Preliminary Work.

How does it come about that the scrap material referred to is transformed into the first-class casting of the highest quality steel, shewn in the illustrations accompanying this article?

In the first place plans of the casting are made. From these plans a model, exact in size and detail to the original design, is made in wood. The model is called a pattern, and is the work of the patternmaker. The pattern is then placed in the sand until a perfect imprint of it is obtained. This work is carried out by moulders, who reinforce the sand with nails, treacle, and fine silica flour, until it is strong enough to stand the ravages of molten steel, which will surge in later and fill every nook and cranny.

Now for the steel, which will compose the casting. Since it requires to stand up to certain loads and vigorous treatment in service, the steel must be strong and ductile. The prescribing of the steel is the work of the chemist, who juggles with the carbon, sulphur, phosphorus and other ingredients until a preconceived arrangement is reached, thus guaranteeing that the steel will stand up to its tests.

All is now ready for the casting, in conjunction with which test bars are cast. These bars are later removed and tested before the process of completion of the casting is taken to a further stage. After the casting of the steel, the mould is allowed to cool off, and the sand is then knocked away, leaving the casting as shewn in the illustration (right). The total weight of the casting as shewn, with runners and risers complete, is 28 cwt.

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The runners and risers are used to balance the “draw” of hot metal. The metal contracts in cooling, and the skilful allocation of the runners and risers prevents the casting from cracking.