When selecting specialist gloves it is often the material strength and stretch which are the most important factors in determining quality and performance. These parameters will give you an indication whether a glove is at risk of tearing under your application conditions, whilst ensuring it still has adequate stretch to be comfortably fitted on the hand and provide the necessary feel.
Medical and cleanroom gloves made of latex, vinyl and nitrile are the subject of various test standards. ASTM D3577 and ISO 11193-1 cover rubber surgical gloves, D3578 covers rubber examination gloves; but each draws upon ASTM D412 for defining the method for tensile testing. This standard covers the measurement of tensile strength, tensile stress, yield point and ultimate elongation properties.
Tensile test methods for rubber and elastomers (ASTM D412)
Dumbell-shaped specimens are cut to a specific size according to the test method chosen. They are pulled at a constant speed (usually 500 mm/min or 1000 mm/min) until they break, and the tensile strength is measured in MPa together with the elongation expressed as a % of initial specimen length. The test is repeated on specimens which have been subject to an accelerated ageing process as per ASTM D3577 and D3578, which is designed to simulate how the glove may perform at the end of its rated shelf-life.
The minimum acceptable tensile strength values specified in the ASTM standards range, depending on the glove type, between 14 – 24 MPa with minimum elongation of 400 – 750%. When stored correctly in cool, dry areas away from sunlight, heat and humidity, many gloves will exhibit significantly better ‘strength and stretch’ characteristics, so it is common to see manufacturers utilise their tensile strength data to specify their products’ storage accordingly. When you consider that it requires typically 200-300% elongation to fit a glove comfortably on the hand, you should expect most gloves to stretch to around 700-1000% before failure.
Puncture resistance test of chemical-resistant gloves (ISO 374)
Gloves designed to provide chemical protection may only offer the defined level of protection for a limited time due to the glove material being adversely affected over time by the chemical hazard itself.
ISO 374-1 describes the method of testing the force required to puncture specimens of the glove material; with and without exposure to the chemical in question. A vial is used to support a specimen piece of the glove, whose outer surface has been treated with the challenge chemical, and held in place under an aluminium crimp-seal cap. Non-treated specimens of the glove are held in the same way. The probe, a cone-shaped stylus is then driven at 100 mm/min through each specimen to determine the peak force to puncture the glove.
The results are reported as a percentage degradation between the 2 sets of specimens as per EN 374-4. A positive percentage degradation indicates the material has become weaker after chemical exposure, which may increase the risk of the glove tearing when used. A negative percentage degradation indicates the materials has become harder and possibly brittle, which may make the glove less comfortable to wear and more liable to crack.
Mecmesin’s MultiTest 0.5-i tensile tester is the ideal choice as a versatile bench-top model capable of performing the full range of tensile and compressive tests. Its extended travel distance ensures the highly elastic rubber can be sufficiently stretched and its 500 N load rating easily covers the puncture resistance forces encountered. Pneumatically-operated plane grips provide efficient and repeatable gripping, the jaw faces reliable and consistently contacting the dumbbell samples under extensive deformation. The Emperor software of the MultiTest 0.5-i automatically calculated the various strength parameters for inclusion in the test report.
- MultiTest 0.5-i tensile and compression test system
- Loadcell ILC 500 N
- Lightweight pneumatic plane grips MEC94
- Puncture Resistance Jig with cone-point stylus
Caption: Puncture resistance test of protective glove material specimen to ISO 374
Sales of antibacterial gels have soared enormously following National Health Service advice telling the public to thoroughly wash hands in order to stay protected from Coronavirus. In fact, even before the 2020 pandemic crisis, the presence of hand sanitisers had already become commonplace, not only in hospitals but also in schools, restaurants and offices.
In the wake of the Covid-19 lockdown, there have been clear guidelines issued to businesses on keeping staff and customers safe. These include wall signs encouraging people to follow hygiene guidelines through to purpose-made floor tape to help enforce social distancing rules. For successful long-lasting application to surfaces, they all rely on the stickiness provided by the humble self-adhesive.
