Testing Machines for Paper Materials...Pin-adhesion-test TAPPI T 821 Testing machine, fixture 30...

Testing Machinesfor Paper Materials

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Intelligent Testing

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Contents Page

The Zwick Roell-Group ................................................................................................................................... 2Paper and paper based materials ................................................................................................................... 3Quality 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: zwicki-Line, ProLine, and Allround-Line ............................................ 8Features of the ProLine, Standard, and Allround line ..................................................................................... 10Zwick Roell Test Software testXpert® II .......................................................................................................... 11Test Methods in the paper industry ............................................................................................................... 13Specimen preparation ................................................................................................................................... 35Customer specific tests ................................................................................................................................. 36Laboratory data acquisition ........................................................................................................................... 38Automation ................................................................................................................................................... 39Sources listing............................................................................................................................................... 39Producing companies, Sales and Service companies ................................................................................... 40

The Zwick Roell Group

Mechanical-technological testing is the oldest disciplinein materials testing. Its importance has constantlygrown to date. In the 15th and 16th centuries, Leonar-do da Vinci and Galileo Galilei already expressedthoughts about flexure loading and the elastic proper-ties of materials. The first testing machines for thesepurposes were made in the middle of the 18th centuryin France.

The Amsler company in Gottmadingen (formally inSchaffhausen, Switzerland) has been involved withmaterials testing since the middle of the 19th century.The Roell & Korthaus company started producinginstruments, machines and systems for material testingin 1920. Zwick started producing instruments in 1937.The Zwick Roell group of companies was broughttogether in 1992, and now markets a complete line ofsystems from hand operated hardness testers tocomplex computerized testing systems.

This brochure gives an overview of the instruments,machines and systems of the Zwick Roell Group forpaper-based materials. Its purpose is to give suggesti-ons and hints to all, who have even the smallestinterest in paper testing.

Many years of experience, a multi-tude of deliveredequipments and constant communications with users,are the basis of our machines and instruments.

Fig. 1: Paper then and now

We achieve high flexibility and „intelligence“ of oursystems with modern mechanics, high performanceelectronics and user-oriented software.

The performance of the Zwick Roell Group reaches farbeyond the delivery of testing instruments. The compa-ny was certified to DIN EN ISO 9001 in 1994, whichguarantees a high degree of product and servicequality. As an accredited DKD Calibration laboratory,Zwick is also authorized to check and calibrate testingsystems. Internationally recognized certificates help tocompete in international markets.

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Fig. 4: Hygienic articles giveprotection

Fig. 3: Paper compounds indaily use

Fig. 2: Paper for technical usesFig. 1: Paper as robustpacking

Paper and paper materials

Paper has accompanied man since ancient times(Fig. 1, page 2). Papyrus rolls show that man searchedfor, and found, a medium with which information couldbe stored and spread, while saving space and weight.This did not remain the only use. Books, and laterindustrial production of paper found new applicationsfor this material. In the broadest sense, paper can be astructural material today, which carries and protectscontents on the inside, while being an attractive infor-mation carrier on the outside (Fig. 1). Paper is tech-nically a highly exacting product, which works depen-dably in its application and is easily recyclable at theend of its useful life.

Paper in technological areas cannot be forgotten. Filter,protection and special papers must be tested for theircharacteristics and they must be monitored (Fig. 2).

In a close relationship to plastics and metals, we findpaper also as a compound material (Fig. 3). Thecombination of characteristics of the compoundpartners gives the end product its special capabilities.

Paper is around us in everyday life: as sanitary orcosmetic tissues in hygienic and care areas (Fig. 4).

Quality control - a key leading to cost- andfunction optimized products

Although continuous quality control makes some effort,it anyway helps to save material and complaint costs.

Example in corrugated board testing:If the raw papers are tested in a separate test lab,fluctuations of the strip crush resistance (SCT) can berecognized impartially and considered. Furthermore, ifstrength values and bending stiffness of the corrugatedboard and the boxes are monitored, variations in thecorrugator or in the following converting machines canbe discovered and adjusted.

The tests mentioned above may also be used for thestrength prediction of a box from the crush results oftheir related papers. A good estimation assures themerchantability of packagings during their lifetime, evenunder consideration of environmental influences duringtransport and storage.

Zwick machines accept all the necessary test tools forthese tests (Fig. 1, next page). Thus, using one machi-ne, one can perform the incoming inspection qualitycontrol on papers, tests on corrugated board, and thefinal quality control of boxes. (Fig. 2, next page)

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Testing of paper for corrugated boardproduction

Testing of corrugated board and itsproducts

Testing of special papers, graphic papersand printing papers

Testing on tissue and hygienic papers

Testing on cardboard and its products

Testing of paper compound materials

Fig. 1: Accessories for strip crush, edge crush and flexural tests Fig. 2: Materials testing machine for all tests to predict the box´sstrength

Test standards - required for comparableresults

An important task of test standards is the creation ofequal requirements for test specimen and test se-quences; and this must be independent of when,where and by whom the testing is performed.

The National European Standards Commission as wellas ANSI (U.S.A.) and JISC (Japan), are harmonizingtheir standards step-by-step with ISO (InternationalStandard Organization). The goal is to improve thecomparison of test results and reduce the costs for thepresent multitude of different testing systems in agrowing global market.

This brochure is based mainly on International (ISO,EN) and important National Standards (TAPPI, JIS).Zwick Roell-instruments also meet most of the corre-sponding national standards.

The separation of paper-based materials into 6 groupsshould assist you to easily finding your own area of useand prompt you to take a look at new possibilities.

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Advanced Crush Test - Testing Machine, loading frame 24

Burst test ISO 2758 Testing Machine, Burst Tester 13TAPPI T 403 Balance 25

Cutter 35

Burst test ISO 2759 Testing Machine, Burst Test instrument 13TAPPI T 807 Balance 25TAPPI T 810 Cutter 35

Bend test, 2-point ISO 5628 Testing Machine, Bending unit 14(Creasing strength) ISO 2493 Strip cutter 50 mm 35

DIN 55437

Bend test, 3-point ISO 5628 Testing Machine, Bending unit 16ISO 11093 Bending unit for carton sleeves 16

Bend test, 4-point ISO 5628 Testing Machine, Bending unit 16

Corrugating medium test ISO 7263 Testing Machine with compr. plates 22TAPPI T 809 Medium Fluter 35

Strip cutter 12,7 mm 35

Thickness measurement ISO 534 Thickness measuring unit 17EN 20534 Cutter 35TAPPI T 411

Thickness measurement ISO 3034 Thickness measuring unit 17TAPPI T 411 Cutter 35

Puncture test ISO 3036 Testing machine, puncture test device 18(PET, LPET) TAPPI T 803

DIN 53142-2

Puncture test ISO 12625 Testing Machine, Penetration unit 19(Tissue)

Elmendorf tear test ISO 1974 Elmendorf-Pendulum Impact Tester 21EN 21974TAPPI T 414

Test Methods, Standards and testing instruments

Type of test Standard Material group Test unit Page

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Flat crush test ISO 3035 Testing Machine with compr. plates 22EN 23035 Circular cutter 35TAPPI T 825

Basis weight EN ISO 536 Balance 25determination ISO 5638 Circular cutter 35

TAPPI T 410 Cutter 35FEFCO Nr. 2 Balance 25

Edge Crush Test EN ISO 3037 Testing machine, compr. plates 23TAPPI T 811 Specimen saw 35

Compressibility test none Testing machine, test head 36

Pin-adhesion-test TAPPI T 821 Testing machine, fixture 30

Crease test DIN 55437 Testing machine, creasing tool 28

Friction test ISO 15359 Testing machine, friction unit 27TAPPI T 549 Cutter 35TAPPI T 816

Ring Crush Test ISO 12192 Testing mach., compr. plates, inserts 23TAPPI T 822 Strip cutter 12,7 mm 35

Box Crush Test ISO 12048 Testing machine, compression plates 29EN 22872TAPPI T 804

Plybond resistance DIN 54516 Testing machine, specimen grips 27 Strip cutter 50 mm 35

