Testing Machines for Paper Materials - zwick.com.t · Testing Machines for Paper Materials FP 290 2.0903.202. 2 The Zwick/Roell Group Mechanical-technological testing is the oldest

Testing Machinesfor Paper Materials

FP 2

90 2

.090

3.20

2

2

The Zwick/Roell Group

Mechanical-technological testingis the oldest discipline in materialstesting. Its importance hasconstantly grown to date. In the15th and 16th centuries, Leonardoda Vinci and Galilei alreadyexpressed thoughts about flexureloading and the elastic propertiesof materials. The first testingmachines for these purposeswere made in the middle of the18th century in France.

The Amsler company in Gottmadin-gen (formally in Schaffhausen,Switzerland) has been involvedwith materials testing since themiddle of the 19th century. TheRoell & Korthaus company startedproducing instruments, machinesand systems for material testingin 1920. Zwick started producinginstruments in 1937. The Zwick/Roell group of companies wasbrought together in 1992, and nowmarkets a complete line of systemsfrom hand operated hardnesstesters to complex computerizedtesting systems.This brochure gives an overview

of the instruments, machines andsystems of the Zwick/Roell Groupfor paper-based materials. Itspurpose is to give suggestionsand hints to all, who have even thesmallest interest in paper testing.

Many years of experience, amultitude of delivered equipmentsand constant communicationswith users, are the basis of ourmachines and instruments.

We achieve high flexibility and„intelligence“ of our systemswith modern mechanics, highperformance electronics anduser-oriented software.

The performance of the Zwick/RoellGroup reaches far beyond thedelivery of testing instruments.The company was certified toDIN EN ISO 9001 in 1994, whichguarantees a high degree ofproduct and service quality. Asan accredited DKD Calibrationlaboratory, Zwick is also authorizedto check and calibrate testingsystems. Internationally recognizedcertificates help to compete ininternational markets.

Paper and paper materials

Paper has accompanied man sinceancient times (Fig. 1). Papyrus rollsshow that man searched for, andfound, a medium with whichinformation could be stored andspread, while saving space andweight. This did not remain theonly use. Books, and later industrial

Fig. 1: Paper then and now

Contents Page

The Zwick-Roell-Group ............................................................................................................................... 2Paper and paper based materials ............................................................................................................... 2Quality control - a key function leading to cost- and function optimized products ....................................... 3Test Standards - required for comparable results ........................................................................................ 4Test Methods, Standards and Testing instruments ...................................................................................... 5Zwick/Roell-Materials Testing Machines: BasicLine, Standard, and Allround Line ........................................ 7Features of the BasicLine, Standard, and Allround line ................................................................................ 9Zwick/Roell Test Software testXpert® ........................................................................................................ 10Test Methods in the paper industry ........................................................................................................... 12Specimen preparation ............................................................................................................................... 27Customer specific tests ............................................................................................................................. 27Automation ............................................................................................................................................... 30Laboratory data acquisition ....................................................................................................................... 31Sources listing ........................................................................................................................................... 31Producing companies, Sales and Service companies ............................................................................... 32

3

Fig. 5: Hygienic articles give protection

production of paper found newapplications for this material. Inthe broadest sense, paper can bea structural material today, whichcarries and protects contents onthe inside, while being an attractiveinformation carrier on the outside(Fig. 2). Paper is technically a highlyexacting product, which worksdependably in its application and iseasily recyclable at the end of itsuseful life.

Paper in technological areas cannotbe forgotten. Filter, protection and

special papers must be tested fortheir characteristics and they mustbe monitored (Fig. 3).

In a close relationship to plasticsand metals, we find paper also asa compound material (Fig. 4). Thecombination of characteristics ofthe compound partners gives theend product its special capabilities.

Paper is around us in everyday life:as sanitary or cosmetic tissues inhygienic and care areas (Fig. 5).

Quality control – a key leadingto cost- and functionoptimized products

Although continuous quality controlmakes some effort, it anyway helpsto save material and complaintcosts.Example in corrugated boardtesting:

If the raw papers are tested in aseparate test lab, fluctuations ofthe strip crush resistance (SCT)can be recognized impartiallyand considered. Furthermore,if strength values and bendingstiffness of the corrugated boardand the boxes are monitored,

variations in the corrugator or inthe following converting machinescan be discovered and adjusted.

The tests mentioned above mayalso be used for the strengthprediction of a box from the crushresults of their related papers.A good estimation assures themerchantability of packagingsduring their lifetime, even underconsideration of environmentalinfluences during transport andstorage.

Fig. 4: Paper compounds in daily useFig. 3: Paper for technical uses

Fig. 2: Paper as robust packing

4

Test standards – required forcomparable results

An important task of test standardsis the creation of equalrequirements for test specimen andtest sequences; and this must beindependent of when, where andby whom the testing is performed.

The National European StandardsCommission as well as ANSI(U.S.A.) and JISC (Japan), areharmonizing their standards step-by-step with ISO (InternationalStandard Organization). The goalis to improve the comparison oftest results and reduce the costsfor the present multitude of differenttesting systems in a growing globalmarket.

This brochure is based mainlyon International (ISO, EN) andimportant National Standards(TAPPI, JIS). Zwick/Roell-instruments also meet most of thecorresponding national standards.

The separation of paper-basedmaterials into 6 groups shouldassist you to easily finding yourown area of use and prompt youto take a look at new possibilities.

Testing of paper for corrugated board production

Testing of corrugated board and its products

Testing of special papers, graphic papers and printing papers

Testing on tissue and hygienic papers

Testing on cardboard and its products

Testing of paper compound materials

Fig. 6: Accessories for strip crush, edgecrush and flexural tests

Fig. 7: Materials testing machine for all tests to predict the box´s strength

Zwick machines accept all thenecessary test tools for these tests(Fig. 6). Thus, using one machine,one can perform the incominginspection quality control onpapers, tests on corrugated board,and the final quality control ofboxes. (Fig. 7)

5

Type of test Standard Material group Test unit Page

Burst test ISO 2758 Testing Machine, Burst Tester 12TAPPI T 403 Balance (50g) 20

Cutter 27

Burst test ISO 2759 Testing Machine, Burst Tester 11TAPPI T 807 Balance (100 g ) 20TAPPI T 810 Cutter 27

Bend test, 2-point ISO 5628 Testing Machine, Bending unit 14ISO 2493 Strip cutter 50 mm 27

Bend test, 3-point ISO 5628 Testing Machine, Bending unit 14ISO 11093 Bending unit for carton sleeves 14

Bend test, 4-point ISO 5628 Testing Machine, Bending unit 15

Corrugating medium test ISO 7263 Testing Machine with compr. plates 18TAPPI T 809 Medium Fluter 27

Strip cutter 12,7 mm 27

Thickness measurement ISO 534 Thickness measuring unit 16EN 20534 Cutter 27TAPPI T 411

Thickness measurement ISO 3034 Thickness measuring unit 16TAPPI T 411 Cutter 27

Puncture test ISO 3036 Pendulum Impact Tester 16(PET) TAPPI T 803

Puncture test Testing Machine, Penetration unit 16(LPET)

Elmendorf tear test ISO 1974 Elmendorf-Pendulum Impact Tester 17EN 21974 Strip cutter 50 mm 27TAPPI T 414

Flat crush test ISO 3035 Testing Machine with compr. plates 18EN 23035 Circular cutter 27TAPPI T 825

Basis weight EN ISO 536 Balance 20determination ISO 5638 Circular cutter 27

TAPPI T 410 Cutter 27

Basis weight FEFCO Nr. 2 Balance 20determination

Test Methods, Standards and testing instruments

6

Test Methods, Standards and testing instruments

Type of test Standard Material group Test unit Page

Internal bond test TAPPI T 541 Testing machine,testing unit 21(z-direction tensile test) Strip cutter 25,4 mm 27

Edge Crush Test EN ISO 3037 Testing machine, compr. plates 19TAPPI T 811 Specimen saw 27

Compressibility test none Testing machine, test head 28

Crease test DIN 55437 Testing machine, creasing tool 23

Friction test ISO 15359 Testing machine, friction unit 22TAPPI T 549 Cutter 27TAPPI T 816

Ring Crush Test ISO 12192 Testing mach., compr. plates, inserts 19TAPPI T 822 Strip cutter 12,7 mm 27

Box Crush Test ISO 12048 Testing machine, compression plates 23EN 22872TAPPI T 804

Plybond resistance DIN 54516 Testing machine, specimen grips 21Strip cutter 50 mm 27

Stacking Crush Test EN 22874 Testing machine, compression plates 23

Strip Crush Test ISO 9895 Testing machine, specimen grips 20TAPPI T826 Strip cutter 15 mm 27

Water Absorbtion (Cobb)ISO 535 Cobb-Testing Unit 24TAPPI T 441 Balance (50g)EN 20535

Tear Test ISO 11897 Testing machine, specimen grips 24

Tensile test (wet) ISO 3781 Testing machine, specimen grips 25TAPPI T 456 Strip cutter 27

Balance (50 g) 20

Tensile test (dry) EN ISO 1924 Testing machine, specimen grips 26TAPPI T 494 Strip cutter 15 mm 27

Balance (50 g) 20

7

Range of application

Materials testing machines areused for the performance of tensile,compression and bending testswith quasistatic loading.

