PRODUCTION CONFERENCE

SESSION V

THE GAS TURBINE AND THEPRODUCTION ENGINEERby W. A. Sales, O.B.E.

Following a commercial apprenticeship in precision engineering, Mr. Salesjoined the design staff of the Royal Aircraft Factory (now the R.A.E.) in1915. He was transferred to Air Ministry H.Q. in 1930, where he wasconcerned zvith aero-engine research and development. In 1936, he wasappointed Technical Controller of the aero-engine shadow industry and sincethen has directed his energies mainly to aircraft production problems.

Mr. Sales became Assistant Director of Engine Production in 1939, DeputyDirector in 1941, and' Director in 1945. In 1951 he was asked to form a newdepartment in the Ministry to sponsor, encourage and initiate specialdevelopments in the aircraft production sphere, which resulted in his presentappointment as Director of Aircraft Production Development.

Mr. W. A. Sales

AS you will appreciate it is not feasible in sucha short Paper as this to deal effectively with

such a wide subject. A thorough review of a widerange of subjects as the following, and a degreeof comparison with production of the earlier pistonengines, would also be necessary to do it real justice :

1. Experience in fabrication of all the newmaterials, e.g., forging, stamping, rolling,stretch forming, welding, brazing, machining,etc.

2. Cost of new materials, yield in weight offinished parts as against ingot, forging orstamping.

3. Capital cost questions, such as new typemachine tool plant, setting up of precisioncasting foundries, etc.

4. The development of automatic welding, inspec-tion and other equipment.

5. Comparison of the number and complexity ofparts per engine—piston and turbine.

6. Cost and weight per horse power equivalents.7. Development as basis for solution of new

production problems.8. Difference in manufacturing problems between

single and double spool compressor type engines,prop jets and plain jets; single and twin turbinedesigns, etc.

9. Strategic supply questions.Accordingly, I propose to deal with some of the

broader issues which, I think, will be of interest andwhich should in the time available indicate thenature of the problems which the production engineerhas had to tackle as a result of the change-over toturbine engines.

Before dealing with these points, I would like toemphasise that, in my view, the difficulties encoun-tered in manufacture of a new prime mover or itemof equipment are good for the engineering industry,in that they serve most effectively to stimulateproduction development. They may also foster theintroduction of new lines of manufacture, thus im-proving trade, both home and export; generallyuplift the standard of engineering and, at the sametime, put new techniques and processes at thedisposal of trades not normally influenced by newproblems to the same extent as the aero-engineindustry.

Stages in Change-over from ReciprocatingEngines to Gas TurbinesThis change-over, at least so far as this country

is concerned, you will remember, occurred in twostages; firstly, the centrifugal compressor engine, andsecondly, the axial flow type.

Although the first of these engines introduced arange of new and difficult materials (concerningwhich Dr. Sutton is speaking) which led, inturn, to new problems of fabrication, e.g., turbinediscs and blades, compressor rotors, diffuser guidevanes, fairly complex fuel and control equipment,etc.; in the main it was regarded as a relativelysimple engine to manufacture.

The change-over to the axial flow compressor typeengine, however, with its multiplicity of compressorblades to close manufacturing tolerances, compressordiscs, fairly complex casings and main shafts, etc.,disillusioned us greatly on the simplicity question.Tn fact, as Sir John Boothman once said when

514

addressing gas turbine engineers, " in his wildestdreams he had not imagined it possible for themto evolve in such a short period of time, such acomplex progeny from such very simple stock ".

Machine Tool Plant and Tooling ChangesWhilst the more universal type of machine tool,

such as automatics, capstans, drills, millers andgrinders were not greatly affected by the change-over from piston engines to centrifugal turbines, somevery expensive adjustments were necessary in thefield of large profiling mills such as those used oncompressor rotors (particularly the single-sidedcompressor having curved blades), boring mills,profiling lathes and broaching machines. At present-day prices, one million pounds buys on an averageabout 250 machine tools, hence it will be seen thatseveral million pounds of new capital can quite easilybe expended in re-equipping a factory of relativelymodest output.

Re-equipping for war, should it come quickly aftersuch an engine change, would naturally be a vastundertaking in that the effectiveness of plant avail-able in other engineering works, such as motorvehicle factories, would be correspondingly reduced.

