Testing Machines and Systemsfor the Medical Industry

Intelligent Testing

FP 7

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Testing Systems

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Table of Contents

1 The Zwick Roell Group ..................................................................................................................................... 3

2 Zwick – The Specialist for Medical Testing Solutions ........................................................................................... 42.1 Medical Packaging ..................................................................................................................................... 52.2 Therapy Systems ....................................................................................................................................... 82.3 Surgical Instruments .................................................................................................................................112.4 Biomaterials ..............................................................................................................................................122.5 Biomechanics ...........................................................................................................................................142.6 Clinical Research ......................................................................................................................................172.7 Textile Medical Products ............................................................................................................................182.8 Silicone Products ......................................................................................................................................202.9 Dental Industry .........................................................................................................................................21

3 Zwick Modular System for Individual Testing Requirements ................................................................................223.1 Quasi-Static Materials Testing: Products and Services ................................................................................233.2 Fatigue and Impact Testing: Products and Services ...................................................................................28

4 System Components .......................................................................................................................................304.1 testXpert® II – Intelligent and Protected from Manipulation ..........................................................................304.2 testControl Measurement and Control Electronics ......................................................................................324.3 Extensometers .........................................................................................................................................334.4 Specimen Grips ........................................................................................................................................344.5 Load Cells ................................................................................................................................................344.6 Testing under Physiological Conditions .......................................................................................................35

5 Zwick Service ..................................................................................................................................................365.1 Application Laboratory and Contract Testing ..............................................................................................365.2 Support for Validation of Zwick Testing Systems .........................................................................................375.3 Service and Support .................................................................................................................................39

This brochure provides an overviewof instruments, machines, systemsand services available fromZwick Roell AG for testing productsfrom the medical technology andpharmaceutical industries and theiruse in R&D, production, quality as-surance and control, and in testinginstitutes and training centers.

The brochure therefore shows onlypart of Zwick Roell AG’s compre-hensive overall range.

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Fig 1: Zwick Roell AG and Zwick GmbH & Co. KG: Administration Building, Ulm, Germany

These companies have comprisedthe Zwick Roell Group since 1992.July 2001 saw the group become acorporation under the name ofZwick Roell AG, incorporating Zwick,Toni Technik and Indentec Ltd.Between them these companiesprovide a comprehensive materials,construction materials and functiontesting program – from manuallyoperated hardness testing instru-ments to complex systems forprocess-parallel applications. AcmelLabo, the French manufacturer oflaboratory instruments for thecement, lime and plaster industry,has been part of the group sinceMay 2002.

Zwick Roell AG’s expertise in sensortechnology for load and extensionmeasurement was enhanced andconsolidated by the acquisition ofGerman company GTM in 2007 andMessphysik of Austria in 2006.

Zwick’s years of accumulatedexperience are reinforced by apolicy of maintaining regular contactwith our many customers. Thisprovides a solid platform from whichthe company supplies a wide rangeof products – from economicalstandard machines to customizedversions for specialized testingsituations. State-of-the-art engi-neering, powerful electronics andapplication-orientated software arethe keynote of these modern, versa-tile, highly intelligent testingmachines and systems.

Zwick Roell AG is far more than justa manufacturer, however. As longago as 1994 the company receivedDIN EN ISO 9001 certification - aguarantee of consistently high prod-uct and service quality. In addition,accredited calibration laboratoriesallow companies in the Group toinspect and calibrate test equipmentand provide internationally recog-nized certification.

1 Zwick Roell AG – Over aCentury of Experience inMaterials Testing

Mechanical testing is one of theoldest forms of materials testing. DaVinci and Galileo were alreadyturning their attention to bendingstrain and the elastic properties ofmaterials in the 15th and 16th cen-turies. Time brought new insights,culminating in the appearance of thefirst testing machines in 18th-centuryFrance.

Roell & Korthaus have been involvedin materials testing since 1920, whileZwick began building machines andinstruments for mechanical materialstesting in 1937. Many years earlier,in 1876, Professor Seger hadestablished a chemical laboratoryproviding scientific advice on acommercial basis to the stoneindustry. During the 20th century thisevolved into the present-dayconcern Toni Technik, leadingspecialists in the field of constructionmaterials testing systems.

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2 Zwick – The Specialistfor Medical TestingSolutions

Medical engineering has joined ma-terials testing in the metals andplastics industries in becoming anincreasingly significant part ofZwick’s activities. In the last fouryears alone the number of ordersreceived from this field has doubled.Safety requirements occupy an evenmore prominent position in medicaltechnology than in most other indus-tries, simply because the productshave a direct influence on humanbeings. To meet these requirements,quality testing naturally includes de-velopment, production and pack-aging of medical products, payingdue attention to legal requirementsand relevant standards; most im-portantly, it must also minimize therisk for patients and users.

No Matter what Segment ofMedical Technology – Zwickhas the Solution

Zwick already has more than 20 yearsexperience of testing medical pro-ducts and can offer a comprehen-sive product range and wide-rangingexpertise in static and fatiguetesting. This is the result of a multi-tude of successful projects andcontinuous development and en-hancement of new and innovativeproducts, backed by collaborationwith universities, associations andindustry.

Mechanical testing in research,development, production, packagingand quality assurance also benefitsfrom this collaboration; working withindustry and research institutes,Zwick develops customized solutionsfor a wide range of segments. A fle-xible, modular range of machines,specimen grips, accessories andsoftware simplifies finding theoptimum equipment, while Zwick’s

comprehensive service portfolioallows the special needs of medicalengineering and pharmaceuticals tobe catered for.

Customized Solutions forMaximum Flexibility

Zwick provides solutions tailored tothe requirements of customers fromthe medical technology and pharma-ceutical industries. The majority ofmaterials testing machines installedin this sector are customizeddesigns; test fixtures in particularmust be adapted on an individualbasis to suit the product in question.The wide degree of freedom offeredby testXpert® II software is of greatvalue in meeting varying testingrequirements and Zwick providessuitable software functions anddetailed documentation to facilitatevalidation in this heavily regulatedsector.

At universities and other educationalinstitutes throughout the world,Zwick supports ground-breakingresearch with tailor-made solutions.In addition to serving in testing andresearch laboratories in educationand industry, Zwick materials testingmachines can also be foundintegrated into production lines for in-process checks. Our testinginstruments and systems can alsobe combined with automaticspecimen feeders, their modulardesign allowing them to beexpanded and adapted to newsituations as required.

Zwick is a member of numerousassociations, bodies and networksand is continually adding to its fundof experience by sharing andexchanging information with variouscommittees and collaborators.

Overview of Segments

Therapy systems:containers and tubing forliquids, catheters, hypoder-mics, injection pens, cannu-lae and injection needles

Clinical research:materials, implants, artificial,human and animal tissues

Medical textiles:wound dressings, plastersbandages, suture materials,surgical textiles, clothing

Biomechanics and orthopaedics:prostheses/implants, trauma products(pins, screws, plates), stents

Latex, rubber andsilicone products:condoms, gloves

Dental industry:metals, ceramics, plasticsand combinations, fillingmaterials, implants, pros-theses

Biomaterials:implants based on body’sown or artificial materials(tissue engineering)

Packaging:various materials, shapesand types of closure/seal,sterile/non-sterile

Instruments:scissors, knives, forcepsclamps, drills, surgicalneedles, endoscopes

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2.1 Medical Packaging

Fig. 2: Testing device with laser positioningfor push-out test

Fig. 1: Peel device for peel packs

Products from the medical tech-nology and pharmaceutical industriesmust be securely packed and alsoensure product safety over a longerstorage period. Packaging is manu-factured from a wide variety ofmaterials, in various geometric formsand may be equipped with specialfunctions.

Push-out Test on Blister Packs

This device is suitable for testing thepush-out force of blister contentssuch as pills and other medicalproducts. Pushed-out remains fallout of the pack via the ejectionchannel in the compression platen.Specimen alignment is facilitated bya laser pointer which illuminates thedie position above the specimenbefore the push-out test.

The spherical laser-pointer die canalso be used for positioning speci-mens from other push-out tests.The compression die is designed fora maximum force of 30 N.

Peel Test on Peel and BlisterPacks

This device is suitable for testing theseal edge of peel-off packaging bypeeling off the lid or sealing materialof dimensionally stable or rigidpackaging media, e.g. individualblister packs for contact lenses. Itpossesses a support block with aholding-down device and screwclamp designed to retain the film inposition. During the test, up to 90 %of the lid is pulled off. The screwclamp has a maximum openingwidth of 2 mm and is suitable forgripping forces up to 300 N.

Toolbox

The “Toolbox” contains elementswhich can be combined in variousways for function-testing com-ponents. A T-slot base platformattached directly to the base cross-head forms the basic workplate, onwhich, for example, the T-slot sup-plementary platform can be mountedvia brackets or pivoted joints. Furthercombinations of the holding-downdevice, various fixed and movablevises, the peel device, the lineardisplacement unit, the clamp setand an adapter plate are possible.

The compression die and the quick-release chuck are attached to theupper connection. All tools can beflexibly combined or linked in avariety of ways thanks to their versa-tile, modular design, allowing a widerange of geometrically differingcomponents to be supported, heldand positioned securely.

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3-point Flexure Test on Snap-off Ampoules with Break Point

The universal 3-point flexure test kitallows break points and break forceson ampoules of various sizes to betested, the ampoule geometry beingaccommodated via shims and amovable anvil. The kit is designed fora nominal force of 500 N and aprotective screen is recommendedfor this test, as glass breakage mayoccur.

