1 3 4 T H E J O U R N A L O F I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y V o l. n , No. 2 T h e in itia l cru sh in g of th e s tra w b o a rd b y th e M u llen
clam p cau scs th e co rru g atio n s to fla tte n in to irreg u lar lu m ps as sho w n in F ig . 2. T h ese a lte rn a te rid g es and h ollow s w eak en th e fa ce s of th e b o ard to such an e x te n t th a t th e M u llen v a lu e s are o ften less th a n th o se sho w n upon te s tin g th e tw o fa cin g s w ith th e stra w b o a rd e n tire ly absen t. M o re o ve r, th e fa cin gs o ften b u rst se p a ra te ly , w hich p re v e n ts a tru e te s t of th e com bin ed b o ard an d o ften g iv e s a va lu e o n ly s lig h tly h igh er th a n th a t of a single fa cin g . T a b le I is a ty p ic a l in stan ce o f th e effe ct on M u llen v a lu e s cau se d b y tig h te n in g th e clam p o v er a sam p le o f co rru g ate d board.
Taui.i; I
T y p ic a l M u llen re su lts on c o rru g a te d b o a rd a n d on th e c o m p o n e n ts of th e sam e b o ard . C lam p b ro u g h t dow n tig h t in each case.
B oard Sam p le N o. 100.
Av e r a g e
S a m p l e M u l l e n R e s u l t s L bs.
C o m plete c o rru g a te d b o a rd (tw o fac
ings a n d c o rru g a te d s tra w b o a rd ). 1 7 5 -1 6 9 -1 6 0 -1 7 6 170 T w o facings a n d flat s tra w b o a r d 2 5 5 -2 1 1 -2 3 7 —210 228 T w o facings o n ly ... 1 8 0 -1 8 7 -2 0 4 -1 9 2 191
F ro m th e sta n d p o in t of th e M u llen te s t, th e re fo re , th e co rru g ate d stru c tu re o ften a p p e ars to b e a source of w eakness, in s te a d of a d d itio n a l stre n g th . T h e new m ach in e w as d evelo p e d in an a tte m p t to re m e d y th ese irreg u larities, b y te s tin g a finish ed b o ard in such a w a y th a t th e tru ssed s tru c tu re is n ot first d estro yed .
Fi g. 2
In order to do th is, th e W e b b m ach in e w a s d esigned to te s t s e p a ra te ly th e co m p o n en t p a rts o f a co rru g ate d board . Since th is is im p o ssible w ith th e M u llen te ster, it w as n ecessary to a p p ro ach th e p ro b lem from a new angle. T h is w as acco m p lish e d b y u sin g a steel p lu n ger, o n e-te n th of an inch in d iam e ter, as a p u n c tu rin g m eans, in p lace of th e ru b b e r M u llen d iap h ra g m , w h ich is s lig h tly o v er one inch in d iam e ter.
B y using a p lu n ge r of th is size, it is. p o ssible to a t t a c k th e sm all p o rtio n of fa cin g ly in g b e tw e e n th e tip s of th e co rru g atio n s, th u s a v o id in g th e s tra w and th e ad h e sive used in glu e in g th ese tip s to th e fa cin g .
In order to p re v e n t th e fa cin g fro m b en d in g u n der th e pressure of th e p lu n ge r, it is n e ce ssa ry to h a v e a firm b earin g b en e ath th e te s t area. I t is also d esir
able to be a b le to te st th e co m p o n en ts o f a box, w ith o u t first te a rin g up th e box. T h ese o b je c ts are a cco m p lish ed b y m eans of a fin ger-sh aped a tta c h m e n t w h ich fits sn u g ly in to th e c o rru g atio n im m e d ia te ly u n der th e sp o t to be te sted . T h is steel finger is a fixed p a r t of th e m achin e an d h as a circu lar “ w e ll” d rilled in it, s lig h tly large r th a n th e p lu n ger. W h en th e p u n c tu re o ccurs, th e plu n ger, to g e th e r w ith th e p ap er to rn loose b y th e p u n ctu re , is receive d b y th is w ell.
