The Value of Science in the Smithy and Forge

THE VALUE OF SCIENCE

IN THE

SMITHY AND FORGE.

BY

WILLIAM HUTTON CATHCART,

MEMBER OF THE IRON AND STEEL INSTITUTE,

MEMBER OF THE WEST OF SCOTLAND IRON AND STEEL INSTITUTE,

PRESIDENT OF THE ASSOCIATED FOREMEN SMITHS OF SCOTLAND.

EDITED BY

JOHN EDWARD STEAD,

D.SC., D.MET., F.R.S., F.I.C., F.C.S.

PREFATORY NOTE BY

PROFESSOR ARCHIBALD BARR,

D.SC., LL.D., M.INST.C.E.

With 75 Illustrations, mostly Photomicrographs.

Copyright © 2013 Read Books Ltd.

This book is copyright and may not be reproduced or copied in any way without the express permission of the publisher in writing

British Library Cataloguing-in-Publication Data

A catalogue record for this book is available from the British Library

Metal Work

Metalworking is the process of working with metals to create individual parts, assemblies, or large-scale structures. The term covers a wide range of work from large ships and bridges to precise engine parts and delicate jewellery. It therefore includes a correspondingly wide range of skills, processes, and tools. The oldest archaeological evidence of copper mining and working was the discovery of a copper pendant in northern Iraq from 8,700 BC, and the oldest gold artefacts in the world come from the Bulgarian Varna Necropolis and date from 4450BC. As time progressed, metal objects became more common, and ever more complex. The need to further acquire and work metals grew in importance. Fates and economies of entire civilizations were greatly affected by the availability of metals and metalsmiths. The metalworker depends on the extraction of precious metals to make jewellery, buildings, electronics and industrial applications, such as shipping containers, rail, and air transport. Without metals, goods and services would cease to move around the globe with the speed and scale we know today.

One of the more common types of metal worker, is an iron worker – who erect (or even dismantle) the structural steel framework of pre-engineered metal buildings. This can even stretch to gigantic stadiums and arenas, hospitals, towers, wind turbines and bridges. Historically ironworkers mainly worked with wrought iron, but today they utilize many different materials including ferrous and non-ferrous metals, plastics, glass, concrete and composites. Ironworkers also unload, place and tie reinforcing steel bars (rebar) as well as install post-tensioning systems, both of which give strength to the concrete used in piers, footings, slabs, buildings and bridges. Such labourers are also likely to finish buildings by erecting curtain wall and window wall systems, precast concrete and stone, stairs and handrails, metal doors, sheeting and elevator fronts – performing any maintenance necessary.

During the early twentieth century, steel buildings really gained in popularity. Their use became more widespread during the Second World War and significantly expanded after the war when steel became more available. This construction method has been widely accepted, in part due to cost efficiency, yet also because of the vast range of application – expanded with improved materials and computer-aided design. The main advantages of steel over wood, are that steel is a ‘green’ product, structurally sound and manufactured to strict specifications and tolerances, and 100% recyclable. Steel also does not warp, buckle, twist or bend, and is therefore easy to modify and maintain, as well as offering design flexibility. Whilst these advantages are substantial, from aesthetic as well as financial points of view, there are some down-sides to steel construction. It conducts heat 310 times more efficiently than wood, and faulty aspects of the design process can lead to the corrosion of the iron and steel components – a costly problem.

Sheet metal, often used to cover buildings in such processes, is metal formed by an industrial process into thin, flat pieces. It is one of the fundamental forms used in metalworking and it can be cut and bent into a variety of shapes. Countless everyday objects are constructed with sheet metal, including bikes, lampshades, kitchen utensils, car and aeroplane bodies and all manner of industrial / architectural items. The thickness of sheet metal is commonly specified by a traditional, non-linear measure known as its gauge; the larger the gauge number, the thinner the metal. Commonly used steel sheet metal ranges from 30 gauge to about 8 gauge. There are many different metals that can be made into sheet metal, such as aluminium, brass, copper, steel, tin, nickel and titanium, with silver, gold and platinum retaining their importance for decorative uses. Historically, an important use of sheet metal was in plate armour worn by cavalry, and sheet metal continues to have many ornamental uses, including in horse tack. Sheet metal workers are also known as ‘tin bashers’ (or ‘tin knockers’), a name derived from the hammering of panel seams when installing tin roofs.

There are many different forming processes for this type of metal, including ‘bending’ (a manufacturing process that produces a V-shape, U-shape, or channel shape along a straight axis in ductile materials), ‘decambering’ (a process of removing camber, or horizontal bend, from strip shaped materials), ‘spinning’ (where a disc or tube of metal is rotated at high speed and formed into an axially symmetric part) and ‘hydroforming.’ This latter technique is one of the most commonly used industrial methods; a cost-effective method of shaping metals into lightweight, structurally stiff and strong pieces. One of the largest applications of hydroforming is in the automotive industry, which makes use of the complex shapes possible, to produce stronger, lighter, and more rigid body-work, especially with regards to the high-end sports car industry.