Special Non-destructiveCompression-test Kit forMedical Injection Vials

For testing the residual seal force offlanged caps, Zwick recommends adevice with inserts and compressiondies of various sizes. Measuring thepre-load force of the rubber stopperon an aluminium flanged cap pro-vides an indication of the security ofthe vial closure. Modular designallows the various inserts to bechanged quickly and easily; aprotective screen is necessary forsafety purposes, as glass breakagemay occur during this test.

Fig. 2: Flexure test kit for testing snap-off ampoules

Fig. 1: zwicki-Line materials testing machine with residual seal force testing device

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Compression Test on Card-board Packaging

Compression tests have various pur-poses, two of which are describedbelow.

• Determining stacking behavior:there are various procedures forthis test according to standard andmaterial. Individual or multiplepackages are loaded until failure,allowing the maximum stackingheight to be calculated.

• Determining inherent rigidity: thistest provides information for thepackaging manufacturing process,as it is loaded with a defined forceon closing (lid attachment) andmust survive this procedureundamaged.

Push & Turn Test on Screw Caps

Test to determine the superimposedcompression / torsional forces onopening and closing of childproofcontainers or pharmaceutical pack-aging. For this a zwicki-Line table-top testing machine of Fmax 2.5 kN

and an additional torsion drive of 5 Nmtorque are used. The two test axescan be used for independent orcombined axial / torsion tests asrequired, the package being openedvia a rotary movement with a super-imposed axial loading. Importantparameters are the opening torquerequired and the functioning of thechildproof mechanism.

Tear TestStandards ISO 34-1, ISO 6383-1,EN 495-2 and DIN 53363 relate totear tests on plastic foils. The testsimulates the behaviour of packag-ing foils when the package is opened.

When opening a plastic bag, theinitial tearing strength should beapproximately as much as theremaining tearing strength. If themaximum force at initial tearing istoo high, the danger exists that theplastic bag will suddenly tear opencompletely and the contents will spillout. The ideal behaviour is not easyto adjust because the tear resis-tance (as well as the tensile strength),is very direction dependent withstretched foils.

Fig. 1: zwicki-Line Torsion for push & turntests on pharmaceutical packaging

Fig. 2: Compression test on cardboardpackaging

Fig. 3: Testing sealed seam strength

Fig. 4: Tear growth test on plastic film

Testing Sealed-seam Strength

Seamed seal strength of seals madeof flexible packaging materials isdetermined to DIN 55529 and pack-aging materials and systems formedical products for sterilization aretested to DIN EN 868ff.

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2.2 Therapy Systems

During treatment of a patient variousproducts are used to carry fluids toor away from the body. Minimum-invasion instruments such ascatheter systems may also beinserted into the body.

2-point Flexure Test Kit forHypodermic Needles, MedicalTubes and Guidewires

A kit for testing the flexure charac-teristics (e.g. buckling strength) ofstiff medical tubes (catheters etc.),guide wires and hypodermic needlesalso with luer lock. Equipment in-cludes a flexure table and twoholding-down clamps for hypodermicneedles, luer lock, guide wire or stiff

medical tube. Differing specimen dia-meters are catered for by differently-shaped holding-down clamps(straight and prism-shaped) whichare easily exchanged. The kit isdesigned for a maximum compres-sion force of 50 N.

2-point Flexure Test Kit forCatheter System Guide Wires

A 2-point flexure test kit for deter-mining the kink resistance of guidewires, designed for forces up to 50 N.Grip-to-grip separation is infinitelyadjustable and the kit includes a dialgage for displaying grip-to-gripseparation from 0 to 55 mm, with anaccuracy of 0.1 mm. Specimenclamping is in the vertical plane, withthe bending angle (max. 90°) gene-rated via the rotating clamping unit.

Fig. 1: 2-point flexure test kit for testinghypodermic needles

Fig. 2: Tensile test on catheter connections

Testing Catheter Connections

Pneumatic specimen grips formaximum tensile forces up to 1 kNare suitable for determining theinsertion and connecting forces ofcatheter tube systems and can alsobe used for testing flat specimensmade of metal, plastics, paper orfoils. These single-actuator grips areclosed by means of a foot pedal,leaving both hands free for fixing thespecimen, while the closing force isinfinitely adjustable via a pneumaticcontrol unit. The low height of thespecimen grips allows optimum useto be made of the test area of thematerials testing machine and Zwickhas available a comprehensive rangeof jaws for widely differing applica-tions.

Device for Testing DentalSyringe Cartridges

This device enables tests toDIN EN ISO 11499 on dental syringecartridges for local anesthesia to beperformed and is used to determinethe force required to move theplunger in the cartridge. It can alsobe used for additional tests, e.g.testing leakage on syringe cartridges.The test fixture has a clampingdevice with prism jaws, a compres-sion die and drain hole in the lowerpart of the test arrangement, while aprotective container providesshielding from slivers and acts as afluid collector.

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Fig. 2: Testing luer-lock connections

Fig. 1: Foil retainer for penetration forcemeasurement

Testing Luer-lock Connections

With catheter connections, as usedwith infusion needles, it is importantthat connections between individualcomponents can be made simplyand reliably. These tests can beperformed with (for example) a ZwickZ020 testing machine with 500 Nmtorsion testing device attached. It isimportant that compression load,torque and indentor cone are stand-ardized.

Testing Device for DeterminingPenetration Force and Ad-vancement Force of Cannulae

This test device has been designedespecially for determining penetrationforce and advancement force ofcannulae and hypodermic needlesup to 200 N following LAB 530. Forthis the force/distance during thevarious phases of the injection isrecorded. The upper clamping fixturecan also hold hypodermic syringeswith needles and auto-injectors witha specimen diameter of 5 – 10 mmor 12 – 18 mm. The device also hasa lower retainer for the penetrationmaterial (usually foil) with variousinserts, ensuring centering of diffe-rent types and sizes of needle.

Fig. 3: Device for simultaneous testing of upto 8 hypodermics

Fig. 4: Determining hypodermic plungeractuation force

8-axis Device with HoldingFixture, for Testing FrictionalForces on Hypodermic Syringes

This device comprises an AllroundLinetable-top testing machine expandedto 8 test axes to hold 8 load cells. Itis equally suitable for use in the labo-ratory or for in-process monitoringand is used for testing the variousfrictional forces between syringeplunger and cylinder, or the sealingrings in syringe cylinders. The syringeholder has acrylic sleeves forsyringes of different sizes, plus twocontainers for catching expelledliquids. This device can also be usedfor testing frictional forces on cylin-drical ampoules.

Test Device with Fluid Reser-voir for Determining PlungerActuation Force

This device was developed todetermine the forces required toactuate the plunger of sterile single-use hypodermic syringes (with con-tents as appropriate) in tests toDIN EN ISO 7886-1 and reproducesworking conditions, i.e. filling anddischarging of fluid. It consists of anupper and a lower clamping devicefor holding the syringes plus aheight-adjustable fluid reservoir withconnecting tube. The device can beeasily dismantled for cleaning.

Variable Alignment of ZwickMaterials Testing Machines

Zwick materials testing machinescan also be used in a horizontalposition for testing different therapysystems.

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Discharging Testing Devicefor Dosimeters and SyringeCartridges

This height-adjustable clamping de-vice was designed for testing dosi-meters and syringe cartridges and isused to determine discharging forcesand volumes. Scales for measuringexpelled volumes are positioned infront of the testing machine and areshielded from external influences byan acrylic housing with removablecover, ensuring reproduciblemeasurement. Carrier sleeves forglass cartridges are available asaccessories. The device is designedfor compression tests up to 100 Nand can also be combined with arobotic specimen feed system,which thanks to its modular designcan be expanded and adapted asrequired to accommodate a widevariety of testing situations.

Fig. 1: Discharging device for testing insulinpens

Fig. 2: zwicki-Line materials testingmachine with integrated torsion drive forautomatic testing of injection pens

Fig. 3: Horizontal testing machine with integrated bath for catheter testing

Automatic Testing ofInjection Pens

Zwick’s test device for automated test-ing of injection pens (e.g. insulin pens)is based on a zwicki-Line Z0.5 TNtable-top testing machine with addi-tional torsion drive, allowing thevarious operations of the pen to betested using a single device. In thisway the dosage setting, releaseforce, stroke and the dose dispensedare all measured in one continuousprocess. The test device can becombined with a robotic specimenfeed system and the test methodsusing either or both axes can becombined as required.

Horizontal Test onCatheter Systems

Catheters, guidewires and otherminimum invasion instruments passthrough three distinct phases tofollow a tortuous path through anartificial aorta. The various catheterforces can be measured in each ofthese phases – insertion into theartery in the inguinal region,straightforward progress along theartery and tracking artery curvaturesof more than 90°.

• Initial insertion force of catheter• Advancement force• Flexibility of catheter tip with

curvature greater than 90°• Physiological environment through

use of temperature-controlledwater-bath using various media(pH value).

Development work on these cath-eter and guide wire systems includesattempts to reduce the co-efficientof friction and the breakaway torque.The horizontal Allround-Line testingmachine offered by Zwick enablesdetermination of shear forces in asimulated catheter insertion withvery high accuracy. The test iscarried out in a horizontal orientationin order to simulate the physiologicalstatus of the patient during thesurgical intervention.