Stacking Crush Test EN 22874 Testing machine, compression plates 29


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Strip Crush Test ISO 9895 Testing machine, specimen grips 25TAPPI T826 Strip cutter 15 mm 35

Water Absorbtion (Cobb) ISO 535 Cobb-Testing Unit 30TAPPI T 441 Balance 25EN 20535

Tear Test ISO 11897 Testing machine, specimen grips 30

Tensile test (initial wet) in Specimen grip 34process

Tensile test (wet) ISO 3781 Testing machine, specimen grips 31TAPPI T 456 Strip cutter 35

Balance (50 g) 25

Tensile test (dry) EN ISO 1924 Testing machine, specimen grips 35TAPPI T 494 Strip cutter 15 mm 35

Balance (50 g) 25

Tensile test (Zero Span) TAPPI T 231 Testing machine, specimen grips, 33Zero-span-Extension

Internal bond test TAPPI T 541 Testing machine,testing unit 26(z-direction tensile test) Strip cutter 25,4 mm 35



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Scope of applications

Materials testing machines are employed to determinethe strength and deformation performance of specimenand components. These are stressed primarily withregard to tension, pressure, and deflection but alsoshear and torsion. These testing machines are charac-terized by large testing travel, high testing speedranges, exchangeable measurement heads, andtesting tools. This allows specimens and componentsof various shapes and dimensions and made fromdiverse materials and material combinations andaccordingly different characteristics to be tested (Fig. 1).

Most of all Zwick-Roell Materials Testing Machinesallow the extension to 2 test areas. The advantage:different tests can be performed time sharing withoutchanging tools and using the same PC-user interface.

Basic concept

In order to be able to offer the optimal machine withthe best cost/performance ratio for every demand, theZwick Roell machine concept consists of three seriesfor static materials testing. The series differ in theirconstruction, equipment, performance and upgradea-bility.

• The zwicki-Line contains high-quality and space-saving testing machines. These simple to operateand transportable single-column load frames wereconceived especially for mechanical tests with smalltest loads up to 2.5 kN.

• The ProLine was developed to satisfy the demand forcost-efficient testing machines for functionalitytesting of components and standard testing ofmaterials. The „Pure Portfolio“, containing the acces-sories for ProLine, guarantees the best system priceas well as the shortest delivery times.

• The Allround-Line solves the most demanding testingchallenges and meets the highest requirements. Itcan be equipped or upgraded from an extensiveselection of accessories. Among other things, thisline allows the connection of special sensors andallows multi-channel measurements.

Materials Testing Machines Load frames

Load frames are developed and produced for ratedloads up to 2000 kN in our standard procedure. Zwickmanufactures special models for special applications,for example for higher rated loads or lateral loadframes.

The Single-Column Design of the zwicki-Line

This load frame is based on a very bending resistantextruded aluminum sheath which was developedespecially for the zwickis. The test area is freely acces-sible from three directions, so that zwickis find theirapplication in component testing and as Zwick hard-ness testers. Their low weight and small base makethis modular system easy to transport and simple tofind room for on any laboratory table.

The Single- and Double-Column Table-topmachines of the ProLine

The double-column load frames of the ProLine areequipped with two round steel columns which guaran-tee precise guiding of the crosshead. In addition, theintegrated spindle and guide protection guaranteesreliable operation in industry or for testing splinteringmaterial.

Single-column load frame ProLine models are availableespecially for testing with small loads up to 500 N.

The Table-top and Floor testing machines ofthe Allround Line

The Table-top testing machines are equipped with twocolumns made from a patented ectruded aluminumsheath. They are light, very bending resistant and alsoserve as the spindle guide and spindle protection. T-slots on the outer sides allow simple mounting ofaccessories such as protectors of furniture free frominterference by the moving crosshead.

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zwicki-Line

ProLineAllround-Line

0,01 0,1 1 10 100 1000 10000

Fig. 1: Range of application of Zwick Roell materials testing machines

Force in Newtons

All Table-top testing machines can be equipped with apedestal to position the workspace at the optimalheight for the application or operater. This allowscomfortably seated operation with sufficient legroom sothat the system is also suited for wheelchair users.

The Floor testing machines achieve a high accuracyfrom hard chromium-plated guide columns and aprecision ball-type linear drive with play-free spindlenuts. Zwick offers different variations on the crossheadinstallation, so that either an upper, a lower or bothworkspaces can be available.

All load frames with electromechanical drives canoptionally be equipped with a second workspacewhich, for example, makes it possible to quicklychange the type of test without having to convert themachine.

Drives

Electromechanical Drives

All electromechanical drives are based on play-free andlow-wear ball-type linear drives and digitally controlleddrives. They are equipped with load frames for testloads up to 600 kN. Combined with digital measure-ment and control systems, they offer the followingadvantages:• Extremely large, infinitely variable speed range• Very low speed settings possible (from about

0.5 μm/min up)• Highly precise and exactly reproducible positioning

The ProLine testing machines with Standard Electro-nics assemblies as well as those of the zwicki-Line areequipped with cost-efficient DC drives, all other testingmachines are equipped with especially low inertia,brushless AC drives.

Functional tests on components(boxes, cores, palettes)

Crush tests (corrugated board)

Crush tests(paper)

Tensile tests (wet)

2-Point-Flexural tests (Paper, board)

Tensile tests (dry)

4-Point-Flexural tests(corrugated board)

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Characteristics of the zwicki-Line, ProLine and Allround-Line

The advantages of the Zwick Materials TestingMachines series:• Extremely large, infinitely variable speed range• Very low speed settings possible

(from about 0.5 μm/min up)

• Highly precise and exactly reproducible positioning

Machine Compenent /Function zwicki-Line ProLine Allround-Line

Load frame• Type

Table-top testing machine (nominal force) 1 .... 2.5 kN 500 N up to 100 kN 5 ... 150 kN Floor testing machine (nominla force) - - 50 up to 250 kN

• Support and guide columns Number of round columns - 2 2 or 4

(Z005 up to Z100) (Floor testing machines) Number of aluminium profile columns 1 1 (Z0.5) 1, optional 2

• Number of test areas 1, optional 2 1 1, optional 2

Drive system• Electro-mechanic

Number of ball screws 1 1 or 2 2 DC-Motor Yes up to Z050 - AC-Motor - from Z050 up to Z600

(with testControl)

Number of connectors Standard Electronics: 2, 2 2 (optional increase to 4(e.g. for measurement sensors) testControl: 4 or 10)

Measurement sensors• Strain gage load cell Yes Yes Yes• Digital crosshead travel monitor integrated integrated integrated• Optical measurement systems Yes - Yes

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Zwick Roell test softwaretestXpert® II - Intelligent and Reliable,The New Software Generation for Mate-rials Testing

Zwick Roell has set the standard with testXpert® forintelligent materials testing software. Unlike othersoftware, Zwick has standardized on testXpert® for allof its applications, both static and dynamic testsmeaning you spend less time learning software andmore time conducting tests.

With testXpert® II, you benefit from over 80 years oftesting experience and from over 10,000 successfulinstallations worldwide.

Some of the significant benefits of testXpert® IIinclude:

Ingeniously Simple testXpert® II is organized so thatyou can operate it intuitively. Expressive symbols andclear structure enable users to become quickly orien-ted and shorten the initial familiarization period. Themenu bar is set up according to the needs of the userwhereby working with testXpert® II is ingeniouslysimple.

Intelligent assistants help you set up or change testprocedures and test reports. Should you have anyquestions our extensive context-sensitive online helpwill quickly deliver the answer.

Modular design – this means that we can offer aspecific testing solution to meet your requirements.Additional testing capabilities can be added as needed.

Compatible with your hardware – testXpert® II iscompatible with all commercially available PCs andlaptops without the need for an additional connectioncard! This means it is easy to switch system computersor even to develop test methods or perform analysis inthe office at your convenience. You always haveaccess to your test data.

Online Language Swapping Needless to say, youcan have testXpert® II in your language of choice.testXpert® II speaks more than one language – all youneed to do is click the mouse in order to change thelanguage online.