Unfortunately, this problem of heavy expenditureon new machine tool plant is aggravated by the factthat the machine tool man is often caught unawaresby the change in demand. The first few off a newtype of machine (the best available at the time) areoften ill-suited to the task and these early machineshave to be replaced by improved types a little later.New designs have to be prepared and developed inthe light of experience gained. For example, oncomplex profiling operations it may well becomenecessary, in achieving the degree of accuracyrequired, to introduce three separate tracer controls,each operating in its particular plane of movement,in place of the one or possibly two available instandard machine tools of the day.

One of the most difficult new problems inmachining confronting the engine manufacturer wasthat of turbine blade production. As will be ap-preciated, very rugged machines were necessary towithstand the heavy and relatively slow speed cuttingof Nimonic and considerable development work hadto be put into this problem before satisfactory resultswere achieved. Several methods of machining bladeaerofoils were thoroughly explored, e.g., shaping,single point cam turning, profile milling, and eachof these methods is still favoured in some degree byblade manufacturers, but multi-spindle versions ofthe original machines are today regarded as essentialto keep down the labour cost.

Since the path of the cutter on most blade profilersis controlled by a compound master cam, mucheffort has been put into development of plant usedin the manufacture of these cams, e.g., the " lofted "spaced sections of prototypes used in the profilingand subsequent contour grinding of the hardenedproduction cams. A machine has been developedrecently which is capable of contouring a compoundcam from solid stock, tracing direct from drawings

of a scaled-up series of profiles; removing the needfor manufacture of the individual " lofted " sections.

The machining of leading and trailing edgeradii, and smooth blending of aerofoil sections intoblade shrouds and root platforms presented manydifficulties which had to be overcome to avoid;expensive handwork. The former problem has moreor less been solved satisfactorily, in spite of the factthat the edges to be radiused are curved and atthe same time tapered (in other words, spiral coned),either by a shaving operation using a non-rotatingradius cutter, swivelably mounted, or abrasive handmachining. The latter, however, still presents somedifficulty, since even the smallest step in the machinedface between the platform radius and the aerofoil isunacceptable on inspection. Hand blending is stilllargely employed.

Root Radiusing MachinesSeveral new root platform radiusing machines are

under development, the best of which will be eithercontour controlled from the machined aerofoil, or,alternatively, will be capable of producing the rootplatform radius at the same time as the aerofoil. Aswill be appreciated, the problem is accentuated insome degree by the expansion angle at the blade rootplatform and the shape of the platform itself, whichis virtually a small section of a large diameter coneformed by the base of the blading from the inletto the delivery end of the compressor.

The machining of fir-tree blade roots in difficultmaterial to the high degree of accuracy demandedhas similarly presented a problem, and even todaysome argument exists as to whether it is better tomill, form grind or broach these roots. Fir-treeslots in the turbine discs must obviously be broachedirrespective of whether they are square to the faceof the disc or at an angle thereto.

Very robust broaching machines with heavyslideways are, of course, essential, and a lot ofdevelopment has gone into the machines achievingpresent-day results. By the same token, considerableeffort has been put into perfecting broach manu-facture, and in this regard considerable credit is dueto the aero-engine manufacturers themselves, as wellas the tool manufacturers, in developing high pre-cision broaches capable of withstanding heavy dutycutting whilst giving long life at the required degreeof accuracy.

Twin-wheel Form GrindersSpecial twin-wheel form grinders have been

developed, both here and in America, for producingfir-tree roots from the solid. This operation, inwhich side thrust on the formed grinding wheel issomewhat uneven by virtue of the fir-tree shape, isan arduous duty for wheel bearings and much creditis due to the machine tool designers concerned inevolving machines which give the present degree ofaccuracy. Having regard to the complex shape ofsome fir-tree root designs, I would say—as a personalopinion—that there is a lot to be said for puttingthis high accuracy contour grinding into broaches,

515

which in turn are capable of producing severalhundred blade roots within drawing limits betweenregrinds, rather than to use it for each individualblade.

Some axial flow compressor blades are pivot-mounted on close fitting pins and it will beappreciated that this design presented a variety ofproblems,- such as accurate spacing of holes in thecompressor discs to maintain the requisite degreeof balance for such a high speed assembly; holeswhich are not only machined to one- or two-tenthsof a thou. accuracy on diameter, but which are alsoone hundred per cent, alignable between the twoflanges of the discs. The fine boring equipmentdeveloped for this work by the engine manufacturers(using surplus wartime precision high speed boringheads) is without doubt a credit to all concerned.

