Adhesive test on capsulated stoppers in Packaging

Solution

• Motorised torque tester
• Chuck-grips adapted to hold capsulated (Bar-Top) stoppers

Benefits

• Enables fast identification of stoppers with weak adhesive bonding
• Provides firm, uniform gripping of low-friction or coated surfaces

Requirement

Capsulated stoppers—commonly known as T-top, Bar-Top, or Altop®—consist of a cork shank bonded into a head made from materials such as wood, polymer, glass, metal, or ceramic. Caps for repeated use are found in many of the more noteworthy spirits, fortified wines, and liqueurs. Their user-friendly aspect makes them popular among consumers and professionals in the sector, particularly in the premium markets.

Closing operations can be automated or manual, depending on throughput and compatibility with materials used. Adhesives, bond systems, and corks are chosen to meet regulatory requirements and to endure multiple switches from compressive loads during use. In service, the stopper must resist separation when subjected to twisting and pulling forces, as failure would directly impact product integrity and brand reputation.

For this reason, evaluating the adhesive bond strength between the cork and the cap is a critical quality-control requirement for both manufacturers and end users.

A leading stopper manufacturer required a dependable and repeatable method to measure the mechanical bond integrity across a range of capsulated designs with varying diameters and cap materials. The solution needed to accommodate multiple configurations while ensuring consistent test conditions and ease of operation.

Solution

The test methodology involves securing the cork portion in one grip while holding the cap in another, followed by the application of controlled torque until bond failure or material breakage occurs. The peak torque value is recorded and assessed against predefined acceptance limits to determine compliance.

Presto’s motorized torque tester applies rotational force at a constant speed, eliminating variability caused by manual testing. Using high-speed data acquisition, measurements are taken to capture the sudden point of failure—either within the adhesive or the cork structure.

Mounting these parts can be problematic because of their slippery or coated surfaces. To overcome this, special grips (chuck-grips) are designed to hold the cork and cap in place using specially designed jaws. Jaws provide consistent clamping action to prevent variations in jaw placement caused by an overdrawn or weak grip.

Test equipment

• Motorised Torque Tester
• Torque Transducer (suitable capacity)
• Torque Indicator / Display Unit
• Custom chuck-grips for capsulated stoppers