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Fig. 2: Penetration test on bone drill

2.3 Surgical Instruments

Medical / surgical instruments arefound in a wide variety of materialsor combinations with widely differinggeometrical forms and can combinemany different functions in oneinstrument.

Hardness Test

To test the hardness of metals orcomponents used in surgicalinstruments, hardness testingmethods to Rockwell, Brinell andVickers (Knoop) or the moderninstrumented indentation method(Martens hardness) are used.

Tensile Test on Metals andMetal Alloys

High-grade steel, high-tensile steeland titanium alloys are tested on adaily basis in incoming inspection orin materials laboratories of medicalconcerns by means of the classicaltensile test. To determine the strengthand deformation behavior of metalsor components they are subjected totensile, flexural and compressionloadings. The requirements for thisare specified in various standards,including ISO 6892, EN 10002,JIS Z 2241, ASTM A 370, andASTM E8. Zwick supplies appropriatetesting machines, extensometers(mechanical and optical), specimengrips, accessories and Master TestPrograms with parameters alreadypre-defined to the specifications ofthe relevant standards for virtually alltesting requirements.

Compression Test on SagittalSaw Blade

The cutting precision and flexuralstrength of sagittal saw blades havea significant influence on operationoutcomes. Function testing thesesaw blades involves simulation ofhandling by the surgeon. The com-plete saw plus blade is clamped inthe testing machine, the saw isstarted and the blade is run againstthe bone substitute material. Press-ing force and depth of cut are meas-ured, to provide tolerance values forcorrect use; calculated characteristicvalues, such as stiffness, provideinformation regarding load influenceswhich will bend or damage the sawblade.

For a further test of saw bladeflexure strength, installation of a 3-point flexure test kit from the Zwickaccessory range is quick andstraightforward. These tests allowthe cutting characteristics andprecision of different saw toothgeometries to be investigated.

Bone Drill Penetration Test

Today’s bone drills face exactingrequirements with regard to cuttingedge characteristics, contact forcerequired, chemical resistance andavoiding bone heating. This testdevice is used to determine contactforce, penetration force and torquerequired for a bone drill. Dependingon the area of use and the bonequality involved, dental drills, corticaldrills, oral surgery drills etc. arescrewed into the appropriate materi-al – dentine, bone or substitutes –using a specified feed pressure andtorque.

The test allows overlaid measure-ment of torque and compressionforce. Zwick’s comprehensivetesting machine concept additionallyprovides flexure fatigue resistancetesting via a 3-point flexure test kitplus hardness testing of the basicmaterial.

Fig. 1: Device for compression tests on sa-gittal saw blades

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2.4 Biomaterials

With increasing life expectancy andgreater demands by our society forunrestricted quality of life into ad-vanced old age, the specialized areaof regenerative and artificial organand tissue replacement (tissueengineering) is assuming increasingimportance. The mechanical prop-erties of regenerative and artificialmaterials are one of the areas ofresearch in the field of biomaterials.

Biaxial Test on ArtificialTissues

The mediX0.1 biaxial testing machineis designed for mechanical testing ofnatural and artificial tissues. Biaxialtesting is often necessary to char-acterize the anisotropic properties ofelastic tissues. With uniaxial testsmechanical properties can changeduring the test due to the potentialfor fibers to straighten along themeasurement axis.

Fig. 2: Specimen grips for biomaterials inbath

Fig. 1: mediX0.1 biaxial materials testing machine with laserXtens

The clamping system must be ar-ranged so that the tissue is heldsecurely during the test withoutbeing damaged. Unrestricted lateralmovements must be possible inorder to ensure homogeneousspecimen deformation under biaxialloading, while the strain measure-ment device must on no accountcause damage to the specimen andmust be able to record strain in allloading directions.

Principal Features• 4 high-resolution linear drives

(stroke 50 mm), which can beposition, load or strain-controlledcompletely independently of eachother.

• Load measurement via four loadcells (two load cells in X and Y-directions respectively) with amaximum test load of 100 N.

• Strain control and/or center-pointcontrol are via the non-contactlaserXtens, which requires nomarkings on the specimen.

• Vibration-damped, movable table.• Height-adjustable bath (for saline

solution or other fluids) withoptional heating.

• Force signal resolution: 0.6 mN.• Travel measurement resolution:

0.1 µm.• Maximum speed: 2000 mm/min

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Tensile Test on Artificial Tissuein Temperature-controlledEnvironment

Rapidly absorbable materials such asthose increasingly used today intraumatology, surgery and wound-healing change their material proper-ties progressively on contact withmedia such as blood, water or salinesolution. This must be controllable sothat absorbable biomaterials can beused in a targeted way. It is importantduring manufacture and develop-ment to be aware of the change inrigidity, tensile strength and proofstress (yield point) and where neces-sary to adjust it.

A temperature-controlled fluid bathhas been added to Zwick’s bio-mechanics accessory range, makingit possible to simulate an in-vivoenvironment for tests on tissues.Suitable submersible accessories forspecimen fixing are also available.

Principal Features• Z2.5TN table-top testing machine,

Fmax 2.5 kN.• Test speed: 0.001 - 1000 mm/min.• Temperature-controlled bath with

separate heating circuit.• Pre-conditioning of specimen in

temperature-controlled bathavailable.

• Optionally available: videoXtens orsubmersible clip-on extensometerand various submersible specimengrips.

Fig. 1: zwicki-Line with temperature-controlled fluid bath and videoXtens (bathlowered for specimen change)

Testing Scaffolds for BoneReplacement

Research into biomaterials requiresthe test environment to correspondto actual conditions as far aspossible. For this reason testing inthis field is preferably carried out influid baths or complete incubators.

In this application, cells from bonemarrow are applied to a carrier ma-terial and cultivated in a liquidnutrient under cyclic mechanicalstimulation. For this an ambienttemperature of 37 °C, 100%humidity and cyclic loading (usingZwick testing actuator) under verylow forces are necessary.

The load is applied to the specimenvia a die integrated into the incu-bator from above and the specimensimmersed in the liquid nutrient areflushed with CO2 or N2 to adjustthe pH value. Extensions lie between30 and 100 µm.

Fig. 3: Compression test on bonereplacement material

Fig. 2: Integration of a temperature chamberinto the test arrangement

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2.5 Biomechanics

Biomechanics is concerned with thefunctions and structures of themusco-skeletal system and move-ments of biological systems. Medicalproducts to be tested are prostheses,osteosynthetic implants, traumaproducts and orthopedic implants.

Fig. 1: Titanium stapes prosthesis (HeinzKurz GmbH Medical Technology)

Fig. 2: Specimen grips for tests onendoprostheses

Function-testing StirrupProstheses

Stapes prostheses are used in Ear,Nose and Throat (ENT) therapy as areplacement for the stirrup, theprosthesis forming a direct connec-tion between hammer and inner ear.The ball-joint allows optimummatching during the operation. Toensure functional integrity, the jointforce must only move in a specifiedarea. The prosthesis is only 5 mm inlength and has a diameter of 0.5mm. Using the zwicki-Line Z0.5table-top testing machine, this forcecan be determined without damageoccurring to the specimen.

Fig. 3: zwicki-Line Torsion for penetrationtests of bone screws

Testing Anchoring of aHip Endoprosthesis

Hip endoprostheses can be an-chored in the femur with or withoutthe use of bone cement. In additionto fatigue tests on the prosthesisitself, the strength of the fastening inthe bone must also be tested. Forthis an endoprosthesis is anchored innatural or artificial bone, the load axisis adjusted by means of a clampingfixture and the entire test device isclamped in an Allround-Line Z020testing machine. During the cyclicloading, loads can be measured,together with any micro-movements(via movement sensors) betweenprosthesis and bone

Torsion-testing Screws in BoneReplacement Material

Here a bone screw is screwed intobone replacement material bymeans of a torsion drive. The rele-vant parameters here are the torquerequired in conjunction with theapplied compression force.

The testing machine used is azwicki-Line Torsion (5 kN nominalforce, 20 Nm torsion drive).

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Fig. 3: Test device for holding hip-jointprostheses

Fig. 1: LTM1000 with spinal implant

Fig. 2: Torsion test on artificial hip-joints

Fatigue Testing onSpinal Implants

In spinal surgery, stabilization of thespine is achieved via a movable (discprosthesis) or fixed (cage) interver-tebral disc replacement. In addition,a stiffening operation using screwsand rods, or the replacement of anentire vertebral body with a vertebralbody replacement implant can beemployed for stabilization.

All spinal implants have one thing incommon – they must withstand alldynamic loads over many years.

Tests of this kind can be performedwith the LTM1000 linear drive testingmachine or with the Amsler HC-Tservo-hydraulic testing machine withadditional torsion components. Inthis way, for example, ISO 12189,ASTM F 2077, ASTM F 2347 or theFDA Guidance specifications, whichdescribe dynamic compression,shear or torsion tests, can beimplemented in compliance withstandards.

Torsion Test onArtificial Ball-joints

Artificial hip-joints must withstandboth compressive loads and torsionloads.

To determine the optimum materialsand alloys, these are tested with aspecial testing unit consisting of a20 kN capacity Zwick materials test-ing machine plus a 500 Nm torsiondrive.

The artificial hip-joint (here made ofmetal) is rotated on a support unit(torsion loading) and at the sametime compression loading is applied.