Language swapping is a function which can be chan-ged at any time, e.g. in setting the test report. FlexibletestXpert® II language swapping offers internationalteams language independent operation of their testingmachine as well as considerably simplified communica-tion.

Industry-Oriented Terminology and Data ExportCapability testXpert® II not only uses your languagebut it also adopts your technical terminology. Forexample, symbols or variables that are specific to thepaper industry are implemented throughout the softwa-re. This provides more relevant meaningful informationfor in your testing application.

Today’s quality assurance standards necessitates thatthe test results may be exported to a company’scentral laboratory database. testXpert® II communica-tes reliably with your IT system by providing flexibleinterfaces and MS-Office integration via Object LinkingEditing (OLE).

Exactly Synchronized Video Recording - OnlytestXpert® II offers you an image-for-image, exactlysynchronized video recording of your test. You caninterpret the measuring curve of the test efficiently withthe help of the recorded image changes of the speci-men.

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Screenshot of the graphical sequence editor

Screenshot of testXpert® II Lims

Synchronized video system in testXpert® II

You can record the test procedure with a video cameraor an USB webcam. testXpert® II saves the recordedimages synchronized with the measuring data.The visual recording shows, for example, when, howand where the specimen necks, buckles or changescolor.

The alterations in specimen dimensions can be measu-red exactly from the captured images. In addition,before the test you can determine which events imagesshould be recorded, for example the point in a cyclewhen compression switches over into tensile stress.

Afterwards you can print these pictures or integratethem into the test report. Thanks to the synchronizedvideo recording the test procedure can be recalled orcompared at any later time.

testXpert® II LIMS - Features only offered bytestXpert® II: An integrated Laboratory InformationManagement System (LIMS). Here you have a powerfuldatabase available to administer your test results inorder to create and archive long-term statistics andreports. All data determined by testXpert® II are avai-lable from any testing system in your company.

Graphical Sequence Editor - The testXpert® IIGraphical Sequence Editor offers all the freedom youcould possibly hope for. It enables you to design testprocedures of any kind very individually, by combiningtest events, parameters and results exactly as yourequire.

The intelligent construction of the graphical se-quence editor makes your work easy. You do notrequire any programming knowledge: The graphic basemakes for quick familiarization with the functionality.The integrated simulation mode offers you safety: Itanalyzes the test procedure you have created incorpo-rating a virtual testing machine, with different specimenbehaviour (e.g. spring, plastic, metal, etc.). You thusfilter out errors from the test procedure in the earlystages, and all this without destroying a single speci-men.

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The burst test

The Zwick Roell burst tester is an accessory of thetesting machine for performance of the burst test(Fig.1). The testing machine takes over the functions ofthe hydraulic pump, the data acquisition and evaluati-on. This makes the burst test a program controlled testwhich assures correct test results with a minimum ofmanual operation.

Fig. 2: Burst tester and pressure pre-selector unit

When clamping a corrugated board specimen, it isimportant for the reproducibility of test results, to applyand maintain an accurate clamping force. For easyuse, Zwick offers a pressure preselector, which allowsfor the application of 5 different clamping pressures bysimply turning the selector knob.

Special attention must be paid to the dynamics of thetesting instrument when determining the burststrength. Since a burst test is performed within a fewseconds, the maximum pressure should appliedprecisely, the data acquisition rate of the testing instru-ment must be correspondingly high. If comparingresults between different laboratories, the data acquisi-tion rate of the instruments must be identical.Zwick Roell instruments can control the data acquisiti-on rates so that systematic deviations between diffe-rent laboratories can be prevented.

Similar conditions are true for the stability of the volumeflow during the test. Zwick Roell testing machines workwith a digital control to insure a constant volume flow,independent of the loading (Fig. 1, next page).

Further, the easy serviceability and the simple membra-ne monitoring must be pointed out. If a constant volu-me is pumped into the test chamber without a speci-men, the maximum pressure indicates if the membraneis still in good condition or if it has become weak. Thetime dependant membrane behavior is automaticallydisplayed and stored with the connected PC.

Fig. 1: Burst tester as a machine accessory

The scope of instruments for mechanical, chemical,and optical testing of paper is very large. It is under-standable, that Zwick Roell does not have all of theseinstruments in its production program.

Articles on products, for which Zwick does not produ-ce, are listed in the technical part of this brochure withthe note ”on request”. If you want such instruments,we recommend that you acquire them from our part-ners. You can also request them through us since ”allfrom one source”, is familiar to us. Speak to our fieldsales engineer. He will work with our sales departmentto find the correct solution for you.

Test Methods in the Paper Industry

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For burst testing of paper materials, there are two stan-dards: ISO 2758 describes tests on paper, ISO 2759describes the requirements for carton, corrugatedboard and corrugated base paper. Zwick offers a testinstrument for each of these standards and therebycovers the range from paper to heavy corrugatedboard.

The advantages:• The operator does not need to worry about the

details and is free to concentrate directly on the testat hand.

• The tests are performed under constant conditionseven when there is a change in operators.

• The bursting of the specimen is recognized by themachine and the test is ended. This way, the memb-rane is stressed less and has a longer lifetime.

• A variable data acquisition rate guarantees compara-ble results between producer and processor.

• The flow is controlled in a very narrow tolerancerange and remains constant even at high loading.

• With the real-time graphics, the operator immediatelysees if the test has been performed correctly.

• Service interfaces and maintenance friendly con-struction reduce idle times and consequential costs.

The 2-point bending test

Bending stiffness is very important in the processing ofpaper and carton. So that processing operations inpackaging and filling machines run dependably andwithout problems, the paper or carton must be flexiblewithin certain limits. During the changing of papercharges, a uniform stiffness characteristic is alsorequired for constant working conditions of a packingmachine.

The 2-point bending test unit from Zwick Roell (Fig. 2)covers two applications: calculation of bending stiff-ness and the determination of the folding behavior atan angle of 90°. Zwick´s high resolution and exactmeasurement technology allows for one load cell tocover a wide range of applications.* These accessories require connecting elements and software to be specified according to

the machine.

Standard ISO 2758Material paperItem numbersBurst tester 320348*Test Program 374150For specimens from 100 x 100 mmTo testing machines from zwicki-Line

Fig. 1: Volume flow-stability guarantees constant test conditions

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

Standard ISO 2759Material corr. board and raw paper for

corr. board, solid boardItem numbersBurst tester 320348*Test Program 374150For specimens from 100 x 100 mmTo testing machines from zwicki-LineAccessoriesItem numberPressure preselector 324538

Load cellBendingunit

Fig. 2: 2-Point bending unit

* These accessories require connecting elements and software to be specified according tothe machine.

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Fig. 1: Bending test on fine paper at 1 mm bending length

When testing fine paper at 15 mm bending length, theforces may be below the lower measuring limit. In suchcases, bending lengths from 1 mm should be applica-ble. Zwick offers a unit which covers bending lengthsof 1, 2 and 5 mm in fixed precision steps. Its jaws arespring operated, so that specimens are always clam-ped under constant conditions without pre-damagingthe sample (Fig. 1). In a limited range, this bending rigallows crease tests according to DIN 55437.

Advantages:• Bending forces from 50 mN to 10 N are measured

with one load cell.• The force measurement error is 1% of the measured

force.• The load cell is placed separately from moving

machine parts so that the data at the lower forcesare reproducible.

• Bending angles larger than 90° are precisely measu-red without changing the load cell or tools

• An extremely high angle resolution of 0,001° guaran-tees highest dependability of measured values.

• Specimen can be gripped with widths up to 38 mm.• The bending lengths can be easily adjusted to 1, 2

and 5 mm in precise steps.• The test program simultaneously determines the

bending resistance, modulus, and bending stiffness.• Graphik display always shows the force-deformation

behaviour (Fig. 2)

Standard ISO 2493 / ISO 5628Material paper, boardItem numbersBending rig 353100*Load cell (from 10 N) e.g. Type I, 318928Test Program 374160For specimens width to 40 mm thickness from 0.1 to 4 mm bending length 5 to 100 mmTo testing machines from zwicki-LineStandard ISO 2493 / ISO 5628Material from fine paper, foilsItem numbersBending rig 320663*Load cell (from 10 N) e.g. Type I, 318928Test Program 374160For specimens width to 40 mm thickness to 0.3 mm bending length 1 to 100 mmTo testing machines from zwicki-Line


Creasing strength

This bending rig is available for combined bending andcreasing tests. Creasing tests can then be performedfrom free spans > 30 mm and angular speeds up to10 °/s.

