Figure 16 shows a sound forging. The bars in Fig. 17 were burst by improper forging, while the die, Fig. 18, burst from a piped center.
Figure 19 shows a piece forged with a hammer too light for the size of the work. This gives an appearance similar to case-hardening, the refining effect of the blows reaching but a short distance from the surface.
While it is impossible to accurately rate the capacity of steam hammers with respect to the size of work they should handle, on account of the greatly varying conditions, a few notes from the experience of the Bement works of the Niles-Bement-Pond Company will be of service.
FIG. 16.—A sound forging.
FIG. 17.—Burst from improper forging.
For making an occasional forging of a given size, a smaller hammer may be used than if we are manufacturing this same piece in large quantities. If we have a 6-in. piece to forge, such as a pinion or a short shaft, a hammer of about 1,100-lb. capacity would answer very nicely. But should the general work be as large as this, it would be very much better to use a 1,500-lb. hammer. If, on the other hand, we wish to forge 6-in. axles economically, it would be necessary to use a 7,000- or 8,000-lb. hammer. The following table will be found convenient for reference for the proper size of hammer to be used on different classes of general blacksmith work, although it will be understood that it is necessary to modify these to suit conditions, as has already been indicated.
FIG. 18.—Burst from a piped center.