The Sheffield Method for Making a Cutlery Knife Blade Content from the guide to life, the universe and everything

The Sheffield Method for Making a Cutlery Knife Blade

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A fork reflected in a cutlery knife blade.

This is a tale of craftsmanship and obstinacy. It shows in full measure the pride and unquenchable work-ethic of industrial England, but the selfsame story reveals the causes of economic decline.

The origins of the Sheffield method of making knife blades are obscure. Invented sometime in the early 1800s in a forgotten place, its adoption by an entire local industry owes much to the assiduous promotion of Sheffield's reputation for fine cutlery. What began as a unique guarantor of quality, however, was to become an inefficient anachronism, and the city cutlers' reluctance to recognise this was a major factor in their fall from market dominance.

Old crafts are marked by superstition, and cutlery-making is no exception. Some of its customs are benign and enduring, such as the tradition of exchanging a small coin in recognition of the gift of a knife1. These customs serve to remind us, though, that knives were charmed only a few generations ago. Little wonder, then, that their makers were prone to delusions of invulnerability.

The Little Mesters

Cutlery-making in Sheffield evolved as a cottage industry. The water power needed to drive forging hammers and grindstones meant that workshops were strung out along the river valleys. The men who operated them were known as the Little Mesters, and they were the smallest of small businessmen. Their livelihoods were precarious and their methods were expedient, and so quality was not uniformly high. Although Sheffield's knives were venerable enough to be noted by Chaucer2, it was soon obvious that some kind of collective management was needed to enforce standards and to preserve the global reputation of the local product.

The mighty Cutlers' Company of Hallamshire was the ultimate manifestation of this craftsmen's guild, and its power is still evident in the opulence of its halls and regalia. The pinnacles of local workmanship, in silver but also in steel, are breathtakingly beautiful, but they are artefacts of luxury. Any entrepreneur worth his salt knows that the key to business success is the satisfaction of the volume need. For every customer prepared to pay for exquisite cutlery, there were a thousand who wanted cheap and functional table-knives.

Properties of the Basic Table Knife

What, then, constitutes this functionality? In use, a knife needs to stay sharp. It needs to be hard and scratch-resistant so that it can be hygienically cleaned and for the same reason it must be chemically inert and resistant to corrosion. Aesthetics are important, not least because in domestic politics the table speaks to the guest. Other properties are really needed for manufacture rather than final use, and chief among these is formability.

To understand the material preferences in knife-making, the evolution of social behaviour needs to be considered. For centuries, people carried their own knife on their person, and they did so as much for self-defence as for cutting up food. Such pocket-knives were for a long time made from steel, for strength and toughness, and these properties were dictated by the weapon function. The idea of offering knives to guests at table was thus originally a gesture of privilege as well as a demonstration of wealth, and this is why silver was favoured. The fact that silver knives are more or less useless for stabbing people3 was probably an advantage in times of rowdier table manners.

The next development, bringing the appearance of silver tableware within the means of ordinary householders, was Sheffield plate. This silver-plated copper product was invented by Thomas Boulsover in about 1740, and the establishment of local expertise in its manufacture helped to consolidate Sheffield's dominance of the cutlery market.

Steel's emergence as a competitor to silver plate was gradual and would only result in complete dominance in the early 20th Century with the invention of stainless steel4. Until then, silver's corrosion resistance was the factor in its favour. Nonetheless, steel was making inroads even a hundred years earlier.

The Evolution of Steelmaking

Cutlery steel was traditionally produced by the cementation process. Iron was made in a blast furnace, gang-hammered in the bloomsmithy and slit to bar. These bars were stacked in brick chests at the base of the cementation furnace, interspersed with layers of charcoal, and fired for up to a week. The surface of the bars took up the carbon, conferring strength and hardenability. When these bars were forged together in bundles, the result was a laminated structure of thin layers of hard and soft steel. It was ideal for knife-making, being both workable but capable of being ground to a keen and durable edge.

Even when Huntsman's process of crucible steelmaking proved itself in terms of improved consistency and purity, the cutlers rejected it. Crucible steel was generally too ductile for knife-making, though it was good for the hollow-ware elsewhere on the table, in spoons and in utensils. The cutlers didn't see the real potential of crucible steel as the clean and repeatable composition that could provided a sound foundation for controlled alloying, and hence customised properties. Their shunning of Huntsman in the late 18th Century was arguably the beginning of their demise.

The cutlers were no kinder in their assessment of the volume steelmaking processes, those of Bessemer and Siemens-Martin, and so now in the last quarter of the 19th Century the suppliers began to outgrow their customers. The typical melting shop could make a hundred tons of steel a day or more, and the cutlers could consume a thousandth part of that output at most. An industry is in danger the moment that its suppliers no longer rely on it, and yet still the cutlers didn't see the writing on the wall.

The Sheffield Process

Traditional table-knives are made in two parts. One part is the handle, usually made of horn or bone or some type of plastic, or alternatively made of die-formed metal in a hollow pressing. The rest of the knife is made as a single forging. There are three distinct zones in this forging: the blade itself, the bolster (the socket into which the handle is mounted) and the tang (a long spike which extends through most of the length of the handle and to which the handle is fixed).

Forging a component in strong steel with three parts like this is not a trivial process. The Sheffield method, though, was surprisingly complex. The steel had to be reheated no less than four times, each time to around one thousand degrees Celsius. The starting blank, or slug, was a flat bar about a centimetre wide, half a centimetre thick and ten centimetres long. The first heating cycle allowed the tang to be beaten out. The next formed the bolster. The third involved the flattening and basic shaping of the blade. The final heating operation was the metallurgically useful one, quenching and tempering the blade before the cold finishing operations of etching to remove the residual oxide, grinding to develop the edge and fitting of the handle.