Fig. 2: Bending resistance before and after creasing

Standard DIN 55437 Part 3max. ca. 10°/s

Material Paper, board up to 250 g/m²Transmission Angle/Displacement: 1,2 °/mmItem numbersBending rig 373835*Load cell (from 10 N) e.g. Type I, 318928Test Program 003125For specimens Length from 30 mm Width ca. 15 up to 40 mmTo testing machines with test speeds

> 500 mm/min* These accessories require connecting elements and software to be specified according tothe machine.

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With the use of the McKee-formula, bending stiffness isimportant for the prediction of the box crush resis-tance. With the 4-point bending method, dependablestiffness values are measured in the machine and crossdirection. This is particularly important for miniatureflute corrugated board, where stiffness plays an increa-sing role, compared to standard flute heights.

With the knowledge gained from the bending units forstructural materials, (aerospace, ceramics and highperformance metals), Zwick developed a 4-pointbending unit for carton and corrugated board (Fig. 1).The result is a tool that is comparable to other existingsolutions at a moderate cost. Another important pointis that the bending unit can be used on the smallestmachine, the zwicki.

Standard ISO 5628Material corrugated board, cardboardItem numbersBending test rig 320364*Load cell (from 500 N) e.g. Type II, 318946Test Program 374160For specimens width max. 100 mm length max. 400 mmTo testing machine from zwicki-Line

Standard ISO 5628Material board, compositesItem numberBending rig 316485*Load cell from Fmax 10 N e.g. Type I, 318928Test Program 374160For specimens width from 50 mm thickness from 2 mmbending length from 100 mmTo testing machines from zwicki-LineStandard ISO 11093Material cores, sleevesItem number on requestFor specimens length to 3200 mmTo testing machines from ProLine

The advantages:• Bending units from the Zwick Roell building blocksystem are light and simple to mount and to operate.• Economical solution, since a bending transducer isnot required.• Customer specific solutions for core testing.


The 3-point bending test has only limited use on paperbased materials. Possible applications are on card-board, paper based compounds or cores. However,the 4 point bending test is standardized on cores. 3point bending tests are carried out following companyinternal standards.

Fig. 1: 4-point bending test rig with high resolution extensometer

Compared to bending instruments which use deadweights for specimen loading, handling is uncomplica-ted and fast: the specimen is simply placed on thebending unit and the test is started. The stiffness iscalculated automatically, taking in consideration of theelasticity limits.

Because of rotatable and swivable supports, shrinkedor warped specimens can be tested within wide limits.



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Fig. 1: Stiffness determination on corrugated board

The advantages:• Test time below 60 s• The test graph allows a fast plausibility control even

during the test (Fig. 1)• Supports of the bending unit are optimized for the

characteristics of carton or corrugated board.• Measured results are mostly independent of warp or

shrink of the specimens caused by production. Thetest is performed within the elastic range of thespecimen.

Thickness measurement

Paper thickness is measured for various reasons:

The stiffness of paper and carton are dependent on thethickness. Therefore, an exact thickness measurementis critical in the stiffness of a carton and processabilityin a packing or printing machine. If the weight per unitarea and thickness of a paper is known, the weight-referenced volume can be calculated. This is importantfor the transportation of larger amounts as well as forthe processing of these materials.

Fig. 2: Thickness gage for corrugated board

Digital thickness measuring instruments, which workcorrectly to Standards and pass their values on tosubsequent systems, save time and ensure securedata (Fig. 1).

The advantages:• Pressure foot area, loading weight and lowering

speed are available for all normal standards.• Individual and series measurements are possible.• PC-connection via built in RS 232 interface.

Standard ISO 534 / EN 20534TAPPI T 411

Material paper, boardItem numberThickness gage 320410Standard ISO 3034 / TAPPI T 411Material corrugated boardItem numberThickness gage 320408

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Fig. 1: LPET test curves

Fig. 2: LPET-Test in a testing machine

The penetration test

The quality of a corrugated board box is not dependenton the stiffness of the material in just the machine orcross directions. During the penetration test, thematerial is loaded in all directions due to the pyramidformed penetrator. Therefore, the tensile, compression,bending, and shear forces, appear simultaneously. Theresult of this test is the energy absorbed during pene-tration of the material. According to recent standards,this test is performed with a pendulum impact tester orwith a materials testing machine. This instrument canbe used Stand Alone or connected to a computer.

Since the penetration test with a pendulum has severalweaknesses, (oscillation of the pendulum, no linearmovement, no constant test speed, test results de-pend on the test speed, difficult handling), Zwick offersan alternative, standardized test with a material testingmachine. With the linear motion penetration test(LPET), the penetration pyramid is pressed through thespecimen in an even movement. The pyramid is drivenand controlled by a testing machine. The force-pathcurve is acquired by the electronics. The result is theenergy required for penetration, which is similar to thependulum impact test (Fig. 1).

The standard deviation of the data due to testingmachines is significantly better than that from a PETpendulum. The result correlation to PET impact testershas been evaluated in cooperation with the germanwfp institute for corrugated board research and is of 5% (Standard deviation) (Fig. 2, page 19).

Since the measurements, force and travel are acquiredelectronically, the measurement range is much largerthan a pendulum impact test.

Theoretically, materials from a basis weight of 80 g/m²,up to heavy duty corrugated board with a thickness of17 mm, and an energy of approx. 40 Joule, can betested without mechanical changement of weights (Fig.2). These characteristics make the testing machinemuch quicker and secure.

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Fig. 1: 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

to heavy corrugated board without retro-fitting• ability to perform wet tests


Standard DIN 56142-2Material corrugated board, cardboardItem numbersPuncture test rig 318619*Load cell Fmax 2.5 kN e.g. Type I, 318914Test Program 374162For specimens width 180 mm length from 180 mmTo testing machines from zwicki-Line

Fig. 2: Very close correlation between PET- and LPET-tests.

Zwick Roell is working with technical paper institutesand well known industrial companies, on the industrialintroduction and standardization of this test.

For tests on tissues, a similar test method has beenset up using a ball indenter. Zwick Roell is able to offerthis test equipment.

20

The burst test on tissue(Ball-Burst Test)

Additionally to the tensile strength, the burstingstrength is an important characteristics of tissuematerials. With a burst test the penetration of a sheetby a rigid body is simulated.

The test fixture is designed for a most simple handling.The specimen is placed upon the lower plate of thefixture and the machine is then started. Specimenclamping is performed automatically and consequentlythe test is carried out without any influence of theoperator (Fig. 3).

The wide force measuring range avoids that a load cellmust be changed: using a 100 N load cell, even forcesbelow 1 N are measured with the required accuracy.Therefore, materials having extreme characteristics orresearch investigations can be carried out with highreliability.

Fig. 1: Burst test on tissue

Fig. 2: Typical force-deformation graphs from tissue

The specimen is horizontally clamped between twoplates, which have a centric circular clearance. With aconstant speed, a posished ball penetrates the speci-men in the center of the clearance (Fig. 1). Measuredvalues are the maximum force (bursting force) and thebursting index (bursting force related to the specimen´sgrammage) (Fig. 2).

Fig. 3: Puncture test rig configuration

21

The tear test

By using a tear test, this gives paper processors anestimated value of the future behavior of the endproduct (multi-layered carton, corrugated board). Thetear test according to Elmendorf, is used as the qualitycontrol criteria for the paper producer (final inspection)as well as for the processor (incoming goods qualitycontrol).

A tear test is performed in seconds therefore, the testdata must be quickly acquired and evaluated.

The Elmendorf-Pendulum fulfills these requirementswith a simple connection to a PC. Thus the raw data(energy values) can be converted into force values andthen easily transferred to a QDA-System.

