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Tensile Strength - Capability Statements

Cattle eartags and the pull-off tester

Plastic identification tags tensile strength and pull-off force

Animal identification tags are important for both legal and health & safety reasons where animal by-products are sold into the human food chain. The tags on dairy cattle are used to record data and trace the animals throughout the milk production process. The tags themselves, attached through the livestock’s ear, comprise of two flexible plastic leaves and a tamper-proof pin fastener. They must remain on the animal – and complete in themselves – when subjected to all expected in-service forces. Specific standards require testing for both tensile strength (by means of a transverse pull test) and pull-off/pull-out forces along the axis of the pin. The software–contolled test stand is able to hold the tags at a target load and then pull further at contolled speed (typically 500 mm/min) until breakage. Once failure occurs, the tags must be unusable as part of the traceability requirements. The transverse pull test can be performed with suitably rated tension wedge grips. The pull-out test on the pin can be achieved with custom grips designed to pull axially and support the leaf surfaces.

Mecmesin Systems: MultiTest console-controlled force test system, 5 kN wedge grips

Case Study: Animal Identification Tags

Fabric trouser tear test

Fabric tensile strength and tear characteristics

Textiles, cloths and fabrics used in both clothing and sporting markets have requirements for flexibility and lightness, but also durability and resistance to breakage – particularly tear damage – when in use. A hot air balloon manufacturer must conform to strict standards, applicable to the aerospace industry despite the textile construction of the product. The variation in coatings for the fabric – due to individual designs – and the fabric itself, requires that the test procedure must be applicable all cases. The strip method tear test for fabrics evaluates tear propagation resistance under constant loading at a constant rate of displacement. For secure retention of the standard size samples, wave-form jawed grips would be suitable, capable of holding the fabric across its full width, up to forces of up to a peak of 350 N, in this case. This tear test may be used as a standard method for measuring the effect, not only of wear-and-tear on the textile, but the impact of sunlight aging the material over time. The same system of a motorised test stand, digital force gauge and results analysis software, plus the versatile grips can also be used to measure the tensile strength of the numerous seams and fastenings of the fabric structure.

Mecmesin Systems: Motorised stand with gauge and software, large vice grip

Case Study: Balloon Cloth Tensile Strength Test

Plastic film tension testing

Food containers and plastic film tensile strength

The effective sealing of food items with plastic film relies on a degree of flexibility and strain within the film in order to enclose and achieve air-tight packaging. A two layer construction, with the outer layer bearing the printed product information, may be quality verified for integrity by a tensile strength test. The packaging material should exhibit a degree of elasticity, but still meet expected levels of tensile strength before breakage. The challenge to securely hold the sample without slipping or damage the thin material is achieved with spring-loaded roller grips. A motorised force test stand with a digital force gauge and software is a repeatable solution for measuring the peak force to break apart the plastic layers under constant speed loading. This compact system is ideal for the quality control or research laboratory.

Mecmesin Systems: M500E motorised test stand with gauge and software, spring-loaded roller grip

Case Study: Plastic Film Tension Test

Lighting fastening tensile strenght and pull-out test

Electrical lighting anchorage pull-off resistance

Electrical lighting displays which are erected on buildings in public areas, such as seasonal illuminations, are subjected not only to specific electrical standards, but also legislation surrounding their installation, operation and removal. The fastening hooks/eyelets securing the cables to buildings or other structures must resist tension forces designed to test pull-out from their anchoring and tensile strength of the attachment or its bolts. Due to the location of these anchorage points – usually in high-up or relatively inaccessible spots – a test system with the emphasis on lightness and portability is required. The ability to also store multiple readings within the gauge’s on-board memory, ensuring traceability of the measured peak force values back to individual fastenings, should also be a requirement. The data may be analysed offline to evaluate the entire electrical system’s integrity once the gauge has collected the information. For additional safety consideration for the operator, a handle for the gauge should be employed.

