An ingenious and very good modern method of brazing broken iron parts (especially cast iron) goes by the name of the Ferrofix Brazing Process. It was devised by Frederick Pich, a German. By this process two fractured pieces of iron are cemented together with a thin film of brass which is so applied that it alloys with the iron surfaces, as deep as 1/16 inch. This was proven by cutting open a brazed joint and planing it down to ascertain its structure. To get this alloy in the joint, which is the secret of its strength, the solder must not melt below 650 deg. Cent.; hence hard brass is used.

Apparatus for Ferrofix repairing consists of:

1. A kerosene pressure tank and two or more Donnelly torches, which is an improved non-carburizing kerosene burner.

2. Fire-bricks and asbestos paper for a small furnace.

3. Ferrofix fluxing powder.

4. Patent brazing liquid.

The torch for heating may be air-coal gas, air-oil, oxy-acety-lene, etc.

The flux is a mixture of equal parts of sodium carbonate and boric acid, with a little common salt to increase fluidity.

1Iron Age, August 24, 1905.

United States patent paper, No. 688030, states that borax, the chief flux for all soldering and brazing, is troublesome because it swells up and falls off of the piece as soon as heat is applied. This, because it is then parting with water of crystallization. The patent flux, on the other hand, acts as follows: the carbonate is a ready absorbent of grease, of which it frees the the iron surface. With the application of heat, the'carbonate also reacts on the boric acid, forming anhydrous borax and carbon dioxid. The borax is thus in close contact with the fresh metal surface, which it frees of rust; and protects from the air.

The soldering compound is described in patent No. 647632 as follows:

"To form my improved soldering compound, I boil together finely pulverized borax and finely pulverized suboxid of copper, so that the same are intimately mixed and so that each particle of the suboxid of copper is surrounded, covered, and protected from the atmosphere by a thin film of the borax. Any desired proportions of the two may be used; but usually I take one-half of each, mixed with sufficient water to dissolve the same thoroughly by the boiling, and to cool down into a sort of paste.

" To use this soldering compound, the cast-iron surfaces to be soldered are cleaned by means of an acid in the usual way, fixed together, and the joints covered or surrounded with the compound. The joint is then heated, and therefore the borax melts and protects the cleaned surface of the iron against oxidization, removes any oxid thereon, and also protects the suboxid of copper against the action of the oxygen of the atmosphere. Consequently the suboxid of copper, likewise heated to a red heat, transfers its oxygen to the red-hot cast-iron surface, which oxygen combines with the graphite contained in the cast-iron surfaces to form carbon monoxid or dioxid, thus decarbonizing said surfaces, while the metallic copper becomes dissociated in a very finely divided condition. At the same time the hard solder is added, and as this solder, which is brought upon the surfaces to be soldered in the well-known manner, is likewise melted by the heat, it alloys itself with the incandescent particles of copper, and this new alloy immediately combines with the red-hot decarbonized soldering surfaces of the cast iron."

The company also issue instructions, which are in brief:

1. "Clean fractured surfaces thoroughly with wire brush. If rusty or oily, burn off with torch.

"2. Mix Ferrofix powder with the brazing liquid to the consistency of paint and apply on the fractured surfaces with brush.

"3. Set casting to be brazed on fire-brick, in perfect alignment, using fire-clay to hold it in place (if it will not stay of its own weight). Be sure that the broken parts fit close. Build a furnace of firebrick around the fractured part, allowing sufficient metal to be exposed, however, to absorb the heat. Leave top of furnace open, covering only with a sheet of asbestos - 3/16 inch thick is sufficient ordinarily. The front of furnace should be left open to admit the torch blast.

"4. Place the torches so that the flame will come directly on fracture; bring casting up to a light cherry-red, almost straw. See that both sides of the fracture keep at the same color.

"5. Apply flux with a steel spoon (made from 3/8-inch Bessemer steel rod flattened out at one end) holding it at the fracture with the spoon, so that from the heat of the casting (not the torch alone) it will melt and disappear through the crack. As soon as it comes through freely and you can see the liquid flux underneath, apply spelter with a very little flux; feed this until it flows through thoroughly. With the spoon the melted brass can be taken from underneath and fed over until the crack commences to fill, then cut off immediately your air and gas, and keep feeding a little more new brass until it will not melt further by heat of casting. Allow to cool down by its own cooling.

"6. Clean casting with file, chisel, or emery wheel.

"The question of expansion and contraction is governed by the construction of the casting and the character of the metal. Care should be taken to see that heat is properly applied and distributed to overcome this feature. Experience on intricate castings is the best teacher."

This is another comparatively new process that is beginning to be known by the foundries, car shops, blast furnaces, and machine shops. The first patent dates 1900. Its success is based on its cheapness, handiness, and strength. The initial expenditure is very low, the burner costing most. The outfit would prove a great saving to any plant which has breaks in its iron machine parts. For a fractured piece could be mended in an hour, whereas it is ordinarily necessary to rivet the old piece together with side braces or to order a new piece under danger of delay and hold up.

As for strength, the company guarantees that the joint is stronger than cast iron; brazed pieces never break in the joint. Moreover, the pieces to be mended are set as closely as possible, as the spelter will penetrate the tightest fracture.

There are "several tests covering the penetration of brass on cast iron treated with Ferrofix and also untreated. This was done by the taking three test bars which had the upper surface smooth, one was left uncoated, one had one coat of Ferrofix applied, and the third had two coats of Ferrofix. They were then placed in the furnace and heated to the same temperature, and the surface coated with brass as in brazing. When cold the coated surface was planed 1/32 inch below the original surface. We found on the untreated piece no evidence of brass, while on the treated pieces brass was distinctly discernible in the pores of the iron. Another 1/32 inch was then taken from the two treated pieces, and we found on the bar that had a single coating of Ferrofix minute traces of brass, while on the double-coated piece the brass was very distinct. It must, therefore, be apparent that the joint we obtain is not simply a surface adhesion, but an actual anchoring of the filling material to the adjacent faces of the fracture."1

Tests Made by Riehle Bros.

Specimens 6" x 6" x 24" long. Cast iron. Supports 20" apart. Load applied at center of specimen.

1 Special information.

Tests Made By Riehle Bros

Two other tests by the same company showed increases of 1 and 6 per cent, for mended bars.

Of three tests by Lewis Foundry and Machine Co., the first showed an increase in strength of 1, and the other two a decrease of 14 and 29 per cent.

Two bars tests by Cramp's broke outside the joint.

Fig. 88. - Broken arm that was made stronger than originally by the ferrofix brazing process.

The process is now used for all-sized repairs, small or very large.

"By accident a spoke was broken from a fly-wheel, 19 feet in diameter, 48 inches width of rim, weighing 21 tons. A new wheel would have cost $2700 and would have involved two or three months' delay. The Pich process was applied; the broken spoke was brazed into place, and $250 charged and paid for the job. The actual cost of doing this work was less than $50.1

Figure 88 shows a break of an important appliance that can be mended by this process.