Basic concept

The Zwick/Roell product line containstabletop and floor standing testingmachines with various frameconfigurations and drives as well asa comprehensive line of accessories.This enables the Zwick/Roell groupto offer a wide range of testingapplications for paper materials.

However, in order to determinethe correct machine, with optimumprice/performance ratio for anyrequirement, Zwick/Roell hasdeveloped an applications relatedconcept. It consists of three basic

Zwick/Roell MaterialsTesting Machines:BasicLine, Standard-and Allround Line

types of machines, which vary inprice, performance characteristics,and expansion possibilities.

• BasicLine testing machines• Standard testing machines• Allround testing machines

The most important testingmachine component is themeasurement and controlelectronics. The type of electronicsdetermines the performancecapability, which components canbe added to the system, and cost.The electronics will determine therange of applications and theexpansion possibilities of thetesting machine. Following is adescription of the main advantagesfor each type of testing machine:

• BasicLine testing machines areused for routine and functionaltests in quality control (Fig. 8).

Its technical capabilities arecomplemented by its shortdelivery time and its attractiveprice.

• Standard testing machinesprovide standard testingcapability with some flexibilityin order to provide a solidsolution to for most commontest requirements, but is alsofavorable in price.

• The Allround-Version is amachine that can be expandedfor more demanding testingtasks. The flexible modularelectronics strength is inresearch and developmentapplications. Expansionpossibilities include theconnection of special sensors,multi-channel measurementtechnology and modularexpansion (Fig. 9).

Fig. 8: BasicLine table top testing machine Fig. 9: 2.5 kN zwicki testing machines: testControl stand alone version (left), PC variant (midand right)

8

2-point bending tests on paper, boardwet tensile tests

3- and 4-point bending teststensile and compressive tests on paperand on corrugated board

functional tests oncomponents such as boxes,cores or palettes

table top or floor model up to 100 kNtable top or floor models up to 10 kN

single column "zwicki"

Fig. 10: Table top machine, profile legs: fortensile, burst and box crush test

Fig. 11: Range of application of Zwick/Roell materials testing machines

Force in Newtons

Measurement and controlsystem testControl(for standard and allround version)

By using the most recenttechnologies and by implementingthe highest quality standards,testControl offers the maximum oftechnical performance and longterm investment:• time-synchronous test data

acquisition with high resolutionand frequency

• real time processing of thetest data in a 500 Hz cycle

• adaptive control for precisereproducible speeds andpositions

Load frames

Zwick/Roell develops andmanufactures load frames fornominal loads of up to more than6,000 kN. As opposed to the normalsingle-purpose testing instruments inthe paper field, Zwick/Roell offersmaterial-testing machines with two

Features of theBasicLine, Standard- andAllround-Line

testing areas with separateconfigurations for two testing tasks.By using two testing areas in onetesting machine, a maximum isachieved use at the lowest cost.Fig. 10 illustrates the use of twotesting areas.

Single column load frame(zwicki)

These load frames are designed withvery rigid aluminum high precisionextruded profiles. The working areais freely accessible from 3 sides.Thus, it is designed to be flexiblefor testing on small parts. The lowestmeasurable force is determinedby the installed load cell and istypically in the millinewton-range.The maximum load is 2.5 kN.

Load frameIn table top version

These load frames are used for alltests with higher loads. They areavailable as BasicLine, Standard- orAllround versions. The Load frame’spatented aluminum high precisionextruded columns are light, veryrigid, and serve both as lead screw

guide and protection. T-shapedgrooves on the outer side allow asimple fitting of accessories suchas safety devices without beingimpeded by the crosshead. All loadframes with two columns, except forthe BasicLine, can be equipped withprofile legs. Advantages are:

• Positioning of the working areato an optimum height for the user

• Comfortable seated operationwith absolute freedom for legmovement and suitable forwheelchair users

Load frameAs floor standing model

These load frames are equippedwith 2 or 4 hard-chrome platedround columns and 2 precision ballscrews. They are preferably used forthe testing of specimens with largeextensions such as corrugatedboard boxes or roll on sleeves. Asmultifunctional machines, they areparticularly qualified for all tests topredict a box’s strength from papercharacteristics to McKee. Accordingto the specific testing requirements,the floor models are equipped withStandard or Allround electronics.

9

Machine component or function BasicLine Standard Line Allround LineLoad frame• Type of set-up

* Table-top machine (nominal force) 500 N to 20 kN 1 to 100 kN up to 100 kN* Floor stand. machine (nominal force) - 50 to 250 kN 50 to 250 kN

• Support and guiding columns* No. of columns 2 2 or 4 2 or 4* No. of Alluminium profiles 1 (Z0.5) 1 or 2 1 or 2

• No. of working areas 1 1 or 2 1 or 2• Expanded design (higher and/or larger) - � �

Drive system• Electro-mechanical

* No. of ball screws 1 or 2 1 or 2 1 or 2* DC-Motor � only zwicki only zwicki* AC-Motor no � (without zwicki) � (without zwicki)

Measurement and control system• BasicLine (also usable without PC) � - -• testControl PC-variant (Standard) - � �

testControl Stand Alone variant (Option) - optional optionalSoftware• test software testXpert® (with PC) optional optional optionalTransducer• Strain gauge load cell 1 (interchangeable) 1 (optional up to 2) 1 (optional up to 3)• Digital crosshead monitor integrated integrated integrated• Digital extensometer - optional 1 � (optional up to 3)• Analogue Extensometer - optional 1 � (optional up to 3)Connection of external systems• Digital extensometer - � �

• Analogue extensometer - � �

• Analogue reduction-in-width-monitor - � �

• Video Capturing - � �

• Switch Contact - � �

• Switch Control - � �

• Further measurement systems - � �

Control of external systems• Specimen grips (mot., pneum., hydr.) - - �

• Extensometer systems - semi-automatic full-automaticSupplementary units for special applications (optional)• Torsion drive - - �

• Torque transducer - - �

• Multi-channel force measuring system - - �

• High-temperature testing equipment - conditional �

• Low-temperature testing equipment - conditional �

10

Applications area

testXpert® is Zwick/Roell´s universaltest software for material, componentand functionality testing. It can run avariety of instruments from materialstesting machines (tensile, comp-ression, bending), pendulum impacttesters, balances, automatic testingsystems as well as refurbished test-ing machines of various constructiontypes and producers

Tasks and functions

The important functions oftestXpert® are:

• Preparation and changing testfixtures of the testing machine.

• Preparing parameter sets fortests or test series.

• Performance of tests, evaluation,and documentation.

• Data management.• Quality management.• Data exchange between

testXpert® and other applications(Word, Excel among others).

testXpert® supports the user in allareas with the software-assistantsand editors, clear pictures, videos,context specific user tips, warnings,error messages and on-line help.

Future-oriented concept

Test software testXpert® uses thespecial characteristics of objectoriented programming for a clearorganization according to tasks andfunctions. Structure and performanceare determined by applications and”software-know-how” from Zwick.The testXpert®-concept is thereforea guarantee for high flexibility andfunctional security as well as simpleoperation.