Mecmesin Systems: Digital force gauge, manual handling kit

Case Study: Festive Lighting

Sequin, diamante and bow pull-off tests

Fabric, textiles and clothing decoration pull-off (test-to-failure)

The performance, durability and safety conformance of clothing must reflect the multitude of styles and materials mix plus functional and decorative additions. These various embellishments: buttons, ribbons, bows, sequins, diamante and other fastenings that have been attached to textiles need to be checked that they have been safely affixed so they will not become choking hazards for infants, for example. The necessary test-to-failure (TTF) indicated by the standards – a code of practice for the design and manufacture of children's clothing to promote mechanical safety – involves pulling the feature until it detaches. The method tests the pull-off/pull-out and tensile strength of the product and also recording the displacement of the crosshead will give a measure of the elongation at break. A selection of grips may be required for securely grasping the decoration – with hooks or slots – depending on the design.

Mecmesin Systems: MultiTest console-controlled force test system, digital force gauge, test hook, popper-cam base

Case Study: Diamante Pull-off Test, Bow Pull-off Test, Button Pull-off Test, Press-Stud Popper Pull-Off Test

Medical tubing and valve tensile testing

Extruded medical tubing tensile strength and elongation

Plastic extruded medical tubing is an essential health care product for the delivery of blood, nutrients and gases to the patient, and for the execution of minimally invasive surgical procedures. The tubes, for example catheters, may also be connected to other medical apparatus such as Luer devices, butterfly valves and pipe junctions. A manufacturer of these products must meet strict regulatory compliance in conjunction with optimising the functional design - for efficiency plus patient comfort and safety - while also meeting production costs. An in-house quality testing regime should consider the in-service forces exerted on the individual components and the complete system of which the tubing will be a part. The tubing itself can be tested for tensile strength and elongation behaviour with a force test stand and a selection of appropriate grips and fixtures pertinent to the product’s performance requirements in situ. A computer-controlled system is perfect for an OEM’s research and development lab, allowing the collection of results and bespoke test programs applicable to a range of products. The challenges to reduce the wall thickness to minimise trauma and maximise the lumen bore to maintain flow capacity can be met with structured, repeatable quality testing processes.

Mecmesin Systems: MultiTest computer-controlled force test system, 5 kN wedge grips, bollard grips

White Paper: Force Testing Medical Tubing

Tamper band bridge tensile test

Bottle cap tamper-evident band bridge tensile strength and pull-off resistance

The tamper-evident caps on bottles are designed to resist breaching through unscrewing torque and/or pull-off force until opened for intended purpose. Correct opening requires unscrewing, with the option of resealing again for consumer convenience. The integrity of the tamper ring may also be tested against other removal forces experienced in transit or mishandling that would compromise the intended functionality. A peak force test to pull the cap (without rotation) until the tamper-proof band breaks away may be used to evaluate the design with respect to in-house standards. A console-operated system is convenient for production environments, with simple touch-screen operation to run a programmed test procedure. To augment throughput efficiency a custom-built fixture which allows one sample to be tested whilst another is loaded may be implemented. The cap is pushed over the fixture collar, manufactured to replicate the exact profile of the bottle neck. A concentrically-mounted compression probe is driven down through the sleeve, engaging inside the cap and compression-loading it until one or more of the tamper ring’s bridges fail. The recorded peak force reflects the overall tensile strength of the bridges and may be used to compare designs or supplier batches.

Mecmesin Systems: MultiTest console-controlled force test systemEmperor™ (Force)

Butt joint tensile strength test through pull-off

Butt joint test for adhesive strength and pull-off resistance

The butt joint is inherently the weakest category of joint between two components, especially if a reinforced type is not used. The tensile strength of the connection is wholly dependent upon the bonding system, whether this is in contact with raw materials or the adherend is the coating on the surface(s). This type of joint has applications in many industries, from wood-working to large engineering systems. With metal components, welding is an option, however the advantage of a glue-based system is that it allows the full surface area of the butted faces to contribute to the strength. The overall failure of the joint under pull-off loading may be cohesive (where the glue suffers a lack of integrity) or adhesive failure at the glue/coating or coating/material connection. The latter is indicative of deficiency in the coating process, or evidence of the bonding agent having a detrimental effect on the coating. A butt joint test system must be capable of exerting enough force to break the butt joint apart, perfect axial alignment and deal with the possibility of a sudden catastrophic failure of the joint.

