Wrought Iron Architectural Metalwork
Designed & manufactured in the U.K
By: Chris Topp & Co Ltd, North Yorkshire
Tel: 01845 501415
Taken from
Elementary Engineering
Crosby Lockwood & Son
Published in 1902
Iron Ore and Cast Iron
Q In what form is iron found?
A In the form of iron ores, chiefly oxides of the metal.
Q What is iron ore?
A Essentially a chemical compound of iron with oxygen or sulphur, by which is metallic character is disguise in that if a stony compound.
Q What does iron ore contain?
A It generally contains oxygen, sulphur, arsenic, phosphorus, carbonic acid and clay.
Q What are the chief kinds of iron ore?
A Magnetic iron ore, red hematite, brown hematite, carbonate of iron and clay and black band ironstones.
Q How is iron obtained from the ore?
A By smelting
Q What is the process?
A The ores are broken into small pieces and mixed with coal, coke, or charcoal and the whole mass is smelted in a blast furnace.
Q What is a Blast Furnace?
A A hollow columnar structure of iron and brick, the interior being shapes like truncated cones placed base to base. The ore, fuel and a flux are fed in alternate charges or strata and fusion and reduction are effected by means of blast from blowing engines.
Q What is the effect of smelting the ore?
A The carbonic oxide from the fuel reduces ferric oxide to metallic iron
Q Is not limestone used in smelting?
A Yes: limestone and quick lime are mixed with the ore to form a chemical union with the siliceous matters present in order that they may be separated more readily from the iron.
Q What is this called?
A A Flux
Q What is the meaning of the word flux?
A It is derived from the Latin word ‘Fluo’ to flow
Q When the iron in the furnace becomes liquid how is it treated?
A A small hole is ‘tapped’ at the bottom of the furnace and the molten metal is ‘cast’ or runs into trenches communication with a centre channel, where it is left to cool.
Q In what form is the iron cast?
A In rough bars of a ‘D’ section about three feet long and four inches in diameter, which are call pigs.
Q What is the weight of a pig of iron?
A About one hundred weight (50kgs)
Q What is the refuse from the blast furnace called?
A Slag
Q How long does it take to smelt the ore?
A From the time the ore is put in at the top, it takes forty to fifty hours in its passage to the bottom of the furnace.
Q What becomes of the ‘pigs’ of iron after being cast?
A Samples are broken and examined and the quality ascertained: they are then wither sent to a foundry for casting into mould or to a rolling mill to worked into wrought iron.
Q How is Cast Iron made?
A The ‘pigs’ are broken and put into cupola furnace with about one-fourth their weight of cole for re-melting.
Q What is the process of re-melting?
A Alternative layers of coke, pig with scrap and flux are subjected to the action of a blast of air, until a temperature of about 3000°F, is obtained, when fusion ensues.
Q What is then done?
A The cupola is tapped and the molten metal is run into ladles and poured into moulds of sand of the desired shapes.
Q How are the moulds made?
A A pattern or model of the article required is made of wood, which is embedded in moulding-sand and on removal leaves an impression into which the molten metal is poured and allowed to cool.
Q What is this called?
A Casting or Founding
Q What is the average tensile strength of cast iron?
A About seven tons per square inch.
Wrought Iron and its uses.
Q How is wrought iron manufactured?
A By depriving cast iron, so far as possible, of all the foreign matters.
Q How is this done?
A By melting pig iron in what is called a puddling furnance.
Q Describe the process
A The ‘pigs’ are broken into small pieces and piled around the inside of the furnace, which is fettled in ‘puddler’s mine’ and ‘bull dog’.
Q What is the object of mixing ‘fettling’ and hammer scale with the metal?
A In order to form sufficient oxide to purify the metal, by oxidation of the foreign elements.
Q What quantity of metal is used as a ‘charge’ in the puddling furnace?
A From four to five hundredweight.
Q When the iron becomes fused, what is done with it?
A The iron is allowed to become almost liquid, and whilst in that state is ‘rabbled’ or stirred with a bar through a small hole in the furnace door.
Q How is the puddling done?
A By a workman who is called a puddler.
Q Is any skill required for this work?
A Yes, great care must be taken to mix the metal at the proper moment, or much waste will take place.
Q What is the object of puddling?
A To mix the semi fluid metal with the melted oxide of iron to purify it.
Q What is the appearance of the metal during this operation?
A A mass of metal at almost white heat boiling and bubbling.
Q What do the bubbles indicate?
A The bubbles are escaping carbonic oxide gas, indication the progress of the removal of the carbon with the iron.
Q Describe how the iron is then treated
A In a short time small clotted lumps of purified metal separate, or come to nature, in the melted metal. These are stirred and rolled by the rabble until a ball or bloom of about sixty pounds weight has be collected.
Q What is done with this?
A It is placed in the hottest part of the furnace so as to thoroughly soften the metallic parts, which are pressed together with the paddle to render tem compact.
Q What is the next process?
A When all the iron in the furnace is thus collected each ball is lifted out of the furnace and placed under a hammer.
Q What is the object of this?
A To Force out the melted slag or refuse and weld the iron into a compact mass.
Q What is then done with it?
A If the iron is required for bars, it is passed whilst still in a heated state through the rolls.
Q What are puddling rolls?
A A pair of massive iron cylinders, the surface of which a are grooved that when placed together that exhibit a series of gradually diminishing openings
Q Is the iron then fit for use?
A No, the iron obtained from the puddling rolls is of very inferior quality and can only be used where hardness and not tenacity is required.
Q How is ‘best bar’ obtained?
A By piling short lengths of bar together, re-heating and rolling again.
Q What is this called?
A ‘Fagoting’ or ‘Piling’
Q Does a repetition of ‘piling’ improve the iron?
A Yes.
Q How often may ‘piling’ be repeated?
A As Often as is necessary to obtain iron of a given quality, usually twice or three times for bars of ‘best, best’ or best, best, best qualities respectively.
Q In what form is wrought iron usually manufactured?
A In plates, round, square and flat bars.
Taken from
Elementary Engineering
Crosby Lockwood & Son
Published in 1902
At Chris Topp & Co re-roll and pile wrought iron, our main source of material today is anchors, chains, old railings and bridges.
