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Closure torque - Capability Statements

ROPP closure removal. breakaway and bridge torque tester

Roll On Pilfer Proof bottle closure breakaway, bridge and removal torque

The ROPP design of glass bottle cap is a popular solution for drinks manufacturers and brewers, featuring pilfer-proof indication by means of a tamper evident ring. The metal closure has a liner to ensure hermetic sealing to prevent leakage and preserve flavour, freshness and gas content of sparkling varieties. To quality assure the capping process is providing an application force and torque to achieve these objectives, whilst still achieving in-specification removal torque, a portable digital torque test instrument may be used at the point of production. An adjustable saddle plate and fixing pegs will allow a variety of shapes of bottle to be quickly accommodated and tested. For additional convenience, repeatability, and ease-of-use – important considerations in rapid through-put automated manufacturing environments – is an audible pass/fail indicator and the ability to connect the instrument to results analysis software and transfer stored data. The closure torque values typical for this solution mean that the simple application of removal torque by hand is possible, rotating the closure through the breakaway and bridge torque points, providing an efficient and representative test standard.

Mecmesin Systems: Tornado digital torque instrument, large saddle plate, adjustable fixing pegs

Case Study: ROPP bottle cap removal torque test

Champagne cork extractor and torque measurement system

Champagne and sparkling wine cork removal torque

The extraction of the cork closure from a glass bottle of Champagne, or similarly sealed sparkling wine, must be able to be performed easily enough to successfully release the beverage for consumption. As with all drinks containers, the stopper has to provide effective sealing to ensure the product remains in perfect condition, free from leakage (even after horizontal storage) and as freshly fizzy as when originally bottled. Additionally, the natural cork material should remain intact under the closure's removal torque required. A prime objective of a testing system to allow repeatable measurement of the peak release torque, suitable for a governing body responsible for evaluating the consistent quality of all products, is to reduce wastage in testing the full bottles of wine. A reliable quality assurance process needs several functional requirements. The ability to securely hold varying bottle sizes – magnum, standard (75cl) and demi – requires a design of fixture with quickly interchangeable jaws, able to grasp different radii and locate glass samples without slippage. Pneumatic operation of the clamps further enhances the efficiency of the method. The clamping of the cork within the upper fixture, must similarly be secure plus allow the cutting of the muselet wire prior to operating the test. The motorised system is geared to rotate the upper fixture as the bottle is simultaneously lowered at a constant speed. This complete, flexible, automated solution includes a safety enclosure to guard against spillage.

Mecmesin Systems: CombiCork-d, Advanced Force and Torque Indicator

Closure cap breakaway torque testing

Tamper-proof bottle cap bridge and removal torque testing

The seals on tamper-proof (or tamper-evident) closures are designed resist an unscrewing torque up to a specific value. The tamper-evident band on the cap should remain intact for safety reasons, until it is positively breached and the bottle opened for intended purpose. Testing of this bridge torque for a range of products is needed to optimise the balance between ease of opening and security. Testing the cap designs in isolation from the bottles themselves in a product design environment can be achieved through the use of bespoke mandrels in the standard manufactured sizes produced by the supplier. These fixtures ensure a repeatable grasp of the cap and a precise hold of the tamper-evident ring for confident back-to-back testing of design variants. A digital torque indicator gauge, with on-board memory - for storage of the peak torque - and data transfer capability allows the collection of results for analysis.

Mecmesin Systems: Advanced Force and Torque Indicator, torque mandrels

Case Study: Torque Tester for Dedicated Caps

Pharmaceutical bottle holders and cap mandrels for torque testing

Multi-way bottle closure grips and mandrels

A pharmaceuticals company wanted to test the closure torque of a series of  square-profile PET bottles. To minimise operator adjustment, they wanted to test all bottles at a constant height, using their Vortex-i torque tester.

Mecmesin responded by designing a set of nesting bottle holders along with a custom-moulded mandrel set. In this way each bottle could be axially aligned and presented at the right height under the torque head, for maximum test throughput.

Custom fixture to clamp a biopsy injector of spring compression testing

Pneumatic top-load control for CRC cap torque testing

Torque testing of child-resistant bottle caps requires application of a simultaneous top load. Raising and lowering this repeatedly in a testing sequence is much easier, quicker and more secure when automated. Our client wanted to eliminate this manual effort by test operators.

Mecmesin supplied a pneumatic lift mechanism for the client's Vortex torque test stand, to lift the top-load weights and lower the torque head into place for each cap test. This makes batch testing quicker, more reliable, and less tiring for the operator to perform.