Fatigue Test onHip-joint Prostheses

The Zwick Amsler HC Compactservo-hydraulic testing machine isused to simulate dynamic loadingson a hip prosthesis stem in accor-dance with the relevant standards,ISO 7206-4, ISO 7206-6, ISO 7206-8and ASTM F 2068. Use of the ap-propriate embedding device enablesthe mechanical conditions specifiedin the standard, such as the orien-tation of the hip-joint prosthesis tothe test load or the embeddingheight, together with the angle ofload application, to be definedexactly.

To test the durability of the stem,dynamic loading on the hip-jointprosthesis during walking, withloosening already present, issimulated; by contrast, the neckregion of the prosthesis, which isclinically well anchored, is subjectedto alternating loading. The Zwicksoftware also allows operator-friendlyLocati tests to be performed.

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Fatigue Test on Lower LegProsthesis

A HC series servo-hydraulic testingmachine is used for fatigue-testingprosthesis stems. The test arrange-ment shows a component from aleg prosthesis under continuous axialloading. The frequencies used are10 Hz, similar to the fatigue test, andcan be increased if a faster pace isto be simulated.

Principal Features• Servo-hydraulic HC 10 for dynamic

testing up to Fmax 10 kN• Testing frequencies up to 100 Hz• Extremely stiff and fatigue-resistant

design• Servo-hydraulic testing machine

for tensile, compression andflexure tests

• Suitable for continuous, static,pulsating and alternating loading inquasi-static and dynamic tests

• Piston stroke 400 mm with end-position damping

• Customized holders for legprostheses

• T-slot table• HydroWin measurement and

control electronics• testXpert® and Workshop user

programs

Advantages and Benefits forthe Customer• Simple, reliable operation via

proven software-controllercombination

• Universal clamping options via T-slot table and easy fixture change

• Extremely stiff, robust designintended for continuous loading atnominal force

• Tailor-made solutions are noproblem thanks to a wide range ofoptions

Fig. 1: Test device for lower-leg prostheses

Fig. 3: Nitinol stent

Fig. 2: Test device for stents

Simultaneous Fatigue Tests on30 Stents

To investigate the durability of stentsa fixture has been developed whichallows up to 30 stents to be ac-commodated simultaneously. Thisfixture, with an electric torsion drive(1 Nm), is used in combination withan HC 10 servo-hydraulic testingmachine (10 kN) and allows both se-parate and superimposed loading ofthe stents with compression andtorsion (5 Hz at ± 60°). The grippedarea of the stents can also beprovided with a fluid bath to enabletesting under physiologicalconditions.

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2.6 Clinical Research

The field of clinical research involvesmostly basic research into human,animal and substitute materials.Characteristic values are determinedwhich provide information on thehealing process after operations orwhen new medical devices ortechnologies are used.

Load Test on Human Femurwith Strain Gages Applied

The test is used to establish to whatextent an implanted endoprosthesisstiffens the bone, thereby causing astress protection effect of the bone.For this a human femur is placed ina Zwick Allround-Line Z020 com-bined with a bearing, intended toeliminate transverse forces. Thefemur head is then loaded axially.Strain gages adhered to the surfaceof the bone enable comparison ofthe surface stress on the femurbefore and after implantation of theprosthesis.

Fig. 1: Femur with strain gages applied

Fig. 3: 3-point flexure test kit for tests onsheep bones

Fig. 2: Femur with implanted endoprosthesisand with strain gages applied

Flexure Test on Sheep Bones

A 3-point flexure test on sheepbones is designed to determineflexural strength after fracturehealing. For this a bone healed afterbreak is fixed or cast at its ends insupports and the load is appliedusing a zwicki-Line Z0.5 table-toptesting machine. The specimen gripsare designed so that rotation of thebone by defined angular degrees ispossible, allowing the flexuralstrength of the entire area of thebone to be determined. Thecharacteristic values obtained in thisway are used in an FEM simulationof the healing behavior of the bonefracture. Expandability of Zwick

Materials Testing Machines• Standard Zwick connecting

elements for easy exchange ofspecimen grips or test devices

• Zwick Toolbox with combinableelements for function-testingcomponents, with T-slot platform,fixed and movable vises andclamp set.

• Tests under temperature andmedia influence possible

• Up to ten digital or analog high-resolution inputs for synchronousdata acquisition

• Integration of external measuringsystems

• testXpert® II All-In-Suite offers acomprehensive range of software:all Master and Standard Test Pro-grams, Graphical Sequence Editorplus all options.

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Fig. 1: Peel test on wound dressings Fig. 2: Determining adhesive forces ofwound dressings

2.7 Textile Medical Products

Textile medical products include elas-tic textiles for compression therapy,rigid systems such as plaster casts,products for treating wounds,surgical textiles (clothing for medicalpersonnel and drapes for patients)and surgical suture materials.

Fig. 3: Unrolling test for gauze bandages

Unrolling Test forGauze Bandages

To avoid the problem of individualfibers of gauze bandages ‘catching’on the winding below and preventingreliable unrolling, it is necessary todetermine the force required tounwind the bandages from a roll. Forthis, a Zwick materials testing ma-chine of 10 kN capacity is used,together with a motor-driven unroll-ing unit. The sequence is controlledby a specially adapted program fromZwick’s testXpert testing software.

Measuring Adhesive Force ofWound Dressings

DIN EN 1939 describes how theadhesive force of adhesive tapes isdetermined. To measure the ad-hesive force of wound dressings orother self-adhesive medical prod-ucts, the specimen is pulled off ametal plate during the test. This canbe performed at various angles.However, the forces measured inthis way are twenty times greaterthan those arising with the com-bination of skin and dressing!Manufacturers of adhesive productstherefore test adhesive force on na-tural skin, in order also to be able todetect any sensation of pain by thepatient, together with any skinirritation which may occur dependingon the used adhesive component.

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Fig. 2: Testing burst strength Fig. 4: Tear-growth test

Fig. 1: Specimen grips for yarns Fig. 3: Testing seam slippage resistance

Fig. 5: Tensile test on non-wovens

Testing Non-wovens used in theMedical Field

These materials are often used aswound dressings and as a compo-nent part of dressing materials, asan alcohol swab for preparinginjections or in physiotherapeuticapplications; they are a componentpart of patient and instrumentdrapes in the operating theater andused as a cover for dental tampons.

The investigations carried out on thismaterial are as varied as the rangeof applications of the end products.One important test in this field is thetensile test on strip specimens(EN 29073-3 / ISO 9073-3 / ASTM D5035).

Measured value is maximum tensileforce. The coefficient of variation forthe results is calculated. Otherimportant test methods includeabsorption capacity (EN ISO 9073-6)and strike-through time for liquids(EN ISO 9073-8). A zwicki or ProLine(Z005) testing machine is typicallyused for these tests.

Testing Surgical Textiles

A further aspect of medical textilesconcerns infection prevention in bothout-patient and in-patient areas.Reusable or single-use textiles forsurgical masks and operatingtheater gowns and drapes areintended to ensure infection preven-tion for doctors and patients.

Standards EN 13795 and EN 14863provide manufacturers with guide-lines and common reference require-ments to be met by surgical textiles.

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2.8 Silicone Products

Many medical products are made oflatex, rubber or silicone, the elasticproperties of these materials beinguseful in this field, while their non-toxicity especially that of naturallatex, plays an important role inmedicine and hygiene in excludinggerms.

Tensile Test on Rubber Gloves

Single-use medical gloves provideprotection in operations, exami-nations and caring activities. Themost important requirement ispreventing the entry of air, fluids andmicro-organisms. Manufacture in-volves immersing molds in solutionsof natural rubber or latex mixtures.The number of immersion and dryingprocesses is repeated until therequired thickness is achieved, afterwhich the gloves are vulcanized incuring ovens.

Fig. 2: Roller specimen grips for testingcondom material

Fig. 1: Tensile test on rubber raw material

So that they do not tear when beingpulled on in use, the gloves mustdisplay sufficiently elastic behavior.

Examples of stresses to which theyare subjected include hooking on orholding pointed or sharp tools, for-eign bodies or instruments. Methodsused to guarantee the requiredoperational reliability, include thefollowing mechanical tests.

Tear-strength tests are performed ongloves with and without a seam, aswell as on artificially aged gloves.zwicki-Line or ProLine testing ma-chines are also used for this andtesting takes place to ISO 37 andASTM D412. Three shouldered testbars are punched out of the palm,back and cuff of the random sampleglove, parallel to the longitudinal axisand avoiding structured areas.

Tensile Test on Condoms

zwicki-Line table-top testing ma-chines are suitable for determiningthe tear strength and strain at tearof condoms. The required forcemeasurement range as specified inthe standard lies between 0 - 200 Nand the load cell suitable for thishas a nominal force of 200 N (meas-uring range from 2 N in Class 1 toDIN EN 10002-2). The crossheadspeed is 500±50 mm/min.

Flanged rollers, arranged horizontallyand mounted at one end only, areused to hold the specimens. One ofthese rollers is driven via a toothedbelt proportionally to the crossheadmovement, loading the condomspecimen uniformly over its entirecircumference. If the rollers werefixed or not driven, frictional forceswould act in addition to the tensileforce and the specimen could beunacceptably loaded and pre-damaged.

A thickness-measuring device canbe connected via the serial port ofthe PC, so that these measuredvalues are automatically input intothe test as well.

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Fig. 4: Test kit for dental implants (DentalClinic, University of Ulm)

2.9 Dental Industry

Materials (ceramics and metals),composite materials and adhesivebonds used in the dental industry,together with dental prosthesissystems, are tested for their hard-ness, strength and fatigue limit.

