Plywood Spec 6V.3

8/3/2019 Plywood Spec 6V.3

1/27

6 V. 3. 'Iui\'. l1|-l:i.\oTE.-Ilre I)Lstitutio', .lesires to cdll dtte tiot to the Jtct tlktt titis SleciticotiotLis tnteuded to incl de tlrc techtical broi'isions neccssdr! -;or tlk suppl! o.i the u,1tcn,,lhcreit rt.ferred to, bttt tlots ,ot Prrtort to coutpisa all thc ,ccessor-r' prot.isro tts o.t n colttroct.

16ritish 5tnrrDnrDs 3nlrtitution.Sncllp.'rrtED b! nlrtal Gblrlel.FoiMEo tl{ I90l 15 THE ENotNEERrtlc S?ANDARos Cov!r:TEr.

lNcoBpoRATED lN l9l8 As rHE BrrtrsH ExcrNeenrNc SfaNoAsDs issocrArroN.

British Standard Spect.fiL'al ttt ior -litt'ra1t )[ateria].HIGH STRENGTH PLYWOOD FOR AIRCRAFT.

\orE :-This Specidcation details requrrements for trvo grades of pl1rr'ood, c.9.,(i) Grade -\, for 3'ply onll'. This grade is intended to be used onll' rvhere rt is necessart fordesign reasons, and for bent parts.(ii) Grade B for 3 ply other than tbat corered by Grade -\, and also for rnultiplr'.

Grade B rvill be supplied uoless otherrvise specified,

PaFt 1.-Species of Tlmben and Quality of Veneor..PaFt 2.-Co6stnuction ol Boends.Par"t 3.-GeneFat PFovisions applyinEl to atl Plywood.PaFt 4. -TestinE.

- PART 1... Species ol Timben and Quality o? VnF.1. specier ot Timbs'.. The species of tirrrber used in the construction of the pl;'r';oodshall be:-_ Birch fEuropeau, Ss'eet, Yellorv or Paper' lEastern and \\'estern) ], and Rock ]Iaplefor both grades of plvs'ood.. F,uropean Beech for Grade B pJ;'nood onl5'. This tiurber rDust oDlt be suppliedwith the concul'rence of the designing firru.

b. guatity 6r vcneF. (a) The veneers, *.hich rnay be rotary or slice cut, sbtll beapproved individually by the Inspector before a,sselnbly.i.yll.d irrcG :/,..-'ice \r'- net. Post -free,

I


2/27

(t,) 'l'lre grotvtlr nntl otltr:t t,lr:rr':tt,tt't isl,ics t'f tlttr vttttt'ttts slrrr,ll lttr ittCharactcristicsr Cradc Allirclr or Ma0lo .,nly

i\{[Iit 0f wi(lth rrot exceeding0'(l I inchn (lulit llot excee(ling (Lcertenl shewn by Fig. I.!

6 V. 3. ,lrrlr', i1l l:|.i I r ' ( ' { ) | ( I i I r r ( i ( ! rvil,lr tlrt foll,rl irrg trr,lrlc :

(;r^,le llllirch or Nl:rl,l0

As ( irirrl: r\(t) C,rrcs- r\s (irarlc A(2) lr,rccr. n (lrrit r{)t cx, ccttinA llrc (:\lcrI sll()Nlby lrig, 2 (rr itpl,roxirnle trluillL rrtl)rrie areirs irr [;tr:e r'crrrx:t s shlll orrly lre Dr,r'rrritttxlto trritrr:iclc whcr tlrc crtcht ol lhe (l{rtc irr orrc l:t|c isn()l gleirier thrur (llnt shervrt ir [iig. l, irn(l tll(' l':rt(:lltirt tlre other f;rr:e rircs not c\ccc(l (hlrt slcrvrr in liig. 2l)olc ext:ccdiog thr: o\lerrt shervrr irr lrig. I rtrrrlirrcgrrl:rr gr:tirr (s,ic (vii) bekrrv) sirrll rrrrt Irc lretrrrittc,lir tlrc sirr e lrlacc in any olle veoucrArlnritAdnrit

