HISTORICAL NOTE

The Manufacture of ScrewsThe concept of the screw, both as a fas-

tener and as a device to move material,has been known since ancient Greek

I times. Not until the age of mechanization,though, were screws produced withenough precision and in sufficient quanti-ties to become crucial components of thedevelopment of technology.

Screws can be made of iron, steel, cop-per, bronze, brass, aluminum, wood, orhard plastics. Mechanically, a screw is acontinuous inclined plane wrappedaround a cylinder.

Several names are often mentioned inconnection with the invention of thescrew. The Pythagorean philosopherArchytas of Tarentum is alleged to be theactual inventor of the screw in the fifthcentury B.C., though the date of thescrew's first appearance as a useful me-chanical object is not clear.

Archimedes (third century B.C.) isoften credited with the invention of thewater screw, or "screw of Archimedes,"though similar devices appear to havebeen used for irrigation in Egypt muchearlier than this.

The Greek scientist Hero, living inAlexandria in the first century A.D.,invented a screw press for squeezingolives and grapes to produce olive oil andwine. Turning the shaft of the screw pressapplied great and constant pressure to thefruit, producing much more liquid thanother simple crush presses could. TheRomans used the screw press for pressingclothes. A drawing of such a clothes presssurvived in the ruins of Pompeii from 79A.D.

External screw threads could be madeby tediously marking the diagonal chan-nels on a wooden rod, then sawing, andfinishing by filing. But cutting the internalthread of a nut or a pipe proved to beproblematic. By the first century A.D.,taps for cutting or grinding internalthreads were also in use.

Many centuries later, as technologyadvanced into the age of mechanization,screws took a more prominent role. Forinstance, England's large Salisbury clock(made in 1380, and perhaps the oldestclock still operating in the world) wasconstructed without a single screw;craftsmen used wedges or rivets to holdits iron frame together. The delicatepieces of smaller precision clocks createdin later years, though, could not obvious-ly be hammered together, but requiredsmall metal screws for assembly.

Metal screws and nuts came into use in

the 15th century. A hexagonal or squarehead was turned with a box wrench. Acentury later, the screws used in armorfeatured nicks or slots in their roundheads, possibly for the use of a screwdriv-er. Centuries later, James Watt (1736-1819), best known for his invention of thepractical steam engine, also designed ascrew printing press: A letter written inspecial ink was screwed up against moistcopy sheets for reproduction.

In his notebooks, Leonardo da Vinci(1452-1519) sketched a machine for cut-ting screws as well as a screw-operatedprinting press.

The wood screw, which deforms thewood itself into accompanying nutthreads, is not mentioned until the mid-16th century. A different variation, themetal screw, is designed to hold sheets ofmetal that are thinner than one groove,which obviates the need for makingthreads inside the material.

A mid-16th century mining treatiseoffhandedly describes a large slot-headscrew tapering to a point (for boring intorock), as if it were a common object. Butnot until the mid-19th century werescrews commonly made with pointedends. Before this time, a hole long enoughto accept the full length of the screw wasrequired. An American traveler, GeorgeEscol Sellers, took a trip to Britain withinstructions from his father "to see andlearn all that was accessible in the way ofcivil and mechanical engineering." Sellerstoured many renowned British factories,but he wrote with some amusement howthose he encountered resisted theAmerican idea of adding points toscrews:

"Mr. E.R. Sheer, a pianoforte maker ofPhiladelphia, in fitting work where woodscrews had to be withdrawn and againdriven in the same holes had found it dif-ficult to make the common square-endEnglish wood screw enter and follow thethread cut by the first insertion...with fileand chasing tool he tapered the end of thescrew like that of a gimlet. He had givenme several of these as samples, with therequest that when in Birmingham Iwould induce some good screwmaker tofill a considerable order of gimlet-pointedscrews. I had gone to the makers...[but]failed to induce any of them to fill theorder; they and their predecessors hadalways made wood screws as they werethen doing, and they would have nothingto do with such new-fangled notions."

Typically, each screw manufacturer

designed the screw threads to his ownconvenience. Threads cut with a sharp Vprofile had disadvantages because theweak, pointed crests broke off in smallpieces and high stress concentration inthe sharp root often caused the screw tofail—resulting in inconvenience, delay,and expense because it was difficult tofind a replacement screw that would fitthe grooves.

In 1841 Sir Joseph Whitworth inEngland proposed that all screw manu-facturers use a rounded fastening threadwith grooves tilted at 55°; this became theBritish standard thread used for generalengineering. In 1864 William Sellers (norelation to George Sellers, mentioned pre-viously) in the United States proposed ascrew with a 60° thread, with crests cutoff and roots filled in, which was accept-ed as the U.S. standard. In 1948 theUnited Kingdom, United States, andCanada together adopted the Sellers stan-dard.

Screws are mass-produced by turningon a special lathe, where the threads arecut with a single-point cutting tool. Diesfor cutting threads, as in pipes, are madewith internal cutting edges of the propersize, shape, and pitch.

