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Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public.

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है”ह”ह

IS 12077 (1987): Code of practice for testing of timbersfor plywood manufacture [CED 20: Wood and otherLignocellulosic products]

IS: 12077-1987

Indian Standard

Reaffirmed 2010

CODE OF PRACTICE FORTESTING OF TIMBERS FOR PLYWOOD

MANUFACTURE

UDC 674-412 : 674-419.32

© Copyright 1987

BUREAU OF INDIAN STANDARDSMANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG

NEW DELHI 110002

Gr 3 December 1987

IS : 12077 • 1987

Indian StandardCODE OF PRACTICE FOR

TESTING OF TIMBERS FOR PLYWOODMANUFACTURE

Wood Products Sectional Committee, BDC 20

Chairman

DRP. M. GANAPA1HY

Representing

Indian Plywood Industries Research Institute,Bangalore

Me,,,ber8

8HRI L. N. DOKANIA

SHRI M. R. MOTAYED

CHIEF CONSER.VATOR OF FOR.ESTS

SURf V. SIVANANDA ( Alternate toDr P. M. Ganapathy )

SHRI B. C. BANSALSHRI P. R. CHANDRASEKHAR.

National Test House, CalcuttaDirectorate General or Civil Aviation,

New DelhiForest Department, Government of Assam,

GuwahatiFederation of Indian Plywood and Panel

Industry, New DelhiSHRI M. R. MOTAYED (Alternate)

SHRI D. P. Gnosu Ministry of Defence ( DOl)SURI J. K. SINHA ( Alternate)

INDUSTRIAL ADVISER Directorate General of Technical Development,New Delhi

SHRI P. V. MEHTA ( Alternate)JOINT DIRCCTOR STANDARDS Ministry of Railways ( RDSQ ), Lucknow

( CARRIAGE - I )SHRI A. K. KADERKUTTY Western Indian Plywood Limited, CannanoreSHRf U. B. KANCHAN Ministry of Defence ( R&D)

SHRI B. B. MEHTA ( Alternate)SHRI K. S. LAULY Indian Plywood Manufacturing Co Ltd,

DandoliPlywood Manufacturers' Association or

West Bengal. CalcuttaSHRI N. M. CHACHAN ( Alternate)

DR A. N. NAYER In personal capacity (C. $9, Indurpurl,New Delhi)

Da A. PuausHomAM Indian Academy or Wood Science, DharwadDR SATISH KUMAR. ( Alternate)

( ContinuedOil JlGI. 2 )

@ Copyrl,ht 1987BUREAU OF INDIAN STANDARDS

Tbll pUblicatioD is protected UDder the llId/lUI COPlrl,ht Act ( XIV 011'57) aadreproductioDIn wboloor in part by anymeans.xcept witb written permisllon of tbopublisher ah.1I b. deemed to be an infrlDlemoDt of copyriaht undor tb. Aid Act.

IS : 12077 • 1987

Manu facturers'SHIU A. K. RAMACHANDRAN

( Continued from pale 1 )

Men,berl Represellting

South Indian PlywoodAssociation, Trivandrum

SHRI JOSEPH K. KURIAN ( Alternate )DR A. V. R. RAO National Buildings Organization, New Delhi

SnRI Sl:N GUPTA ( Altemate )SURI P. R. RJGHSJNOHANJ Engineer-in- Chief's BI anch, Arrny Headquar-

ters, New DelhiMAJ D. R. KOHLI ( Alternate)

SHRt S. K. SANOANERIA Assam Plywood Manufacturers' Association,Tinsukia

SHRt S. N. SANYAL Forest Research Institute and Colleges ( TimberMechanics Branch ), Dehra Dun

SECRETARY Indian Tea Association. CalcuttaSHRI SHARAN SINOH Directorate General of Supplies and Dispo"a I."