Turbine and compressor discs, together with thewide range of large diameter flanged rings commonto gas turbine engines generally, similarly presenteda problem to the machine shop, in that boring millsor big lathes equipped with contour turning equip-ment capable of machining two sides of a turbinedisc at one operation, had to be evolved.

This contour machining operation on steel com-pressor discs has been eased to a great extent recentlyby the introduction of hot flow forming of disccontours. Similarly, by the introduction of extrudedsections for the series of large rings referred to, aconsiderable number of man hours has been savedin machining. These new developments are referredto elsewhere in the Paper.

Reference has already been made to the problemof machining the tough heat resisting materials usedin turbines, e.g., Nimonics, stainless steel, H. R.Crown Max., etc., and the difficulty of introducingmulti-spindle profilers in consequence of the irregu-larity in wear of individual cutters. Considerabledevelopment work has gone into the evolution ofmuch improved cutters, not only in the high speedsteel class, but also the ground-tooth tungsten carbidevariety and the high speed spindles and bearingsrequired to drive the latter.

Whilst a fair amount of experience had alreadybeen gained in America on the grinding of tungstencarbide cutters and burrs from shaped blanks, nofacilities existed in this country when turbine pro-duction expansion was first mooted. This positionhas since been rectified and the cutters are nowavailable as a standard supply on the market.

Tool CoolingAll forms of tool cooling have been thoroughly

investigated with the object of increasing the cuttingspeeds and feeds, of these difficult materials,particularly for single point turning where thecutting edge is constantly under load.

Probably the most important development in thisfield is CO2 cooling. The Americans spent manythousands of dollars in an effort to make a successof this method, but eventually it was dropped infavour of high pressure oil and vapour cooling usingsoluble oils, etc.

With the valuable help of the Distillers Companywe have pursued this development to the point whereit looks by far the most promising of all the variousmethods at our disposal.

Tool life in some cases on the more difficultmaterials has been increased to as many as twenty-five times normal; moreover—and this I regard asmore important—we have discovered in consequenceof being able to maintain a sharp cutting edge atthese higher speeds and feeds, that the " finish"obtainable at speeds up to ten times above normalis far superior to that obtained at the present slowspeeds and feeds with conventional cooling.

No attempt whatsoever is made to cool the chip.The tool tip is cooled internally by expansion ofliquid CO2 fed through a fine capillary within ahollow unhardened steel tool shank. Exhausting ofthe expanded gas takes place immediately below thecarbide tool tip and spills on to the workpiece.

In view of the much increased life of the cuttingedge it has been possible to reduce considerably thethickness of tungsten carbide tips; this, in additionto improving still further cooling at the cutting edge,has resulted in an appreciable reduction in cost oftools—allowing for the extra work of producing ahollow tool shank with its capillary. Another majorasset is shop cleanliness, the process being dry. Theelimination of centrifuging equipment normallyemployed to separate coolants and lubricants fromthe chips before bagging for despatch, also representsa big economy.

Whilst it has not been feasible to demonstrate alarge range of production developments on theM.O.S. Stand at the "Production for Plenty"Exhibition, we considered it of sufficient importanceto single out CO2 cooling for exhibition; accordingly,you will be able to see the process in operationshowing the stage to which it has already beendeveloped.

It is by no means regarded as a final developmentat this stage; none the less, some thirty-eight setsof equipment have been put to use in aircraft firmson difficult machining operations, not only with theidea of getting wider experience, but also foralleviating day-to-day manufacturing problems.

The full economics of the process have not yetbeen worked out, but broadly speaking the gain inproduction time is such that one lathe out of three,together with its operator, can be dispensed withwhere tough materials are concerned, and this ratiomay well be advanced in the relatively near futureto two out of four machines.

The same principle of cooling will, of course,eventually be employed in milling, grinding, drillingand high speed boring operations; the best methodof applying it in these cases yet having to bedetermined.

A central supply can be arranged for CO2 shouldit be desired to segregate a batch of machines intoone shop for the machining of tough materials;alternatively, individual supply units can beemployed.

516

Die ManufactureSince precision stamping was the accepted method

of producing all axial flow compressor blades whenthis design was first introduced, it quickly becameapparent that unless some improvement could beeffected in die manufacture, the skilled tool roomcapacity available to us would be totally inadequatein the event of a threatened emergency expansion;moreover, it would not be a feasible proposition toexpand this type of capacity at a rate commensuratewith the rest of production, an output of severalmillion blades per month being visualised.