Fig. 1: Correlation between the LPET and the Elmendorf test

LPET in J

The advantages:• easy PC connection via RS 232 interface• Connection to testXpert® II offers all advantages of

electronic data processing• established robust instrument

Empirical tests can be performed on a testing machine.Tensile grips or the LPET penetration test rig may beused for such tests. Test results from LPET and Elmen-dorf showed a strong linear correlation (Fig. 1). Thecorrelation should be crosschecked for individual papergrades.

Standard ISO 1974 / TAPPI T 414Material paperItem numbersElmendorf-Pendulum tester 636687 / 355559For specimens length 62 mm (ISO)

63 mm (TAPPI) width 50 mm (ISO)

53 mm (TAPPI)

0,00

2

4

6Tear force in N

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

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

Even results exceeding the usual range of 5 to 20 Nare exactly captured. Additionally, the force-deformati-on-behaviour of a material can be analysed, as atesting machine always captures the deformationvalues, too.

Standard ISO 12625Material tissueItem numberTest rig 324914*Load cell Fmax 100 N e.g. Type I, 318922Test Program 374160For specimens angle length from 175 mmTo testing machines from zwicki-Line and ProLine


22

Fig. 2: Flat crush test: test curves showing correct and pre-damagedmaterial

Crush tests on corrugated board and corruga-ted board raw paper

It is important for these tests (Fig. 1), that the forces areapplied exactly vertically to the specimen during thetest. Precision guided compression plates provide anextremely high transverse stiffness. They insure thereproducible results of the crush characteristics incorrugated board raw paper and corrugated board.

The Corrugating medium test

The Corrugating medium test provides informationabout the behavior of a corrugated paper after it hasbeen formed in a fluter. A section of corrugated paperis glued one-sided, to a carrier paper and then loadedin compression. The maximum load characterizes thebehavior of the paper during the converting processingsteps (punching, printing) after board production. Adisadvantage of this method is that only the A-corruga-tion is tested.

For other types of corrugations, the behavior in com-pression mode must be mathematically calculated.

In addition, this method takes a lot of time and requiresmuch skill in making the specimen. For these reasons,Zwick-fluters are delivered which include a „third hand“.With its help, a specimen can be easily and quicklyprepared (see page 35, Fig. 4).

The Flat Crush Test

In the flat crush test, a single-flute corrugated boardspecimen is loaded perpendicular to its surface. Theresistance this corrugated board presents to the force,gives an indication of its behavior in further processingand use.

Characteristic curve: according to the height of theindividual flutes, the highest flutes break first, then themiddle ones and then finally, the rest of the flutes.

Standard ISO 7263 / TAPPI T 809Material corr. medium paperItem numbersCompr. test kit up to Fmax 10 kN 318539*Test Program 374012Fluter 320625For specimens length 155 mm width 12.7 mmTo testing machines from zwicki-Line

Fig. 1: Specimens for: flat crush test, ring crush test and corrugatingmedium test


pre-damaged

ok

23

If the corrugated board has leaning or crushed flutes, ithas been pre-damaged, and the curve is fundamentallydifferent. The crush energy and data curve, provide theuser with valuable information about the degree ofdamage.

Modern miniature flutes tend to crush only at forcesgreater than 10 kN, requiring excessive lateral stiffnesson the compression plates. For these applications,Zwick offers the suitable compression test rig, too(Fig.1).

Fig. 2: Edge crush test using guided compression plates

The Edge Crush Test

This gives information about the strength of corrugatedboard at standing flute orientation (Fig. 2).

The edge crush resistance goes into the McKeeformula that is so important for quality control incorrugated board factories. The specimen must haveclean, parallel and perpendicular edges, and thematerial must be free of pre-damage.



Material corrugated boardItem numbersCompr. test kit up to Fmax 10 kN 318539*Comp. test kit up to Fmax 250 kN 316447*Test Program 374156Circular cutter 320450For specimens diameter 112.8 mmTo testing machines from Allround-Line Standard ISO 3037 / TAPPI T 811

Material corrugated boardItem numbersCompr. test kit up to Fmax 10 kN 318539*Test Program 374152ECT-saw 320629For specimens length 100 mm height 25 mmTo testing machines from zwicki-Line

Fig. 1: Compression plates for the flat crush test on miniaturecorrugated board (left, F > 10 kN) and on standard corrugated board(right, F < 10 kN)

A hinged scissors or a knife is not suitable for cutting.Good results have been achieved with a circular sawfrom Zwick (see page 35, fig. 3).

The Ring Crush Test

The ring crush test is similar to the strip crush test inthat the strength of liner or fluting is measured in themachine and cross directions.

The results in this test are highly dependent on properspecimen preparation. The specimen, as well as thetest fixture must be parallel in order to insure an exactdetermination with the ring crush strength.

Since the ring crush test provides more informationabout the buckling behavior rather than about crushbehavior, it is being replaced by the strip crush test.


24

Item numbersACT-Test 362886Fmax 500 NHeight x Width 80 mm x 80 mmDiameter 0,5 mm up to 2 mmConnection dia. upper and lower 20 mmTest Program 372430To testing machines from ProLineAdditional requiredLoad cell Fmax 2.5 kN e.g. Type I, 318914(as integral part)

ACT-Test

This tool is used for compressive tests on micro-corrugated board sqare disks.

The disk is placed into a frame, which can be openedat its right side. The frame itself consists of 90° not-ched legs. At the left side of the frame, a screw drive istnotched leg frame together with the side load simulatethe glued edges of a box, made of the same material.

During the test, the compression fin (upper frame part)pushes against the sample and squeezes it until it fails.The fin is supported via ball bearings and remains itsposition constant over the entire test sequence.

In the test, the sample´s deformation is similar to that ofa box (bulge effect).

The advantages:• light, precision guided compression plates prevent

lateral yielding of the specimen during the test• suitable compression plates for miniature flute board

in Zwick´s standard program• automatic recognition of breaking on all flutes pre-

vents misinterpretation in the flat crush test• inserts for the ring crush test fit into the compression

plates without a problem. Lateral yielding of thespecimen is also prevented.

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

Standard ISO 12192 / TAPPI T 822Material corr. medium paperItem numbersCompr. test kit up to Fmax 10 kN 318539*Inserts 316243Test Program 374158Strip cutter on requestFor specimens length 152 mm height 12.7 mmTo testing machines from zwicki-Line

Therefore (customer´s statement) there is a very closecorrelation between this test an a crush test on a box.As a result the first maximum of the monitored force isused.

Fig. 1: Test rig for the ACT-Test

Fig. 2: Force-deformation behaviour in the ACT-Test


25

The Strip Crush Test

The paper’s characteristic „compressive strength” canbe determined by the strip crush test with high accura-cy. Because of the short test length of only 0.7 mm,the load bearing fibre portion of the material is takeninto consideration more than with the traditional testingmethods (ring crush test, corrugated crush test orlinear crush test). The Zwick test arrangement (Fig. 1)has unique characteristics compared to the normalhorizontal machines:

• Zwick uses a load cell with a high nominal load. Thismakes the measuring chain very stiff and keeps post-test effects from the machine to the specimenreduced to a minimum.

• Specimen and load cell lie in the same symmetricalaxis. Erroneous bending moments are nonexistent.

Since resolution and accuracy of the Zwick measure-ment electronics is extremely high, paper can beaccurately measured from ca. 100 g/m² up to400 g/m² and higher (Fig. 2). Because of its technologi-cal advantages, the Strip Crush Test is being moreaccepted worldwide.

Fig. 1: Strip crush test grips

Determination of basis weight

Selection criteria are: accuracy and resolution of thebalance and the electronic transfer of the weight to acomputer. In order to balance feature and price requi-rements, Zwick Roell and its partners offer a range ofprecision balances from highly accurate analyticalbalances to balances with a limited range.