New DelhiDR Y. SINOH Central Building Research Institute (CSI R ),

RoorkeeSHal L. K. AOARWAL ( Alternate)

SUPERINTENDING SURVEYOR OP Central Public Works Department, New DelhiWORKS (NZ)

SURVEYOR OF WORKS ( NZ ) ( Alternate)SARI H. THOMSON Sitapur Plywood Manufacturers Ltd, SitapurSHRI G. RAMAN, Director General, BIS ( Ex-officio Member )

Director ( Civ BDII )

Secr,ta,J'SHRI P. SATYANARAYANA

Assistant Director ( Ci v Bogg ), BIS

Plywood Subcommittee, DDC 20 : 1

Western India Plywood Ltd, Baliaptam

Convtner

5HRI A. K. KADERKUTTY

Memblrl

SHill N. M. CHACHAN Plywood Manufacturers' Association of WestBengal, Calcutta

SHal P. R. CRANDRASBKHAR Directorate General of Civil Aviation,New Delhi

DIRECTOR Indian Plywood Industries Research Institute,Banga]oro

SKRI V. SIVANANDA ( Alternate)SHIU P. O. DESHMUKH Indian Institute of Packaaina, Bombay

Sual C. s. PURUSH01'HAMAN ( Alternate )

( Continued onPQ" 9 )

AMENDMENT NO.1 AUGUST 1992TO

IS 12077: 1987 CODE OF PRACfICE FOR TESTING OFTIMBERS FOR PLYWOOD MANUFACTURE

(Page 3, clause%.1 ) - Delete the matter 'IS: 303-1975t and'.

(Page 3,!oot-nOle markedwilli 't' mark) - Delete.

(Ptlge 7, clause4.2.2.3) - Substitute 'IS 303 : 1989' for 'IS: 303-1975 t•

( Page 7, clause4.2.4 ) - Substitute cIS303 : 1989' for cIS : 303-1975'.

( Page 7, [oot-note marked with ct' mQrk) - Substitute the following Cor tbeexisting foot-note:

'*Specifialion for plywod for general purposes (third revision).'

I PQge 8, clause4.3(G), line 1 ) - Substitute 'MR' for 'CWR'.

(CED20)Rcproarapby UDit, BIS,NewDelhi, lodi.

IS : 12077 • 1987

Indian StandardCODE OF PRACTICE FOR

TESTING OF TIMBERS FOR PLYWOODMANUFACTURE

o. FOR E W 0 R D

0.1 This Indian Standard was adopted by the Bureau of IndianStandards on ;9 April 1987, after the draft finalized by the WoodProducts Sectior al Committee had been approved by the Civil Engi­neering Division Cour cil.

0.2 This standard has been formulated to guide the industry in arrivingat the most efficient way of processing the timber logs during manu­facture of plywood, 1 he various tests specified in t his standard alsoaid in assessing the suitability of the species of timber.

0.3 For the purpose of deciding whether a particular requirement orthis standard is complied with, the final value observed or calculated,expressing the result of a test or analysis, shall be rounded off inaccordance with IS : 2 - 1960*. The number of significant placesretained in the rounded off value should be the same as that of thespecified value In this standard,

1. SCOPE

1.1 This standard covers requirements of timber and its source,' itsprocessiDI to determine the peeling, drying and splicing characteristicsand sluing properties of veneer and assessment of the timber for itssuitability for plywood manufacture.

2. TERMINOLOGY

2.1 For the purpose of this standard, the definitions given in IS : 303­1975t and IS : 707 - 1976: shall apply.

-aules for roundial off'numerical values ( revllrd).fSpecificatJon for plywoodror aeDcral purposes( Itcond ,tvl,lo" ).tGIOIsary of terms applicable to Umber teclanololY aDd utilization ( ItCOili

,.,I,lon ).

3..

IS : 12077 • 1987

3. MATERIAL

3.1 Veneer logs, preferably of diameter 0·4 m and above (mininlumgirth 1·20 m ), length 1-5 m and multiples thereof, with a total quantityof not less than 3 m8 of timber are required for detailed examination ofeach species.

3.2 Tests should be carried out on freshly-felled logs. Each log shouldpreferably come from a separate tree. Bark should be left on, and endcoating and spray treatment against fungal and insect attack appliedimmediately after felling.

4. PROCEDURE4.1 Details of Timber Under Investigation and Its Source

4.1.1 The source of supply of the timber species and their trade andbotanical names together with their density in kg/rn 3 in the green stateand when dried to 12 percent moisture content shalt be recorded.

4.1.2 The mean diameter of the bolt shall be measured after cross­cutting the log and a record be made of its straightness, shape, knots,corrugations, gum pockets, decay, insect attack, spiral grain and of anyshakes and splits.

NOTE - It is recommended that information on whether the logs are typicalof the forests or selected specimens, their availability. usual girths lengthsestimated extraction rates and liability to degrade after felling, storage and transitshould also be recorded.