This problem had to be tackled on a wide front.The first and obvious thing to do, whilst workingon longer term ideas which it was hoped wouldvirtually reduce the problem of die making to aproduction job, was to develop quickly mechanicalaids to existing methods, thereby reducing the skilledlabour element and further to introduce improveddie steels which would give longer life betweenre-cuts.

A number of mechanical aids were developedquickly and put into use :

1. High speed flexible abrader discs in a varietyof sizes for use with flex spindle drives, in whichthe abrasive discs were supplied in pack formwith stick-a-sole adhesive on the back so thata worn disc could be rapidly discarded andreplaced by a new one.

2. High speed oscillating hand tools taking avariety of small shaped files for hand finishingon a variety of contours following machineprofiling and before hardening and polishing.

3. Ground-tooth tungsten carbide burrs in avariety of shapes and sizes for general contour-ing and fine finishing, also for simplifying there-sinking of hardened dies.

Long term development resulted, amongst otherthings, in the application of spark erosion machining.Early experiments showed that by using a suitablyshaped brass electrode it was possible to re-sink theblade root portion of hardened dies (probably themost difficult part of re-sinking) in a matter of afew hours, with virtually no expenditure of skilledlabour. Encouraged by these early results, tests wereextended to re-cutting of the whole die surface andfor this purpose electrodes were " struck" from anew die accurate to form.

We now find that it is feasible to " re-cut" aworn die completely by this method in the hardenedcondition and to follow this up by a mere polishingoperation.

The inference from this, of course, is that newdies can be hobbed, hardened, spark erosionmachined and polished, which virtually reduces bladedie manufacture to our original objective of aproduction job.. The many thousands of hours ofskilled labour thus saved, to say the least, is mostencouraging.

Stamping and ForgingThere has been much controversy amongst

production engineers as to the relative merits of

precision stamping of blades (with attendant rela-tively short die life) and coarser limit stampings(attended by longer die life) machined all over, andeven today this problem has not been thoroughlyresolved, largely because a number of new featureshave been introduced into blade aerofoil shapes, allof which affect either one method or the other.

There is obviously something to be said for bothprocesses, particularly if one considers the range ofmaterials still employed for compressor blades, e.g.,light alloy, aluminium bronze and stainless steel.

Die life in the case of light alloy is obviously verymuch higher than in the case of stainless steel,therefore there is a lot to be said for precisionstamping in this case; the same may be said in alesser degree for aluminium bronze. Nonetheless,the process involves very close control of the followingif twist and other errors are to be avoided :

1. Temperature of the metal "uses" immediatelyprior to stamping.

2. Method and time of handling between thefurnace and the dies.

3. Temperature of die blocks and the extent (inarea) of contact between the thin blade sectionsand the die before the actual stampingoperation.

4. The avoidance of scale by correct furnacecontrol.

Added to this is the detailed inspection problembetween each stamping operation on precisionstamped blades; in which extreme care has to betaken to detect surface imperfections, which, ofcourse, can be disastrous on such highly stressedcomponents.

The problem of training an army of skilledinspectors for this job to deal with rapid expansionin an emergency cannot be glossed over lightly, andthis lends some tone to the alternative method ofusing coarser stampings with attendant longer dielife, where a minimum of .012"/-015" of metal isremoved to eliminate any surface imperfections thatmay be present; so long as a fast, accurate andcheap method of removing this metal is available.

The American Ex-Cell-O method of machining,in which milling and subsequent grinding of theblade aerofoils are controlled by an accurately madecompound cam, certainly produces an excellent bladewith fully contoured leading and trailing edges andat the same time ensures good blending betweenthe root platform radius and the aerofoil, but thesecams are very expensive to produce; moreover, thedeveloped area of blade aerofoils with their ever-increasing length represent a fairly formidablemachining problem. This, having regard to theflimsy section of blades, the speeds and feeds per-missible for the material employed, etc., obviouslygoverns the rate of output and, consequently, theprice.

The Jameson controlled abrasive band contouringmachine, in which one side of the aerofoil (excludingleading and trailing edge radii) can be machined atone bite in the case of blades up to approximately

517

4" long, and in two bites, plus a traversing operationin the case of longer blades, is a time-saver ascompared with single point attack in contouringof an aerofoil.