Fig. 2: Strip crush test-series

Standard ISO 9895 / TAPPI T 826Material raw paper for corrugated boardItem numbersGrips 317990*Load cell Fmax 2.5 kN e.g. Type II, 318942Test program 069002.58.00 / tc-xxxStrip cutter 320412For specimens length > 110 mm width 15 mmTo testing machines from zwicki-LineSpecial gripsfor cardboard on request

Standard EN ISO 536 / ISO 5638Material paper, boardItem numbersBalances 50 g 318230220 g 001410For specimens diameter 113 mm or any area, to 1 %

accurate

The advantages:• an inexpensive accessory to be used with a Zwickmachine• has the necessary stiffness for compression tests be-cause of the load cell with high nominal load• very little retroactive affect on the specimen due to thesymmetrical design• Easy-to-use user interface for quick control of the test run


26

Internal Bond Test(z-direction tensile test)

For multi-layered materials (duplex paper, coatedpaper), the internal bond strength of the layers to oneanother is an important characteristic. It determines thefurther processability. When testing to TAPPI T 541, theload on the specimen must be perpendicular to thesurface of the specimen. In order to eliminate theeffects from grips or fixtures to the separation of thelayers in a test, the tensile force must be maintained inits vertical direction through rupture. High lateralstiffness and absolute parallelism of the specimenholders is critical for a proper test. Therefore, Zwickdeveloped a special test rig for holding the specimens,which are crossed over at an angle of 90 °, and whichaccept a paper strip of 5 specimens. Thus, using onesingle application, 5 tests can be performed withoutfurther handling of the specimen (Fig. 3, page 26 andfig. 1, page 27)

The specimen holders are mounted on precisioncompression plates and are parallel and stiff in alldirections. How the specimen is applied: using adouble sided self adhesive tape, a paper strip is glued

onto one specimen holder. The second holder isapplied with only a double adhesive tape. During thetest, the specimen is at first pressed against the twospecimen holders. Compressive loads, as well aspressing time are freely adjustable. After the compres-sive phase, the tensile test is performed within half asecond (Fig. 2).

Fig. 2: Internal Bond Test - Compressive sticking and tensile test inone procedure

Fig. 36: Laboratory balance

Standard FEFCO Nr. 2Material corrugated boardItem numberBalance 220 g 001410For specimens length 250 mm width 200 mm

The test result is the tensile strength, which is themaximum tensile load, related to the sample’s surfacearea. The z-tensile test rig is available as a manualversion, as well as a semi-automatic one. With thesemiautomatic test rig, a second paper sample can beprepared during the time while testing the first sampleset of 5 specimens.

Fig. 3: Internal bond test, test run

Fig. 1: Balance

27

The advantages (TAPPI T 541):• quick placement of the specimen by using a semiau-

tomatic machine even while running a test series• pressure step and z-tensile test without specimen

handling• compressive strength and compression time are

freely adjustable• Use of only half the standard area for tests on high

strength papers

Fig. 1: Internal Bond Test - test rig and sample preparation unit(bottom right)

Standard TAPPI T 541ISO -> in process

Material duplex-papers, plybondsItem numberTest rig manual 623069 automatic 623286Test Program on requestFor specimens length approx. 140 mm width 25.4 mmTo testing machines from zwicki-LineEquipment for on requestply bond strengthto DIN 54516Scott bond tester on request

Measuring Coefficient of Friction

Friction of paper and paper compounds is importantfor further processing in automatic systems. For thedetermination of the coefficient of friction, an importantfactor is the material of the two surfaces to be measu-red, „paper against paper“, or „paper against othermaterials“. Another deciding factor is whether thestatic friction or the dynamic friction is to be measured.Zwick Roell offers tools and software programs for allof these methods. This gives the user confidence in thetest results and then ultimately in finding a solution forpacking or printing problems. Two basic measuringtechniques are available:

• the „Horizontal Plane Method“ (Fig. 2, page 27 andfig. 1, page 28), in which the static and kinetic frictionare determined with one sled

• The „Strip Method“: two material strips are pulledover pressed rolls in opposition to one another. Theadvantage of this method is that the only surfacesthat are tested are the ones that have not been incontact with each other (Fig. 2, page 28).

Fig. 2: Determination of static and dynamic friction

Most tests using the „Horizontal Plane Methods“, aretested to TAPPI. The ISO methods are more complica-ted, since the entire measuring operation (applicationand driving of the sled) must not be performed manual-ly. Initial studies of tests on corrugated board [1]showed that the values tested to ISO correspond toTAPPI.

Compared to Scott bond tests, the z-tensile test hasproved to have much less result dispersion.

Similar tests: ply bond strength to DIN 54516 and ScottBond Test to TAPPI T 403. In these tests, the specimen issubjected to peel loading. The Scott Bond Test is perfor-med with a pendulum impact tester. This takes intoconsideration the high processing speeds of this material.

Static friction

Dynamic friction

28

Laboratory creasing

A testing machine can be used for the determination ofcreasing parameters. In a laboratory test a specimencan be creased with freely adjustable values for:

width of the creasing tool,width of the nut, nut depthand creasing stroke. Because of the high creasingspeed and the excellent positioning accuracy, ascompared to manual creasing presses, creasing canbe determined very precisely. For fast and easy deter-mination of best fitting creasing parameters, creasingchannel and knife blade are changeable.

Zwick-Software testXpert® II determines a wide rangeof friction results: static and dynamic friction, peakvalues, upper and lower median of peaks. This provi-des the user with results that are needed for subse-quent material processing.

Fig. 1: Horizontal plane method

Standard TAPPI T 549 / TAPPI T 816Material paper, foilsItem numbersFriction test rig 319395*

316251*Test Program 319190Cutter on requestFor specimens length 300 mm width 150 mmTo testing machines from zwicki-Line/ProLine

Fig. 3: Creasing knife overspecimen and creasing channel

Fig. 4: Creasing tool

Standard without (strip method)Material paper, foilsItem numbersFriction test rig 618538Test Program 374014Strip cutter 15 mm width 320412 25 mm width 320416For specimens length 300 mm width 25 mm and 15 mmTo testing machines from zwicki-LineStandard ISO 15359Item number on requestStandard DIN 53119Item number on request

The advantages:• Friction units to TAPPI with fast placement of the

specimen• A wide variety of friction tests

results are available in testXpert® II• Strip friction unit for tests on „virgin“ surfaces

Fig. 2: Friction test, strip method


29

Box Crush and Stacking Crush Tests

These tests are used to determine the strength and thestacking capabilities of corrugated board boxes (Fig.2). The complete box is compressed to a specifiedload or until failure.

The European Standards require rigid compressionplates if the behaviour of a box is being tested byloading it on opposite corners or sides. The upperplate must be spherically pivoted when loading the boxon opposite surfaces. However, TAPPI always requiresrigid compression plates. The European Standardsdistinguish between the Box Crush Test and theStacking Crush Test.

In the Box Crush Test, the corrugated board carton isloaded steadily to nominal load or until failure. In theStacking Crush Test, a certain load is held constant fora certain time or until failure of the box.

Fig. 2: Box-crush tester for specimen up to a footprint of 2 m by 2 m(authorized by SCA Packaging Research, European TechnicalCentre, Aylesford)

Standard DIN 55437Material paper, boardItem numbersCreasing tool 618337Load cell Fmax 2.5 kN e.g. Type II, 318942Test Program 618336For specimens length 40 mm width 50 mmTo testing machines from zwicki-Line

StandardBox crush test ISO 12048 / EN 22872

TAPPI T 804Stacking test EN 22874Material corrugated boardItem numbersCompression plates400 x 400 mm 317942*400 x 600 mm 317944*Special versions on requestLoad cell (from Fmax 5 kN) e.g. Type II, 318940Test Programs Box crush test 347178 Stacking test 357693For specimens length x width x height Boxes according to the

machine´s test space

To testing machines from Allround-Line

Fig. 1: Laboratory creasing: force-deformation characteristics

Machines, either standard or to customer specificati-ons, also offer correct applicable solutions for combi-ned tests.

