Book Description

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1917 edition. Excerpt: ... prevent it. Do not attempt to prevent a casting from expanding by means of clamps. If you should be so foolish as to try, and the clamps were strong enough, distortion of the casting would inevitably result. As most castings are of irregular shape, and the metal usually varies in thickness, it is necessary to take some precautions in heating so that the heavy parts will expand in the same ratio as the thin parts. If this is not done either breaking or distortion is very apt to occur. This precaution is uniform heating and in order to secure a uniform heat sloiv heating is necessary. For pre-heating of cylinders and like castings in order to take care of expansion, remember to heat slowly and uniformly and of course to take care of contraction cool slowly and uniformly.That is the "meat in the cocoanut," heating slowly and uniformly and cooling slowly and uniformly. When the foundryman made the casting it was poured from molten metal possessing the same temperature throughout and flowed into a mold where it was entirely protected from the air by the sand, which permitted an even and uniform cooling. Welding with the oxy-acetylene flame is simply re-casting and the beginner would do well to study and follow foundry practice in a number of instances. Unless the beginner studies and thoroughly understands the principles of expansion and contraction and applies it to the work at hand he will not be a success, regardless as to how well he may manipulate the torch. In the majority of cases it is just as important to maintain alignment as it is to make a good weld. If the welder ignores expansion and contraction, it is inevitable that one of three things will happen: 1st--The casting on cooling will break in or near the weld....