face and gage, drawing qualities, bond adhesion, and sag test.
As the steel is received, enough sheets are checked to determine if they are free from damage — that is, dings, scratches, etc. At the same time, the sheets are checked for gage. A record showing average gage, weights and esti
mated weight of each shipment is kept.
Representative samples then are selected and sent to our control laboratories for testing.
On all difficult drawing jobs, sam
ples are tested before acceptance for three physical properties. Tests include the cup test on testing machine to deter
mine ductility, rockwell hardness tests to determine surface hardness, and elonga
tion on test machine to determine elas
ticity. Over the years, limits have been determined from the results of these three tests that tell, without setting the dies, whether or not the material "’ill do the job for which it was purchased.
While suppliers are kept informed of the physical limits of our tests, we instruct them to make steel for the application.
In any case, where tests indicate the steel
81 ?
82
L eft, below— A typical sag test set-up, used to compare various steel samples. Results are used in grading suppliers
\
Directly below— The bio-photometer determines if men responsible for checking color are deficient in vitamin.. A, a condition w hich prevents
accurate visual analysis o f color variation
j5 questionable, it is not rejected until nrst set our dies and actually try out
“te material.
Follovving the regular physical test, a
®iple is sent to the laboratory where 1 ls given a thickness controlled ground
“ at of enamel. It is then tested in a eSular impact tester, after which the Percentage of steel with enamel still ad- enng is determined. Limits can be S0 decisions can be made Iil er the steel is satisfactory for bond
"esion. The height of drop of a
5-^bruary 26, 1945
pound weight varies according to the thickness of the steel.
Sag tests are conducted in line with t e n t a t i v e specifications established through the Porcelain Enameling Insti
tute. The samples tested are 1 x 12 inches, placed on a nickel chromium rack
%-inch in diameter with 10-inch centers.
The entire unit is placed in the center of a furnace which has been heated to 1600 degrees (plus or minus 5 degrees) Fahr. The samples remain in this tem
perature for 10 minutes, after which they
L e ft Numerous tests are performed cm finished samples. (1 ) Enam el hardness test for vitreous finishes; (2 ) Im pact resistivity test for vitreous enamel; (3 ) Cross bend test for vitreous enamel; ( 4 ) Test for adhesion
of enamel to steel
are removed and allowed to cool to room temperature. Sag from horizontal is then measured. The results obtained are of a comparison type and are used in grad
ing our suppliers.
In general, the regular feeder section inspection is the foreman’s responsibility.
In the machine shop an inspector with a toolmaker’s training checks the first and last piece; that is, when the die set
ter sets the die in the press and runs the first piece, he obtains the release before operating the press. The last piece is also checked against the first piece and if found defective, it is the responsibility of the foreman and the operator to in
spect the entire lot in detail. This puts ( Please turn to Page 118)
^hom 2500 p o u n d ,
. . . - - ' i / j
ekruary 26. 1945
Steel in transit from strip mill to tube p la n t is p re v e n te d from shifting by careful b a n d in g a n d p a c k in g . C om pensation fo r variatio n s in sk elp thickness, a n a lysis a n d condition is e ffe c te d b y ch a n gin g s p e e d o f strip going through mill ra th e r than a lterin g p ressu re o f o xy g e n an d a ce ty le n e , electronic con trol w id e ly e m p lo y e d . Lo o p in g system p ro v id e s fo r joining
o f co il en d s w ithout interrupting w eld in g opera tio n
o y j. N . U U H A N N O N Plant M a n a g e r S p i c e r M f g . C o r p .
P o t t st o w n , P a . a n d
F. J Ü D E L S O H N Engineering Supervisor A i r R e d u c t io n S o l e s C o .
P h i l a d e l p h i a
HARD-PRESSED to meet urgent Ar- my-Navy demands for high-quality welded power-transmission tubing for air
craft, tanks, trucks, and other mobile units, Spicer Mfg. Corp., Pottstown, Pa., tamed to the unprecedented expedient of planning and building an entire plant (or production of such tubing. Already in operation for over a year, the brand- new streamlined tube mill—probably the wodd’s first plant annex erected exclu
sively for tube welding— is turning out many miles of badly needed tubing on two large continuous units and one small unit. Twenty-four hours a day, seven
Fig. 1— Engineering and produc
tion personnel w ho planned the welding mill; seated left to right:
C. M. Shaner, production super
intendent; J. N . Bohannon, plant manager; C. H. Burdan, foreman tubing department; R. Hoel, chief ins/rector. Standing left to right:
B. M. Sm ith, machine and tool en
gineer; M. P. Allen, production manager; R. Teitlebaum , metallur
gist; C. Bracewell, chief draftsman;
. H. W alker, tim e study engineer
days a week, finished propeller shafts roll off the production line.
Welded tubing is especially suited to use in parts which must rotate at high speeds without whipping, and support heavy loads without buckling. For auto
motive shafts and similar uses, high speeds require accurate balancing in the tubing; out-of-balance creates whipping.
Therefore welded tubing which utilizes flat strip in which uniform thickness is maintained, is generally desirable, espe
cially for high-speed drives.
The new plant is designed to incor
porate the most advantageous and
up-to-Fig. 3— Strip from compensator system is guided into first vertical breakdown rolls which impart a
shallow U-shape
Fig. 4— Coil in th e guide stand is supported on leather-faced rollers.
Strip passes over the straightening
date features of welded tubing manu
facture everywhere—including several new company developments.
The building is large enough to house all of the forming, welding, and testing machinery without crowding and still leave sufficient storage space and room for expansion—46,125 square feet of floor space in all, enough for three times present production. A high ceiling and special ventilating features guarantee proper ventilation without any sort of draft. The entire building is as nearly moisture-proof as possible to prevent rust-
( Please turn to Page 102)
table and is then trim m ed for butt-w elding
Fig. 5— Control house for oxygen and acetylene. Both gases are piped to regulators alongside indi
vidual w elding and forming units
Fig. 2— Juxtaposed ends of strip are clamped together and butt- welded to provide tw o coil lengths
for the mill
Extensive use of solders
SINCE the most acceptable substitutes for tin-lead solders, particularly those containing cadmium, have been on the antimony, bismuth, arsenic, and silver;
but changes in soldering technique have been far more effective in compensating for the lower tin content.
Solders: Before World War II, soft solders in this country were of rather simple composition, consisting mainly of lead and tin with occasional additions of antimony in amounts of 2 per cent or less. Cadmium-base solders and tin- antimony solders were used for special applications. Since war started, however, many variations have been developed.
Present low-tin solders generally have higher melting points and longer freezing ranges, requiring a different technique in use than with the high tin-lead solders.
The compositions and freezing ranges of some of the more common solders are given in Table I. Emergency specifica
tions of the American Society for Testing Materials covering this general field are given in Table IV. Just as the normal tin-lead solders have different properties suiting them for various applications, so also do the low-tin and tin-free emer
gency solders have specific properties that fit them for particular uses.
Lead-Silver Solders: The greatest con
servation of tin in solders can be made, silver, however, solderability is markedly increased and the melting range is low greater assurance of solderability, but for the sake of economy the tendency has been to drop silver to 2 per cent, or even 1 perjt.Cehty if tests showed such change to produce the desired joint properties.
Probably the most important commer
cial substitution of silver-lead for high