The advantages:• Standard and customer specific machines for optimal

testing• Available solutions for box widths up to 2000 mm



30

Water absorbtion to Cobb

Water absorbtion of raw paper is determined with theCobb Test.The principle is:• The dry specimen is weighed• The specimen is placed under a cylinder with an

inner diameter of 100 cm². Specimen and cylinder lieon a rubber and a steel plate

• Approx. 100 ml water is poured into the cylinder• After a specified waiting time, the water is poured

out. Excess water is removed from the specimenwith blotting paper and roller.

• The specimen is weighed while wet and the amountof water is calculated that 1 m² of specimen materialwould absorb.

The advantages:• Operator friendly instrument with quick clamping• also available for corrugated board

Tear Propagation Test

This characteristic is important for finding and avoidingweak spots in packaging with folded edges or bondedseams. It can be performed on a low cost testingmachine such as ProLine machines for tight budgets.In addition, it gives valuable information about thequality of materials and about the consistency of theproduction process.

The advantages:• Tensile and tear propagation tests can be performed

with the same equipment.• Peaks and median values are calculated in one

operation• Easy to use menus simplifies the work

Fig. 1: Tear test: diagram

Standard ISO 11897Material paper-foil, compoundsItem numbersGrips 316264*

316322*Test program 318035For specimens dimensions acc. to the productTo testing machines from zwicki-Line/ProLine

Tensile tests

They inform about a number of characteristics: stiff-ness, modulus, tensile strength, tearing length andenergy absorbtion.

Pin adhesion test

In a pin adhesion test, the upper and lower layer of acorrugated board strip are separated from the flutingwith two rows of inserted steel pins (Fig. 1, page 31).Test result is the maximum force, related to the totalglue line length between layers and the fluting. TheZwick test rig is stiff (Fig. 2, page 31), works in tensilemode and requires no compression plates.


Material paperItem numberCobb test kit on requestFor specimens diameter 112.8 mm


31

Inserts for A-,B- or C-flute

Fig. 2: PAT-Test rigFig. 1: Corrugated board stripover steel pins


Standard ISO 3781 / TAPPI T 456Material tissueItem numbersFinch clamp 318512*to grip 316264*Test Program 374120Strip cutter lever shear on requestFor specimen length approx. 200 mm width 50 mmTo testing machines from zwicki-Line

Offset-printing papers

When running paper through the printing units of a 4-color offset printing machine, the humidity of the paperincreases steadily on the printed areas. This increase ofhumidity causes an elongation of the paper in themachine and cross directions. While the elongation inmachine direction can be corrected by gage pins, itcannot be corrected or adjusted in the cross direction.In order to avoid „fan out“ of the individual color prints,the elongation in cross direction must remain withinspecific limits.

The importance of not exceeding these limits increaseswith increasing recycling rate and decreasing basisweight of the paper. Testing the force-deformationbehavior during incoming quality control, is a powerfulcosts saving tool. For a valid test, the paper must bepreconditioned at a well-defined humidity and thentested within a very short time.

Wet tensile test

These tests are useful for determining several differentpaper characteristics such as usage properties oftissues, printing quality of offset printing papers, andrunability characterisics in the wet end of a papermachine.

Tissue

The wet strength is one of the most important materialcharacteristics for papers that are used wet or aresubsequently processed. Zwick offers a quick, depen-dable method for the determination of wet tensile toFinch (Fig. 3). Simple handling of the Finch clamp and afast change over between wet tensile and other testshighlights the use of Zwick´s testing technology.

Fig. 3: Wet Tensile Test

Standard TAPPI T 821Material Corrugated boardItem numbersPAT-Test rig 638412Test program 374010For specimenA- and C-flute: 50 x 150 mmB-flute: 32 x 100 mmTo testing machines from ProLine

32

Fig 1: zwicki, equipped with horizontal test space and automatic teststart

Standard ISO 1924Material paperItem numberMaterials testing machine 623336Test Program 374010Strip cutter 320416For specimens length approx. 240 mm width 25 mm

The slope of the elongation-force-curve can be used todetermine the limits of high quality offset printing. Forthis type of test, Zwick has developed a testing machi-ne system that can test a specimen within secondsafter taking a specimen out of a conditioning box(containing a water-acetone-solution in an exact ratio).Thus, the degree of humidity does not change withinthis short test time.

Only the elongation between the grips is needed fordetermining the force-elongation behavior of thespecimen. Zwick´s standard grips and jaw faces fulfillthese requirements and prevent grip slippage andfailures within the clamping area of the sample (Fig. 4).

Fig. 2: Tensile test at defined humidity, elongation as a dependantvariable

0 0

10 3020 40Stress in N/mm²

Elongation in %

1

2

3

4Cross direction, 5 % humidity

Cross direction, dry

Machine direction, 10 % humidity

Machine direction, dry

Fig. 3: videoXtens measures extension and transverse strain

Fig. 4: Force and Poisson ratio vs. elongation

Helpful for paper optimizing is its Z-dimensional force-deformation behaviour. Using the videoXtens (Fig. 3),extension and transverse strain can be measuredsimultaneously, when using a wider specimen. Fig. 4shows the conventional force-elongation curve toge-ther with the paper´s Poisson ratio.

33

Zero Span Test

The web´s fibre strength is measured with the ZeroSpan Test. Using an initial gage length near zero, atensile test is performed. Now, mainly the pulp fibresare loaded (Fig. 1).

Fig. 2: Zero Span Test

The Zero Span Test is usually performed with dedica-ted instruments, being accordingly complex andexpensive. If Zero Span Test are not frequently used,Zwick´s modular system of grips and accessoriesoffers an affordable solution:

For an exact horizontal and angular grip alignment,Zwick offers a mechanical extension kit. The gripalready must despond to some minimum accuracyrequirements, which is achieved by pneumatic grips.

Standard withoutMaterial PaperItem numbersTest Program 374010For specimens Length ca. 150 mm Width ca. 40 mmTo testing machines from zwicki-LineSpecimen grips Pneumatic grips Fmax 500 N

(320723)Longstrokeextensometer 325934

Fig. 1: Force- deformation behaviour in tensile test and in Zero SpanTest

Standard TAPPI T 231Material PaperItem numbersSpecimen grips 320723Accessories forZero Span Test 373921, 373749 and 003779Jaws for conventionaltensile tests 373748Test Program 317972Load cell from 500 NFor specimens Length from approx. 80 mm Width 20 mmTo testing machines from ProLine

Zero Span

StandardTensile test

The Zero Span jaws protrude from the grips inner edgeand allow a free span of approximately 0.1 mm (Fig. 2).This can only be achieved with numerically controlledmachine such as Zwick´s ProLine or zwicki-Line, whichguarantee best reproduceability and reduce the risk ofdanger to a minimum.

34

Fig. 1: Tensile test on initial wet paper

The advantages:• correct specimen gripping• fast and easy handling• high flexibility through the testXpert® II Master Test

Program

Standard In processMaterial initial wet paperItem numberGrips 358182*Test program 374010For specimens length approx. 200 mm width 50 mmTo testing machines from zwicki-Line

Runability at the wet end

The paper is very susceptible to web breaks when itleaves the paper former machine and runs without anysupport by a felt or a screen. Adjusting and controllingthe web tension, as well as using wet paper withminimal initial tensile strength values, can avoid webbreaks. The minimal tensile strength of the paperdepends on the stock composition (ratio of long andshort fibers, chemical additives). The optimal price-strength-ratio can be evaluat-ed through initial wettensile tests. Special tensile grips (Fig. 1) assure correctclamping, draining within the clamping area of thespecimen, and prevents specimen breaks within theclamping area.

Fig. 2: Tensile test according to ISO 1924, dry specimen


35

Specimen preparation

Specimen preparation is critical to obtaining goodresults.The factors that effect creating a good speci-men are, clean cuts perpendicular to the specimen,parallelism, service life of cutters, and speed. ZwickRoell has partners that specialize in manu-facturinghigh quality cutting units. Figures 1 to 4 show a seg-ment of the instruments used for specimenpreparation.