In the earliest times of steel knife-making, all these operations were performed by hand, assisted only by hardened steel dies. For example, the blank was hammered into a die at the second step to shape the bolster. Only the final heating cycle helped to develop the metallurgical properties of the knife. All the others were necessary simply because the work-piece lost heat too quickly to allow further processing steps to be taken.

An early Victorian cutlery forge was a labour-intensive workplace. A skilled craftsmen could make perhaps two hundred knives in a week, heating several dozen in the furnace at a time, and performing one of the four process steps on all of them on a given day. Once processed, the blank would be thrown onto a pile and the next one drawn out. The method provided a level of repeatability in product outcome, which is what the guild were looking for. Accordingly, the method was recommended, taught and all but mandated as a condition of guild membership.

Later Development of the Process

The machine age arrived in the middle of the 19th Century. The method was progressively refined in operational terms, but the basic procedure of four reheating cycles was not altered. The forming of the tang was soon being carried out by means of a spring hammer, and air-cooling in piles until the next day was replaced by quenching and returning to the furnace to heat up again for the next process.

The spring hammer is still used by some traditional smiths. Like all the machine tools of the Victorian factory, it could be powered by a belt driven through a line-shaft, allowing several identical machines to be operated in parallel. The belt drove a cam which in turn drove the top anvil, mounted in a spring-frame. Some hammers had complex cams, so that several hammer strokes of different amplitudes were executed for each revolution of the drive shaft, and this meant that altering the bottom anvil height by means of a treadle gave a range of effective speeds from a single drive.

Quenching and reheating from cold seems like a wasteful method and certainly offends modern ideas of manufacturing sustainability. It was done for operational convenience rather than any metallurgical reason, allowing several operatives' blanks to be batched together so that all would come to heat at the same time. Productivity was thereby aided and could be monitored by the clock, to everyone's benefit in a time of piece-work.

The second forging cycle was now carried out in a drop-stamping machine, using a profiled die to form the bolster. After a further quench and heating cycle, the blade was rough-formed by deforming the square end of the blank between eccentric rollers.

The fourth and final reheating cycle remained a slow one, of several hours' duration, for the purpose of annealing the metal of the blade. Excess metal was trimmed off using a pattern shear before a final quench. This completed the hot operations, unless the tang was off-straight or the blade was bowed, in which case another heating cycle would be needed before straightening out. The knife was now ready for the same finishing process as always, of etching, grinding and fitting of the handle.

The Modern Process

The hot forging process described above was still in use in Sheffield as late as the 1980s, albeit only for the luxury end of the stainless steel table-knife market. By this time, a much more efficient process had been in widespread use for at least twenty-five years, and distinct improvements on the Sheffield process were developed elsewhere much earlier than that.

The process generally used today closely resembles one reported by Britain's Cutlery Research Council in the mid-1960s. The observations were made at works at Solingen in Germany. The machinery was extremely powerful by comparison with Sheffield's hammers and presses. A hydraulic cold press first stamped out a blank much nearer to final shape than the rectangular slug. There was a single heating operation at the forging stage, with the blanks automatically transferred to the hammer, which made three separate strikes using different dies in a rotary anvil. The annealing and finishing operations were broadly similar to the Sheffield method, although more fully automated.

It's unlikely that the Sheffield cutlers really believed this new process to be inferior to their own. Its repeatability was higher, for one thing, with a consequent benefit in the consistency of product quality. The larger forces employed in forging lead directly to better properties. The German producers, moreover, put a lot of effort into alloy development, finding compositions that would suit their process and so maximise the resulting final properties. Back in Sheffield itself, metallurgical development of this kind was commonplace in the edge tool industry and the engineering steels businesses that had supplanted cutlery as the city's staple trades. Cutlery, though, was fixated with its craft tradition and relied too little on a scientific approach to product and operational refinement.

The Germans didn't go straight for the kill. They had a decisive manufacturing cost advantage relative to the historic market leader, as well as superior quality. They did the smart thing, undercutting the price of the Sheffield product by a little, and turning the bulk of their advantage into margin. As a result, the demise of Sheffield cutlery was a slow one. The industry bled to death over several years, until the mercy of a precipitous final decline was assured by Far Eastern market entrants from the 1980s onwards, at prices that put an end to the old manufacturing methods overnight.

Looking Back

Cutlery made Sheffield's metals reputation, but ultimately damaged it. The industry was the birthplace of process metallurgy and many of the operations management techniques on which the modern world of manufacturing commerce is founded. Instead of building on this formidable start, though, the cutlers became complacent and fell back on spurious notions of craftsmanship and quality. Gifted businessmen passed on their factories to indolent sons. The families on which the once-glorious cutlery industry was founded went from the resourcefulness of necessity to the decadence of privilege in a couple of generations.

The society of the cutlery industry still preens itself in South Yorkshire, but most of the modern businesses of the region shun their self-indulgence. The best of Sheffield now lies remote from that quarter. It's a pity in some ways, because of what was and what might have been, but it's time to move on. No place on earth can thrive by dwelling on the vanities of a past age. Time was when Yorkshire folk would inspect every knife and tut their disapproval at the absence of a familiar mark. Now they know better. These are just knives; things for the table, tools. The food on the plate and the conversation across it says so much more about us. There can be no sympathy for traditions that do not heed the changing of the times.

1The money is supposed to ensure that the knife does not cut the ties of friendship.2'A Sheffeld thwitel bare he in his hose.' - The Reeve's Tale.3Unless they're werewolves, of course.4By another Sheffielder, Harry Brearley.

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