Container cap removal torque test system

Hygienic disposal bin closure testing

A manufacturer of hygienic disposal bins came to us with a nappy (diaper) disposal unit with a rotary intake mechanism. The bin was 30 cm wide and the opening at 45 degrees, making holding of the bin for proper axial rotation somewhat difficult.

Mecmesin designed a rotating platform at 45 degrees to rotate the bin about the axis of the rotating mechanism, but the width required an additional modification of our standard Vortex torque tester for increased column separation. The result was a tester for rapid and effective, repeatable testing to ensure consistent quality of the manufactured units.

Cap testing of syringes

Luer-lock syringe cap release torque

Our client provides prefilled syringes, closed with Luer-lock caps. The release torque of these is quality controlled for consistency, requiring precise measurement and total repeatability for any syringe tested. For efficiency of throughput, the fixture was requested to be single-handed operation and for syringes of different sizes.

At Mecmesin we devised a simple but precise drop-on mandrel for the cap, and an open-sided column to receive the syringe, with flanges for different lengths. Mounted on a Vortex-i torque tester, this povided a rapid and efficient throughput system for quality assessment.

Custom are required mandrels for container closure tests

Custom bottle cap mandrels

Plastic bottle caps and T-corks have individual profiles for finger gripping, and the best way to torque-test their performance is by providing an exact machine grip at as many points as possible. Many well-known brands and manufacturers come to us for custom-profiled mandrels to use on their torque testers.

A custom mandrel is much quicker to place and release than a screw-fit clamp, and by precise positioning offers true repeatability in testing of bridge torque, removal torque and running torque.

Cosmetics jar lid torque testing equipment

Split mandrels for closure torque testing

Smooth twist caps on bottles and jars require an adequate and symmetrical grip without distortion. For any particular product line and size, a customised grip will always perform best and produce the most reliable results.

At Mecmesin we regularly design and manufacture mandrels for specific closures, and one approach is the convenient split mandrel with a simple screw clamp, for quick application and release. Items such as cosmetics containers can especially have designs that are easy for the hand, but difficult for machine holding, so a modified or custom grip may also be needed for the container. Again, our custom engineering service can provide a suitable fixture design for you.

Custom mandrel to secure closure sample for torque testing

Child Resistant Closures (CRC) mandrel

Child Resistant Closures (CRC) require axial force and simultaneous torque, for testing removal torque, or reverse-ratchet torque. Mecmesin torque testers, such as the Vortex and Helixa, will do this to international industry standards and regulation, but the most reliable results will be obtained by using a custom-profiled mandrel for the cap.

We regularly design and provide custom mandrels, especially to the pharmaceuticals packaging sector. Contact us with your requirements for a quick response towards improved testing.

Cosmetics container release torque and pull-off test

Cosmetics container caps, lids and closures release torque and pull-off force

A consumer packaging manufacturer may produce a variety of containers for the cosmetics industry, which in addition to their functional requirement, may have strong design influences. The range of shapes and sizes that result need a versatile quality testing solution to evaluation the effectiveness in sealing plus ease of opening for the container caps. An adjustable clamp, able to securely grip different bottles and jars (possibly made from glass) is needed to measure the torque required to release the lid of the jar. A simple, light and portable digital desktop instrument, measuring the peak value as the lid is released by hand can quickly assess the quality of the screw top closure. For flexible plastic containers, with plastic caps, there could be a danger of the lid being pulled off. A tensile tester with appropriate grips and fixtures will provide repeatable pull-off resistance appraisal.

Mecmesin Systems: MultiTest motorised test system, CAPTEST

Case Study: Cosmetic Packaging Pull-Off Test

Torque testing requires concentricity for accurate measurement

Closure torque measurement with large or irregularly shaped containers

Closure torque testing involves a range of tests for events designed into screw caps, lids and unthreaded stoppers. It can include a measure of the turning force required to initiate twisting, possibly to overcome safety features (e.g. CRC Types I and II) and tamper resistance features, and also to secure the closure. Other rotational systems, for example bearings, also benefit from the evaluation of the required torque to turn—both breakaway and running torque. Accurate measurement of the torque characteristics of these systems requires alignment of the rotational components with the grips and fixtures of the testing equipment. In the case of large or irregularly shaped products, custom designed fixtures may be needed to assure concentricity of the closure with the crosshead, and permit adequate clearance throughout the complete angle of rotation performed in the test.

Mecmesin Systems: Vortex torque testing systems with customised testing fixture design


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