W h en te stin g flat sh eets, such as o rd in a ry p aper,
“ solid fib e r” b oard , e tc., th e u p p er p a rt o f th e m ach in e
Fi g. 3
T h is m eth o d of m easu rem en t is b ase d u po n th e a p p lic a tio n of H o o k e ’s la w of e la s tic ity — th a t th e d e
flectio n of a steel sp rin g is a c c u r a te ly p ro p o rtio n a l to th e stress a p p lied , p ro v id e d th a t th e e la stic lim it of th e sp rin g is n o t reach ed .
In order to a v o id in tro d u c in g a n ew set of u n its to th e tra d e , th e dial on th e n ew te ste r w as first c a li
b ra te d a g a in st th e M u llen te ste r. T h is w as done as a c c u r a te ly as p o ssible, u sin g so -called p e rfe ct p ap e r.
T h is la t te r w as a h igh q u a lity d ra w in g p a p e r h a v in g as sm o o th an d ev en a te x tu re as it w as p o ssible to find, an d h a d a b u rstin g stre n g th o f a p p ro x im a te ly 100 lbs.
can be slipp ed in to a low er le v e l in th e b ed p la te , th u s co n cealin g th e finger. F igs. 3 an d 4 illu s tra te th ese tw o p o sition s.
In a p p e ara n ce, th e W eb b te ste r is ro u g h ly th e size and sh ap e of an o rd in a ry d esk te le p h o n e. P ressu re is a p p lie d to th e p lu n ge r b y m eans of a h elical steel sp rin g su rro u n d in g th e u p p er p a rt or “ b a rre l” of th e plu n ge r.
T h is sp rin g ’is com pressed b y tu rn in g a sm all h a n d w h eel, th e fo rce b ein g tra n s m itte d b y su ita b le g earin g.
A d ial, a c tu a te d b y a ra c k an d pin ion, m easu res th e d eflectio n of th e sp rin g and is c a lib ra te d to rea d in p o u n d s per sq u are inch.
F e b ., 1919 T H E J O U R N A L O F I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y p er sq. in .1 A fte r lo c a tin g th is p o in t as e x a c tly as
po ssible on th e new m ach in e, th e dial w as th e n d ivid ed in to eq u al u n its fro m o to 600 lbs. per sq. in ., based on th e deflection of th e sp rin g. T h is is th e usual m ethod of c a lib ra tin g h elical sprin gs, such as sp rin g balan ces, d ra w b ar sp rin gs on railro ad d y n a m o m e te r cars, etc.
I t is possible to c a lib ra te th e n ew m achin e w ith th e M u llen in th is w a y , b ecau se it has been fo u n d th a t th e M u llen ¿ester w ill g iv e reliab le resu lts w hen used on fla t sh eets of w ell-m ad e, e v e n -te x tu re d p aper. A s w ill be show n la te r, h o w e ver, th e M u llen resu lts te n d to b ecom e e rra tic w hen th e coarser te x tu re of fiber fa cin g s and bo ard s are en co u n tere d .
F i g . 4
In te stin g a fla t, sin gle sh eet on th e W eb b m achine, th e sam ple is p lace d on th e b e d p la te b etw e en th e well and th e p lu n ger an d held firm ly w ith th e clam p . T h is clam p is o p erate d b y a sp rin g and cam and resu lts in a co n stan t p ressu re.2
A fte r secu ring th e sam p le in th is m anner, th e d ial is set a t zero, and b y tu rn in g th e sm all h an d w h eel th e sp rin g and p lu n ge r are m o ved d o w n w ard inside th e o u te r barrel as a u n it u n til th e plu n ger to u ch e s th e
1 K euffel a n d E s s e r’s “ A risto n " B ra n d , c alip erin g 0.0135 in.
2 I t has been found in th e case of th e M u llen m achine t h a t th e resu lts car. be varied b y using differen t clain p pressures on th e v ariab le pressure c la m p used on t h a t ’m achine.
sam p le. U p to th is po in t th e re h as been no d eflec
tio n in th e sp rin g, so th a t th e dial does n o t begin registerin g u n til th e p lu n ge r to u ch e s th e sam ple.