As (irtrlr '\(i) Splits( ii) l)ote

(iii) Stteak rliscolouratiorr(iv) Ingrown bark(Sec Fig. l0)

(v) Burr (Sce Fic. ll)

(t)(r) L'olc's. lirr ltl[:l."rt cs. ,\s (irirrle :\

ArlrrtitDxclu


3/27

). 266

Amendment No. I : JulY, 194'fto

6 V 3. High Srrengtb Plywood for AircraftCorrigendum3. I tcn \/-Burt.

he p- rt rvording in columns 2 and 3, Grade A and Grade Bor te ro be deleted, and io each column the follorvirrgbe .-ded r-" Adm,t nor exceeding the extent shorvn h1, 6gure 11."


4/27

(viii) Ilough cutting lixclu


5/27

6 V. 3. Julr'. 1!,13.PART 2.Constnuction of Boar.ds.3. l*embly of vneeF!. The follou'ing precautiol)s slull be ,rllscrtetl in it.sellrbiilrq

t.]r e leneels :-(a) L-nles.s otlierrt'ise sper:ified in the coutttct, the gr.atn 6f fhg 0uter' \-el)eel'i of 3-pl.\'shall rnn ptlallel to the leugth of rire boald, and thrrt of the cole sl:riil rrru rrt right ;trrde.th ereto.. ,.1b1 t-nless otherrlise specilieti iD tLre cr)ntract, the gr:riu of tdjaceuc leileels of urultil)1.\'shrr,ll cross at light au:.lles lhl.oughout the thicliDess of the boartl.

(c) Beech leneels shall not be ruised nith leneers of birch or locli rrrirple. lllirch rrurllock maple veneel s lltLr)' be utised).4. Edge doin. in venon., (a) Veueers tra)' contain edge joins. i.c.. joius r.urrniuipalallel to the grain rlitection, 'fhe uuurbel of such joins shnll be nt the'option of !lr,'lna,nufactufer.(b) The.joins shall be c:ompleted in tbe iudisiduai r-eneem befole rssernbly of t[eveueers into boards.(c) AII joiuted veneers sbali be approred individualll bv the Inspectcil before asserul)h.td) -{.ll joins shall be squar.e cut.(e) -\.ll joins in cole veneers shall be edge glued.(r) All joins in flce teueers shall be either eclge gluerl or tapecl n irh prrper'. Thetape shall be on thlt firce of the r-eneer l-hich ri'ill be an outel lace oi a board, al,ri t[e taue

"irtr.ll be rerroved froru the board befor.e deliter.r'.. ..5. .t1lctners. (n) f-uless orherl'ise specitied on the order, the thicknesses oI the tLr,'nrds shrll be as shorvn in -tpperrdix B. ' I

16) The trvo outer seneers in the linished board shall be of tire same norninal tbickness. ,(c) Tbe nonrinal thickness of the core of 3-ply shall be not less thau one-third anrl noi rgreater thau tive-trvelfths of the nourinal thicknlss of the board. I(d) The thickness of any ven-eer in rnultilply shall not exceed trvice tlie thichness ofan.\' other veneer in the same board.(e) Each vener sha,lJ be of uaiform thickness.(/) No veneer sball exceeil 0.110 in. iu thickness.6. tvp" or Glu.. The glues used in the rlanulacture of the plyrvood sball be of the hotpress, therrnosetting, syathetic resin type.7. Soer.r loin. in Bo.Fdr. Scarf joins throuqh the the thickness of the board shall bepermitted only' rvith the concurrence oi the desigriing firm.

4


6/27

,i t;{:'-I1l', .!;

.'ll' !'..:

Ftc, l. \laximum clore. either in one band. as in rhrs illustration, or distributed, rvhich ts permitted inpanels for all plies oi Gracle .\ ior cores ol Grade Lt (tjirch or )Iaple) and the faces of .Beechboards, in aol.rlrdth of I ioot rrreasurecl ilcross the grarn of rhe veneer. (\atural size), 5


7/27

,..:{,l' rF ..., ,,-....!J l.r .:.lil .iii;:"'.i.,; :.i gi: ,.i . F:$,t,'l :il "i

:.r:

t:

,:ti...:''JI 'rjIi1L::

':..i' r.:|' _lI i,pi

i,!

