THE ART OF DROP-FORGING
"Who made the law that men should die in meadows,
Who spake the word that blood should splash in lanes,
Who gave it forth that gardens should be boneyards,
Who spread the hills with flesh and blood and brains?
Who made the law?"
Seldom, perhaps, does a plain question receive so plain an answer as
that coming direct from so qualified an authority as Prince Lichnowsky,
former German Ambassador to the Court of St. James, who, in the course
of his confessions, which he entitles "My Mission to London," says,
simply and quite candidly, "We insisted on war." Herr Harden, too,
writing in _Die Zukunft_ in November, 1914, even if a trifle more
impetuous, more brutal, is none the less frankly outspoken: "Let
us drop," he protests, "our miserable attempts to excuse Germany's
action.... Not against our will, nor as a nation taken by surprise, did
we hurl ourselves into this gigantic venture. We willed it ... it is
Germany that strikes."
And having fixed the blame, the moral responsibility, equally
plain-sailing is it to establish the blood-stained guilt; evidence of
it fairly "stinks" no matter where one turns to look; from emperor to
general, from statesman to author, exudes the _credo_ of Teuton Kultur;
no more lurid interpretation of which can perhaps be found than in
the words of Herr Hartmann, a native of Berlin, who, after serving as
an artillery officer, turned his attention to matters literary, being
_inter alia_ a believer in evolutionary progress. "The enemy country,"
he insists, "should not be spared the devastation, the profound
misery engendered by war. The burden should be and remain crushing.
Immediately war is declared, terrorism becomes a primary essential
absolutely imperative from the military standpoint."
There is, however, all the difference in the world between the
transitive and intransitive senses of a verb, and if we take the verb
to "terrorise" as an apposite example, the transition from the former
sense to the latter, _i.e._ from terrorising to being terrorised, is
apt to be very noticeable, indeed unpleasant. Granted that British and
Boche ideas on the particular subject in no way harmonise, the British
method ultimately of diffusing an unlimited supply of high explosive
over the Boche lines nevertheless had the desired effect of "putting
the fear of God" into the right individuals, at the right time, and
in the right place. One employs the prefix "ultimately" of necessity,
for obviously the diffusion of metal prior to the latter phases of the
war was, except upon certain occasions which were few and far between,
anything but unlimited; it was, in fact, at one particular period of
the war of so limited a nature as to infuse into the mind of the late
Lord Kitchener a fear of stalemate on the Western Front, sufficient
to impel his acquiescence in that diversion, so ardently advocated by
"amateur strategists" but destined to prove nothing but a prodigious
and costly failure, to wit the Dardanelles expedition.
Thanks, however, to the staying powers of the workers, to the
inflexible will to win by which they were animated throughout, the
crushing superiority, early attributable to the enemy, gradually became
less and less apparent; in fact, after hanging for a time evenly in the
balance, the scales indeed tipped the other way, eventually dipping to
such an extent in Entente favour as to become a source, at first of no
little astonishment, then of concern, to the German "Imperial Staff
of Supermen." General Ludendorff in his memoirs ["My War Memories,"
1914-1918, Vols. I. & II., Hutchinson & Co. 39s.] makes no attempt to
conceal his surprise, if not indeed his dismay, at the awkward trend
of events. "Whereas we had hitherto been able to conduct our great war
of defence" (_sic_), so he writes (cp. page 240, Vol. I.), "by that
best means of waging war--the offensive--we were now (by the autumn
of 1916) reduced to a policy of pure defence.... The equipment of
the Entente armies with war material had been carried out on a scale
hitherto unknown"; the boot was plainly on the other leg, for (cp. page
242, Vol. I.) "the Battle of the Somme showed us every day how great
was the advantage of the enemy in this respect." Evidently the one
and only Ludendorff no longer had any doubt in his own mind as to the
"writing on the wall," its lettering was clear, its meaning ominous
and unmistakable; from the German point of view things were going from
bad to worse; "At the beginning of June (1917)," he continues (cp.
pages 428, 429, Vol. II.), "the straightening of this (the Wytschaete)
salient really ushered in the great Flanders battle.... The heights of
Wytschaete and Messines had been the site of active mine warfare," and
ultimately, "The moral effect of the explosions was simply staggering."