A t th is p o in t, th e p lu n g e r’s m otio n ceases and co n tin u e d tu rn in g of th e h a n d w h e el com m en ces to b u ild up com pression in th e sp rin g, w h ich com pression is registered on th e d ial in te rm s of po u nd s per sq u are inch. T h is is co n tin u ed u n til th e p a p e r fa ils, w hen th e p lu n ge r su d d e n ly b u rsts th ro u g h . T h e h a n d on th e dial a u to m a tic a lly sto p s a t th e in s ta n t o f ru p tu re , since th e dial is a d ju ste d to sh o w o n ly th e com pression in th e sp ring.
F o r te stin g th e co m p lete c o rru g a te d b o ard , th e u pp er p a rt of th e in stru m e n t is slip p ed in to th e h igh er le v e l in th e b ed p la te, th u s a llo w in g th e steel finger to be exp osed (F ig. 4). T h is finger is sh a p e d to fit e x a c tly in to one c o rru g atio n of th e stra w b o a rd . B y th is m eans, each fa cin g m u st be te s te d se p a ra te ly . T h e m ach in e is so d esigned as to m a k e it im p o ssible to p u n ctu re th e en tire b o a rd a t o n ce .1
T h e c a p a c ity of th e te s te r is a b o u t 600 lbs. p er sq.
in ., and th e sp rin g is su fficie n tly o v ersize to h a v e a large fa c to r of sa fe ty . D u e to th is, th e d eflectio n of th e sprin g is a t all tim es w ith in its e la stic lim it. D u r ing th e p a st tw e lv e m on th s, b etw e en 10,000 and 12,000 p u n ctu re s h a v e been m ade w ith one m ach in e, and no v a ria tio n h as been n o ted in th e a ctio n of th e sp rin g.
S am p les used in th e se te sts h a v e ran ge d fro m tissu e p ap er to solid fiber b o ard te s tin g s lig h tly o v er 500 lbs.
per sq. in. T e s ts m ade one y e a r a g o ,o n th e “ p e rfe ct p a p e r” used for ca lib ra tio n h a v e ju s t b een re p e ate d , using th e sam e sam ple. T h e resu lts agreed w ith th e form er m easu rem en ts w ith in 2.0 per cen t, w h ich v a r i
a tio n is no larger th a n th e a v e ra g e v a ria tio n b etw e en in d iv id u a l p u n ctu re s.
I t h as been fo u n d th a t th e rea d in g s on th e M u llen te ste r on fiber b o ard s can be v a rie d to a co n sid erable e x te n t b y v a r y in g th e sp eed of th e h a n d w h e el w hich b u ild s up th e h y d ro s ta tic pressure. T a b le I I show s som e ty p ic a l M u llen resu lts o b ta in e d on th e sam e cor
ru g a te d b o ard b y u sin g v a r y in g w h eel speeds.
Ta b l e I I — Mu l l e n Te s t s w i t h Va r y i n g Wh e e l Sp e e d s Sa m p l e No. I I S 1 7 5
H an d w h eel A verage of
Speed 10 P u n c tu re s M ax im u m M in im u m
R , P . M . L bs. L b s. L bs.
30 181.1 195 147
120 19 2 .0 209 165
In order to a v o id th is sou rce of erro r in th e n ew m ach in e, th e ge arin g is a rran ge d in su ch a m ann er th a t th e lim its of speed a t w h ich th e sm all w h eel can be tu rn e d b y h a n d m a k e a h a rd ly p e rc e p tib le v a r ia tio n in th e speed a t w h ich th e p lu n ge r descends.
1 In a d d itio n to th e re g u la r m odel, th e W ebb te s te r is m ad e in a p o ck et size. T h is sty le resem bles a n o rd in a ry m icro m eter. T h e o p e ra tin g p rin ciple is sim ilar to t h a t of th e la rg e r m ach in e, n a m e ly , a helical steel sp rin g a c tu a tin g a steel p lunger. In th is case th e sp rin g is com pressed d irectly b y tu rn in g a k n u rled sleeve on th e b a rre l a n d th e v alu es a re re a d upon th is b a rre l as in th e case of a m ic ro m e te r. T h e p lu n g er a n d su p p o rtin g finger a re id e n tic al w ith th o se on th e la rg e r m achine.