The important characteristics are:

• Common software basis forall applications,

• Software building blocks fortest requirements

• Software tools for user support.

Modular system

Zwick/Roell creates the testprograms from a selection of severalhundred software building blocks.The building blocks are placed ingroups such as test parameters,test sequence phases, and screenviews. They are constantly beingupdated and expanded with newinformation and requirements. Thismakes testXpert® an intelligentsoftware and enables the realizationof test programs that conformstrictly to test standards, as well astest programs related to practicalapplications (Fig. 12).

Its versatility makes it possible fortestXpert® to meet a variety oftesting applications as well as tobe used in most types of testingmachines.

Test programs

The test programs determine howa test will be performed. Theseprograms are built from pre-selected software building blocks.These building blocks connect therequired functions to each otherwith pre-configured, fixedparameters. Zwick delivers afinished „test template“,in which the user only enters a fewtesting parameters. testXpert® isavailable in three levels accordingto the general testing requirements:

• Master test programs• Standard test programs• Customized test programs

International quality standard

To comply with international qualitystandards, each and every versionmust be transparent, documentedand archived for 10 years. ThetestXpert® test software fully meetsthese requirements and even theparticularly strict guidelines of theGood Manufacturing Practices(GMP).

Zwick/Roell test softwaretestXpert®

Fig. 12: testXpert®, variable screen layout

11

The complete development processof the software and its componentsis carefully documented and archivedfor every version and for everyphase from analysis to specification,design, implementation, and up totest. This is done from the sourcecode up to the software tools used.Conformity with Standard ISO9000-3 has been confirmed withaudit report No. QM-F-96/1016.

Security in detail

Windows-Software is normally usedin offices. However, testXpert®

takes over an additional, especiallycritical task: monitoring andcontrolling machines. TestXpert®

does not use overlapping windowsin the test mode in order to avoidhiding important displays or keyfields. This will prevent injury topersonnel and damage to themachine.

Automatic acceptanceof system data

Various test jobs require separatetesting machines with differentinterchangeable components. Thespecific jobs are characterized bythe system data (nominal force,travel, speed range, mountingheight, calibration factors etc.).System data also belongs to theabove, e.g. the series numberor date of the last calibration.

testXpert® reads in this dataautomatically after starting theprogram:

• for the specific test settings,• for determination of safety limit

values,• for the correct measurement

signal evaluation.

Zwick/Roell test softwaretestXpert®

In addition, testXpert® checks if• the test can be performed with

the specified configuration,• all settings have been made and• the data has been changed for the

new testing.

Simple operation

Operation is reduced to a one-button, i.e. activating the startbutton, for standard applications.This is possible because testXpert®

automatically records the test data,controls and monitors the testsequence, and determines andstores the test results.

Only two steps to testing

Preparation of a test series requiresonly 2 steps:

• Loading the desired test program.• Input of the variable parameters

Optimum user information

All displays necessary for carryingout a test and a test series can begrouped together in a clear andconcise manner in one single screensetting:

• Input fields for specimen-specific testing parameters

• Curve diagrams (individualor multiple curves)

• Table for test results• Table for test result statistics

Data saving for further use

Depending upon specific selectionsin the test program, selected resultsand test parameters of a single testor test series can be saved alongwith the data curve. Saving of alldata offers the possibility of tracingthe result data from the original datato the configuration and settings forthe testing machine. The standard-

ized measurement data, i.e. the dataconverted to its basic units, canbe repeatedly displayed in thesimulation mode as well as evaluatedaccording to other criteria.

Video capturing

The test software testXpert® notonly supports the user by meansof „help“ videos. It is also possibleto carry out multimedia tests byusing a video camera and avideo capture card, with the picturesbeing recorded time-synchronouslywith test data (Fig.13).

• With the cursor keys, a ”videowindow” can be moved overthetest curve displaying thecorresponding picture.

• The pictures can be capturedat pre-selected measuring pointsor at a specified event.

• The video can also be playedalone apart from the testingmachine.

• The picture can be used tomeasure distances betweentwo points, angles betweenthree points, radii, diameters,and areas.

• Alternatively, the pictures canbe exported with dimensionlines and test data.

Fig. 13: Box compression test using video-capturing

12

The burst test

The Zwick/Roell burst tester is anaccessory of the testing machinefor performance of the burst test(Fig.14). The testing machine takesover the functions of the hydraulicpump, the data acquisition andevaluation. This makes the bursttest a program controlled test whichassures correct test results with aminimum of manual operation.

When clamping a corrugated boardspecimen, it is important for thereproducibility of test results, toapply and maintain an accurateclamping force. For easy use, Zwickoffers a pressure pre-selector,which allows for the application of5 different clamping pressures bysimply turning the selector knob.

Fig. 15: Burst tester and pressure pre-selector unit

Special attention must be paidto the dynamics of the testinginstrument when determining theburst strength. Since a burst testis performed within a few seconds,the maximum pressure should becaptured precisely, the dataacquisition rate of the testinginstrument must be correspondinglyhigh. If comparing results betweendifferent laboratories, the dataacquisition rate of the instrumentsmust be identical. The dataacquisition rate of Zwick/Roellinstruments can be controlled, sothat systematic deviations betweendifferent laboratories can beprevented.

Similar conditions are true forthe stability of the volume flowduring the test. Zwick/Roelltesting machines work with adigital control to insure a constantvolume flow, independent of theloading (Fig. 16).

Fig. 14: Burst tester as a machine accessory

Product program for papertesting

The scope of instruments formechanical, chemical, and opticaltesting of paper is very large. It isunderstandable, that Zwick/Roelldoes not have all of theseinstruments in its productionprogram. Articles on products,for which Zwick does not produce,are listed in the technical part ofthis brochure with the note ”onrequest”. If you want suchinstruments, we recommend thatyou acquire them from our partners.You can also request them throughus since ”all from one source”, isfamiliar to us. Speak to our fieldsales engineer. He will work withour sales department to find thecorrect solution for you.

Test Methods in thePaper Industry

13

Further, the easy serviceability andthe simple membrane monitoringmust be pointed out. If a constantvolume is pumped into the testchamber without a specimen, themaximum pressure indicates if themembrane is still in good conditionor if it has become weak. The timedependant membrane behavior isautomatically displayed and storedwith the connected PC.

For burst testing of paper materials,there are two standards: ISO 2758describes tests on paper, ISO 2759describes the requirements forcarton, corrugated board andcorrugated base paper. Zwickoffers a test instrument for each ofthese standards and thereby coversthe range from paper to heavycorrugated board.

Fig. 16: Volume flow stability guaranteesconstant test conditions

The advantages:

• The operator does not need toworry about the details and isfree to concentrate directly onthe test at hand.

• The tests are performed underconstant conditions even whenthere is a change in operators.

• The bursting of the specimen isrecognized by the machine andthe test is ended. This way, themembrane is stressed less andhas a longer lifetime.

• A variable data acquisition rateguarantees comparable resultsbetween producer andprocessor.

• The flow is controlled in a verynarrow tolerance range andremains constant even at highloading.

• With the real-time graphics(Fig. 16), the operatorimmediately sees if the testhas been performed correctly.

• Service interfaces andmaintenance friendlyconstruction reduce idle timesand consequential costs.

The 2-point bending test

Bending stiffness is very importantin the processing of paper andcarton. So that processingoperations in packaging and fillingmachines run dependably andwithout problems, the paper orcarton must be flexible withincertain limits. During the changingof paper charges, a uniformstiffness characteristic is alsorequired for constant workingconditions of a packing machine.The 2-point bending test unit fromZwick/Roell (Fig.17) covers twoapplications: calculation of bendingstiffness and the determination ofthe folding behavior at an angleof 90°. Zwick´s high resolutionand exact measurement technologyallows for one load cell to covera wide range of applications.

When testing fine paper at 15 mmbending length, the forces may bebelow the lower measuring limit. Insuch cases, bending lengths from1 mm should be applicable. Zwickoffers a unit which covers bending

Fig. 17: 2-Point bending unit, set-up* These accessories require connecting elements and

software to be specified according to the machine.