This method, basically requiring stampings withsome 12/15 thou. to remove, depends very .largelyon the accuracy of these stampings in respect totwist of the aerofoil if the quickest and cheapestresults are to be achieved. Indications are that byusing the Garrington method of high frequencyheating of blade " uses" to a timed cycle, withthermostatic acceptance or rejection of " uses"immediately prior to automatic feeding into the dies,controlled die temperatures, etc., such blade stamp-ings will be practically free from twist errors.

The Jameson process, however (as at presentemployed), leaves the root radius blending andplatform machining to be done as a separate opera-tion as well as the leading and trailing edge radii,(though the latter, of course, is already accepted asa standard machining requirement even on precisionstamped blades).

There is a possibility that, as a result of develop-ment work now proceeding, root radiusing andplatform machining can eventually be done at thesame time as the aerofoil. If this improvement canbe effected, then the Jameson process may well proveto be one of the best and cheapest methods of bladeaerofoil machining.

Depending on the grit size employed in theabrasive belts there is the question of fine scratchmarks across the aerofoil which, from a fatigue failurepoint of view, must be closely watched. However,developments are in hand to determine whether itis better to use a fine grit belt as at present withno other form of " finishing ", or a coarser grit beltwith its faster cutting propensities, finishing theaerofoil surfaces together with the root radius bythe liquid abrasion process referred to later, whichnot only gives the requisite degree of finish, but alsoimproves resistance to fatigue failure. Testspecimens thus treated seem to indicate that whensubjected to natural frequency vibration to the pointof destruction, three or four times the life ofuntreated parts can be achieved.

Briefly then, we are still in doubt as to the bestmethod of manufacturing compressor blades and, inconsequence, a variety of processes continues to beused both here and in America. The problem will,we hope, eventually be resolved, but a number ofincidental factors, probably not foreseeable at thisstage, such as thinner aerofoils with higher twistand other special features, can obviously affect thesituation.

The foregoing remarks are related primarily tocompressor blade manufacture. In the main, whereturbine blades are concerned, because of the natureof the materials being handled, it seems safer tomachine approximately .080" off the aerofoils, ratherthan chance the disastrous effects of cold working—which is a risk in precision stamping. In any case,the number of blades in the turbine is small whencompared with the compressor.

Since it is difficult to detect overheating ofmaterial in finished components the importance ofclose temperature control in the heating cycle whenstamping, referred to above in connection withblades, even for parts such as gears, etc., cannotbe over-stressed. Only a small percentage of theparts going through the shops at any particular timemay be affected if the risk of over-heating is present.In consequence, it is most difficult to ascertain thedegree to which total production may have beenundermined should failure of finished parts occurin actual use.

Other improvements in forging and stampingtechniques are undergoing development at thepresent time—there is still ample room for improve-ment—and it is anticipated that these, if successful,will not only cheapen stampings, but will alsointroduce further guarantees against risks of failureof finished parts.

Brazing and Hard SolderingContinuous rolled section stainless steel blading,

which is now available to the designer, cut off tolength and suitably twisted, offers a relatively cheapform of construction for compressor stator blading;notably for short life engines, where cheapness isof paramount importance.

In this form of construction inner and outersupport rings (suitably pierced to take the ends ofthe blade section) are used, hard soldering or brazingbeing employed to secure the assembly.

Present-day techniques on brazing and hardsoldering need to be improved, however, before thisform of construction can be safely used—particularlyat the higher temperature end; hence, work is nowproceeding on :

1. the development of improved high temperaturebrazing;

2. suitable high temperature furnaces with neutralatmosphere to overcome the need for fluxes.

Deburring and FinishingEven in the case of piston engines it has been

estimated that some 15% of the total productionman hours was expended in the removal of burrs,sharp edges and machining marks—mostly handwork—and the development of mechanical deburringas a worthwhile process had not been vigorouslytackled until recently, i.e., until large scale removalof sharp edges in combustion equipment arose—components being subjected to both high temperatureand reverberatory loading.

It was felt that the " seashore" type of erosionnormally employed in barrelling was the best meansof accomplishing our objective, but whilst it waslogical to subject relatively small regular shapedparts to normal barrelling, irregular shaped com-ponents such as flame tubes could not be dealt within this manner.

However, by a more scientific application of theprocess, in which the peculiar shaped objects couldbe supported suitably within the barrel whilst beingsubjected to the normal abrasive action, it wasthought that good results could be obtained.