Hardness Test on DentalCeramics

Dental ceramics used as filling ma-terials or as restorative materialsmust, in addition to health and visualconsiderations, satisfy requirementsregarding strength, wear and dura-bility.

Visual requirements can be cateredfor by replicating the light effects ofnatural mineral dental enamel,including opalescence, fluorescence,transparency, through layers of colorof varying intensity.

Strength properties can, for example,be verified by means of hardnesstesting. Due to limited reflectivity, theoptical hardness testing method toVickers can only be employed to arestricted degree.

However the instrumentedindentation test, based onmeasurement of indentation depth,has proved very effective, as othermechanical characteristics in additionto hardness can be derived from theentire test sequence, for exampleallowing creep or relaxation of thedental material to be measured.

Fig. 2: Fully automatic Zwick/ZHU2.5/Z2.5universal hardness testing machine withmotorized displacement unit

Fig. 1: 4-point flexure specimen grippingunit for dental ceramics

4-point Flexure Test Kit forTests on Ceramics

• Die and lower bending table for4-point flexure tests for tests ondental ceramics to ISO 6872 andon advanced technical ceramicsto EN 843-1 Specimen Shape A

• Die and bending table eachconsist of 2 hardened anvils withrollers with adjustable span

• All rollers can be rotated, withswiveling or fixed mountings asrequired (lockable via pins)

• Can also be used as 3-pointflexure test kit via simplemodification

Fatigue Test on DentalMaterials(Chewing simulator)

For tests on teeth, dental prosthesesand filling materials a test standbased on the HCT-10 servo-hydraulictesting machine has been developedwhich enables dynamic loading withan axial force up to 10 kN andtorque up to 100 Nm. Up to 5 speci-mens can be in a water-bath at thesame time and are loaded with atesting frequency of up to 25 Hzaxially, torsionally or with a trans-verse movement via an adaptabletest piece. The forces are recordedby a load cell placed betweenactuator piston and die or via 3-component load cells underneaththe water-bath.

Fig. 3: Dental specimens

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3 Zwick Modular System for Individual Testing Requirements

Material testingmachines

Biaxial testingmachines

Static Testing Machines

Servo-hydraulictesting machines

Vibrophores

Pendulum impacttesters

Materials testingmachines with lineardrive

Dynamic and Fatigue TestingMachines

Hardness testers Vicat testers

Extrusionplastometers

Testing Instruments

Load Cells, Specimen Grips and Extensometers

Load cells Non-contactmeasuring systems

Specimen grips Contact measuringsystems

Temperaturechambers

AutomationHigh-temperaturefurnaces

Specimenpreparation

Individual Testing Solutions

testXpert® II testControl

Testing Software / Measurement an Control Electronics

+ testXpert® IIMedical option

Torsion testingmachines

Materials testingmachines with lineardrive

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3.1 Quasi-Static MaterialsTesting: Products and Ser-vices

Materials Testing Machines

ApplicationsMaterials testing machines are usedto determine the strength and de-formation behavior of specimens andcomponents, mostly under tensile,compression and flexure loading.Shear and torsion loads are alsoused. These testing machines fea-ture long travel, wide test-speedranges and interchangeable sensorsand tools, allowing testing of speci-mens and components with widelydiffering forms and dimensions,made from various materials andmaterials combinations and withcorrespondingly different character-istics.

Basic ConceptZwick has three series of quasistaticmaterials testing machines, differingin design, equipment, performancecharacteristics and expandability.This allows us to provide the mostsuitable machine for every budget.

• The zwicki-Line consists of high-quality, compact machines. Theseportable, easy-to-use single-columnload-frames have been speciallydesigned for mechanical testingwith low test loads of 0.5 to 5 kN.

• The ProLine was developed tosatisfy the demand for cost-effective testing machines forfunction- testing components andstandard tests on materials. The‘Pure Portfolio’ accessory rangefor the ProLine ensures an attrac-tively priced system and shortdelivery times. Test loads are from5 kN to 100 kN.

• The Allround-Line provides thesolution to challenging testingsituations and fulfils the most ex-acting requirements. It can beequipped or upgraded via a com-prehensive accessory range andused with special sensors andmulti-channel measuring technol-ogy.

Load FramesOur standard production load framesare rated for loads up to 2000 kN.We design and manufacture specialversions for specific applications, e.g.for higher rated loads or horizontallyaligned load frames for testing in thecomponent installation position.

zwicki-Line Single-columnModelThis load frame is based on a highlybend-resistant aluminum extrusion,which was developed especiallyfor the zwicki-Line. The workspaceis freely accessible from threedirections, making the zwicki-Linealso suitable for small componenttesting and for use as a hardnesstester. This modular system’s lowweight and compact base make iteasily portable – and it will fit on anylaboratory table.

ProLine Single and Double-column Table-top MachinesProLine load frames incorporate tworound steel columns, providingprecise crosshead guidance, whilethe integrated spindle and guideprotection guarantee reliableoperation in industrial applications orwhen testing splintering materials.

Fig 2: ProLine Z050TN with CE conformingprotective screen

Fig 1: The zwicki line is available in threedifferent heights

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Hard-chrome plated guide columnsand a precision ball screw with play-free spindle nuts guarantee a highlevel of precision for the floor-standingmachines. Various crosshead con-figurations are available, providingeither an upper or lower test area –or both. All load frames with electro-mechanical drives can optionally beequipped with a second test area.Benefits include rapid change to adifferent type of test without havingto reconfigure the entire machine.

Drives for Quasi-static TestSituations

Electromechanical DrivesAll electromechanical drives incor-porate play-free, low-wear ballscrews and digitally controlled drivesand are used with load frames ratedfor test loads up to 2000 kN.Combined with the digital measure-ment and control system, they offerthe following advantages:

• Extremely wide, infinitely variablespeed-range

• Very low speed-settings possible(from about 0.5 µm/min)

• Highly precise, exactly reproduciblepositioning and speeds

The ProLine and zwicki-Line testingmachines are fitted with DC motors.All other testing machines haveespecially low-inertia brushless three-phase AC motors.

Allround-Line Table-top andFloor-standing Testing MachinesThe table-top testing machines areequipped with two columns made ofpatented extruded aluminum. Theyare light and highly bend-resistantand combine the functions of spindleguide and spindle protection. T-slotson the outer sides allow simplemounting of accessories such asfixtures or safety guards, unrestrictedby the moving crosshead.

All table-top testing machines canbe fitted with stands to bring theworkspace to the optimum heightfor the application or operator. Thisallows, for example, comfortableseated operation with plenty oflegroom, making the system wellsuited to wheelchair users also.

Fig 1: Allround-Line floor-standing machineZ100

Hydraulic DrivesThis drive is located centrally to thefixed crosshead, making the testarea below easily accessible. Aservo or proportional valve regulatesthe oil flow between the hydraulicunit and differential cylinder. The oilpad in the upper pressure chambereliminates the familiar problem ofplunger pistons “jumping” when aspecimen breaks. For high test loadsin particular, the hydraulic drive is anextremely cost-effective solution.

Hybrid DrivesThese patented drives combine theadvantages of the electromechanicaldrive (high precision) with those ofthe hydraulic drive (high forces). As aresult, even long-stroke cylindersdesigned for very high loads can bemoved and positioned very precisely.This approach allows two parallelmounted cylinders coupled to themoving crosshead to be traversedwith precise synchronism andregardless of their respectiveloadings. They follow, accuratelyand virtually without hesitation, theposition parameters set by anelectromechanical pilot drive. Specialfeatures of this drive:

• Long travel range (no adjustmentof fixed crosshead necessary

• Relatively low load-frame height

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Biaxial Materials TestingMachines

The mediX0.1 biaxial testing machineis designed for testing natural andartificial elastic tissues. Biaxial testingis often necessary to characterizethe anisotropic properties of elastictissues. During uniaxial tests there isa possibility of fibers straighteningalong the measurement axis,causing the mechanical character-istics of the specimen to change. Aclamping system is therefore requiredwhich holds the tissue securelyduring the test without damaging it.

Unrestricted lateral movementsshould be possible in order to ensurehomogeneous specimen deforma-tion under biaxial loading, while thestrain measurement device must onno account cause damage to thespecimen and must be able torecord strain in all loading directions.

mediX0.1 has four high-resolutionlinear drives (stroke 50 mm) whichcan be position, load or strain-controlled completely independentlyof each other. Load measurementtakes place via four load cells (twoload cells each in X and Y directions)with a maximum test load of 100 N.

Strain control and center-pointcontrol is via a laserXtens extenso-meter, which requires no gage markson the specimen.

Possible Applications• Planar mechanical test• Uniaxial, equibiaxial, non-uniform

loading• Determination of mechanical

properties of elastic tissues.

Equipment• Vibration-damped, movable table• Laser-speckle extensometer• Height-adjustable fluid bath (for

saline solution etc.)• Optional: temperature control unit.

SpecificationsForce measurement range per loadcell: +/- 100 NForce signal resolution: 0.6 mNTravel: 50 mmDisplacement measurementresolution: 0.1 µmMaximum speed: 2000 mm/min.

Fig. 1: mediX0.1 biaxial materials testing machine with integrated laserXtens.Inset.: Specimen grips for biaxial tests on biomaterials

Fig. 2: Strain measurement with laserXtens(laser-speckle principle)

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Drive Axes as Individual andExpansion Solutions

Additional Zwick drive axes can beused as a flexible individual orexpansion solution for materialstesting machines. Combining severaldrive axes is also possible.

