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Case Studies / Adhesive test on capsulated stoppers in Packaging

Adhesive test on capsulated stoppers in Packaging

Rotational force test for adhesive bond integrity between cork shank and wooden top

Adhesive bonding strength test for AFTI capsulated cork stoppers

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

Presto Stantest's adhesive testing system for encapsulated stoppers can be used to help manufacturers gauge the bond strength between the cork shanks and bar-top caps for premium wine, spirit, and fortified beverage packaging. Capsulated stoppers such as T-top stoppers, bar-top (universal) stoppers, and Altop® stoppers are popular since they can be opened and closed repeatedly without loss of product freshness or closure integrity.

The testing solution features an automatic torque testing machine with specially designed chuck grips that fix and grip the cork and cap tightly for the testing process. This special gripping system enables precise testing of stoppers of different diameters and for different cap materials such as wood, plastic, glass, porcelain, and metal.

In the test, a rotation force is applied at a controlled speed until the adhesives' bond breaks or the cork itself fails. The torque data is recorded at high resolution during the test and enables a clear and accurate evaluation of the peak torque values and pass/fail criteria in accordance with defined quality parameters.

Requirement

Capsulated stoppers—commonly known as T-top, Bar-Top, or Al top —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.