Mecmesin Systems: MultiTest computer-controlled 50 kN machine

Case Study: High Performance Plasma Coatings

Univeral testing machine and fixtures for zipper testing

Zipper testing methods for tensile and separation strength

Zippers (zips, fly, fly fasteners) are used for the fastening together, or binding, of the edges of fabrics, textiles and other flexible materials. Usage in the clothing, furniture, outdoor pursuits and sporting industries is common. The fairly complex mechanical nature of the clasping mechanism, involving interlocking teeth and a hinged pull-tab, requires a set of tests to ensure the quality assurance of the complete assembly. The crosswise (ordinary zipper) strength per 2.5 cm of the chain, tests the peak load that the interlocked teeth can endure before being pulled apart laterally. The webbing at either side of a the chain is securely held with 25 mm wide grips and pulled apart at a constant 300 mm/min. The top stop (zip closed position) and the bottom stop (zip open position) are also tested. The top stop holding strength by holding the lower edge of the interlocked zipper and pulling the slider firmly in the closing direction. The bottom stop holding strength pulls each of the chains apart at right angles to the zipping direction in a manner similar to a trouser tear or T-peel test. The separating unit crosswise strength pulls the webbing apart at the point of the bottom stop with the zipper closed. The slider/tab configuration is also tested for its locking strength—resistance to sliding as a result of the chains being pulled apart—and, for relevant designs, the tab itself is tested for ultimate tensile strength when pulled away from its housing at 90 and 45 degrees. Custom-designed fixtures may be required for the complete suite of tests, primarily JIS-S3015 and ASTM D2061.

Mecmesin Systems: MultiTest universal testers, Customised force testing applications

Electronic component strength testing

Electrical assembly component strength

Soldered, fused and welded parts in electrical and electronic assemblies can be difficult to grip in ways that mimic the forces applied when in use, because they are complex or asymmetric. Our client manufactures safety-critical alarms and asked us to provide custom fixtures for pull-out and push-out force testing.

Mecmesin designed an assemblage of fixturing parts for different components under test, in order to correctly align easily them every time. These included a sliding table, a chuck and a cylindrical sleeve holder.

Cosmetics product pull-out testing

Cosmetics packaging performance

Sometimes a client approaches us with a range of requirements for a number of their products. Using their universal testers for a variety of testing, they also need custom and versatile fixtures. Cosmetics packaging, for example, frequently combines design-led profiling with light handling, as in mascara tubes and brushes, attractively-curved lotion containers, and lipsticks. Some of these imply very light rotational torque, others maximum strength in lightweight design, for daily use.

Mecmesin custom grips assure axial alignment, secure holding and minimal deformation that might adversely influence test results and repeatability. In this example, compression, tensile strength and torsion strength were addressed in a suite of fixtures for a variety of popular products.

 
Welded joint strength testing

Cost effective cable strength testing

A major manufacturer of wire harnesses and connectors approached us for a cost-effective solution to strength testing cables of different diameters and welded joints, up to 1 kN. Standard cam grips to this rating proved too heavy and bulky.

Mecmesin designed narrow-profile lever cam grips for the required application, enabling rapid sample insertion and maximum throughput on a minimum requirement test system.

Closing force of transport doors for safety

Train door safety override testing

A UK train operator needed a method of testing the obstacle detection sensitivity of carriage sliding doors. They already had a method for adjustment, but needed to measure the forces acting between stalled-opening and stalled-closing door leaves that would not interfere with their test brackets.

At Mecmesin we devised a sliding bracket to house a digital Advanced Force Gauge, attached by four quick-release suction cups. Attached across the open-door gap, the force required to open and restall the doors could be measured, allowing readjustment and remeasurement.

Plastic weld strength testing solution

Injection moulded assembly integrity

Plastic injection-moulded subassemblies can be clipped or welded, and the integrity of the whole must be tested at several points. However, their shape can make them very difficult to hold, and places to grip for pulling hard to identify. Our client needed a complete custom fixturing solution.

Mecmesin engineers designed profiled nests and retaining plates, an X-Y table for positioning the test sample, and a range of hooks to pass through apertures and engage edges in the assembly. This enabled a defined sequence of pull-off tests to be made consistently across a number of samples for batch testing.

 
Packaging fold-out tensile testing

Cardboard beverage bottle carrier unfolding

A manufacturer of flat-supplied cardboard beverage bottle carriers, wanted to quality test the fold-out force for a variety of designs. Ideally the faces needed to be pulled evenly apart.