Vaccine delivery device and packaging testing
As COVID-19 has rapidly spread around the world, there is a concerted global effort to find a vaccine. Whether administered via an oral, subcutaneous, intramuscular, intradermal, or intranasal route, vaccines need to be administered via a medical device, and these must be tested to esnure they are safe and meet stringent standards and regulations
PET preforms - repurposing production for COVID-19 test kits
PET preforms are typically blow-moulded to create the ubiquitous plastic bottles containing carbonated and still beverages. The production process to fill and seal these bottles with a screw-cap is a demanding one, so a number of tests are performed to ensure quality control specifications are met for this core packaging.
Probiotic drink packaging testing
As demand for dietary supplements continues to surge, immune-boosting products, such as prebiotics and probiotics, are amongst the most popular. Getting these liquid probiotic products noticed by the consumer relies on eye-catching innovative packaging which must be easy-to-open and reseal whilst remaining economic to use for the beverage producer.
Face mask strength testing
Manufacturing masks is not as easy as you might imagine. International test standards exist to make sure the face masks can be verified to protect clinicians and patients from pathogens spread by blood, body fluids and secretions and now to limit the spread of COVID-19 coronavirus.
Pharmaceutical tablet crush and break strength
Many products come in tablet form, with a durability designed for both packaging and for use. Too brittle or too hard, and they may not be fit for use, or at best perform below expectation. The only way to determine consistency is mechanical testing of samples.
Lipstick tube force and torque testing
Testing the mechanical performance of the lipstick tube is a crucial part of the quality-control process for cosmetics manufacturers. Leading players in the cosmetics industry have come to rely on Mecmesin’s range of affordable force and torque testers to carry out checks on batches of lipsticks produced.
Mecmesin's materials testers
Testing the physical strength properties of materials, in accordance with international or in-house standards, is a key part of determining their characteristics to better understand the effects of process improvements. With this in mind, Mecmesin has designed a range of static-load Materials Testers powered by intuitive VectorPro MT software.
Top-load crush of plastic bottle with semi-automated test process
To guarantee their containers would perform as expected along customer production lines and remain intact during transportation and storage, US company, Silgan Plastics wanted to undertake top-load tests according to internal, customer and Supplier Packaging Information (SPI) standards.
Dispensing pump assembly testing
Mecmesin's customer manufactures a range of dispensing pumps for the cosmetic and beauty-care industry. A requirement was identified to measure the actuation force of the pump assembly and the pull-off force of the pump handle. The VersaTest motorised test stand was chosen as it gave the necessary repeatability and consistency independent of operator, which a manual stand could not.
The food packaging industry has long had concerns about pinholes, flex cracks and leaks in the flexible materials and seals of retort flexible lidded packaging. A famous global food and drink maker needed to test the laminated retort (and other thin film) packaging solutions that protect products such as their popular microwaveable stir-in pots.
Wine cork extraction test to ISO 9727-5
The customer, AMORIM & IRMÃOS, S.A – Unidade Industrial da Valada, required an economic and easy-to-use system to test the extraction force of corks from glass wine bottles. The test specifies a speed of 300 mm/min according to ISO 9727 and the corkscrew should be applied to a depth of minimum 3 mm below the base of the cork.
Nail varnish bottle closure removal torque and capping check
Barry M Cosmetics Ltd is a leading British colour cosmetics brand, offering a comprehensive range of products for face, eyes, lips and nails. The company required a quick, reliable and repeatable test method to check the capping equipment of their nail paint range. Mecmesin supplied a Tornado digital torque tester of 3 N.m capacity, which is a complete, portable, benchtop instrument.
Cosmetic packaging pull-off test
A bench-top testing system was required to repeatably test the pull-off force on a variety of cosmetic containers. The system needed to allow a relatively high volume of containers to be tested with the minimum level of training required for users. Mecmesin's solution avoided the risk of damaging the loadcell by excessive torque on tightening the collet grip, and the lipstick barrel was first inserted in the grip and then connected to the gauge by a flexible chain-link.