Bending unitLoad cell

Standard ISO 2758Material paperZwick-Item-Noburst tester 070376.01.00*test program 069002.54.fffor specimens from 100 x 100 mmto machines from zwickiStandard ISO 2759Material corr. board and

raw paper for corr.board, solid board

Zwick-Item-Noburst tester 070376.00.00*test program 069002.54.fffor specimen from 100 x 100 mmto machines from zwickiZwick-Item-NoAccessoriespressure 8096.00.00pre-selector

0

500

1000

1500

2000

volume flow

pressure

0

1

2

3

4

0 5 10 15 20 25Piston travel in mm

Pressure in kPa Volume flow in ml/s

14

lengths of 1, 2 and 5 mm in fixedprecision steps. Its jaws are springoperated, so that specimens arealways clamped under constantconditions without pre-damagingthe sample (Fig. 19).

Advantages:

• Bending forces from 50 mN to10 N are measured with oneload cell.

• The force measurement erroris 1% of the measured force.

• The load cell is placedseparately from moving machineparts so that the data at thelower forces are reproducible.

• Bending angles larger than 90°are precisely measured withoutchanging the load cell or tools(Fig. 18).

• An extremely high angleresolution of 0,001° guaranteeshighest dependability ofmeasured values.

• Specimen can be grippedwith widths up to 38 mm.

• The bending lengths can beeasily adjusted to 1, 2 and5 mm in precise steps.

• The test program simultaneouslydetermines the bendingresistance, modulus, andbending stiffness.

• The test curve allows therecognition of possibleirregularities during thetest (Fig. 20).

Fig. 18: Measurement of the folding momentat 90° deflection

* These accessories require connecting elements andsoftware to be specified according to the machine.

Fig. 19: Bending test on fine paper at 1 mmbending length

Fig. 20: Test series: board at 90° deflection


The 3-point bending test hasonly limited use on paper basedmaterials. Possible applicationsare on cardboard, paper basedcompounds or cores. However,the 4 point bending test isstandardized on cores. 3 pointbending tests are carried outfollowing company internalstandards.

The advantages:• Bending units from the Zwick/

Roell building block system arelight and simple to mount andto operate.

• Economical solution, since abending transducer is notrequired.

• Customer specific solutionsfor core testing.

Standard ISO 2493ISO 5628

Material paper, boardZwick-Item-Nobending rig 070289.04.00*load cell(from 10 N) 066140.03.00 fftest program 069002.59.fffor specimenswidth to 40 mmthickness from 0,1 to 4 mmbending length 5 to 100 mmto machines from zwickiStandard ISO 2493

ISO 5628Material fine paper, foilsZwick-Item-Nobending rig 070289.05.00*load cell(from 10 N) 066140.03.00 fftest program 069002.59.fffor specimenwidth to 40 mmthickness to 0,2 mmbending length 1 to 100 mmto machines from zwicki

Standard ISO 5628Material board, compositesZwick-Item-Nobending rig 070292*3-pointload cell 066140.03.00 fftest programm 069002.20.fffor specimenswidth from 50 mmthickness from 2 mmbending length from 100 mmto machines from zwickiStandard ISO 11093Material cores, sleevesZwick-Item-No on requestfor specimens length to 3200 mmto machines from Z 005

15


With the use of the McKee formula,bending stiffness is important forthe prediction of the box crushresistance. With the 4-pointbending method, dependablestiffness values are measured in themachine and cross direction. This isparticularly important for miniature

flute corrugated board, wherestiffness plays an increasing role,compared to standard flute heights.

With the knowledge gained fromthe bending units for structuralmaterials, (aerospace, ceramics andhigh performance metals), Zwickdeveloped a 4-point bending unitfor carton and corrugated board (Fig.21). The result is a tool that iscomparable to other existingsolutions at a moderate cost.

Another important point is thatthe bending unit can be used onthe smallest machine, the zwicki.

Compared to bending instrumentswhich use dead weights for specimenloading, handling is uncomplicatedand fast: the specimen is simplyplaced on the bending unit andthe test is started. The stiffness iscalculated automatically, taking inconsideration of the elasticity limits.

Because of rotatable and swivablesupports, shrinked or warpedspecimens can be tested withinwide limits. Testing specimenswith excessive shrink or warp, thevalidity of the test can be decidedwith unambiguous criteria.

Fig. 21: 4-point bending test rig with high resolution extensometer

Fig. 22: Stiffness determination on corrugated board including monitoring of start phase.Recognition of excessively shrunk or warped specimens by limits.

The advantages:

• Test time below 60 s• The test graph clearly shows if

a test is valid or not (Fig. 22).• Supports of the bending unit

are optimized for thecharacteristics of carton orcorrugated board.

• Measured results are mostlyindependent of warp or shrinkof the specimens caused byproduction.

• The test is performed within theelastic range of the specimen.

Forc

e in

N

Deflection in mm

Standard ISO 5628Material corrugated board,

cardboardZwick-Item-Nobending test rig 070290.00.00*load cell TC-LC0500N.F02 fftest program 069002.20.fffor specimenswidth max. 100 mmlength max. 400 mmto machines from zwicki

16

Thickness measurement

Paper thickness is measured forvarious reasons:The stiffness of paper and cartonare dependent on the thickness.Therefore, an exact thicknessmeasurement is critical in thestiffness of a carton and process-ability in a packing or printingmachine. If the weight per unit areaand thickness of a paper is known,the weight-referenced volume canbe calculated. This is important forthe transportation of larger amountsas well as for the processing of thesematerials.

Digital thickness measuringinstruments, which work correctly toStandards and pass their values onto subsequent systems, save timeand ensure secure data (Fig. 23).

The advantages:

• Pressure foot area, loadingweight and lowering speed areavailable for all normal standards.

• Individual and seriesmeasurements are possible.

• PC-connection via built inRS 232 interface.

The penetration test

The quality of a corrugated boardbox is not only dependent on thestiffness of the material in just themachine or cross directions. Duringthe penetration test, the materialis loaded in all directions due tothe pyramid formed penetrator.Therefore, the tensile, compression,bending, and shear forces, appearsimultaneously. The result of thistest is the energy absorbed duringpenetration of the material.According to recent standards, thistest is performed with a pendulum

Fig. 23: Thickness gauge for corrugated board Fig. 24: LPET-Test in a testing machine

impact tester. This instrument canbe used stand-alone or connectedto a computer. Since the penetrationtest with a pendulum has severalweaknesses, (oscillation of thependulum, no linear movement, noconstant test speed, high measuredvalues deviation, poor handling),Zwick offers an alternative testwith a material testing machine.

With the linear motion penetrationtest (LPET), the penetration pyramidis pressed through the specimen inan even movement (Fig. 24 and 26).The pyramid is driven and controlledby a testing machine. The force-pathcurve (Fig. 25) is acquired by theelectronics. The result is the energyrequired for penetration, which issimilar to the pendulum impact test.

The standard deviation of thedata due to testing machines issignificantly better than that froma PET pendulum (Fig. 27 and 28).On a lot of materials, the correlationbetween a PET pendulum and theLPET method is very close. It is neverthe less recommended to individuallycheck and measure the correlationof different materials.

Standard ISO 534EN 20534TAPPIT 411

Material paper, boardZwick-Item-Nothickness gauge W070550.00.00Standard ISO 3034

TAPPIT 411Material corrugated boardZwick-Item-Nothickness gauge W070540.00.00

Standard ISO 3036TAPPIT 803

Material corrugated boardcardboard

Zwick-Item-Nopendulum tester on requestfor specimenswidth 300 mmlength 300 mm

17

Fig. 27: Test result distribution on single-flutecorrugated board

Fig. 28: Test result distribution on triple-flutecorrugated board

Since the measurements,„force“ and „travel“ are acquiredelectronically, the measurementrange is much larger than apendulum impact test. Theoretically,materials from a basis weight of 80g/m², up to heavy duty corrugatedboard with a thickness of 17 mm,and an energy of approx. 40 J, canbe tested without mechanicalchangement of weights. Thesecharacteristics make the testingmachine much quicker and secure.