.1

1

.l.l,'1

i.t:tr

t:i,' .

,.1.d:

t .rli,l't..'1i-

Flc, J. llarinunr degree ofdore perrnirted in \-eneer for Grade B (IJirch or. llaple) face:-. {\iurrral sizcl.

',le ";.,jrg,'iitr:


8/27

':;&:il'.-Yir.:;ilf.ia'!t...;1;d:i i}" I:! s .{F'.i. ,'

.li i';. tir.!ii

''; i llltrrtrtLittt short gtarrr l)ernlIteC in r'-,neer ior all plies of Grade A, for cores of Grade lj rllrrch or ltaple)and ror ajl plies ,rf Orade lJ (ljeechr. (\atural size).7

-a


9/27

"..: l\..F


10/27

I.t,;.5. \lasinrunrrlegreeofshorrgrainpenl)irtedinleneerforfacesofGra,leBtBirchorllaple'. \rLtrrral size) I


11/27

Ftc. i. llarinrumdegreeofs5ortgrainpernrittedin'eneerforfacesofGradeB(Birchorllaplel. \atural size)'I


12/27

.\ut

llarirnunr degree of short grain pernritted in r-eneer lor faces oi Grade B (Brrch or \lapler' \atrtrll size)'I


13/27

Flc.6. -\n exarnple of the maximum degree ol rr rldJrat:.i"#tiil* in .eneer ior faces of Grade U ( Uirch or llapl10

{(

..lit .1lit.t{ri.i, t:i li;ill :']r i1lir,,u^r 'li ..l' I'.i;..' L


14/27

li.ll

ili;.

Fl(1. ;. .\n example of the ma\imum degree of \\ ildgrain permitted in venecr for faces of Grade !t (I)irch or llaple\'

(Natural size) ll


15/27

--

t

lrlr,li rI

tE\' .\n e\an)ple oi rire nra\int)nr .lggree oi tr.ilful:^i:;:i:,, rn 'eneer ror iaces of ( irarle Li {lirrctr or \laple .


16/27

"1.1it.';-; ..' i-'t|t ': 't ,

. '-,''. I.t, tt ..,' 1

?I. /:,

i \il^.i

l..t,tlL

J

"i:.- ,, ':.i t.az T/' l'4,r'",

,.9..\nexampleofrrildgrainconsiderablvnroreseterelilanispelnirredforGrarlellface.,ljrlcirorll;t1rle).(\atural size l.13


17/27

l:tc. It). lngrorln bar]i. The actual bark srreirli is seen ro rhe riqhr and lhe burr


18/27

FrC, 13. Naximum degree of rough cutrins permitted in all plies of Grade Il (Birch or lr{aple). (Natural size)'rU


19/27

:+:5:--.!--.. Jl

'.c -'er*

Flr; l.l. l'rorrr-rutrced birds ele no! l)enriued under Clause I lb) (\). To be dealt l'ith indilitlulllt aslinots uutier Clarrse I (b) (ir). (Narural size).rA

t

:.i{:',:i\,: 5;Ftc. 15. Delinearion of a knot to indicate its size for purpose of nl*$urenlent. (Natural size)'

Irl(;. !6. DeliDeation of a hnot, rthich although surrounded by short grain as in the example illustratedin Fig. 15, is withour the s'ell deined core, .\s shown in the illustralion, nreasurement is tobe taken from the point \vhere there is a rnarked change in the rvidth of the grorvth rings. Intbe absence of an! such indication there is no alternative but to assume a dimension appropriatelo the degree and extent of slrort grain. (Natural size).16

0it


20/27

Ll .(az,s r"rnrri - suo.s'snrr t:i'1.1i*[::3]i',,," .'0"" al?tpalurarur P": :l='ls" .afe sprq r?uq lnq .,\rsualxa ".,"1i-:;;;;, g ii''9 'q eld"l\ (Ir a ia sPrrq Jo aerBaP unur)il'lf 1l DIJ

f,fi';:a51l*.i;ir .r,

!:l,;,. i;,'''i .'.

t

I i Yt::..'.:i !l'''.,"3d.;io

:i,l


21/27

Fr(;. ls. \\'a\') Grain. (Natural size).

