be used where needed.

ELECTRICALLY OPERATED JIB CRANE. Whiting Foundry and Equipmant Co.

ELECTRICALLY-OPERATED JIB CRANE. Whiting Foundry and Equipmant Co.

Three Part Flasks 100425

Fig. 63.

Three Part Flasks 100426

Fig. 64.