Zwick/Roell is working withtechnical paper institutes andwell known industrial companies,on the industrial introductionand standardization of this test,which is in its introductory stage.

For tests on tissues, a similar testmethod has been set up using aball indenter. Zwick/Roell is ableto offer this test equipment.

Fig. 25: LPET test curves

Fig. 26: Puncture phase

The advantages:• small deviation in the results• no changing of weights• no system friction• no erroneous oscillations• no manipulating hold-back

collars• tests can be performed on

materials from 80 g/m² up toheavy corrugated board withoutretro-fitting

• ability to perform wet tests• similar test rig for tissue tests

The tear test

By using a tear test, this gives paperprocessors an estimated value ofthe future behavior of the endproduct (multi-layered carton,corrugated board). The tear testaccording to Elmendorf, is used asthe quality control criteria for thepaper producer (final inspection) aswell as for the processor (incominggoods quality control ).

A tear test is performed in secondstherefore, the test data must bequickly acquired and evaluated.The Elmendorf-Pendulum fulfillsthese requirements with a simpleconnection to a PC. Thus theraw data (energy values) can beconverted into force values and theneasily transferred to a QDA-System.

Energy in J2,5 3,0 3,5 4,0

0

10

20

30

40

Pendulum 1

Pendulum 3Pendulum 2

Testing machine

Rel. probability

Energy in J

0

1

2

3

25 27 29 31 33 35

4

Rel. probability

Testing machine

Pendulum 1

Pendulum 2

Pendulum 3

Standard DIN 53142-2 inpreparation

Material corrugated board,cardboard

Zwick-Item-Nopuncture test rig 070378.00.00*load cell 066070.03.00

TC-LC2:5KN.P01test program 069002.63.fffor specimenswidth 180 mmlength from 180 mmto machines from zwicki

Standard prEN ISO/FDIS12625-9

Material tissueZwick-Item-Nopuncture test rig X070378.00.00-

001*load cell 066140.03.00

TC-LC0010N.P01test program UZV001for specimenswidth 180 mmlength from 180 mmto machines from zwicki

18

The advantages:

• easy PC connection via RS 232interface

• established robust instrument

Fig. 29: Correlation between the LPET andthe Elmendorf test

Crush tests on corrugatedboard and corrugated boardraw paper

It is important for these tests(Figures 30 to 33), that the forcesare applied exactly vertically tothe specimen during the test.Precision guided compressionplates provide an extremely hightransverse stiffness. They insurethe reproducible results of the crushcharacteristics in corrugated boardraw paper and corrugated board.

The Corrugating medium test

The Corrugating medium testprovides information about thebehavior of a corrugated paperafter it has been formed in a fluter.A section of corrugated paper isglued one-sided, to a carrier paperand then loaded in compression.The maximum load characterizesthe behavior of the paper duringthe converting processing steps(punching, printing) after boardproduction. A disadvantage of thismethod is that only the A-corrugat-ion is tested. For other types ofcorrugations, the behavior incompression mode must bemathematically calculated.

Addition, this method takes a lotof time and requires much skill inmaking the specimen. For thesereasons, Zwick-fluters are deliveredwhich include a „third hand“. Withits help, a specimen can be easilyand quickly prepared.

The Flat Crush Test

In the flat crush test, a single-flutecorrugated board specimen isloaded perpendicular to its surface.The resistance this corrugated boardpresents to the force, gives anindication of its behavior in furtherprocessing and use. Characteristiccurve: according to the height ofthe individual flutes, the highestflutes break first, then the middleones and then finally, the rest ofthe flutes. If the corrugated boardhas leaning or crushed flutes, it hasbeen predamaged, and the curveis fundamentally different. The crush

Fig. 31: Flat crush test: test curves showingcorrect and pre-damaged material

Fig. 30: Specimens for: flat crush test, ringcrush test and corrugating medium test

Empirical tests can be performedon a testing machine. Tensile gripsor the LPET penetration test rigmay be used for such tests. Testresults from LPET and Elmendorfshowed a strong linear correlation(Fig. 29). The correlation should becrosschecked for individual papergrades.

0,0

LPET in J

0

2

4

6

Tear force in N

Tear resistance = 3,286 * LPET - 1,503R² = 0,9978

0,5 1,0 1,5 2,0 2,5

ok

predamaged

Standard ISO 7263TAPPI T 809

Material corrugatedmedium paper

Zwick-Item-Nocompression 070457.00.00*platestest program 069002.67.fffluter XW90000-016for specimenslength 150 mmwidth 12,7 mmto machines from zwicki

Standard ISO 1974TAPPIT 414

Material paperZwick-Item-NoElmendorf- on requestpendulum testerfor specimenslength 62 mm (ISO)

63 mm (TAPPI)width 50 mm (ISO)

53 mm (TAPPI)

19

energy and data curve, provide theuser with valuable information aboutthe degree of damage.

Modern miniature flutes tend to crushonly at forces greater than 10 kN,requiring excessive lateral stiffnesson the compression plates. Forthese applications, Zwick offersthe suitable compression test rig,too (Fig. 32).

Fig.33: Edge crush test using guidedcompression plates

Fig. 32: Compression plates for the flat crush test on miniature corrugated board (left, F > 10kN) and on standard corrugated board (right, F � 10 kN)

The Edge Crush Test

This gives information about thestrength of corrugated board atstanding flute orientation (Fig. 33).The edge crush resistance goesinto the McKee formula that is soimportant for quality control incorrugated board factories. Thespecimen must have clean, paralleland perpendicular edges, and the

material must be free of pre-damage. A hinged scissors or aknife is not suitable for cutting.Good results have been achievedwith a circular saw that Zwick offersfor this purpose (see page 27).

The Ring Crush Test

The ring crush test is similar tothe strip crush test in that thestrength of liner or fluting ismeasured in the machine andcross directions. The results inthis test are highly dependent onproper specimen preparation. Thespecimen, as well as the test fixturemust be parallel in order to insurean exact determination of thering crush strength. Since the ringcrush test provides more inform-ation about the buckling behaviorrather than about crush behavior,it is being replaced by the stripcrush test.

The advantages :

• light, precision guidedcompression plates preventlateral yielding of thespecimen during the test

• suitable compression platesfor miniature flute board inZwick´s standard program

• automatic recognition ofbreaking on all flutes preventsmisinterpretation in the flatcrush test

• inserts for the ring crush testfit into the compression plateswithout a problem. Lateralyielding of the specimen isalso prevented.

• a data graph of the test run isstandard with all tests.


Standard ISO 3035EN 23035TAPPI T 811

Material corrugated paperZwick-Item-Nocompr. plates 070457.00.00*up to 10 kNcompr. plates 070456up to 250 kNtest program 069002.67.00circular cutter W070560.00.00for specimensdiameter 112,8 mmto machines from Z005/TS1S


Material corrugated paperZwick-Item-Nocompression 070457.00.00*platestest program 069002.68.ffECT-saw W070600.00.00for specimenslength 100 mmheigth 25 mmto machines from zwicki


Material corrugatedmedium paper

Zwick-Item-Nocompression 070457.00.00*platesinserts 070455test program 069002.51.ffstrip cutter on requestfor specimenslength 152 mmheigth 12,7 mmto machines from zwicki

20

The Strip Crush Test

The paper’s characteristic„compressive strength” can bedetermined by the strip crushtest with high accuracy. Becauseof the short test length of only0.7 mm, the load bearing fibreportion of the material is takeninto consideration more than withthe traditional testing methods(ring crush test or corrugated crushtest). The Zwick test arrangement(Fig. 34) has unique characteristicscompared to the normal horizontalmachines:

• Zwick uses a load cell with ahigh nominal load. This makesthe measuring chain very stiffand keeps backlash effects fromthe machine to the specimenreduced to a minimum.

• Specimen and load cell lie inthe same symmetrical axis.Erroneous bending momentsare nonexistent.

Since resolution and accuracy ofthe Zwick measurement electronicsis extremely high, paper can beaccurately measured from 80 upto 400 g/m² and higher (Fig. 35).

Fig. 34: Strip crush test grips

Because of its technologicaladvantages, the Strip Crush Test isbeing more accepted worldwide.