Milling is useful for producing largeand accurate threads. Rolling a screwblank between flat or cylindrical diesallows a high rate of production; thismethod was introduced for manufactur-ing cheap stove bolts, but improvementshave made possible the high-volume pro-duction of superior screws and bolts.

Today, modern machines create bil-lions of screws and bolts each year. Thesemachines are essentially automatic turretlathes with one or more spindles; eachcomponent of the multiple-tool holder isbrought into action on a pivot as the man-ufacturing steps proceed: turning andthreading bar stock, forming the head,and cutting off the screw or bolt. Specialscrews can be manufactured by usingchasers or comb tools controlled by mas-ter screws.

Few simple ideas have had so great animpact on the development of human civ-ilization.

KEVIN J. ANDERSON

FOR FURTHER READING, consult Nuts andBolts of the Past: A History of AmericanTechnology, 1776-1860, by David FreemanHawke, Harper & Row, 1988; and TheDiscoverers by Daniel J. Boorstin, RandomHouse, 1983.

68 MRS BULLETIN/FEBRUARY 1994

https://www.cambridge.org/core/terms. https://doi.org/10.1557/S088376940003935XDownloaded from https://www.cambridge.org/core. IP address: 65.21.228.167, on 20 Mar 2022 at 13:12:42, subject to the Cambridge Core terms of use, available at

VMt MRS ExhibitBooth No. 611,613

HANDBOOKOF

CRYSTAL GROWTHedited by D.T.J. Hurle

The Handbook is, by far, the most comprehensive compendium on crystal growth ever published and,for the first time, authoritatively documents in one publication the fundamentals of the subject.

It is designed to become the definitive work on the science of crystal growth and to remain so for a very long time.

Volume 1

FUNDAMENTALSPart A - Thermodynamics andKineticsVolume 1 - Fundamentals addressesthe underlying scientific principlesrelevant to all the techniques of crystalgrowth. Following a Foreword byProfessor Sir Charles Frank and anhistorical introduction, the first partcontains eight chapters devoted tothermodynamic, kinetic andcrystallographic aspects includingcomputer simulation by moleculardynamics and Monte Carlo methods.

Part B - Transport Processes andStabilityThe second part, comprising a furtherseven chapters, is devoted to bulktransport effects and the influence oftransport-limited growth on the stabilityof both isolated growth forms (such asthe dendrite) and arrays, and on thecooperative effects which lead topattern formation. All the presentationsare superbly authoritative.

1993 xiv + 1218 pages (in 2 parts)Price: US$ 388.50 / Dfl. 680.00Subscr. price: US$ 330.00/ Dfl. 578.00ISBN 0-444-88908-6

552s

Volume 2

BULK CRYSTAL GROWTHPart A - Basic TechniquesPart A reviews the principal techniquesused for bulk single crystal growth frommelt, solution and vapour and forindustrial mass crystallisation, startingin chapter 1, with Nature's techniques.The growth of synthetic crystals of awide range of materials for researchand commercial use is covered indepth, with emphasis placed on thosetechniques which are of currentimportance; techniques of onlyhistorical interest have not beenincluded.

Part B - Growth MechanismsPart B covers the basic mechanismsand dynamics of melt and solutiongrowth covering segregation, meltconvection, stress in the coolingcrystal, polyphase solidification, growthin gels, spherulitic crystallisation andthe numerical modelling of Bridgmanand Czochralski growth processes.

1994 xviii + 1316 pages (in 2 parts)US$ 397.00/Dfl. 695.00Subscr. price US$ 337.00/ Dfl. 590.00ISBN 0-444-815546

ELSEVIERSCIENCES

Circle No. 6 on Reader Service Card.

Volume 3

THIN FILMS AND EPITAXYPart A - Basic TechniquesPart A reviews the basic techniques ofhalide, organometallic and molecularbeam epitaxy, liquid and solid phaseepitaxial techniques, rapid solidificationby pulsed laser annealing and laserablation of oxide thin films. The finalchapter is devoted to the growth ofdiamond films.

Part B - Growth MechanismsPart B covers the underlyingmechanisms and dynamics of epitaxialgrowth processes including nucleation,structural, kinetic and transport effects.In addition, refinements of some of thegrowth techniques described in Part Asuch as atomic layer,migrationenhanced and photo-assistedepitaxial processes are also described.

(to appear Fall 1994)ISBN 0-444-81556-2

Please ask for your descriptivebrochure with:

Elsevier Science B.V.Attn: Karien van der HarstP.O. Box 1031000 AC AmsterdamThe NetherlandsFax: +31 20 5862320

In the U.S.A. and Canada:

Elsevier Science Inc.Attn: Judy WeislogelP.O. Box 882Madison Square StationNew York 10159U.S.A.

https://www.cambridge.org/core/terms. https://doi.org/10.1557/S088376940003935XDownloaded from https://www.cambridge.org/core. IP address: 65.21.228.167, on 20 Mar 2022 at 13:12:42, subject to the Cambridge Core terms of use, available at