Electromechanical ServoTesting Actuator

Zwick’s full range of electromechani-cal servo testing actuators combineversatility in use and high travel ac-curacy with high test speeds. Theyrequire no special hydraulic equip-ment or power packs, are a cost-effective solution for quasi-static andcyclic component testing and arecompatible with testControl andtestXpert®.

They can be used in many differentsituations, being available in a loadrange from 1 – 30 kN, with strokefrom 200 – 400 mm. Their speedrange is between 26 and 500 mm/s.

Pneumatic Testing Actuator

Zwick pneumatic testing actuatorscomplete the drive systems forfatigue tests on components. Theirlow installation cost makes them acost-effective alternative for simpletests.

Torsion Drives

Torsion drives from 2 Nm to 2000 Nmare available for the various materialstesting machines for tests on com-ponents or materials which includetorsion loading in addition to tensile/compression loading.

The torsion drives were developedas a modular system and can there-fore also be retrofitted. In addition toa testXpert® II Master Test Programfor multiple test axes, a graphicalsequence editor for four test axes isalso available.

For pure torsion tests there are theTorsionLine testing machines, whichcover a torque range from 20 to2000 Nm.

Fig. 1: Biaxial tensile testing with fourelectromechanical servo testing actuators

Fig. 2: Electromechanical servo testingactuator with external fixation of fractures

Fig. 3: zwicki-Line with torsion drive Fig. 4: Allround-Line with torsion drive

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Fig. 1: Zwick/ZHU2.5/Z2.5 fully automaticuniversal hardness testing machine withmotorized displacement unit

Fig. 2: Indentation cone after Vickershardness test

Hardness Testing

ZHU/zwicki-Line UniversalHardness Testing MachineBased on the zwicki-Line, the ZHU/Z2.5 universal hardness testingmachine can, in addition to theclassic Rockwell, Vickers, Knoop,Brinell and ball indentation hardnesstesting methods, be used for the in-novative instrumented indentationtest for determining hardness plusadditional materials parameters ofmetallic materials (so-called Martenshardness, DIN EN ISO 14577). Installthe patented hardness measuringhead (resolution 0.02 µm) withintegrated digital depth and loadmeasurement system in a zwicki-Line materials testing machine withmodified drive, add state-of-the-arttestControl measurement andcontrol electronics and testXpert® in-telligent testing software and theresult is an ideally balanced high-precision measuring system.

The ZHU/zwicki-Line can beupgraded to a fully automatic unitwith motorized linear displacementunit controlled via testXpert®,eliminating potential operator errors.

Vickers Hardness TestersThe range of Vickers hardnesstesters covers various load rangeswith differing levels of operatorconvenience, allowing the rightinstrument to be selected for everyapplication.

Zwick/ZHV1 and ZHV2 Micro-Vickers Hardness TestersZwick micro-Vickers hardnesstesters cover the load range fromHV0.01 to HV2 and support thefollowing standards:• Vickers (HV) to DIN EN ISO 6507,

ASTM E 92• Knoop (HK) to DIN EN ISO 4545,

ASTM E 384.

For both load ranges there is achoice of operating concept:

ZHV-m (manual) – measuring isperformed manually by the operator,using a microscope. The automaticturret allows one-button controlwhen changing between lens and

indenter, while the automatic testsequence and predetermined timeframe eliminate operator influenceduring hold time.

ZHV-s (semi-automatic) / ZHV-a (fullyautomatic) – both feature completelyautomatic operation to the user'sspecifications. The semi-automaticversion differs in having manualindentation focusing against motor-ized auto-focusing. Motorized load-change, automatic indentationmeasuring, automatically controlledturret (via testXpert®) for exchangingindenter and lens positions,motorized cross-table and fullyautomatic test sequences – usesinclude hardness profile tests withmultiple sequences.

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3.2 Fatigue and ImpactTesting: Products and Ser-vices

Fatigue Testing Machines

Servo-hydraulic TestingMachinesServo-hydraulic testing machines areuniversally applicable for materialsand component testing under pul-sating or alternating load, withperiodic or random signals. Quasi-static and continuous loading arealso easily achieved.

Special Features• Precisely aligned load frames

featuring extremely high stiffness• Hydrostatic bearings, making the

actuators virtually frictionless – andalso wear-free

• LVDT extensometer with highresolution and linearity integratedcentrally in the actuator rod

• Precision strain-gage load-cell formounting on actuator rod or fixingto crosshead as required

• Wide range of hydraulic powerpacks

• Comprehensive range of acces-sories (specimen grips, extensom-eters, temperature chambers etc.)

Amsler HC-compactThe Amsler HC-compact servohy-draulic testing machine consists of ahydraulic power pack, test frameand test actuator and is suitable formaterials and component testingunder static and oscillating loads.

Advantages• Space-saving design with inte-

grated hydraulic power pack• Whisper-quiet power pack allowing

installation without additional noiseprotection measures in virtually anylaboratory

• Testing actuator mounted in topcrosshead permitting easy set-upfor flexure and component testing

• T-slot platform hard-chromed fortests with corrosive media, e.g.saline solutions

• Seal-free testing actuator withhydrostatic bearings, guaranteeingsignificantly longer maintenance-free operation than with any otherdesign.

Amsler HCT and HBT Tensileand Compression/TorsionTesting MachinesThe servo-hydraulic testing ma-chines in the Amsler HCT and HBTseries are used to test the behaviorof materials and components undercombined tensile and compression/torsion loading. The tests can beperformed with pulsating, cyclingand static loading.

Fig 1: Servo-hydraulic testing machineAmsler HCT 10/100

Fig 2: Servo-hydraulic testing machineAmsler HC-compact

SpecificationsModel HC• Type/version table• Load frame

nominal force [kN] 10 – 25• Test stroke [mm] 100/250• Specimen length [mm] 100 – 700• Hydraulic power pack

System pressure [bar] 210/280Feed rate [l/min] 9 – 30

• Motor nominal power [kW] 5 – 20

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LTM1000 Materials TestingMachine with Linear Drive

Developed for quasi-static and fa-tigue tests on materials and compo-nents, Zwick’s testing machine withlinear drive is used in industrieswhich place maximum demands ontechnology and cost-effectiveness,such as medical engineering (e.g.implants, dentistry), electrical engi-neering (e.g. switches and PCBs)and micromechanics (e.g. miniaturecomponents). It is also ideal formaterials development, for examplefor testing miniature specimens, andwith the addition of suitable attach-ments can be employed for environ-mental simulations in temperaturechambers and baths.

The linear drive allows high-precisiontesting with excellent dynamicresponse in a wide range of appli-cations. This low-maintenancemachine features compact, space-saving design and a very low noiselevel and can quickly be put intooperation. All it requires is an elec-tricity supply – no need for water, oilor compressed air.

Fig. 1: LTM1000 materials testing machinewith linear drive

Advantages• Piston stroke measurement

directly adjacent to the specimeneliminates the need for separateextensometers in manyapplications

• Space-saving, low-noise design• No additional fluids such as

pneumatics, water or oil required• Static tests can also be performed

easily using testXpert® II universaltesting software.

Features• Long stroke for fatigue and static

testing over a wide range ofapplications

• Precision, low-wear bearings onactuator

• High-resolution displacementtransducer adjacent to specimen

• Easy quick adjustment of test areavia separate crosshead

• Intelligent cooling system withautomatic control

• Proven Zwick testControlelectronics

• Intelligent testXpert® II testingsoftware for simple, intuitiveoperation

SpecificationsModel LTM1000• Stroke [mm] 70 (Amplitude ± 35)

• Continuous force (static) [N] ± 800

• Peak force (dynamic) [N] ± 1000• Frequency [Hz] 10• Weight [kg] approx. 120 (electronics not included)• Electrical supply requirements [V / kVA] 1x230 / 1.6

Fig. 2: Testing a spinal implant

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4. System Components

4.1 testXpert® II –Intelligent and Protectedfrom Manipulation

testXpert® has set a standard for in-telligent materials testing software.Using testXpert® II allows you to reapthe benefits of more than 80 years’experience of materials testing andover 15,000 successful installationsworldwide. During developmentZwick works on the principle that itis better to check everything at leasttwice, using multiple-stage tests toguarantee uniformly high testingsoftware quality. The focus is onproducing secure software withreliable result determination andmaximum dependability.

Comprehensive User Manage-ment

Do you wish users only to carry outfunctions from a specified range oftasks? Or would you like to maketheir work easier by hiding un-needed functions in the menu bar?testXpert® II’s powerful user manage-ment, which is already contained inthe Basic Program, enables you todo so.

Choose from default user groups ordefine your own; you can authorizeor disable individual menu items,standard actions (e.g. printing

reports) or Test Programs. In thisway you avoid input errors andprevent manipulation. In addition,user management allows passwordguidelines to be defined individually.

Test Programs/Free SequenceProgramming

testXpert® II already contains pre-pared Standard Test Programs for amultitude of international test stand-ards. For the medical and pharma-ceutical industries Zwick has aspecially designed Master IndustryPackage for medical technology,which in addition to Master Test Pro-

Fig. 1: User Management and digital logging

Fig. 2: Compression test on dental shock absorbers

grams for cyclic tests and teargrowth tests also contains the‘Expanded Traceability’ option.Additionally, Zwick offers customizedTest Programs which are createdaccording to customers’ specifi-cations and/or factory standards.Through extensive testing we canguarantee that all Standard Moduleswill be compatible with earlier ver-sions within the testXpert® II productrange. In research in particular, it isoften necessary to be able to pro-gram the test sequence freely. In thetestXpert® II Graphical SequenceEditor you have an extremely com-prehensive tool; simply program thetest sequence you require, usingstraightforward function blocks on agraphic interface.