The advantages:

• an inexpensive accessory tobe used with a Zwick machine

• has the necessary stiffness forcompression tests because ofthe load cell with high nominalload

• very little retroactive affect on thespecimen due to the symmetricaldesign

• Easy-to-use user interface forquick control of the test run

Fig. 36: Laboratory balance

Determination of basis weight

Selection criteria are: accuracyand resolution of the balance andthe electronic transfer of the weightto a computer. In order to balancefeature and price requirements,Zwick/Roell and its partners offera range of precision balances fromhighly accurate analytical balancesto balances with a limited range(Fig. 36).

Fig. 35: Strip crush test-series


Material corrugated boardraw paper

Zwick-Item-Nogrips 070377.00.00*load cell 066070.02.00

TC-LC2.5KN.F02test program 069002.58.ffstrip cutter W070500.00.00for specimenslength �110 mmwight 15 mmto machines from zwickispecial grips on requestfor cardboard

Standard EN ISO 536ISO 5638

Material paper, boardZwick-Item-Noanalysis balances50 g W40022.01.00100 g W40022.02.00for specimensdiameter 113 mmor any area, to 1 %

accurateStandard FEFCO Nr. 2Material corrugated boardZwick-Item-Noanalysis balancesup to 400 g on requestfor specimenslength 250 mmwidth 200 mm

21

Internal Bond Test(z-direction tensile test)

For multi-layered materials (duplexpaper, coated paper), the internalbond strength of the layers to oneanother is an important characteristic.It determines the further process-ability. When testing to TAPPI T 541,the load on the specimen mustbe perpendicular to the surface ofthe specimen. In order to eliminatethe effects from grips or fixtures tothe separation of the layers in atest, the tensile force must bemaintained in its vertical directionthrough rupture. High lateralstiffness and absolute parallelismof the specimen holders is critical fora proper test. Therefore, Zwickdeveloped a special test rig forholding the specimens, which arecrossed over at an angle of 90 °,and which accept a paper stripof 5 specimens. Thus, using onesingle application, 5 tests can beperformed without further handlingof the specimen (Fig. 37 and 38).The specimen holders are mountedon precision compression platesand are parallel and stiff in alldirections.

Fig. 37: Internal Bond Test – test rig andsample preparation unit (bottom right)

How the specimen is applied: usinga double sided self adhesive tape,a paper strip is glued onto onespecimen holder. The second holderis applied with only a doubleadhesive tape.

During the test, the specimen isat first pressed against the twospecimen holders. Compressiveloads, as well as pressing timeare freely adjustable. After thecompressive phase, the tensile testis performed within half a second.

The test result is the tensile strength,which is the maximum tensile load,related to the sample’s surface area(Fig. 39).

The z-tensile test rig is available asa manual version, as well as asemi-automatic one. With thesemiautomatic test rig, a secondpaper sample can be preparedduring the time while testing thefirst sample set of 5 specimens.

Compared to Scott bond tests, thez-tensile test has proved to havemuch less resultant dispersion.Similar tests: ply-bond strength toDIN 54516 and Scott Bond Testto TAPPI T 403. In these tests,the specimen is subjected to peelloading.

Fig. 38: Internal bond test, test run


Fig. 39: Internal Bond Test – total test curve(top) and tensile phase (bottom)

The Scott Bond Test is performedwith a pendulum impact tester. Thistakes into consideration the highprocessing speeds of this material.

-1000

-500

0

500

0 5 10 15

Test time in s

Stress in kPa

-1500

compressivephase

tensile phase

200

400

600

16,85 16,90Test time in s

Stress in kPa

0

16,95

Standard TAPPI T 541Material duplex-papers,

plybondsZwick-Item-Notest rigmanual X070457.00.00-01automatic X070457.00.00-02test program on requestfor specimenslenght appr. 140 mmwidth 25,4 mmto machines from zwickiEquipment for on requestplybondstrength toDIN 54516Scott bond on requesttester

22

Measuring Coefficient ofFriction

Friction of paper and papercompounds is important for furtherprocessing in automatic systems.For the determination of thecoefficient of friction, an importantfactor is the material of the twosurfaces to be measured, „paperagainst paper“, or „paper againstother materials“. Another decidingfactor is whether the static frictionor the dynamic friction is to bemeasured. Zwick/Roell offers toolsand software programs for all ofthese methods. This gives the user

Fig. 40: Determination of static and dynamicfriction

The advantages:

• Friction units to TAPPI with fastplacement of the specimen

• A wide variety of friction testsresults are available in testXpert

• Strip friction unit for tests on„virgin“ surfaces

The advantages (TAPPI T 541):

• quick placement of the specimen by using a semiautomaticmachine even while running atest series

• pressure step and z-tensiletest without specimen handling(Fig. 39).

• compressive strength and com-pression time are freely adjustable

• Use of only half the standard areafor tests on high strength papers

confidence in the test results andthen ultimately in finding a solutionfor packing or printing problems.Two basic measuring techniquesare available:

• the „Horizontal Plane Method“(Fig. 40 and 41), in which thestatic and kinetic friction aredetermined with one sled

• The „Strip Method“: two materialstrips are pulled over pressedrolls in opposition to oneanother. The advantage of thismethod is that the only surfacesthat are tested are the onesthat have not been in contactwith each other (Fig. 42).

Most tests using the „HorizontalPlane Methods“, are tested toTAPPI. The ISO methods aremore complicated, since the entiremeasuring operation (applicationand driving of the sled) must notbe performed manually. Initialstudies of tests on corrugatedboard [1] showed that the valuestested to ISO correspond to TAPPI.

Zwick-Software testXpert®

determines a wide range of frictionresults: static and dynamic friction,peak values, upper and lowermedian of peaks. This provides theuser with results that are needed forsubsequent material processing.

Fig. 41: Horizontal plane method


Fig. 42: Friction test, strip method

Standard TAPPI T 541TAPPI T 816

Material paper, foilsZwick-Item-Nofriction test rig 070415.00.00*manuall 070412.00*test programm 069003.02.ffcutter on requestfor specimenslenght 300 mmwidth 150 mmto machines from zwicki/

BasicLineStandard w/o

(strip method)Material paper, foilsZwick-Item-Nofriction test rig X8100.00.00-032test programm 069003.00.ff plus

XD069003-002strip cutter15 mm width W070500.00.0025 mm width W070510.00.00for specimenslenght 300 mmwidth 25 mm und 15 mmto machines from zwickiStandard ISO 15359Zwick-Item-No on request

23

Laboratory creasing

A testing machine can be usedfor the determination of creasingparameters. In a laboratory test aspecimen can be creased withfreely adjustable values for:

• width of the creasing tool• width of the nut,• nut depth• creasing stroke.

Because of the high creasingspeed and the excellent positioningaccuracy, as compared to manualcreasing presses, creasing canbe determined very precisely. Thediagram (Fig. 43) shows that adecrease in force occurs duringthe reversal of the creasing tool.This is a measurable indication thatthe internal fibre bond is partiallydamaged, which corresponds tothe creasing characteristics in theproduction process.

Fig. 43: Laboratory creasing diagram

Box Crush and Stacking CrushTests

These tests are used to determinethe strength and the stackingcapabilities of corrugated boardboxes. The complete box iscompressed to a specified loador until failure. The EuropeanStandards require rigid compressionplates if the behaviour of a boxis being tested by loading iton opposite corners or sides.The upper plate must be spherically

pivoted when loading the box onopposite surfaces. However, TAPPIalways requires rigid compressionplates. The European Standardsdistinguish between the Box CrushTest and the Stacking Crush Test.In the Box Crush Test, thecorrugated board carton is loadedsteadily to nominal load or untilfailure. In the Stacking Crush Test,a certain load is held constantfor a certain time or until failureof the box.Machines, either standard or tocustomer specifications (Fig. 44),also offer correct applicablesolutions for combined tests.