Mecmesin designed a base plate with locating flanges for each design to be tested. The underside of the flattened pack was held in place by vacuum pumped suction, and the upper pulled up by a cluster of suction cups. Test samples could then be laid quickly and the vacuum engaged, then the pulling fixture similarly lowered and suction engaged on the upper surface. Accurate measurement of the pulling force to open each box out could then be made.

 
Testing several samples of adhesive ensures consistent quality in the batch

Adhesive performance and batch testing for tackiness

A global chemical company’s R&D laboratory required an improved testing method for the evaluation of adhesive formulations. Internal quality standards necessitated the measurement of tack in viscous adhesive pastes–with the ability to make comparative analyses between multiple samples in a single batch. The procedure also needed to be performed with the glue being sustained at an elevated temperature to simulate real-world environmental conditions. Mecmesin worked with the customer to design a fixture system with six identical circular cross-section sample containment recesses, with integrated heating platen rated to a maximum temperature of 150° C (and able to sustain a constant 120° C for the test itself). The fully programmable computer-controlled UTM is able to load-hold at a constant compressive force for a set time when applying the probe surface to the specimen substrate, then retract at constant speed after the specified dwell time in the adhesive material. This action is repeated number of times to gauge the evolution of the tackiness over multiple contacts. The software analyses the data and performs calculations to return the peak force information for each sample, indicating the tensile strength of the formulation under pull-apart loading. The results are available for each individual specimen, its repetitions and the averaged value for the complete set. This solution provides a consistent methodology for the chemistry lab to implement in back-to-back adhesion testing of products for tack, texture and other attributes which determine ease of application, handling, longevity and ultimate adhesion performance.

Mecmesin Systems: MultiTest computer-controlled force test system,

Yarn and filament tension testing with bollard grips

Yarn testing for strength, toughness, tenacity and elongation

The tensile testing of yarns may involve several specific procedures, intended to evaluate the performance of individual yarns and quantify comparative evaluation between alternative materials or suppliers. Accurate testing of material behaviour or ultimate failure strength can be achieved with a motorised universal tester, appropriate grips and a test program design to apply the relevant standard. Typical procedures apply axial loading to the test sample—either individual threads, or multi-filament if applicable to the intended usage. A motor-driven test stand ensures constant speed of loading for optimum repeatability; suitable for any test standard for textile and fabric strength, e.g. ASTM D5034 – grab test procedures for elongation and break strength. Measurement of peak force at failure and elongation at break are important properties of the textile, as are further industry-standard calculations such as breaking tenacity (force divided by linear density, or denier) and toughness (the energy absorbed over the deformation). Accuracy of the measured values is highly dependent upon proper fixturing of the sample to eliminate breakage at the point of gripping. Mecmesin’s selection of bollard/roller and filament grips provide reliable breakage testing due to smooth sample contact surfaces and ball socket joints to ensure consistent axial alignment.

Geotextile strength testing ensures in-service performance quality

Geotextile in-service performance testing

Geotextiles undergo a range of forces in their intended applications and determination of their suitability for in-service conditions involves a number of test types. The variety of materials utilised—both synthetic polymer and natural—and method and construction—woven, knitted or non-woven—means that quality testing requires consideration of the sample gripping, manner of deformation and loading capacity. Mecmesin has a range of force testing systems from mid-capacity single column configurations up to 50 kN twin column UTMs. A geotextile fabric may undergo forces which could stretch, tear, puncture or penetrate the membrane and an appropriate replication of the relevant loading is essential to quantify the performance of the textile in its environment. Typical international standards targeting these test types include: ASTM D4533, trapezoid tearing strength of geotextiles; ASTM D6241, static puncture strength of geotextiles and geotextile-related products; ASTM D4632, grab breaking load and elongation of geotextiles.