T h is sm aller in s tru m e n t h as b een c a lib ra te d a g a in st th e la rg e r one, a n d w hile n o t so sen sitiv e is v alu ab le a s a p re lim in a ry , o r m in im u m te ste r, since i t will q u ick ly in d ic a te w h e th e r a box is a b o v e o r below its specifica
tio n . A lo aded box c a n be te ste d b y c u ttin g a sm all s lit in one of th e flaps a n d in se rtin g th e steel finger. W ith th is in s tru m e n t, th e box can be te sted in situ w ith o u t d is tu rb in g its c o n te n ts. T h is m odel is co m p a ct a n d inexpensive an d co uld be su pplied to ra ilro ad in sp ecto rs, p u rc h a sin g ag en ts, etc.
136 T H E J O U R N A L O F I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y V o l. 1 1 , N o. 2
M u llen resu lts th a n th e sam p les w hose fibers w ere m ore e v e n ly d istrib u te d ¡11 all d irectio n s. A high M u l
len te s t in th is con n ection is n o t a tru e in d icatio n of stre n g th , b ecau se, o w in g to th e m eth od of its m an u fa ctu re , a load ed co rru g ate d b ox h a s, w ith v e ry few excep tio n s, eig h t of its tw e lv e edges e x e rtin g tension across th e m achin e d ire ctio n fibers.
F e b ., 1919 T H E J O U R N A L O F I N D U S T R I A L
F i c 5— T y p i c a l B r e a k M a d s b y M u l l B n T e s t e r o n 1 0 0 f .n . F i b e r F a c i n g . A c t u a l S i z e
In order to m ake a go o d sh ip p in g con tain er, th e fibers m a k in g up th e stru c tu re of a box should be
“ fe lte d ” in all d irectio n s. T h e a b o v e te sts show th a t to do th is, it is n ecessary to increase th e p ro p o rtio n of th e cross-direction fibers. T h e o n ly w a y to do th is w ith o u t in creasin g th e th ick n e s s of th e p a p e r is to d ecrease th e excess of fibers in th e m achin e d irectio n.
T h e re su lt is a lo w erin g o f th e m ach in e-d irectio n te n sile stre n g th , b u t a raisin g of th e cross-direction tensile stre n gth . C o m p ariso n of th e b re ak s m ade b y th e tw o m achin es (F igs. 5 and 6) sh o w s th a t th e te n d e n c y of th e ro u n d m e tallic W eb b p lu n ge r is to ta k e in to a c co u n t all of th e fibers regard le ss of th e ir d irectio n.
T h e s e v a ria tio n s in th e ten sile stre n g th o f a fiber b o ard (d ep en din g upon th e d ire ctio n in w h ich th e te st is m ade) are em p h asize d b y th e use of a w ed ge-sh ap ed p lu n ger in p la ce of th e ro u n d p lu n ge r m en tion ed ab o ve.
T h is p lu n ge r has a ro u n d ed r e c ta n g u la r fa ce 0.10 in.
lon g b y 0.07854 in. w ide an d g iv e s th e sam e readin gs as th e rou nd p lu n ge r a n d th e M u llen te ste r on the
“ p e rfe ct p a p e r ” d escrib ed a b o v e . W h en su b stitu te d , h o w e ver, fo r th e rou nd p lu n ge r a n d ap p lied to fiber b oard s, fa b rics, etc. (w h ich h a v e v a ria tio n s in ten sile stre n g th dep en din g u po n th e d ire ctio n of th e te s t), th e a ctio n of th is w ed ge p lu n ge r is v e r y m arked . T h u s, w hen th e p lu n ge r is a p p lie d p a rallel to th e m achin e d irectio n, a m uch lo w er rea d in g is registered th a n w hen ap p lied a t r ig h t a n gles to th is d ire ctio n . T h is a ctio n is exp lain e d b y th e fa c t th a t in th e first in
sta n ce th e p lu n g e r’s te n d e n c y is to cu t o n ly th e w eaker tra n sv e rs e fibers (or w oof th re a d s), w h ile in th e second in stan ce th e stro n g, m ach in e-flirectio n fibers (or w arp th read s) are cu t.