With the help of Rotofinish, Ltd., this problem

518

was tackled vigorously and our earlier surmise provedto be correct. Today, a considerable percentage ofthe hand work involved in the earlier stages hasbeen eliminated and the end result shows a con-sistency of finish not normally achievable by theold hand methods. The automaticity of the processalso eases inspection. One problem remained,however : irrespective of whether holes are drilledor punched in sheet metal or whether the edges ofsheet are sheared, there is usually a much biggerburr on one side than the other, and it is stillnecessary at the moment to remove the bigger burrroughly by hand before subjecting the parts to themechanical erosion process above referred to.

A different method of tackling this problem,applied on an experimental basis, has shown thatit is now feasible by mechanical means to removethe worst possible burr in a matter of two hoursor so and to produce a perfect radius in its place.

The next problem is to find the best and cheapestpossible way of applying this new development,whilst making the utmost use of existing equipment.

In the latter connection, the method first describedis, of course, applicable to a very wide range ofcomponents in addition to flame tubes, such ashighly stressed gears and other parts where, say,sharp edges at the ends of teeth require to beremoved.

If the problem of " finishing " is one of removingmachining marks, as opposed to burr removal, thenthe latest liquid abrasion process, in which the waterabrasive media is given its high velocity by centri-fugal slinging, can be used to good effect.

In addition to removing machining marks quickly,this process results in a mild shot peening effect onthe surfaces treated which, as stated earlier, isbeneficial from the fatigue failure standpoint.

Welding and Welded StructuresAs is well known, several forms of welding are

employed in gas turbine manufacture. Quite apartfrom the difficulty of training more skilled operativesin an emergency, hand methods can be somewhatof a menace, depending on the state of theoperator's liver, etc. Moreover, inspection of weldsis a difficult matter. Accordingly, considerableeffort has been put into the study and ultimateadoption of automatic welding equipment.

All the latest American techniques in this fieldwere closely studied and every effort made to getequivalent British equipment placed at the disposalof manufacturers to reduce the human element toa minimum.

Welds produced by these automatic methods,particularly those using inert gas shielded arcs,represent a big advance and such welds are capableof being worked to a very high degree in subsequentspinning or pressing operations. Even deep sectionspinning such as the syphon tube expansion jointon large diameter components is quite feasible andthe end result is thoroughly dependable.

Extrusion versus Centri-castReference should, I think, be made to the glass

lubricated die technique (which came from France)

by means of which hot extrusion of heat resistingmaterials such as Nimonic, H. R. Crown Max. andstainless is possible.

As you are aware, there are a large number andvariety of large diameter rings employed in turbineswhich were normally produced by machining fromheavy centri-cast tubes; a method which in largescale production would lock up many tons of highalloy steels—often involving strategic alloyingelements. Whilst this material problem wasalleviated to some extent by installing boring millsat the casting plant, to rough machine the ringsand to put the turnings back into the pot quickly,a great deal of metal was still machined off by theengine makers and sold as scrap.

Today, it is feasible to extrude these difficultmaterials in sections within .080" of finished sizeat approximately 15 feet per second, which can berolled into rings, flash butt welded and stretchformed to size before final machining, i educingmanufacturing costs by approximately 20%. Thedies used in this extrusion process are relatively easyand cheap to produce and there is an addedadvantage in that the material thus extruded hasforged properties.

This extrusion process is also of value when shortruns of a particular section normally produced byrolling are required and where the cost of setting-upthe rolls would not be justified.Casting Techniques

It is a well-known fact that investment or so-calledprecision casting (sometimes referred to as " LostWax") has played a very important part in thegas turbine, engine production field, having beenused extensively for the production of stator bladesof complex shapes, as well as for a range of otheritems which lend themselves to precision castings.

It has also been put to very wide use in thecommercial field; accordingly, the capacity createdoriginally to meet a special need has proved to beof great value to industry generally. A more recentdevelopment of this process which employs frozenmercury for patterns in place of wax or plastics,in conjunction with an improved investment tech-nique, renders it feasible to produce patterns of verycomplex shapes of fairly large dimensions in anumber of separate pieces which, on being broughtinto contact with each other, automatically weldaccurately together as a whole.

InspectionIn this field also the gas turbine has produced

a number of problems, not the least of which hasbeen in the inspection of blading. Several yearsback this particular problem was tackled mostvigorously, it being realised that some form ofautomatic inspection would be essential if thequantity of blades ultimately envisaged was to behandled effectively. It was also realised that ifweaknesses in tooling setups were not detectable inthe early stages of manufacture, with big scale pro-duction running into millions, considerable scrapwould be built up before corrective action was taken.