One of the most important, and widely incorporating roles in metalwork, comes with the welding of all this steel, iron and sheet metal together. ‘Welders’ have a range of options to accomplish such welds, including forge welding (where the metals are heated to an intense yellow or white colour) or more modern methods such as arc welding (which uses a welding power supply to create an electric arc between an electrode and the base material to melt the metals at the welding point). Any foreign material in the weld, such as the oxides or ‘scale’ that typically form in the fire, can weaken it and potentially cause it to fail. Thus the mating surfaces to be joined must be kept clean. To this end a welder will make sure the fire is a reducing fire: a fire where at the heart there is a great deal of heat and very little oxygen. The expert will also carefully shape the mating faces so that as they are brought together foreign material is squeezed out as the metal is joined. Without the proper precautions, welding and metalwork more generally can be a dangerous and unhealthy practice, and therefore only the most skilled practitioners are usually employed.

As is evident from this incredibly brief introduction, metalwork, and metalworkers more broadly, have been, and still are – integral to society as we know it. Most of our modern buildings are constructed using metal. The boats, aeroplanes, ships, trains and bikes that we travel on are constructed via metalwork, and mining, metal forming and welding have provided jobs for thousands of workers. It is a tough, often dangerous, but incredibly important field. We hope the reader enjoys this book.

PREFACE.

IT is not usual for anyone who is constantly engaged in the workshop to attempt to write and lecture on the practical application of modern science. Mr Cathcart, however, who has been thoroughly trained in practical smith-work in the blacksmith’s shop, has not only attempted but has succeeded in writing on the subject, showing clearly how much benefit blacksmiths would derive if they were to apply more science in the conduct of their everyday work. It is evident that the author has by patient study mastered the elements of metallography and the effect of heat on the structure of iron and steel, for he has in most lucid language sought to show how such knowledge can be applied. Knowing that there is still much prejudice in the mind of the practical worker against theory, the author has taken some pains to show that the practical worker himself bases his practice on theory, and that theory and practice are inseparable. The practical man is always of necessity a theoretical man, whether he admits it or not. What is clearly shown is the necessity for blacksmiths having more theory in order that their practice may be the more perfect. Most of the very excellent photomicrographs illustrating the lecture are Mr Cathcart’s own work. As a result of his private research on welding iron, he has revealed the interesting fact that, when heating to welding temperature in a smith’s forge, the iron absorbs carbon on the surface, and that the juxtaposed faces of finished welds, in such cases, may contain between 0·2 per cent. and 0·8 per cent. carbon, and are actually steel. As a consequence, the welded portions show greater tensile strength than the iron on each side of the weld.

If the little encouragement and assistance I have given the author has helped him in his study of metallography, and led to the better understanding of iron and steel, I am deeply gratified. I feel sure that Mr Cathcart’s book will do much to lead others to see the value of modern science in the blacksmith’s shop.

J. E. STEAD.     

MIDDLESBRO’.

PREFATORY NOTE.

I HAVE read Mr Cathcart’s manuscript with very great interest. With his thesis—the value of science in the workshop—I need hardly say I am in complete agreement, and I would further say that he has upheld it admirably.

His treatment of the subject in the early pages is excellent. Much of the distrust of technical education—or training in science, as I should prefer to call it—is due to writers who ought to know better, but who, lacking any sound knowledge of science themselves, and priding themselves on being practical men, have endeavoured to make people believe that there are two classes of men connected with any craft or profession: those who are practical men and those who know something of the science pertaining to the craft;—as if a man could not be a practical man if he had taken the trouble to learn the science that underlies the processes with which he deals.

The latter part of the work has naturally been of special interest to me, as it contains many matters which I have not hitherto studied in such detail, and these are undoubtedly of great importance to men of his craft, as well as to those practising other branches of engineering.

His conclusion is very excellently put and very true.

I look forward to the publication of Mr Cathcart’s work. It will be of very great interest and value to many outside the circle of his own great craft. One cannot but admire the perseverance with which he has laboured to achieve the results he records. His own photomicrographs are splendid and intensely interesting, and anyone who masters what he offers for study will know a great deal of which most smiths and engineers have very little conception—much less true understanding.

ARCHIBALD BARR.     

ANNIESLAND, GLASGOW,

     24th August 1915.

AUTHOR’S PREFACE.

THE following pages are the outcome of a lecture delivered at a meeting of the Associated Foremen Smiths of Scotland for the purpose of interesting the members in the scientific training of the rising generation of smiths and forgers. That the object was favourably received, not only by those to whom but by those in whose interests it was first presented, and also by distinguished educationalists, is fully borne out by the fact that it has been repeated by request on several occasions; not the least gratifying of which repetitions has been one specially requested by a deputation of smiths, who organised a meeting which