When does who do what, and why?

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Expanded Traceabilityas per FDA

testXpert® II generally records allactions during the test in order tomake your results traceable. The‘Expanded Traceability’ option isavailable especially for medicalengineering and the pharmaceuticalindustry. This function provides all thetools required to fulfill, in combinationwith organizational procedures, theessential requirements stipulated bythe FDA in 21 CFR Part 11 (‘electronicrecords’). Your administrator stipu-lates what is recorded and for whichactions and events the user mustenter explanations. Afterwards all re-levant actions, events and changesto important data are recorded andarchived in secure binary format.

Together with User Managementthis function gives your administratorthe necessary tools to regulateaccess to the testing machine andtest data clearly and definitively.

Synchronized Video Recording

A test can be recorded with anordinary video camera, the videoimages subsequently beingsynchronized with the test data fromthe testing machine. The video canbe played back in testXpert® II, whilethe test data synchronized to the vi-deo images is highlighted in a specialgraph.

Fig. 2: Expanded traceability in testXpert® II

Comprehensive ExportInterfaces

All data from testXpert® II can betransferred extremely easily viastandardized interfaces to all currentWindows formats and otherapplication formats (MS Excel,Access, Word, LabView, SAP,Oracle, ASCII). As a further optionthe integrated Online LanguageSwapping enables the test report tobe produced in other languageswithout difficulty.

Fig. 1: Programming example testXpert® IIGraphical Sequence Editor

32

± 10V± 10V

PP I/OI/O FF

UU II

ss RR tt

4.2 Zwick testControlMeasurement and ControlElectronics

Measurement and control electronicsare an essential component of anytesting machine. Their design andfeatures determine which drive canbe operated, which measuring sys-tem connected and which functionscontrolled.

Zwick’s powerful testControl meas-urement and control electronicshave up to 10 digital or analog high-resolution inputs available for time-synchronous data acquisition. Anycommonly used analog or digitalsignal can be connected to thesestandard interfaces. All signals areprocessed in real time and trans-mitted to the PC in high resolution at500 Hz.

Many medical applications requireadditional measurement signals aswell as the usual channels such asforce and elongation. testControloffers the flexibility demanded ofmeasuring systems in such applica-tions, whether for applying additionalstrain gages to a specimen or si-multaneously measuring tempera-ture. In addition to these direct

interfaces to testControl, externalmeasurement systems such as theHBM MGCplus can be linked.

This gives the further option ofquarter, half or full-bridge measure-ment of resistances, pressures,temperatures, accelerations, andsingle strain gages etc.

Fig 1: Full integration of a HBM MGCplus in testXpert® IISmall picture: Digital I/O box, additional with two output channels

Fig 2: Analog and digital signals can be connected to testXpert® and testcontrol

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4.3 Zwick Extensometers

Measuring elongation and/or strainplaces extremely high demands on amodern testing system. For manyyears Zwick has been leading thefield in developing digital extensom-eters for a wide range of applications.

Today Zwick has the most compre-hensive range of analog and digitalextensometers, both contact andnon-contact. In 1998 Zwick haddeveloped and introduced the worldsfirst digital clip-on extensometer. In2004 the portfolio of extensometerswas extended with the optiXtensand multiXtens.

2007 saw the unveiling of laserXtens,offering high-resolution (down to0.15 µm), contact-free elongationmeasurement without the need toattach gage marks to the specimen.This system makes completely newapplications possible, such as thetesting of small specimens with gagelengths down to 1.5 mm. Thistechnology and heritage allowsZwick to provide the optimumextensometer for every application.

Fig 1: videoXtens

Fig 2: multiXtens Fig 4: Selection process of extensometers

Fig 3: laserXtens with round specimen

Contact Measurement Systems• multiXtens• Macro extensometer• Long-travel extensometer• Clip-on extensometer

Non-contact Measurement Systems• lightXtens• videoXtens• laserXtens• optiXtens

Extensometer Portfolio

Measuring Priciple,Properties

Functionality(auto / manual)

Environmentalconditions

Purchase,Running Costs,

Ease of Use

Specific Test Application

Comparsion and selection processcriteria (“must have“ / “should have“)

Material(component)

Test Method,Standard

EnvironmentalInfluences

Budget

MaterialProperties

Specimen, TestSequence, Test Result

Temperature, Light,Noise

Purchasing,Running Costs

ExtenosmeterProperties

ExtensometersRequirements

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4.4 Zwick Specimen Grips

Zwick’s comprehensive range ofspecimen grips of various designsand for differing test load ranges andtest temperatures covers a wide fieldof application. The specific applica-tion range of a specimen grip islargely determined by its operatingprinciple and maximum permittedtest load; for tests in a temperatureor climatic chamber the temperaturerange in which it can be used is alsoof significance.

Zwick develops customized speci-men grips for the medical industrywhich are exactly verfied to thecustomer’s specimen.

Load Transfer betweenSpecimen and Grips

With most specimens the test loadcan only be transmitted indirectly i.e.by friction. This means that thefrictional force between the specimenends and the jaws of the specimengrips must always be greater thanthe test load. The gripping forces(perpendicular to the test load)required for this are generated exter-nally (e.g. by pneumatic pressure) orderived mechanically from the testload (self-tightening specimen grips).

Gripping Force

Specimen grips with externallygenerated gripping force apply theset force level throughout the test.Especially with thick or soft speci-mens, however, specimen materialcan flow out of the grips under theinfluence of the test load, reducingthe specimen thickness. Withhydraulic and pneumatic specimengrips the gripping force remainsconstant, because the pressuregenerator supplies more pressurizedoil or compressed air. The grippingforce of screw grips decreases tosome extent depending on thestiffness and resilience of the grips.

Gripping Surface

Frictional force depends on both themagnitude of the gripping force andthe coefficients of friction of thecontact surfaces. For this reasoninterchangeable jaws or jaw insertswith various types of grippingsurfaces (differing shape, surfacestructure, material etc.) are providedfor many specimen grips.

Clamping Travel and OpeningWidth

Specimen grips with external gripp-ing force generation have longclamping travel and thus also a largeopening width, leaving a larger freearea for convenient specimen in-sertion, even with thick specimens,and eliminating the need for ex-changeable jaws for different speci-men thicknesses.

4.5 Load Cells

Load cells are available for accuratemeasurements starting from 0.02 N.In combination with testControl digi-tal measurement electronics theyoffer the following advantages:

• Measurement accuracy: Class 1(1 % of measured value) from 0.2to 100 % of nominal force andClass 0.5 (0.5 % of measuredvalue) from 1 to 100 % of nominalforce

• Resistant to parasitic influences(bending moments etc.)

• High flexural strength limit and tor-sional strength limit against break

• Zero point and characteristic valuetemperature compensation overthe entire measurement range upto overload

• Very high effective measured valueresolution and measurementfrequency in combination withtestControl

• General overload protectionthrough testXpert® II; mechanicalprotection also available for loadcells with low nominal force

• Automatic sensor identificationsystem

Fig 1: Pneumatic grips Fig 2: Load cell Xforce; design: multiplestrain-gage

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4.6 Testing underPhysiological Conditions

Test in Liquid Media

In the field of biomaterials, researchis carried out into the mechanicalproperties of both regenerative andartificial materials. To reflect thephysiological conditions of the body,the mechanical test should be per-formed in a temperature-controlledfluid bath. Stents made of Nitinol arealso tested in a temperature-con-trolled medium as the materialdisplays different characteristics at37 °C from those at room tempera-ture.

Temperature-controlled Bathfor Medical Tests

• Suitable for static and servo-hydraulic testing machines

• For applications in media such assaline solution, ethyl alcohol, bloodetc.

• Container (Duran glass) can bemoved axially to enable clampingof the specimen outside the liquidmedium

• Various test fixtures or specimengrips can be connected /attachedto the internally located mountingstuds - Zwick has a large range ofsubmersible specimen grips

• Quick dismantling for easycleaning; disinfection also possiblein autoclave at up to 120 °C

• Optional temperature control unitfor installation in temperature-controlled bath: heat exchangerwith separate heating circuit, heat-ing power 2 kW, temperaturerange: Room temperature to 80 °C.Temperature control on the speci-men via sensor arms; includesseparate container for pre-condi-tioning specimen.

Horizontal Water-bath for Testson Catheters etc.

• Determining friction coefficients ofcatheters, guide wires and otherminimum invasion instruments(flexible endoscopes)

• Testing insertability of cathetersinto 3D models

• Performing horizontal tests, also intemperature controlled medium(can be heated from 30 - 80 °C)

Testing under TemperatureInfluence

Many materials change their me-chanical properties quite significantlyaccording to the ambient tempera-ture. For testing applications atelevated or low temperatures Zwicksupplies various versions for quasi-static and servo-hydraulic testingmachines. The temperature cham-bers are also suitable for retrofittingexisting machines and applications.

Fig. 2: Horizontal testing machine with fluidbath

Fig. 1: Media container with temperaturecontrol unit

Fig. 3: Temperature chamber integrated intomaterials testing machine

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7 Zwick Services

Applications Test Laboratoryand Contract Testing

In the last few years Zwick's applica-tions laboratory has become compe-tence-center of materals testing withactive scientific exchange.