Fig. 44: Box-crush tester for specimen up to a footprint of 2 m by 2 m (authorized by SCAPackaging Research, European Technical Centre, Aylesford)

Creasing stroke in mm

0-0,1

Force in N

0

0,1

0,2

0,3

0,4

0,5

20

40

60

80

100

0,4 0,6 0,8 1,0 1,2Test time in s

Standard DIN 55437Material paper, boardZwick-Item-Nocreasing tool on requesttest programm on requestfor specimenslength 140 mmwidth 50 mmfor specimens from zwicki

24

The advantages:

• Standard and customer specificmachines for optimal testing

• Available solutions for box widthsup to 2000 mm

Water absorbtion to Cobb

Water absorbtion of raw paper isdetermined with the Cobb Test.The principle is:

• The dry specimen is weighed• The specimen is placed under

a cylinder with an inner diameterof 100 cm². Specimen andcylinder lie on a rubber and asteel plate

• Approx. 100 ml water is pouredinto the cylinder

The advantages:

• Operator friendly instrumentwith quick clamping

• also available for corrugatedboard

• After a specified waiting time,the water is poured out. Excesswater is removed from thespecimen with blotting paperand roller.

• The specimen is weighed whilewet and the amount of water iscalculated that 1m2 of specimenmaterial would absorb.

A complete Cobb-Test-Kit can beobtained from Zwick or its partner.

Tear Propagation Test

This characteristic is important forfinding and avoiding weak spotsin packaging with folded edges orbonded seams (Figures 45 and 46).It can be performed on a lowcost testing machine such asBasicLine machines for tightbudgets. In addition, it givesvaluable information about thequality of materials and aboutthe consistency of the productionprocess.

The advantages:

• Tensile and tear propagationtests can be performed withthe same equipment.

• Peaks and median values arecalculated in one operation

• Easy to use menus simplifiesthe work

Fig. 45: Tear test: diagram

Fig. 46: Packing edge with bonded seam in atear test

Standardbox crush test ISO 12048

EN 22872stacking test TAPPI T 804

EN 22874Material corrugated boardZwick-Item-Nocompressionplates400 * 400 mm 070091.55.10*400 * 600 mm 070091.55.14*special versions on requestload cell 066050.02.00 ff

TC-LC005KN.F02fftest programsbox crush test- 069000.00.ffstacking test 069015.09.fffor specimenslength boxes according towight the machine´s testhight spaceto machines from Z005/TN2Sff

Standard ISO 11897Material paper-foil-

compoundsZwick-Item-Nogrips 8133.00.00*

8253.00.00*TC-LC2.5KN.F02

test program 069003.01.fffor specimensdimensions acc. to the

productto machines from zwicki/

BasicLine

Standard ISO 535EN 20535TAPPI T 441

Material paperZwick-Item-NoCobb test kit On requestfor specimensdiameter 112,8 mm

25

Wet tensile test

These tests are useful fordetermineing several differentpaper characteristics such asusage properties of tissues, printingquality of offset printing papers,and runability characteristics inthe wet end of a paper machine.

Tissue

The wet strength is one ofthe most important materialcharacteristics for papers thatare used wet or are subsequentlyprocessed. Zwick offers a quick,dependable method for thedetermination of wet tensile toFinch (Fig. 47). Simple handlingof the Finch clamp and a fastchange over between wet tensileand other tests highlights theuse of Zwick´s testing technology.

Fig. 47: Wet Tensile Test

Offset-printing papers:When running paper through theprinting units of a 4-color offsetprinting machine, the humidityof the paper increases steadilyon the printed areas. This increaseof humidity causes an elongationof the paper in the machine andcross directions. While theelongation in machine directioncan be corrected by gauge pins,it cannot be corrected or adjustedin the cross direction. In order to

Fig. 49: Zwicki, equipped with horizontal testspace and automatic test start

avoid „fan out“ of the individualcolor prints, the elongation incross direction must remain withinspecific limits. The importanceof not exceeding these limitsincreases with increasing recyclingrate and decreasing basis weightof the paper. Testing the force-deformation behavior duringincoming quality control, is apowerful costs saving tool. Fora valid test, the paper must bepreconditioned at a well-definedhumidity and then tested withina very short time. The slope ofthe elongation-force-curve canbe used to determine the limitsof high quality offset machinesystem that can test a specimenwithin seconds after taking aspecimen out of a conditioningbox (containing a water-acetone-solution in an exact ratio). Thus,the degree of humidity does notchange within this short test time.

Only the elongation between thegrips is needed for determiningthe force-elongation behavior ofthe specimen. Zwick´s standardgrips and jaw faces fulfill theserequirements and prevent gripslippage and failures within theclamping area of the sample.

Fig. 48: Tensile test at defined humidity,elongation as a dependant variable


Elongation in %


Material tissueZwick-Item-NoFinch grips 070465.10.00*to grip 8133.00.00*test program 069001.47.00strip cutter lever shear on

requestfor specimenslenght appr. 200 mmwidth 50 mmto machines from zwicki

Standard ISO 1924

Material paperZwick-Item-Nomachine XZ2.5/TS1S-005test program XD069001-005

069001.00.ffstrip cutter W070510.00.00

for specimenslenght appr. 240 mmwidth 25 mm

26

Runability at the wet endThe paper is very susceptible toweb breaks when it leaves thepaper former machine and runswithout any support by a felt or ascreen. Adjusting and controllingthe web tension, as well as usingwet paper with minimal initial tensilestrength values, can avoid webbreaks. The minimal tensile strengthof the paper depends on the stockcomposition (ratio of long and shortfibers, chemical additives). Theoptimal price-strength-ratio canbe evaluated through initial wettensile tests. Special tensile grips(Fig. 50) assure correct clamping,draining within the clamping areaof the specimen, and preventsspecimen breaks within theclamping area.

The advantages:

• correct specimen gripping• fast and easy handling• high flexibility through the

testXpert® master program

Fig. 50: Tensile test on initial wet paper

Tensile test

As a common test on papermaterials (Fig. 51), tensile testsprovide valuable informationabout properties such as stiffness,modulus, tensile strength, tearinglength and energy absorbtion.

Since only the tear strength ortearing length result is to be

Fig. 51: Tensile test on dry paper,pneumatic specimen grips

determined in many cases, otherresults can be hidden by software.The testXpert® software fromZwick accomplishes this withtwo functional levels. The first levelis the use of built-in Standard tests.Standard tests contain only testsequences and results whichare required by test standards.The adavantage of using theStandard tests is that trainingcan be accomplished in a shorttime. The second level is theMaster program. This level willprovide functionality to meet allcurrent and future needs formaximum flexibility.


Standard ISO 1924Material initial wet paperZwick-Item-Nogrips X8100.00.00-058*test program 069001.00.00

for specimenslenght appr. 200 mmwidth 50 mm

to machines from zwicki

Standard EN ISO 1924TAPPI T 804

Material paperZwick-Item-Nogrips 070465.10.00*test programm 069001.00.00strip cutterwidth 15 mm W070500.00.00width 25 mm W070510.00.00width 50 mm W070520.00.00for specimenslength appr. 200 mmwight 15, 25, 50 mmto machines from zwicki/

BasicLine

27

Specimen preparationCustomer specific tests

Specimen preparation

Specimen preparation is criticalto obtaining good results.Thefactors that effect creating agood specimen are, clean cutsperpendicular to the specimen,parallelism, service life of cutters,and speed. Zwick/Roell haspartners that specialize inmanufacturing high quality cuttingunits. Figures 52 to 55 show asegment of the instrumentsused for specimen preparation.

Customer specific tests

The area of paper materials doesnot begin with paper manufacturingand does not end at the processor

for Zwick. Suppliers and endusers also profit from Zwick/Roellsolutions. A partial list of potentialcanidates for this equipmentwould be, suppliers who must testtheir chemicals on finished paper,printers who must optimise thestiffness values of bindings, largepackaging customers. Ourcustomized tests could enhanceyour quality control:

Fig. 55: FluterBild 54: Strip cutter

Fig. 52: Circular cutter for FCT specimen Fig. 53: Saw for ECT specimen

Determination ofProportionality Load Fprop

During the storage of packedgoods, the packaging is subjectto load variations in stacking andremoval operations. They are alsosubject to static force changescreated in transport. Therefore,testing is performed so thatpackaging can be manufacturedthat can withstand long term elasticform changes. The limit of theelastic deformation (ProportionalityLoad) is measured as follows:• the maximum slope on the force-

deformation curve is determined• from the maximum, a slope

declination of x % is definedin the direction of the tests end

• the load found here is theapplicable ProportionalityLoad Fprop (Fig. 56).