T h is w ed ge plu n ger, th e re fo re , offers a re a d y m eans o f d ete rm in in g th e m inim u m stre n g th of a sam ple w h en it is n ot desirable to m ake a c tu a l ten sile tests.
A N D E N G I N E E R I N G Ç H E M I S ' TRY
F i o . 6— T Y r ic A L B r h a k M a d e b y W e b » T u s t e r o n 1 0 0 I ,n . F i b e r F a c i n g X 12
C O N C L U S IO N S
T h e W eb b te ste r and its v a rio u s a tta ch m e n ts h a v e been c a re fu lly in v e stig a te d in th is la b o r a to ry . In m akin g th ese te sts, several h u n d red sam p les of cor
ru g a te d b o ard , represen tin g p r a c tic a lly a ll th e v a rie tie s kn o w n to th e trad e , h a ve been co lle cted . T h e s e sa m ples w ere all stu d ie d an d th e d a ta ta b u la te d as fo l
low s:
1— R a w m a terial used (as re v e a le d b y th e m icro
scope).
2— P h y s ic a l p ro p erties, such as b en d in g q u a lity , th ick n ess, etc.
3— D egree o f w ater-p ro o fin g, if a n y .
4— D egree to w hich fibers h a d been “ fe lte d ” or
“ fo rm e d ,” as in d ica te d b y ten sile stre n g th and elo n g a tio n in m achine an d cross directio ns.
5— A p p e a ra n ce (im p u rities, “ scre en in g s,” e tc .).
6— C e rtified stren g th . 7— A c tu a l M u llen te sts of
(а) C o m p o n e n ts b efore assem b lin g.
(б) F in ish e d b oard.
8— A c tu a l W eb b tests.
P re v io u s to th e in v e n tio n of th e n ew te ste r, th is la b o ra to ry h a d d e v o te d n e a rly a y e a r to a tte m p tin g to a d a p t th e M u llen m ach in e to te s tin g co rru g ate d fiber p ro d u cts. N o p ra c tic a l m eth o d w as fo u n d for doin g th is.
S U M M A R Y
I— T h e W eb b te s te r is c o rre c tly d esig n ed and co n stru cte d from a m ech an ical sta n d p o in t.
I I — T h e W eb b te s te r g iv e s a m ore a cc u ra te m eas
u rem en t of th e v a lu e of p ap e r p ro d u cts (e sp e cially co r
ru g a te d fiber board ) th a n is p o ssible b y th e use of th e M u llen te ster.
i3§ T H E J O U R N A L O F I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol. n , No.
I I I — In a d d itio n to th e p u n ctu re te s t, th e W eb b m ach in e m a y be used for ten sile te sts, elo n ga tio n te sts, an d com p ressio n te sts. T h e ten sile te s t, e sp e cia lly w h en “ across th e g r a in ,” is an im p o rta n t in d e x of th e v a lu e o f a fiber box as a sh ip p in g co n tain er. T h is
“ across th e g ra in ” v a lu e m a y also be fo u n d m ore q u ic k ly b y a p u n ctu re te s t, using th e “ w e d g e ” p lu n ger.
IV — T h e p o ck et-size m odel m akes it po ssible to te st co rru g a te d boxes u n der con d itio n s w h ich are im p ossible a t present.
V — B esid es co rru g ate d p ro d u cts, th e W eb b m achine c a n be used for te stin g m a n y o th er fla t su b sta n ces, such as p ap e r, c ard b o ard , “ solid fib er” b o ard s, gu m m ed ta p e , fa b rics, etc.