 
Medical textiles need to meet strength checks and other hygiene requirements

Medical textiles and fabrics testing

Medical textiles reach their end user in both yarn or fabric forms, necessitating a specific test in order to evaluate the quality of the product for its intended purpose. The materials themselves must meet stringent requirements over and above their physical properties such and strength and flexibility—relating to hygiene and resistance to infection, or the need to be non-reactive in the case of implantable textiles. Individual yarns (for example suture thread) should be tested for ultimate tensile strength, to minimise uncontrolled breakage, but facilitate breakage or cutting when required by the surgeon. Motorised test stands fitted with roller or bollard grips ensure reliable measurement of truly representative sample breakage, away from fixture clamping. Clothing and other protective garments must be evaluated for tear, peel and puncture/penetration resistance as well as ultimate strength and elongation properties. Mecmesin’s universal testers and dedicated peel and tear test systems can accurately measure the performance of medical fabrics to international standards against Delft, tongue, single rip (trouser), trapezoidal and Graves tear procedures. Computer controlled systems enable specific in-house tests to also be performed. Some fabrics may also require a degree of penetration resistance which is easily evaluated by our UTM systems. Patient dressings must be flexible enough to cover any part of the body and also protect and support many types of injury, thus the measurement of elongation and ultimate tensile strength enables the manufacturer to quantify the performance of the textile completely.

CD007 Airbag Connector 220

Pull-testing of safety critical welds in vehicle airbags

Automotive safety-critical systems, such as welds in vehicle airbag connectors, require rigorous testing for zero defects. Pull-off and pull-out testing to destruction at a constant and consistent speed and with complete repeatability enables maximum conformity to quality control standards. To enable the testing to be performed by production staff on the factory floor, special customised quick-release fixtures, enabling batches of test samples to be changed very simply for maximum throughput, enhance the suitability of this solution for automotive assembly applications. Data output is easily achieved from digital gauges for transmission to the organisation’s Statistical Process Control (SPC) software.

Mecmesin Systems: MultiTest motorised test system, digital force gauge

Case Study: Safety-critical welds in vehicle airbags

 

Needle pull-off/pull-out testingNeedle and lancet pull-out testing

Surgical needles and lancets may be located in their hub or ferrule by a variety of methods, including bonding, moulding, welding, mechanical interlocking, and sealing. The retention, or pull-off strength of the assembly method must be sufficiently high that the peak frictional force during usage does not cause disassembly or seal failure resulting in the needle remaining in the patient. To test the pull-off/pull-out performance, the test system is normally fitted with a suitable mounting block, to support the hub in such a way as to leave the needle tip exposed vertically. In the case of smaller needles and lancets, a lever-operated pin vice may be used to grasp the tip, and for larger gauge needles, a wedge grip may be required to hold the sample. An axial tensile load is applied at a constant rate, until the needle is completely dislodged from the hub. For safety considerations, the test system should be contained in a protective enclosure to provide protection from the fracture and breakage of sharp objects.

Mecmesin Systems: MultiTest motorised test system, digital force gauges, manual test stands

Case Studies: Lancet needle retention test, needle pull-out test

White Paper: An Examination Of Needle And Syringe Force Testing

Car door closure tensile force measurement with the interiorCar door closure force

The effort required to open and to close car doors is variable throughout their travel, and is optimised for the anticipated strength of a wide range of users. The tensile force measurement in situ is difficult due to the typical confines of a vehicle interior. With such a wide variety of designs of interior cabins in the automotive sector, a portable and customised system may be needed to measure and store the changing forces during opening and closing, for a range of vehicles. A force gauge and loadcell for allowing storage of detailed and accurate measurements for subsequent analysis would need to be connected through a bespoke system design, connected to the interior arm-rest, which will facilitate the application of a preloading tension.

Mecmesin Systems: Advanced Force and Torque Indicator, S-Beam loadcells

Case Studies: Car Door Closing Energy Tester

 

 

CD014 carboard beverage tension test system 220Glued cardboard packaging tensile strength

The use of paper and cardboard consumer packaging has many advantages in terms of lightness, cost and recycling possibilities. A supplier of beverage carriers, would need to ensure that the production processes are able to manufacture these containers to a quality level which will maintain their shape and functionality whilst in service. Typically, cardboard beverage carriers are manufactured flat and opened out whilst moving along the production line. During the process, the glue must set, excess glue must not create unwanted adhesions, and the unfolding must not detach or weaken glued seams. Quality assurance of the carrier's integrity to the required point of glue setting, requires tensile testing at forces applied by both production machinery and manual end users. To test the opening of the cardboard carrier it may be required to design a bespoke fixture to handle the lightweight material in the same manner as an end-user application. In this example, the automated test stand employs a vacuum fixture to lift one side of the container to a maximum load while the opposite side is clamped firmly in position.