Dimension measurement

Boxes for consumer goods arefilled and closed by automaticsystems, and they are oftensold from automatic machines.Size accuracy is an importantcharacteristic so that theseautomatic operations areperformed without hindrance.

maximum stiffness (Modulus) = 100 %

stifness decrease of x-%after the max. stiffness:

Fprop

Fprop

Force

Deformation

Stiffness

Fig. 56: Measuring the proportionality load

Zwick-Item-NoStrip cutter15 mm width W070500.00.0025 mm width W070510.00.0050 mm width W070520.00.0015 & 25 mm width W070530.00.00Circular cutterdiam. 112,8 mm W070560.00.00diam. 79,8 mm W070570.00.00ECT-saw W070600.00.00Medium fluter W070600.00.00

Other on requestinstrumentsfor specimenpreparation

28

Location dependentdeformation measurement

Good stackability of goods lowersstorage costs. However, due tosafety and economic concerns,there is a limit to how high goodscan be stacked. The location andmode of failure of packaging is animportant factor for an engineerto consider when optimising thepackaging. A Zwick/Roell machine,equipped with several travelmeasurement systems, determinesthe deformation of a corrugatedboard carton including the innerpacking and contents (Fig. 58).The location of the maximumdeformation can be mathematically

calculated from several individualdeformations measurements. Thedeveloper of the packaging cangain valuable information aboutpossible weak spots. Box CrushTests and Stacking Crush Testscan also be performed correctlyto Standards with this machine.

Compressibilitycharacteristics

The compressive force-deformation-behaviour is important for thedeveloper of high quality offsetpapers. Proper printing, withoutmissing or blurred dots can beachieved by optimizing the elasticand plastic behaviour of the paper.Both characteristics can beevaluated through a compressibilitytest. In this test, a sample is loadeduntil a compresive force is reachedthat is similar to that in an offsetprinting unit. Force and deformationare measured simultaneously.Because of the small deformationsin the µm-range, a high resolutionextensometer is required. TheZwick solution comes fromhardness testing, where comparablysmall deformations must bemeasured. A floating compressionplate is loaded via a spheric loadingbar and applies the compressive

Fig. 57: Measurement of the buckling of afilled, folded box

Fig. 58: Measuring the local variationdeformation of a packing box

Fig. 59: Compressibility test head prior to test

Fig. 60: Compressibility diagram

force to the paper. The deformationof the paper is measured with aresolution of 64 nanometres. Thetest graph shows the specimen´sbehavior during the loading phaseas well as during the unloadingphase. From both sections of thegraph, the following test results arecalculated (Fig. 60):

• the maximum stress• the total deformation before

and after a dwell time• the plastic deformation• the elastic deformation from the

difference of and

From these results, the design –engineer gets a complete pictureof the force deformation variablesthat effect the paper during theoffset printing process.

Zwick/Roell testing machines arevery well suited for statistical sizecontrolling because of their broadmeasurement range and accuracy.In such a test, the machinemeasures several height differencesrelative to a reference point(Fig. 57). The measured pointscan be approached purely manuallyor automatically. The data maybe exported in many ways forsubsequent evaluation of measuredvalues, from local printer up to PCprogrammes for statistical qualitycontrol.

3 4

1

2

3

4

0 0

4 86 102

100

200

300

400

Stress in kPa

2 3

1

4

Deformation in µmNominal size

Oversize

29

Customer specific tests

The advantages:

• Cost efficient equipment throughuse of standard components

• Deformation of a single sheet ofpaper can be measured directlyand with very high resolution.

Fig. 61: Compressibility test using zwicki


Dynamic tests

For endurance test on packages,static tests are necessary, but notsufficient. Acceleration forces asapplied during loading, transportor stacking that can only cansimulated with dynamic machines.Zwick/Roell Group manufacturesthese type of testing machines.testXpert® can use the same user-interface as the static systems ondynamic systems to performendurance tests under realisticconditions, high-speed tests(Fig. 62), and shock tests. Thismakes packaging design moreefficient by shortening thedevelopment time, costs, andfailures.

Fig 62: High speed testing machine, up to 20m/s

Standard customer specificZwick-Item-Nodetermination of on requestpropertionality load

dimension-measurement on request

location on requestdependentdeformationmeasurement

compressibility 065241.00.00*measurement X065240.21.00-001

X065240.21.00-002X069006.00.00-24

30

Automation

Since quality control is not anend in itself, cost efficiency is veryimportant in testing and evaluation.Automation can be a valuabletool to save costs and obtainreproducible results with fewervariations.

Automated specimen feeding isavailable in “Clip“ type constructionthat is suitable for non-stablesamples such as paper or fleece.When the corresponding specimen

Laboratory data acquisition,Subsequent data evaluation

Quality Control does not end withthe testing of the end product.The consistency of all productionprocesses can be measured withthe aquired data. However, this isonly possible if the acquired datais studied over a long period of timeand if data can be correlated fromvarious tests. By applyingconclusions to the production,the control loop is closed from theinitial material to the end product.

clamps are used, tests on carton orcompounds can be automated aswell.

The testing system in Fig. 63consists of a tensile testing machineand an automatic specimen feedingsystem (Handling System). TheHandlng System has two controlleddriving axes and a circulating carrierchain with up to 200 specimenpositions. The positions can bemade of metal clips or clamps andare optimised for various specimenforms.

With the freely programmable,servo controlled driving axes,the carrier chain can be preparedwith the most varied specimenholders. The system is monitoredby a control which is storageprogrammable. The test evaluationis performed by testXpert®. Thepossibility of manual testingwithout retro-fitting is standard.

Good-bad sorting, via toleranceinputs, and controlled removal ofspecimen remains are options.

Fig. 64: testXpert® test reportFig. 63: Automatic testing machine: tests on sanitary products

31

List of sources

[1] Urs Ernst: Determinationof the static coefficient of frictionon corrugated board and linerpaper Corrugating International,April 1999

Product illustrations

Title page:Papiertechnische Stiftung,München

Fig.3:Paul Hartmann AG, Heidenheim

Fig.4:Hengst Filterwerke, Münster

Fig.5:Staatl. Molkerei Weihenstephan AG

Fig. 43:SCA Packaging Research,European Technical CentreAylesford

Reserved to technical modifications

The ddw-GmbH in Lübeck andZwick have worked together foryears in the area of statisticalprocess control. The target of bothcompanies has been to collectand analyze data from varioustesting processes in differentdepartments of a company.(Fig. 65). The Quality Data Analysis-(QDA) Software of ddw fulfills thisfunction and offers an extensivespectrum of performance.

In the simplest case, the followingcomplement each other:

• the test protocol (Fig. 64)provides a snapshot of theproduct’s quality

• the control card as a control instrument (Fig. 65) for mediumobservation time frames

• the long-time diagram (Fig. 66)for an ideal overview.

Histograms (Fig. 67), frequencydistribution of sums and technicalstatistical evaluations, make theQDA-Program a very usefulinstrument for the control of aproduct’s quality.

It is natural that all data must becollected before the evaluation.Modern instruments are equippedwith a standard data interface. Withthis, the test data are written intothe corresponding fields of theQDA-program. If instrument datatransfer interfaces are missing, theQDA-software also offers manualinput possibilities. Special Zwickinstruments can be connected intothe data network quickly andwithout problem via testXpert®.

Data acquisition, data storage andanalyses are not just limited to thequality data of the end product andmechanical testing. Just as import-ant is the tie-in of important datafrom the raw materials as well asenergy and emission values.Zwick/Roell and its partners arealso ready to help you in this areathrough know how and expertpersonnel.

Fig. 66: Long time diagram Fig. 67: Histogram, classification of testresults

Fig. 65: Process control card

Documents

Testing Machines for Paper Materials - zwick.com.t · Testing Machines for Paper Materials FP 290 2.0903.202. 2 The Zwick/Roell Group Mechanical-technological testing is the oldest