Me l l o n In s t i t u t e o p In d u s t r i a l Re s e a r c h Un i v e r s i t y o p Pi t t s b u r g h, Pi t t s b u r g h, Pa.
LEAD IN PHARMACEUTICAL ZINC OXIDE
B y W . D . C o l l i n s a n d W . F . C l a r k e R eceiv ed J u ly 25, 1918
Soon a fte r th e o u tb re a k of th e p rese n t w ar, d ifficu lty w as exp erie n ced in o b ta in in g p h a rm a c e u tic a l zin c o x id e w h ich w o u ld m eet th e req u irem e n ts of th e United States Pharm acopoeia. W h en th e m a tte r w as first consid ered, th e s ta te m e n t w as m ade th a t zin c oxid e of th e req u ired p u r ity w as v e r y e a s y to ob tain . I t w as ev en sta te d t h a t m a terial b o u g h t for use as a p ig m en t in p a in tin g m ig h t b e m ore n e a rly fre e from le a d th a n a certain sam p le of p h a rm a ce u tica l zin c o xid e w h ich co n tain ed a b o u t 0.2 per cen t of lead.
M r. C . L . B la c k o f th e P h ila d e lp h ia S ta tio n of th e B u re a u of C h e m is try re p o rte d in M a y 19 17 th a t a n a ly sis of such sam ples o f zin c oxide as cou ld be p ro cu re d on th e m a rk e t a t th a t tim e in d ica te d th a t p r a c tic a lly all th e zin c o xid e o b ta in a b le co n tain ed m ore lea d th a n w as p e rm itte d b y th e U. S. P . te st.
Som e m a n u fa ctu re rs a t th is tim e sta te d on th e lab els th a t th e zin c oxide sold b y th e m c o n tain ed h e a v y m etals s lig h tly in excess of th e U. S . P . lim it. P ro f.
C . H. L a W a ll1 p u b lish ed an a rticle c allin g a tte n tio n to th is m a tte r and m ade th e su g g estio n th a t all sam p les o f p h arm ace u tica l zin c oxide shduld be te ste d for lead.
In order to learn w h eth er it w o u ld be possible to o b ta in zin c o xid e re a so n a b ly free fro m lead, sam p les w ere o b ta in e d on th e m a rk et an d from m a n u fa ctu re rs, an d th e qu estion w as ta k e n up w ith
th e U . S. G eo lo gical S u rv e y and w ith m a n u fa ctu re rs of zin c oxide. I t w as learn ed fro m M r. C . E . Sieben- th a l of th e U . S. G eo lo gical S u rv e y th a t one co m p a n y p ro d u cin g zin c in th e U n ite d S ta te s ow n ed a m ine w h ich c o n tain ed no lea d m inerals and , th erefo re, sh o u ld be able to p rod u ce zin c oxide free fro m lead . I t w o u ld seem p ro b ab le t h a t zin c o xid e m ad e fro m e le c tr o ly tic zin c should be free fro m lead . I t w as learn ed fro m m a n u fa ctu re rs th a t zin c oxid e w as b ein g m ade a cco rd in g to b o th o f th e se p rin cip les, and th a t th e p ro d u c ts co n tain ed m uch less lea d th a n th e a m o u n t
th e U . S. G eo lo gical S u rv e y and w ith m a n u fa ctu re rs of zin c oxide. I t w as learn ed fro m M r. C . E . Sieben- th a l of th e U . S. G eo lo gical S u rv e y th a t one co m p a n y p ro d u cin g zin c in th e U n ite d S ta te s ow n ed a m ine w h ich c o n tain ed no lea d m inerals and , th erefo re, sh o u ld be able to p rod u ce zin c oxide free fro m lead . I t w o u ld seem p ro b ab le t h a t zin c o xid e m ad e fro m e le c tr o ly tic zin c should be free fro m lead . I t w as learn ed fro m m a n u fa ctu re rs th a t zin c oxid e w as b ein g m ade a cco rd in g to b o th o f th e se p rin cip les, and th a t th e p ro d u c ts co n tain ed m uch less lea d th a n th e a m o u n t