Again in August of the same year (cp. page 480, Vol. II.), "In spite
of all the concrete protection, they (the Germans) seemed more or
less powerless under the enormous weight of the enemy's artillery,"
and "With the opening of the fifth act of the great drama in Flanders
on the 22nd October (cp. page 491, Vol. II.) enormous masses of
ammunition, such as the human mind had never imagined before the war,
were hurled upon the bodies of men who passed a miserable existence
scattered about in mud-filled shell-holes. The horror of the shell-hole
area of Verdun was surpassed. It was no longer life at all. It was mere
unspeakable suffering. And through this world of mud the attackers
dragged themselves, slowly, but steadily, and in dense masses.... Rifle
and machine-gun jammed with mud. Man fought against man, and only too
often the mass was successful." The long and the short of it, in a
word, amounted just to this, the Hun had "insisted on war," and now he
was "getting it in the neck."
Napoleon is credited with the opinion that "Good infantry is beyond
question the soul of an army, but"--and no doubt it is a big "but,"
as will be seen from the way in which he goes on to qualify his
opinion--"but if it has to fight any considerable time against a very
superior artillery, it becomes demoralised and is destroyed." In
order to determine how completely has been justified this view in the
light of modern warfare, one has but to turn again for the space of
a brief instant to the memoirs of Ludendorff--Ludendorff who "lived
only for the war," whose life had been one of work for his "Country,
the Emperor, and the Army,"--the note of bitter chagrin cannot be
mistaken. "Against the weight of the enemy's material" (cp. page 542,
Vol. II.) "the troops no longer displayed their old stubbornness of
defence; they thought with horror of fresh defensive battles."
Such in effect, then, was the net result obtained by an intense
application by the Entente Armies of "a very superior artillery,"
rendered possible by the untiring efforts of the workers, by the plant
at their disposal, and by the brains which created and controlled.
There can be no parallel in the whole history of international warfare
to compare even approximately with the abnormally severe conditions
imposed upon pieces of artillery during the present-day conflict,
conditions which perforce had a considerable bearing not only on the
design of integral parts, but also on the nature of the material
employed in the manufacture of those parts.
One of the most remarkable features in this latter respect was the
frequent necessity to substitute a steel forging where a casting
had previously been considered "the last word," and if we take as a
convenient and typical example so ordinary and obvious a part as is
the trunnion bracket of a howitzer gun, this will afford a very good
idea of the difficulties which present themselves when in compliance
with Government specifications recourse must needs be had to the
hammer as opposed to the mould, difficulties, in fact, which could
only be overcome by the employment of what is commonly known as the
drop-hammer.
If proof positive were ever needed in support of the argument that
bread may be found again which has been cast upon the waters, not
merely many days previously, but weeks, months, and years, the
money sunk by the London and North-Western Railway Company in their
drop-hammer plant at Crewe affords the proof; for, thanks to the
existence of this plant, thanks too to the invaluable experience gained
during the years following upon its installation, not only were the
staff engaged in operating the hammers able, figuratively speaking
to forge right ahead, literally speaking to commence drop-forging,
directly they were required to do so, those sorely needed "sinews
of war" which a pre-war generation of feeble-gutted politicians had
neglected to provide against the evil day of reckoning, but Mr. Cooke
found himself in the unique position of being able to undertake
forgings which were admittedly altogether beyond the scope of firms
whose speciality was none other than that of drop-forging, and of which
the Directors of Army Ordnance were well-nigh at their wits' end to
secure an adequate, if indeed any, supply at all.
[Illustration: LIMBER HOOKS: ILLUSTRATING DUPLEX METHOD OF DROP
FORGING.]
[Illustration: TRUNNION BRACKETS FOR 6-INCH HOWITZER GUN, DROP FORGING.
[_To face p. 145._]
Significant, and sufficiently expressive of appreciation, if not of
actual open-mouthed astonishment, is the following letter received by
Mr. Cooke from a well-known Government Department: "I have to thank you
and your staff on behalf of the Ministry of Munitions for the excellent
work you have done in producing stampings of trunnion brackets. The
part in question has hitherto been considered almost impossible to
produce as a stamping, and the work you have now produced will add
materially to the efficiency of this important equipment. I should be
glad if this letter could be brought to the notice of your subordinate
staff who carried out the work." From the same source, but at a
later date, came this further little note of esteem: "Your previous
production of the trunnion bracket has been the means of great saving
to the State, and it is with great satisfaction that I am able to again
congratulate your operating staff on a renewed success in your stamping
department."