4.2 Proeessiog Trials - The object of processing trials is to indicate themost efficient way of processing the timber at each stage of plywoodmanufacture.

4.2.1 Peeling - The quality of veneer peeled depends to a largeeJteDt on the quality of timber and lathe settings. The effect of lathesettings on the veneer quality is assessed on the basis of uniformityin thickness, Iurface rouahness and lathe checks. The important lathesettings which affect the quality of veneers are : <a> horizontalgap, (b) vertical gap, (c) knife angte, (d) knife bevel angle and(e) knife height with respect to spindle centro ( see Fig- I). Boiling!steaming the bolts helps in increasing the veneer yield. improving thosurfacequaUty and reducingthe splits.

4.2.1.1 Lathe letting - The horizontal lap varies depcDding ontimber Ipocies, log temperature, moisturecontent, veneer thIckness, etc,and rangos Dormally from 75% to 9S% olthe thicknessof venoer peeled.Vertical lap should bekept at 20% to 25% of the thickness of veneerpeeled. The knife anllo varics dependiDI on timber species, veneer

IS : 12077 • 1987

FIG. 1 RELATIVE POSITIONS OF KNIFB, PRESSUJ.BBAR AND VENEER

thickness and usually ranges from 93° to 91 0 at a maximum bolt diameterof 1·5 m and 920 to 90.) at a minimum bolt diameter of 0·2 m. Knifeedge height shall be aligned in a horizontal plane with respect to spindlecentres. Knife is generally ground to a bevel angle of 200 to 220

• Lathesettings, for getting desired quality of veneers for each species aredetermined by trial and error method within these requirements andrecor ded in Table 1.

TABLE 1 LATHE SETTINGS

( Cia"" 4.2.1.1 )

VENEERTHICKNESS

(rom)

HORIZONTALGAP

(mm)

VERTICALGAP

(mm)

KNIPE ANGLB

r--------A..-----1At Maximum At Minimum

Bolt Diameter Bolt Diameter( Del-mia ) l Deg-min )

4.2.1.2 Green venee« yield - Generally the Breen veneer yield oftimber species ranges from 40 to 60 percent of the total volumeof timberyield measurements shall be recorded as shown in Table 2.

5

IS : 12077 ·1987

TABLE 2 GREEN VENEER YIELD

( Clause 4.2.1.2 )

DESCRIPTION

1. Veneer yield2. Core loss3. Rounding loss4. Spur trim loss5. Green clipping loss

Total

VOLUME PERCENT

100 percent

4.2.2 Drying - Temperature for drying veneers should be around140°C. The moisture content of veneer after dryirg should be 6-8percent and 10 percent for manufacturing plywood with phenol formal­dehyde and urea formaldehyde resins respectively. Drying defects suchas development of splits, waviness, metal staining, gum exudation, etc,that occur during drying may be recorded. Dried veneers should bestacked for about 8·10 days in order to achieve uniform moisturecontent before using them for further processing,

4.2.2.1 Drying time -l'he drying times for veneers of differentthicknesses ( for example, 1·0. 1'6 and 2-4mm ) may be determined andrecorded as shown in Table 3.

TABLE 3 DRYING TIME

VENEERTHICKNESS

mmMOISTURE CONTBNT 0'

VENBERr-----A.---~

Initial Finalpercent percent

DRVERTEMPERATUkE

°C

DaVINO TIMBmin

Generally, drying times for 1·0, I" and 2'4 mm thick, veneersvary from 4-6 min, 6·12 min, and 1S·21 min respectively at a driertemperature of 120°C, moisture content of dried veneer 8 to 10 per­cent and initial moisture content of veneer, 65percent.

~.2.2.2 V."ee, ,i,'nkage ....Shrinkage of veneer during dryiDg IbaJIbe determined on the basil of initial aDd Dnal measurement of width IDd

IS : 12077 • 1987

thickness. Percentage shrinkage of veneers shall be recorded as shownin Table 4._....._._-~ .._-- _.._._-'.._------

TABLE 4 VENEER SHRINKAGE

( Clause 4.2.2.2 )

l\,tOISTURF CONTF.Nt OF\ VENEER

r------"----.--~Iuit ial Finalpercent percent

SHRINKAGE OFVENEER,.--- ..A... ~

Width Thicknesspercent percent

4.2.2.3 Features of dry veneers - These are determined in relationto growth and processing characteristics of the species, namely, whetherthe veneer contains discolouration (sound and unsound), dote, insecthole, knits ( dead and tight), pia knots (dead and live ), splits, swirl,etc. Based on these defects, the veneers should be initially assessed ifthey are suitabl ~ for d.fferent types of surfaces for plywood in accor­dance with IS : 303-1975*.