18


22/27

PD 936Amendment No. 2 : tuly, 1949

to British Standard 6 V.3High strength plywood for atrcraft

Page 19. Clause l0 b). Delete.Clause l0 (c) becomes Clause l0 (b).


23/27

6 V.3, Jul\'. lg{:i.Tbe glue used for uaking the joius shall tourpll s-ith the requireueuts specitieC inClause 6.Scarf joins rla5. be in aul positiol il the borlrd rtuless othenvise speciiied b.v tltcdesigning firm.The inclination of the scarf shall [,e not steeper tht]D I ir) ll. lThis provisiol oppliesonlr- to scarf joins made b1' plysoocl ruauuf;r,cturers] .

PART 3.Genenal Pnovisions applyinEl to a'll Plywood.8. M.nufaotuFing Dcrct3, )Ianufacturiug defects shall be Iimited ir) a('cordir,rlce'n'ith the follorving table:-Type of Defect Gnde A Gra(lc ll

(i) Blisterst ii) Pleats and overlaps

iiii) Gaps and open joins

ErcludeExclude, unless otherwiseagreed bl tbe Purchaser.

s'hen the maxinrumdoes not ericeed 0.01

Erclude.\dmit in faces and cores in boartlsordered as " standard " or " falling " sizes,subject to the consent of the purchaser.Boards containing these defects shall bemarked to indicate their position..\dnrit s'hen the maximuru rvidth doesnot exceed 0'01 in..{dmitrvidthinch.

t.r

f. itoi.tu. oontont. The moistule content, of the conditioned plyrvor-rd, deterurinedll' the ruethod described in Appendix C rnust be not gl'eater than l.l per cent or less thul? per cent.10. Finirh, (a) The edges of tlle boftrds shall be t,rirnured square.(l) Fach board shall be sanded on both feces, urd shall be Ilalked in au approvedr rallner.(r) Slight glue sbains shall be perrrritted.

11. Ma"kinll. (a) The folloling prutioulars shall be starnped clearll' oir one side oIach board :-(i) The Manufacburer"s distinguishing urark.(ii) Tbe number of this Specification.(iii) The graale of plywood.(iv) The veneer species, lvhen beech is used.(v) The }fanufacturer's batch nurnber (f


24/27

G V. 3. Juh. 19{3.PART 4.Tating.

12. sotection of Tost ssmpler, Boards of the satle thrckness tutde iu &ll1' olte l)l.essper daJ', flotrr the salrre roll of fi/ru glue ol the same ruixing of Iiquid glue. sbrrll bc regrinlt'rlas uue batcb, and oue board shall be selecled br the lnspector ft'olr ench batch lor'the tes[.specified in Clause 13. The board selected shrr,ll be that t'hich is nearest tu tlrr' plrlteu ofthe ptess for the longest tiue befole the press is closetl. in an.r'oue of the pless l,rrrds.13. T3t.. Tbe following tests shall be calried out to tire satisfactiou of tLe Inspet.tot.on the board selected as speciiiecl in Olause 12.(a) Adltesion of t-eneers. The boald shall be stu\\'n into suall pieccs, npploxir rrltel,v4 in. square and none of t.he pieces shall shorr signs of separatiou of the verre.,r's. 'l'lreadhesion of the teneers shall be testcr'l b5' ftlrcibll: separating the lnlels of r rrrrrrrlrer ofthe snq,ll pieces, the rumber seiected beiug ai the discretion ol the Irrspector. 'l'lte leneelsrntrst offer appreciable resisbance to sepnr.ation.(b) Ilesistance to IVatet. The resistance to l'ater shall be snch that l'lrtn tested br'the ruethod described in Appeudix D, the uraterial rnusb (i) show no signs of seprtrl,t ion rilthe. edges of the veneers or fouualion of blisters, and (ii) the veneers rriust ofiel ir,pprer,iablelesistance to separation.