For the benefit of those uninitiated in the fascinating art of
drop-stamping or forging, it may not be considered superfluous if a
brief explanation is given of the principles embodied in the system,
and for this purpose one cannot do better than read and inwardly digest
the opinion which has been advanced by Mr. Brett, founder of the Brett
Patent Lifter Company of Coventry and inventor and patentee of the
hammer in question.[8] "Having in mind," he says, "that the plastic or
forgeable condition of wrought-iron or steel, when obtained, cannot be
retained beyond limited periods, especially in the case of articles
having thin or light parts, when its duration is very brief," it rests
with the engineer "to provide for the forger a suitable form of power
for actuating the dies or tools by means of which properly-formed
forgings may be obtained." Further, "this power must be capable
of instantaneous application," similar in all essentials to that
produced by the smith "with hand hammer or sledge; that is to say, a
perfectly elastic blow of sufficient force to produce an immediate and
substantial effect upon the material."
[8] [Extract from Paper read by Mr. Brett before the Engineering
Conference of the Institution of Civil Engineers, June, 1899, and
published in _Engineering_, June 30th, 1899.]
The secret of providing this particular form of power lies obviously in
the Brett drop-hammer, and in it alone, and the method evolved consists
in the raising of the hammer-head or "tup" between a pair of parallel
and vertical guides to a certain height by pressure of steam exerted
within an overhead cylinder; no sooner is this pressure shut off than
the "tup" automatically descends by force of gravity, delivering
the hammer-blow simply with the weight of its falling mass, and
rebounding, is lifted once again by re-admission of the steam into the
cylinder, preparatory to the next descent and the delivery of a further
succession of blows. It is largely thanks to a flexible cord and strap
connection between the "tup" and the piston and piston-arm working in
the overhead cylinder that the blow delivered is not only "smashing"
in effect, but altogether resilient, in direct contrast to that of a
steam-hammer, the blow of which is more in the nature of a dull thud or
a rigid push.
It is obvious, as Mr. Brett goes on to point out, that "the vibrations
from blows of sufficient power and elasticity (or sharpness) to cause
metal at a moderate heat to flow completely into the impressions of
the dies," _i.e._ the blocks in which are cut the impression of the
required forging, "and to make clean work, are calculated to destroy
any rigidly built machine." Hence the fact, which a cursory glance at
the hammers cannot fail to establish, that nothing has been overlooked
or omitted in regard to detail in design, "not any of the parts
affected by the work are bolted together or in any wise rigidly fixed;
the guides are held and the dies set in position by flexible means,
_i.e._ the lower end of each guide fits into a recess into the base
block, the top end passes up into a socket having sufficient clearance
for wood packing, the wood is intended to absorb the vibrations which
pass up the guide-rod."
The plant at Crewe as originally installed in 1899, by the late Mr.
F. W. Webb, of "compound" fame, consisted merely of one "battery"
of hammers, comprising two 7-cwt. stamping hammers, and one 5-cwt.
"dummying" or roughing-out hammer, and although the production of small
stampings for signal apparatus etc., was all that was attempted in
those early days, little by little the variety of work became extended,
embracing, ere long, locomotive parts of small dimensions such as
brake-rod ends, joints, levers, handles, etc., with the result that
as time went on and as ever-increasing experience with confidence
proportionate accrued to the staff employed, jobs of still greater
variety were successfully tackled.
[Illustration: THE 4-TON DROP HAMMER. [_To face p. 148._]
There are at the present time no fewer than eight "batteries" of
hammers "in action" at Crewe, the actual number of hammers being
twenty-two, and some idea of the extent of the progress made may be
gauged by the fact that the yearly tonnage output of stampings rose
from 400 tons in 1902 to 1450 tons in 1917, a time when the plant
was largely devoted to the manufacture of a regular "pot-pourri" of
essential munitions of war.
It was primarily due to the urgent demands of the Ministry of Munitions
for a supply of trunnion brackets, which, cast in steel, were proving
defective, and which had "been considered almost impossible to produce
as stampings," that Mr. Cooke determined on the course of laying down
an additional hammer, having a "tup" weighing no less than four solid
tons.
Complete with gas-producers, stationary boiler, gas reheating furnaces
and cranes, the estimated cost of installation was £15,100. The hammer
foundations necessitated a cavity being dug to a depth of 18 feet,
which was filled in with 321 tons of granite and cement, and upon which
repose the base blocks, cast in steel and weighing a further 58 tons.
