Removal torque of 'squeeze and twist' child-resistant cap

Solution

  • Manually-operated digital torque tester
  • Custom-designed adjustable container holed fixture

Benefits

  • Simple and reliable test procedure
  • Consistent results from a low-cost solution

Requirement

Reckitt-Benckiser are manufacturers of the distinctive HDPE (High Density Polyethylene) swan-neck 'Harpic' cleaning fluid bottles. The specification outlined by the customer was to check the torque to 'twist-off' the polypropylene child-resistant caps fitted to 2 different swan-neck bottle samples containing 'Harpic' cleaning fluid. The tests were to be carried out on a Mistral closure torque tester with modified fixturing.

The sample could not be gripped using traditional clamping methods, as this would have positioned the sample off-centre to the axis of the transducer. Resultant torque readings would have been inaccurate and damage to the torque transducer itself would have been highly probably during the testing process.

Solution

To ensure that the neck of the sample was axial to the transducer, the bottle was inclined and located into a recessed shoulder. Both bottles were slightly different lengths and depths so the fixturing had to be adjustable in order to locate both samples in relatively the same position.

Test equipment

Mistral Closure Torque Tester (superseded by Orbis and Tornado)

Modified container holder fxturing

 

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