In the manufacture of modern machinery three classes of castings are employed, each one having its individual physical properties, such as strength, toughness, durability, etc. These castings are as follows: gray iron; copper alloys, i.e., brass, bronze, etc,; and mild steel. By far the greatest number of castings made are of gray iron, that is, iron which may be machined directly as it comes from the mold without any further heat treatment.
The main purpose of this book is to explain the underlying principles involved in making molds for gray-iron castings, and the mixing and melting of the metals for such castings. The articles on Malleable Cast Iron as well as the articles on Brass Founding and Steel Casting emphasize only those features of the methods used which differ from gray-iron foundry practice. The article on Shop Management is intended to set students thinking on this subject; because the whole trend of modern shop practice is toward specialization and system in handling every department of the work, in order to increase efficiency and reduce cost.