As a result of intensive development work, in

519

addition to the optical method by means of whichdeviations from true contour on blade aerofoils canbe seen on a screen at approximately 10 times fullscale, we now have equipment which is capable ofinspecting automatically 300 blades per hour,measuring at 28 points relative to the blade rootfixing at one setting. This equipment, developedby The Sigma Company employing coloured distilledwater height gauges, indicates clearly in front of ascreen the rate of tool wear in addition to the erraticresults emanating from setting up between different

operations, etc., so that tool setters can take earlycorrective action.

This development has in fact led to a position inwhich inspection of a large range of commercialwork, as well as gas turbine components, is virtuallymonitoring production, thus reducing scrap to aminimum.Acknowledgment

I would gratefully acknowledge the facilitiesprovided by the Ministry of Supply for thepresentation of this Paper and for their kindpermission to read it to you.

" It All Depends on Management " (continued fromThat is partly contributed to by our national habit

of promoting the expert to top level management,on the grounds that he is good at his own technique,has many years of service and is a good sound man." We cannot go wrong," it is said, " with So-and-so.He is a good sound man. He will be the next manfor director". Now, the good sound man is oftenthe strong, silent type, beloved of certain novelistsin English literature. Such people are frequentlystrong because they had to play many games intheir youth, and they are silent simply because theyhave nothing to say, neither of which is anyrecommendation for top level management. Broadlyspeaking, the functional expert tends to be anintrovert, knowing more and more within the narrowconfines of his subject and he is happy in so doing.He is like a horse put in blinkers so that he doesnot see or care about anything else.

Early Training Essential

It is, therefore, most important in finding andtraining people for management to spot themsufficiently early, so that they do not become tooexpert in any one field of the business. It is truethat most of them will have to climb up one of thetechnical ladders, such as finance or production, butdo not let them climb too far. When you havespotted a man as a person of real quality for toplevel management, take him out of a purelytechnical field and see that he gets a broader training.

General • Motors, the largest private enterpriseorganisation in the world, with a labour forceof about 250,000, have done this sort of thingfor years. They evaluate a promising youngman in the early or middle thirties and say:" Yes, he is good at this and this, but badat that". They then give him a job of minorresponsibility in a field in which he is not good,because in no better or quicker way can he find outhis weaknesses. Further, if he is to lose moneythrough the things which he is bad at, he loses itat a level which will not bring the whole businessdown. This is the catholic approach to generalmanagership that I advocate.

Finally, I want to tilt, not at your expertise setforth in this Exhibition, but at the expertise of thepsychologist, the economist and the philosopher, who

page 524)are invading the industrial field. Professor Macegave an instance of this with which I am going todisagree. He said: " If predictions are not entirelyout of order, the guess might be hazarded that thenext great phase of technological advance will beone in which human factors in the technologicalsituation are accorded the same scientific regard asare given to raw materials and machines; and whentechnologists begin to think in terms of the man-machine-materials unit."

That frightens me out of my life, because whentechnologists begin to tackle something the first thingthey do is to acquire a vocabulary which they canunderstand but nobody else can! Although Profes-sor Mace says that the scientific approach to thehuman factor is a prediction, it has, in fact, startedalready. A book has been recently published whichis a symposium of seven talks to the British Associa-tion last year by psychologists, philosophers andeconomists on the very important problem ofmanagement and the process of decision. I willquote from that book to illustrate my meaning. Itrefers to a book called " Liquidity and Uncertainty ",by Marschak, and this is what it says:

" The rationale of minimaxing the regret is notshewn; it is not clear that this policy has anyrelationship to the maximisation of profits, or of theutility of profits, over time."

I hope you are all with me !" If the ' minimax regret' is not a deduction from

postulates of rational behaviour, it might be anhypothesis concerning actual behaviour. But in thiscase I do not see that minimax regret is always abetter hypothesis than maximin complacency. It isparticularly difficult to understand the logic ofminimax regret in Marschak's second example. Ifthe firm will not know whether it has missed theboat or not, why should it plan to minimax themiss? "

This illustrates, I think, a development of theattack on management from, I will not say thescientific side, but from the academic side by thosewho use words but, happily, have never to followthem up with action. It is a perfect example ofmy contention that if you are skilled in an expertise,you must create a vocabulary so that nobody elsewill be able to understand you and, therefore, be ina position to criticise!

520