Description Item numberStrip cutter15 mm width 32041225 mm width 32041650 mm width 32042215 & 25 mm width 320446Circular cutterdia. 112.8 mm 320450dia. 79.8 mm 320452ECT-saw 320629Medium fluter 320625Other instruments for On requestspecimen preparation

Standard EN ISO 1924 / TAPPI T 494Material paperItem numberSpecimen grips 318512*Test program 374010Strip cutter width 15 mm 320412 width 25 mm 320416width 50 mm 320422For specimens length approx. 200 mm width 15, 25, 50 mmTo testing machines from zwicki-Line/ProLine

Fig. 4: Fluter

Fig. 2: Strip cutterFig. 1: Circular cutter for FCTspecimen

Fig. 3: Saw for ECT specimen

Tensile test

Since only the tear strength or tearing length result is tobe determined in many cases, other results can behidden by software. The testXpert® II software fromZwick accomplishes this with two functional levels. Thefirst level is the use of built-in Standard tests.

Standard tests contain only test sequences and resultswhich are required by test standards. The adavantageof using the Standard tests is that training can beaccomplished in a short time. The second level is theMaster program. This level will provide functionality tomeet all current and future needs for maximum flexibili-ty.


The advantage:• New: With videoXtens for Poisson´s ratio determinati-

on

36

Nominal size

Oversize

Fig. 2: Measurement of the buckling of a filled, folded boxFig. 1: Measuring the local variation deformation of a packing box

Dimension measurement

Boxes for consumer goods are filled and closed by au-tomatic systems, and they are often sold from automa-tic machines. Size accuracy is an important characteri-stic so that these automatic operations are per- formedwithout hindrance.

Zwick Roell testing machines are very well suited forstatistical size controlling because of their broadmeasurement range and accuracy. In such a test, themachine measures several height differences relative toa reference point (Fig. 1). The measured points can beapproached purely manually or automatically. The datamay be exported in many ways for subsequent evalua-tion of measured values, from local printer up to PCprogrammes for statistical quality control.

Location dependent deformation measurement

Good stackability of goods lowers storage costs.However, due to safety and economic concerns, thereis a limit to how high goods can be stacked. Thelocation and mode of failure of packaging is an im-portant factor for an engineer to consider when optimi-sing the packaging.

Customer specific tests

The area of paper materials does not begin with papermanufacturing and does not end at the processor forZwick. Suppliers and end users also profit from ZwickRoell solutions. A partial list of potential canidates forthis equipment would be, suppliers who must test theirchemicals on finished paper, printers who must optimi-se the stiffness values of bindings, large packagingcustomers. Our customized tests could enhance yourquality control:

A Zwick Roell machine, equipped with several travelmeasurement systems, determines the deformation ofa corrugated board carton including the inner packingand contents (Fig. 2). The location of the maximumdeformation can be mathematically calculated fromseveral individual deformations measurements. Thedeveloper of the packaging can gain valuable informati-on about possible weak spots. Box Crush Tests andStacking Crush Tests can also be performed correctlyto Standards with this machine.

Compressibility characteristics

The compressive force-deformation-behaviour isimportant for the developer of high quality offsetpapers. Proper printing, without missing or blurred dotscan be achieved by optimizing the elastic and plasticbehaviour of the paper.

Both characteristics can be evaluated through acompressibility test. In this test, a sample is loaded untila compresive force is reached that is similar to that inan offset printing unit. Force and deformation aremeasured simultaneously. Because of the small defor-mation sin the μm-range, a high resolution extensome-ter is required. The Zwick solution comes from hard-ness testing, where comparably small deformationsmust be measured.

37

Fig. 2: Compressibility test using zwicki

Fig. 1: Compressibility test head prior to test

Fig. 3: Compressibility diagram

The advantages:• Cost efficient equipment through use of standard

components• Deformation of a single sheet of paper can be

measured directly and with very high resolution.


Standard customer specificItem numbersDetermination ofproportionality load on requestDimension measurement on requestMeasurement location dependentdeformation measurement on requestTest Program 374016Compressibility measurem. 318531* (Hardness measure-

ment head, Fmax 200 N)623146 (Transducer foot)623147 (Transducer foot)623192 (Test Program)

Dynamic tests

For endurance test on packages, static tests arenecessary, but not sufficient. Acceleration forces asapplied during loading, transport or stacking that canonly can simulated with dynamic machines. Zwick-Roell manufactures these type of testing machineswithin Zwick-Roell Group. testXpert® II can use thesame user-interface as the static systems on dynamicsystems to perform endurance tests under realisticconditions, high-speed tests (Fig. 4), and shock tests.This makes packaging design more efficient by shor-tening the development time, costs, and failures.

Fig. 4: High speed testing machine, up to 20 m/s

A floating compression plate is loaded via a sphericloading bar and applies the compressive force to thepaper (Fig. 1 and 2). The deformation of the paper ismeasured with a resolution of 64 nanometres. The testgraph shows the specimen´s behavior during theloading phase as well as during the unloading phase.From both sections of the graph, the following testresults are calculated (Fig. 3):

• the maximum stress• the total deformation before

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

From these results, the design - engineer gets acomplete picture of the force deformation variables thateffect the paper during the offset printing process.

Englisch nachziehen!

38

With this completely integrated solution in testXpert® IIyou can• Perform a complete evaluation of materials and

components from various tests,• Display long-term statistics and trends of individual

characteristics,• Create interdependent test reports.• Histogram functionThus you can ensure higher product quality quickly andefficiently. testXpert® II does all of the above for youautomatically!

Laboratory data acquisition,Subsequent data evaluation

Quality Control does not end with the testing of the endproduct. The consistency of all production processescan be measured with the aquired data. However, thisis only possible if the acquired data is studied over along period of time and if data can be correlated fromvarious tests. By applying conclusions to the produc-tion, the control loop is closed from the initial materialto the end product.

Fig. 1: testXpert® II test report

In the ideal case, the following complement each other:

• the test protocol (Fig. 1) provides a snapshot of theproduct’s quality

• medium observation time frames• export to databases in-house• Control card (Fig. 3) and histogram (Fig. 4)

testXpert® II LIMS

Features only offered by testXpert® II: An integratedLaboratory Information Management System.Here you have a powerful database available toadminister your test results in order to create andarchive long-term statistics and reports – also forspanning a number of test series.

Fig. 2: testXpert® II LIMS

Fig. 3: Control card

Fig. 4: Histogram

39

List of sources[1] Urs Ernst: Determination of the static coefficient offriction on corrugated board and liner paperCorrugating International, April 1999

Product illustrationsTitle page:FOGRA, München

Page 3, Fig. 4:Paul Hartmann AG, Heidenheim

Page 3, Fig. 2:Hengst Filterwerke, Münster

Page 3, Fig. 3:Staatl. Molkerei Weihenstephan AG

Page 29, Fig. 2:SCA Packaging Research

Page 34, Fig. 1Voith GmbH & Co KG, Heidenheim

Reserved to technical modifications

Automation

Since quality control is not an end in itself, cost efficien-cy is very important in testing and evaluation. Automati-on can be a valuable tool to save costs and obtainreproducible results with fewer variations.

Automated specimen feeding is available in“Clip“ typeconstruction that is suitable for non-stable samplessuch as paper or fleece. When the correspondingspecimen clamps are used, tests on carton or com-pounds can be automated as well.

The testing system in Fig. 1 consists of a tensile testingmachine and an automatic specimen feeding system(Handling System). The Handlng System has twocontrolled driving axes and a circulating carrier chainwith up to 200 specimen positions. The positions canbe made of metal clips or clamps and are optimised forvarious specimen forms.

Fig. 1: Automatic testing machine: tests on sanitary products

With the freely programmable, servo- controlled drivingaxes, the carrier chain can be prepared with the mostvaried specimen holders. The system is monitored by acontrol which is storage programmable. The testevaluation is performed by testXpert® II. The possibilityof manual testing without retro-fitting is standard.

Good-bad sorting, via tolerance inputs, and controlledremoval of specimen remains are options.

Zwick Roell AGAugust-Nagel-Str. 11D-89079 UlmPhone +49 7305 10 - 0Fax +49 7305 10 - [email protected]

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Testing Machines for Paper Materials...Pin-adhesion-test TAPPI T 821 Testing machine, fixture 30...

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