Role of Torque Testing In Opening and Closing of Bottle Caps

A loose cap is unacceptable to some packagers. A loose cap adversely affects the perception of the customer regarding the safety of the product. On the packaging line, two types of torque are to be addressed i.e. Application and Removal torque also called on and off torque. Application torque evaluates how tightly the cap is affixed. Removal torque evaluates of how much force is needed in removing a cap. Too much of application torque can damage the cap and the end user may not be able to open it. Too little results into leakages or may vibrate loose in shipping.

Capper operation is monitored by testing the removal torque periodically. Improper testing results in various complications. Many torque testing machines are available in the market such as Digital Torque Tester. Fully automated systems are designed to test the torque level of bottle caps. The bottle is clamped into a base, the user removes the cap and the meter shows how much removal force is required to lose the cap.

Pacorr’s Torque Tester-Digital cum computerised model is used to test the force required to open a closed cap of PET bottle. The result is displayed in digital format. It has high-end advanced read out with Auto Tare set facility and Peak hold arrangement. The model sends the reading to a printer of memory for future analysis. Digital readouts are preferred as they minimise the possibility of operator reading error.

Some technique used by the operator may cause inconsistencies such as a gradual pressure is applied to the cap until it breaks free. Another method is by applying a sharp twist to break the cap free. It usually provides a higher removal torque reading than the gradual technique.

Another problem that is faced in this regard is the amount of force applied to the cap. Various operators can grip the cap at various positions that can change the amount of removal torque registered. Cap and bottle materials, design and tolerances also influence torque. Placing caps is an important step in capping. The trend toward light-weighting caps makes it important than ever. The reduced rigidity and depth of some lightweight caps make them more prone to deformation.

Cap Torque Tester is easy to use the machine for PET bottle industry vertical. It is portable which can be placed on the shop floor or in the laboratory. Its unique self-adjusting holding fixture can accommodate any shape and size of bottle 4 having zero slip assurance.