This veritable monster commenced operations during the critical days of
the early spring of 1918, and no sooner had the seemingly impossible
been shown to be possible and the successful production of trunnion
brackets had become "the means of great saving to the State," than
there followed in quick succession orders for other and indispensable
gun-mountings, such as front stiffening bands, upper sight brackets,
trunnion-seatings, etc., etc.
"Peace," as we know, "hath her victories no less renowned than war,"
and no sooner was the mantle of munition manufacture laid aside than
efforts were once again concentrated on the production of locomotive
parts, the whole of the Walschaerte valve gear appertaining to Mr.
Cooke's latest express passenger engines, the well-known "Claughton"
class, being now produced under the 4-ton drop-hammer.
Standing in the immediate vicinity of the hammers ranged in convenient
positions in regard to gas furnaces, "dummying" hammers, and "finning"
or "trimming" presses, the average and intelligent visitor never
fails to be impressed as he witnesses the operations in process, and
notes the lightning rapidity with which, as if by the magic of a
magician's wand, a bar or billet of gleaming, glistening whiteness
is battered and transformed into some previously determined shape,
curiously contorted, maybe, with corners, elbows, and recesses, ere
the dazzling brilliance dims and fades, paling imperceptibly to lemon
tint and orange hue, till finally the blood-red flush of angry sunset
supervenes, and nothing remains but that the finished stamping should
be trimmed and laid aside, gradually to resume the slate-grey cool of
dawn.
How natural it all seems, how almost childish in simplicity! And yet
on second thoughts, how come these various shapes and forms, these
corners, elbows, and recesses, these well-nigh perfect surfaces,
pure and clean, free from blow-holes, dirt and scale? True, we know
the crashing and resilient hammer blow is there, and then a little
closer acquaintance with, or examination of, the hammer is all that is
necessary, for this will reveal the fact that it is the effect of the
blow on a pair of "dies," one of which is held rigidly in the "tup,"
the other on the base-block, that causes the metal at a moderate heat
to "flow" completely into the impressions which are in the dies, and
which ensure the fashioning of the article required.
To cut an impression in a pair of "dies," to put the "dies" in the
hammer, and to obtain a forging, sounds the simplest thing in the
world. Yet in actual practice, so many are the problems which present
themselves, so diverse are the obstacles to be overcome, that a volume
might be written on the craft of the die-designer, whose efforts
result in work of so great beauty, and whose "dies" must be capable
of withstanding the punishment, and of enduring the wear, which the
crashing blows of the "tup" inflict and are ever striving to induce.
What is the most suitable metal to employ in the manufacture of
the dies? and having found that metal, what is the best process of
hardening? are two of the first questions to be decided. Will the
forgeman bestow every care in the use of his "dies," and will he set
them accurately in the hammer? Much depends on answers being in the
affirmative. Whether to cast the impressions in the die-blocks, or to
machine them out _in toto_, and if machined out how to do so, are
further knotty propositions. Correct taper on the walls of holes,
bosses, and recesses; egress for imprisoned air; size of bar or billet
to be stamped, after making suitable allowance for contraction and
waste; control of waste metal or "fin"; method of duplex stamping. Such
are the more potent problems with which the die-designer is faced, and
whilst lack of insight will assuredly foreshadow failure, ability to
grasp their import cannot fail to spell success. Obviously the mind
of the die-designer must ever be planning, plotting, scheming how
best to make his metal "flow;" and concentrated attention, and study
extending over years, are the only means of approaching that degree of
perfection which in the art of drop-stamping, as in all other branches
of mechanical science, the engineer is ever striving to attain.
Incredible, then, that public money should have been continuously
lavished on that legion of "inexpert experts," more than one of which
worthless clan, gloriously clad in khaki, was known to claim admission
to Crewe Works for the avowed purpose of "satisfying himself" (_sic_)
that the engineers of the London and North-Western Railway locomotive
department were "making the best use of the drop-hammer plant."
Even if we generously assume that these gentlemen were the exception
rather than the rule, such glaring exhibitions of ignorance and
impudence combined could not but tend to bring out in full relief
the anomalies which, although possibly unavoidable, existed none the
less in a system of universal and compulsory service; and with every
apology to the talented soldier poet, author of the initial stanza
introducing this chapter, one may be pardoned if, in conclusion, one
feels constrained to put this further little conundrum:--
"Who made the law that nincompoops and asses
Should 'cushy' jobs, immune from risk, infest,
While other 'blokes,' undaunted--aye in masses,--
Naught asking, bit the dust, and so--'went west'?
Who made the law?"