, (c) Moistzn'e Content. 'Ihe uroisture coutent shall be s'ithin the liurits spe


25/27

6 V. 3. Juir.. tg{S.L lrgrot;:rr Barh, Bark in a flute or pocket or arouod a kDot, io the stem of the tree is often completelyiclosed by iubsequeqt grorsth. \\-heo such a log is peeled the bark appears as a black streali follorving tbei,.",ton of tbe grain, u'tth a burr streak (g.o.) each side of it. Tbe black strea! dimioishes i! s'idth rrithuccessise Dceling cuts aod fnalll disappears, follo*ed in turD b-v tbe burr streli. This feature is illustratedn Fig. 10, which sho\\'s tbe actual bark suea! to the right aud the burr streak to the left.5, Burr, This feature consists ol \'ery small koots set iu 6nely contortcd graio, and obtaiDs whe! thepeeling cut passes tbrough a group of dormant buds. Burr is illustrated il Fig. l1'6. Bird Pechs. Bird pecks are small operings in tbe veneer with tbeir lengtb follo$'irg the grar1, asshervr io Fig. l?. The opeoings may or lnay Dot be filled \i'itb dark brown tissue.7. Pleats and Ow afs. \Ihere any veneer is lolded parallel to the grain to form threc thicknesseslocall-v the defect is known as a pleat, \\'here tbe adjaceot pieces of vcnecr on citber side of a split or edge joinoverride aDd form tvo tbickosses locally, th defcct is koowt as al over-lap.8, Irregulor Grafu. The term " Irregular Grain " is a comprchensivc oDe, coveriDg all cases v/here thegraio, noticeabh', is oot parallel to the appropriate edgcs aud to tbe tacc of the venecr. (The quali6cation istt""e"s"ry as perfectl!' straigbt grain is qon-cxistest). Io tbis counection it is irnportalt to Dote thar graiDdirection refers to tbe djrection of the 6bres, to rvhich the so-called '6gure' in peeled lenecr resulting from thevariations in colour or cell structure across each annual growth ring, is no guide whatcvcr. (See Fig. 18).The main forms of irregular graiD ale as follows :-(a\ Short Grairr This, as shorrn iD Figs, 3 and 5, rcsults from crook in the log. It is also present inmore acuta form surlousdiug or in close proximity to kDots, whcn ir is caused by tire kuife cutring across thervood {'ith which the branch rras envelopcd in the growing tree; itl such instances the ioclination of tbegrain to the face of the veneer may approacb 90 dcgrees in the extreme case.(bl Wavy Grain (See Fig. l8). The fibres are aavy, but the waviDess is in the planb of the veDeer.\\:heie waviless is present it is generally fairly uniform and cootiluous.GJ Witd Gr.titt (Sce Figs. 4, 6, 7, 8 and 9). \Vild graiD occurs when the log has a corrugated exterior.l\'hen such a log is peeled the fibres run in and out of the surface of tbe veDeer in transrerse baDds, correspondingto the ridges on the log. The e\.enDess of the peeling cut mal' be disturbed, resulting in a ridged surface iD thesebands, in addition to the inclined grain. In viev of the orieutation of these bands rvhich extend for manf inchcsat right aogles to the grain, this form of defect may result in rreakness in tbe plywood under mosi conditions ofloading. lt is to be noted tbat tb'e Eriation in light reflectioo of the surface due to the changiug grain direction,wb]chlives tbe veDeer a distinctil'stliped appearance, generally regarded as "6gure", is not a true rneasure ofrhe degree of grain disturbaoce and is therefore not a reliable iodex of the strengtb of thc vner.In srudying the illustrations of irregular grain, Figs. 3-9, due allowance grust be made for the dificulty iDreproducing grain defects by means of pbotographs, accentuated io many cases by the false imprcssion created bythe variation in light reflectiol in zones of wild grain, to vhich reference has been made. The illustrations cannotbe expected, therefore, to provide definite criteria of acceptance or rejection for every example of rvild grain whichmay be encourtered, but so long as the'illusFatiols and descriptioDs are studied together, tbe margi! of error iDinterpreiiDg tbe speciicatioD sbould be negligible.L0. Rough Crttilg. This is shown in Fig. 13.!1. Bids .Eye. A small, roughly circular marking due to contorted grain, which appears on rotary cutmaple (See Figs. 14 and 17);