Mecmesin Systems: MultiTest motorised test system

Case Study: Glued cardboard packaging integrity

Video: Tensile test on beverage carrier packaging

CD016 safety net bollard grip 220 Construction safety netting tensile strength testing

Product safety in the construction industry is critical and test standards are in place to ensure that the protection of workers is maintained. Safety nets, specifically, are used for arresting falls from scaffold systems and also for protection from falling debris. A supplier of these products must adhere to strict quality processes as the nets are returned, repaired and tested for tensile strength, against the manufacturer’s criteria for withdrawal, and industry standards. Age, wear and tear, and UV degradation all contribute to the reduction in the strength of nets over time. The use of bollard grips, designed for the retention of samples of the nature of rope, cord, string, fibre, yarn, thread or tape, provides secure clamping of the individual net cell whilst minimising the risk of “jaw break”. Performing these tests at an in-house facility means that nets are set aside for assessment for the least time, those nearing minimal compliance can be monitored, and all those meeting standards have an immediate certification. Additionally, test control software provides consistent speed, force and displacement, acquires detailed data for analysis, and shows an instant pass/fail indication.

Mecmesin Systems: MultiTest motorised test system, large circular bollard grips, Emperor™ (Force)

Case Study: Construction safety netting certification testing

CD017 Marine al frame in grips 220Marine vessel aluminium frame fastener shear and pull-out strength

The marine industrial construction and engineering sector requires stringent testing of the integrity of the fastening systems employed in sea-going vessels. The materials utilised may also be particularly specialised and light weight, thus needing rigorous evaluation to ensure confidence in the strength of the assembly. A bolted aluminium structural element may be tested to accurately simulate its loading in the complex operational environment in order to measure the critical strength of the entire bolted assembly. The weakest element could be the fastener itself, suffering shear failure, or pull-out, or the hole in which the bolt is located could undergo deformation due to the tensile forces and compromise the structure. This testing is thus able to evaluate the lap joint’s performance and provide objective data as to the quality of the batch of supplied fastenings or any modifications to the frame’s cross-section, design or material specifications. Typical shear forces up to 10 kN are able to be handled with appropriately rated wedge grips and a suitably cut-down sample.

Mecmesin Systems: MultiTest motorised test system, 10 kN wedge grip

 

CD019 Metal case handle test 220Metal case handle and lock hasp operational strength

The functional attachments of transit packaging products: handles, locks, latches, hasps and clips, etc. are essential to the operation of the container. In the case of a military implementation – such as an ammunition case – it is imperative that these components perform as intended. The non-destructive testing of every production item for such a critical article, would also require a system that can hold the container securely yet allow swift change-over time between tests. In order to test both the handle and hasp of the locking mechanism for resistance to pull-off forces or material failure under tensile load, large and robust custom fixtures are required to grip the unusually-shaped features of the case. A console-operated test stand is suitable for a production environment, with the test programs able be run from a touch-screen icon to then apply the required load value for each element.

Mecmesin Systems: MultiTest touch-screen test system

 

 

CD021 Suture thread tensile strength 220Surgical suture thread tensile strength and elongation at break

In the biomedical engineering industry, the reliable performance of surgical sutures is vital to wound healing and hence the wellbeing and recovery of the patient. Differences in gauge and material constructs (e.g. hybrid metal wire/polymer yarn, or other specialist textiles) are required for different purposes, with functional requirements such as being absorbable/non-absorbable or antimicrobial also affecting the physical qualities of the thread. The measurement of the strand’s elongation at break and the force required to snap the thread provides an objective and comparable method of evaluating these advances in medical technology. To successfully test the ultimate tensile strength of the fibre, it must be ensured that the grips securely hold the sample, whilst being light enough to allow the use of a loadcell with the optimum accuracy for the force range. Any slippage will compromise the precise measurement of the elongation, which may be a critical parameter in the back-to-back comparison of alternative constructs. The use of a computer-controlled force test stand with specific fixtures allows healthcare product OEMs to optimise the design of medical textiles for effective healing and minimal cosmetic impact.

Mecmesin Systems: MultiTest computer-controlled test system