Due to the wide increase in the usage of PET bottles for various products like food items, beverages, chemicals etc., it is crucial to measure the quality and strength of the PET bottles. The safety of products is the primary concern of all the manufacturers. The main problem that arises is the bad quality caps or lids. It easily gets opened during transit or storage.

Torque is the angular force required to rotate something like force. Seal or bottle cap torque is an important property that explains the quality of PET containers. To assure the seal strength of bottle caps, many tests are conducted on the bottles in various testing labs of PET and preform industries. It is performed to check leakage and leak integrity properties, opening and closing strength of products. Torque testing is conducted in PET industries to check the quality of the bottle caps. The test method measures the quality of the bottle caps in an accurate manner.

Torque Tester is one of the most popular testing device used in PET products manufacturing industries to evaluate opening and closing strength that is required to open a bottle torque. This testing method is conducted before the packaging process starts. It is a destructive testing method in which various samples are needed to analyse the weakness in the torque strength of bottle caps at the time of the process of screwing.


Performing torque testing using Cap Torque Tester, various methods are applied such as:

  • The testing instrument explains the torque tolerances of the bottle caps.
  • Two limits are set while conducting the test in accordance with the type of bottles i.e. upper and lower limit.
  • The lower limit of the test is examined as the minimum strength needed to open the cap of the bottle. It is defined correctly to prevent the fatal accidents that are caused due to leakage from the bottle caps.
  • The higher tolerance of the test is examined as the maximum strength that users exert to open the bottle caps.
  • After the tolerances are set, the torque testing machine checks the torque strength of bottles.
  • Change in temperatures also changes the characteristics of products and torque measurement varies accordingly.


Hence, manufacturers must check and control the torque strength of the bottle caps in various temperatures at least for 24 hours after the process of packaging.

Labtiger’s Cap Torque Tester is the best in measuring the minimum and maximum strength needed to open caps of the bottles.  It is designed by skilled engineers considering various standards.