Coefficient of friction test
A print factory needed to test the packaging material they were using in order to improve their processes and establish optimum machinery settings. The company sought a solution, which provided consistent results and reliable performance. Mecmesin advised the company to use a coefficient of friction test to determine the 'slip' properties of the packaging.
Closure torque tester validation check
The customer had a number of Tornado closure torque testers, and wished to carry out regular validation checks without the need to return the units to either Mecmesin or an approved laboratory. The closure tester was securely mounted in the vertical plane and a load beam was placed centrally in the universal-clamping fixture.
A system was required to measure the push-on force and removal force of an injection-moulded cap from a new design of oil can. Mecmsin's test was set-up by sliding a can into the lower fixture, while locating a cap, resting on the can's neck, into the self-centering swivel fixture attached to the gauge.
One of the largest packaging tube suppliers in Central Europe specialises in laminated plastic and aluminium tube containers for the cosmetics industry. Mecmesin supplied a MultiTest 2.5-i test stand with a specially-constructed sample holder. Working in collaboration with Mecmesin engineers, a series of collars were made, into which the various tube samples are screwed.
A major global supplier of medical gas devices and components required quality control tests to assess part of a new product. One of their components, a 5ml pressurised aluminium cylinder filled with helium gas, is incorporated into a needle-free powder intradermal analgesic injection system for children.
Beer bottles and cans benefit Mecmesin's torque and top-load testing
A leading European brewing company, part of a global group, produces economy brands in plastic (PET), as well as glass bottles. The PET bottles must be quality-tested for top-load crush strength, and the caps for both unscrewing and release of the tamper-evident ring. Many tests must be done each day on the production line to ensure consistent compliance against internal quality standards.
Food packaging made from thermoformed plastics and intended for freezing, requires testing to ensure optimum functionality when closing and sealing the container. The closing effort of the lid is measured by using a motorised force tester controlled by software together with a custom-designed fixture to hold standard-sized ice cream tubs. In addition the ‘top-load’ crush strength of the container itself can also be tested on the same machine to guarantee it is rigid enough to avoid buckling and spillage when the lid is applied.
What force is required to remove a DVD from its box?
A leading supplier of boxed DVD’s had experienced a wide variation in the amount of force required to remove the DVD from the central spigot of the case. In extreme cases, this resulted in damage to the actual disc. A 1000 N capacity MultiTest-i computer-controlled test system was provided by Mecmesin to measure the release force.
Mecmesin develops Combi Cork-i Extraction Tester for leading Scottish whisky
To improve the quality and storage of a premium product, the R&D team at a leading Scottish whisky maker needed to optimise the design of their bottle stoppers. They decided that the strength and performance of their reusable stoppers could be ensured by systematic testing of the characteristics of both portions of the stoppers. Working closely with the R&D team, Mecmesin developed the Combi Cork-i Extraction Tester, an innovative multi-function cork extraction testing system that tests both phases of de-corking synchronously.
Medical Pouch Heat Seal Tensile Test
Rocket Medical PLC are award winning designers and manufacturers of medical devices for a wide range of clinical applications. These medical devices are packed into pre-purchased pouches and sealed in-house before being sent off-site for sterilisation. The heat seal on these pouches must conform to British Standard BS EN 868-5:1999 (Packaging materials and systems for medical devices which are to be sterilised).
ISBT sports closure rotational test simulates biting or pulling on the spout
The rotational force needed to remove the closure spout from a sports cap body is measured using the Steinfurth Rotation Tester for Sport Closures mounted on a Mecmesin tensile tester. This ISBT test simulates a person biting or pulling on the spout when attached to a PET preform and requires specific tensile test equipment to meet the standard.
- Jo Webb
- Product Info
- Created 27 Jan 2020
- Modified 28 Jan 2020
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