Functions:• Demonstrations and pre-testing• Performing and evaluating tests on

customers’ behalf

Services:• Use of full Zwick portfolio• Design and adaptation of specific

testing devices• Documentation and interpretation

of component failure• Access to expert knowledge of

highly experienced staff• Evaluation and documentation of

tests• Fast testing service to international

standards, works standards andspecial regulations

• Advice on products, testingmethods and test performance

Laboratory for Fatigue andImpact Testing

• Determining S-N curves for fatiguestrength measurement of bonds,structures, and weld seams

• Fatigue test investigations undermulti-axial load

• Fatigue strength investigationsunder in-service loadings- single and multi-stage testing- testing under temperature

(-60 °C to +1200 °C)- connecting rod testing under

simulated engine conditions- corrosive media on request

• Determining cyclic materialbehavior (LCF)

• Determining fracture mechanicalcharacteristic values

• Performing tests under impacttest force

• Application of measuring methodsto obtain the relevant mechanicalvalues (crack propagation, crackdetection, local strains, tempera-ture sequence etc.) for specimensand components

Laboratory for Quasi-StaticApplications

• Tensile, compression, flexure andtorsion testing

• Testing under temperature (-40 °C to +200 °C)

• Testing in high temperature range(+200 °C to +900 °C)

• Determining impact strength• Hardness testing• Melt index testing• Component testing• Viscosity testing• Fracture mechanics testing

Fig 1: Zwick fatigue and impact testing laboratory Fig 2: Zwick laboratory for quasi-staticapplications

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5.2 Support for Validationof Zwick Testing Systems

Legal Requirements andDirectives

Very high demands are placed onthe quality and reliability of productsused in medical engineering. Qualityassurance is therefore an essentialitem in national and internationallaws and directives, for example theGerman Medicine Act (AMG) relatingto the manufacture of medicines inGermany; the Code of Federal Re-gulations (CFR), which forms the le-gal basis of the US Food and DrugsAdministration (FDA); the GMP(Good Manufacturing Practice) codeof practice with its adjuncts, the PIC(Pharmaceutical Inspection Con-vention) and the relevant standardsof ISO 9000ff.

These laws, directives and guidelinesrequire that all processes, systemsand activities directly or indirectlyrelated to product manufacture mustbe suitably regulated monitored andsupervised. These regulatory require-ments also apply to computerizedsystems consisting of hardware andsoftware. The documented verifica-tion is summarized under the um-brella term validation.

Definition of Validation andResponsibility

Through validation, documentedverification is generated to demon-strate that methods, processes,materials and (computerized) systemsconsistently lead to the expectedresults and conform to the principlesof Good Manufacturing Practice andfulfill the pre-determined specifica-tions. The responsibility for validationlies with the company subject toregulation, which must establishguidelines and procedures to fulfillthe legal requirements. GoodAutomated Manufacturing Practice

(GAMP) serves here as a code ofpractice for validation recognizedworldwide. It describes the tasksand duties of the supplier and theend user together with the validationprocess.

Qualification – a ComponentPart of Validation

A significant element of validation isthe technical inspection of individualplant and instruments/devices. Thispart is described as Qualification andcontains all steps from the planningphase with new plant (performance/technical specifications; designqualification) through the correctdelivery and installation of the plant(Installation Qualification), checkingfor correct operation (OperationalQualification) and inspecting themeasuring sensors present(calibration); to the inspection ofreproducibility of specified sequencesor parameters (PerformanceQualification).

➊ Design Qualification (DQ)Performance and TechnicalSpecifications

The design qualification as first stepof qualification stipulates the func-tional and operational specificationsof a plant or a system. Even at thisearly stage it must be verified thatthese specifications conform to theregulatory requirements.

➋ Risk Analysis andAssessment

Risk analysis is an importantinstrument of qualification. Potentialrisks are assessed regarding theirprobability of occurrence, togetherwith their consequences for systemowners and patients. Risk analysis isthe basis for the description of IQand OQ test cases.

➌ Installation Qualification (IQ)

Installation Qualification documentsthat the plant or system correspondsto the specifications of the DesignQualification and has been correctlydelivered and installed.

Fig. 1: Sequence of validation process

User RequirementsSpecification

checked

DQ

Technical Specifications(Application Specifications)

Design Specifications(Hardware & Software Design)

Installation Qualification(IQ)

Operational Qualification(OQ)

Performance Qualification

System Creation

Result:Final Validation Report

Risk Analysis

and Assessment

PQ

IQ

OQ

CustomerSupplier

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➍ Operational Qualification(OQ)

In the scope of OperationalQualification the operation of theplant or system is checked. Theinspection takes place on the basisof suitable test cases, for which thetest items and correspondingacceptance criteria are defined andspecified in advance.

➎ Performance Qualification(PQ)

Performance Qualification takesplace following successfulperformance of OperationalQualification and involves checkingwhether a plant or system alsoactually achieves the definedperformance parameters under realproduction conditions. These testsare repeated at regular intervals.

Zwick Qualification Services

Zwick supports its customers in theDQ, IQ and OQ steps in the form ofcomprehensive and individualqualification documentation, and inperforming qualification on-site. ForPQ, Zwick provides assistance withsuitable options for testing definedperformance parameters.

Qualification Documentationfrom Zwick

Documentation is individuallyadapted and produced to suit theequipment of the testing system.Regulatory requirements areobserved during creation of thedocumentation. All documents areto be authorized in advance.

Performing Qualificationon-site

Experienced service technicianscarry out the qualification at thecustomer’s premises on the basis ofthe qualification documentationproduced.

The individual test items areperformed and each IQ or OQ testsubsequently signed by qualifier andsystem owner.

The results of IQ and OQ aresummarized in the IQ and OQ Planand Report and all deviations foundduring IQ and OQ are documented,assessed as critical or non-criticaland measures to eliminate them areevolved.

Fig. 1: Zwick service technician implementing Qualification (IQ/OQ) at the customer’spremises

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5.3 Service and Support

SupportDesk

For further advice or assistance,such as technical or softwaresupport, the Zwick SupportDesk is inmany cases a better option than anon-site visit. Our experienced staffwill use their wide-ranging technicalknowledge to provide you with ananswer speedily and effectively.

Worldwide Service

Customer satisfaction has thehighest priority at Zwick Roell A.G.Local service organizations in over50 countries ensure optimumutilization and maximum availability ofyour testing systems.

Servicing

Zwick Service helps you reducedowntime significantly throughregular servicing of your testingmachines.

The condition of the machine isrecorded at the service and neces-sary repairs are carried out and wearparts replaced immediately, wherepossible. The service engineer willalso advise on preventive and/orprecautionary measures.

Repair

If, despite careful servicing andmaintenance a fault develops in atesting machine, an engineer fromthe large Zwick Service Networkteam will be with you in the shortestpossible time. Many spare parts canbe dispatched within 24 hours.

Calibration

Zwick's calibration service is ac-credited by DKD1), UKAS2), COFRAC3)

and A2LA4) to DIN EN ISO/IEC17025 for on-site calibration ofmaterials testing machines.

The reference measuring equipmentused is regularly recalibrated. De-pending on the customer's require-ments, either a works calibration(Zwick calibration certificate), ISOcalibration (Zwick certificate withdocumentation showing measuringequipment supervision to ISO9001)or DKD calibration (DKD certificate) isperformed.

If necessary, the testing machinesand associated sensors will beadjusted during calibration.

1) DKD: Deutscher Kalibrier-Dienst2) UKAS: United Kingdom

Accreditation Service3) COFRAC: Comité Français

d´Accréditation4) A2LA: American Association for

Laboratory Accredition

Software Upgrade/Update

An update gives you access to theongoing development of testXpert®

software and opens the door to anexpanded range of functions.Changes to testing standards arealso incorporated into the latestversions.

Upgrading from an old DOS operat-ing system to the latest Windowsequivalent provides a secure, reliableroute to the new technology. Up-grade from testXpert® to testXpert® IIand enjoy access to all the latesttestXpert® developments, with theirmany benefits for everyday use.

Retrofit/Modernization

Converting the old into new –ZwickService specialists profession-ally perform the modernization ofyour existing materials testingmachine, regardless of the originalmanufacturer. This allows the latestdigital control technology andsoftware automation to enhance theperformance of your testing systemat the fraction of the cost of a newsystem.

Zwick Asia Pte Ltd.25 International Business Park#04-17 German CentreSingapore 609916 · SingaporePhone ++65 6 899 5010Fax ++65 6 899 5014www.zwick.com.sginfo@zwick.com.sg

Zwick USA1620 Cobb International BoulevardSuite #1Kennesaw, GA 30152 · USAPhone ++1 770 420 6555Fax ++1 770 420 6333www.zwickusa.cominfo@zwickusa.com

Zwick Testing Machines Ltd.Southern AvenueLeominster, Herefordshire HR6 OQH Great BritainPhone ++44 1568-61 52 01Fax ++44 1568-61 26 26www.zwick.co.uksales.info@zwick.co.uk

Zwick France S.a.r.l.B.P. 45045F-95912 Roissy CDG Cedex FrancePhone ++33 1-48 63 21 40Fax ++33 1-48 63 84 31www.zwick.frinfo@zwick.fr

Zwick Ibérica Equipos de Ensayos S.L.Marcus Porcius, 1Pol. Les Guixeres, s/n Edificio BCIN08915 Badalona (Barcelona) - SpainPhone ++34 934 648 002 Fax ++34 934 648 048www.zwick.escomercial@zwick.es