4.2.3 Splicing - Veneers of different thicknesses ( for example, 1-0,1"6 and 2·4 mott ) may be spliced at different speeds using splicingadhesives ( for example, UF resin, UM resin, etc) for determining thebest speed of splici ng. Splicing speeds, generally, vary depending ongluing properties of the species. The splicing speed in terms of linearspeed of the jointed length of veneer is normally 5-26 m/min for veneerswith thicknesses rarging from 2-4 to 1·0 mm and when spliced at atemperature of 175°C using UF resin.

4.2.4 Gluing Properties - For determining gluing properties, 3-plyplywood panels of equal construction using 1-6 mrn veneers shall bemade and tested for conformity in accordance with IS : 30)·1975*and the results are recorded in Table S.

4.3 Assessment - A detailed report on the tests with all technical datashould be given to aid the user to make his assessment regarding thesuitability of the species of timber for plywood manufacture. Followingpoints may be kept in view while determining the suitability of speciesof timber for plywood manufacture•

•Speciflcation for plywood for aeneral purposes ( secolld revtsto« ).

7

IS : 120'7 • 1987

TABLE S GLUE ADHESION STRENGTH

( Clause 4.2.4 )

GRADE OF DRY STATE WET STATE MYCOLOGICALPLYWOOD r---..A.._~ ,---_.A._--, rr>:..--.A.----~

Failmg Glue Failing Glue Failing GlueLoad Failure Load Failure Load Failure

kg percent kB percen1 kl percent

A: timber may be classified as unsuitable if it has markedly shownODe or more of the following characteristics:

a) Contains internal stresses or shakes that cause the bolts tobreak up in peeling or lead to the production of maximumveneers of narrow width,

b) Growth features are such that a large core of timber unsuit­able for peeling is left,

c) Contains mineral deposits such as silica that rapidly blunt theknife,

d) Adjustments to the lathe settings have failed to reduce appre­ciably wooJiness or 'pick out' of the veneer surface,

e) The veneer dries patchily, splits or distorts and is difficult tohandle or is unduly brittle,

f) Glue adhesion properties are extremely poor,

8) When plywood is made using CWR type adhesive and testedas described in 4.2.4 samples do not give the required failingload and give persistent wood failure, and

h) Distorts strongly when made into plywood.

8

( Continued frompal' 2 )

Memberl

DRR. OANAHARANSHRf N. K. GHAI

IS :"12017 • 1987

Repre,entln,

Kerala Forest Research Institute, PeechiIndian Tea-Chest Battens Manufacturer'.

Association. Yamuna NagarSHRI J. N. KAPUR ( Alternate)

SHRI V. K. GUPTA Forest Research Institute & Colleges ( TimberMechanics Branch ), Dehra Dun

INDUSTRIAL ADVISER Directorate General of Tecbnical Development,New Delhi

SRRf P. V. MEHTA ( Alle'''''te)SRIlI T. P. KURUVILLA South Indian Plywood Manufacturers Associa-

tion, TrivandrumSHRr 10SEPH K. KURIAN ( Alternate )

SHRI K. S. LAULY Indian Plywood Manufacturing Co Ltd, BombaySHIll S. S. NANDKEOLYAR Tea Board, Calcutta

DR. K. K. MitRA ( Alternate)SHRt A. C. NANDY Calcutta Tea.Chest Fittings Manufacturer's

Association, CalcuttaSHRI B. K. KHAITAN ( Alle'IIol_ )

PRESIDENT/SECRETARY Assam Plywood Manufacturers' Association,Tinsukia

SECRETARY Indian Tea Association, CalcuttaSHRI K. S. SHUKLA Forest Research Institute & Colleges (Composite

Wood Branch ), Dehra DunDR. M. S. RAJAWAT ( Alternate)

SRRI A. R. VUAYENDIlA RAO Central Food Technological Research Institute( CSIR ), Mysorc

9

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