2t


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6 V.3. Juiy, 1943.APPE'{DII B.

Str,ndaFd 7lrlokn6a... ot Boiid..CodcNo- 1o)crrlcc Bo(o&l-.rnit

iDchcsTbicLDlss lEquiv.)cnlincbe! U/M

\r.3/ 100 '793 i l0 per ccnt%.\t.3i 110 '047 I 1. 190 t l0 per cert

\,.3h20v.3/130

v.3/140v.3/150v.3/160 3'968 .15 pcr ceat . 164 . 148

.028

.M2

.119

+.762 15 pet ce\t .178t5 per cent.t 5 per centl5 per cent

12,70 1.2tr per ccat1).d/5 lzt per ceDt19'05 t2i per cent '73122,225 X2L per cert .85325.4 ',t 2i pet ceol t.o25 .97 5

0

v.31170

v.3/180v.31190v 3t20qv.3l2r0v.31220

v.31230

V .312+0

v 3/250

Ya. 187 s

91.o.3125t6.375

Y..?5%.87 5

'156

u.25

.50

),.)

It'0

.078 I 1.984 + 10 per cert2'381 t lO per ccot3. 175 i 5 per cent

22


27/27

6 V. 3. JuJy, 1913.

APPETIDIX C.Mthod o? Dt.rrnlnlna llol.tur Gont.nt.

A small sample, about 2 iuches square shall be weigbed (Wt) and shall then be dried iD aD oven at aremperature ol 2L2'F. to 22lo F. (100o C. to 105'C.) ultil the wcight is coostant (\\'o)Tbe perceatage of moistrre sball be calculated as follor*s :-

Perceotage of moisture = \=llo x 1ggCare should be takeD to pleveDt anl'char:ge iu moisture colteDt between the cuttiDg of tbe sample aDd thefirst *'eighing, or betweeD removal from tbe oveD aDd the subsequeDt weigbiog.

APPENDIX D.mcthod of D.toFmlnlnll thc nG.lat.,noa to lflat.r..

A test piece approximatell'+ iDches square, cut from e3ch selected board and containiDg a join if tbere arcjoiDs in the board (includiog a taped join if such joius are in the board) shall be submcrged completely in boilingrr-ater for three hours.The test piece shall tben be removed from the boiliug water and pluuged immediately into cold water.After coolirg to ordinary atmospheric temperature iD the wate!, the test piece shall be removed from the rraterand rvhiist still vater-soaked sha.ll be tested for complia:rce x'ith the requirements of Clause t3 (D).

This Specification rras a,pproveal bv tbe Aircraft Inclustry Committee andendorsed b5: the Chairman of tie Engineering Divisional Coudcil, was publisbetlby the authority of the General CouuCil of the InstitutioD &s & British Standardon 5th July, 1943.

NOTE.Irt otder to heeb abrcdst of progress in the lrdustries concented, the British StottdardS?ec;fcations dre subt'ect.d to beliodicdl t.'[email protected] itn,rolrerte\ts, addressed to th. Bit;sh Startdolds Irrstit(l;ort,28 V ictot"ia Strcel,Lortdon, 5.W.1, will be aelcomed ot all tit,tes. Theg will be recotded a*d. itt dte co*rce brou{htlo the ttotice oJ the Cornrnittees charged uith the revisiott ol the Slecifcatiotrs to \oh;ch the! refer,

28

Plywood Spec 6V.3

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Transcript of Plywood Spec 6V.3