DIN 53295 Testing of Sandwich Structures - Peel Test with Drum Assistance

The standard “DIN 53295 Testing of sandwich structures - Peel test with drum aid”, published by the German Institute for Standardization (DIN), describes a test method for determining the peel resistance (or peel strength) of adhesive bonds in sandwich structures. Sandwich structures typically consist of two thin, rigid surface layers (e.g., aluminum or composite layers) bonded to a lightweight core material (e.g., honeycomb, foam, or balsa wood). These materials are widely used in aerospace, automotive, railway vehicles, building panels, and other industries where high strength-to-weight ratios are required.

This standard focuses on evaluating how well the adhesive holds the surface layer to the core under peeling forces. Poor adhesion can lead to delamination, a critical failure mode in sandwich panels. The test provides a quantitative measure of bond quality, typically expressed as peel moment (torque per unit width) or average peel force.

This method uses a special fixture known as a climbing drum (or drum peeling apparatus). The working principle of the test is as follows:

• Sample preparation: A rectangular sandwich sample is prepared (typical dimensions are approximately 75 mm wide x 300 mm long, but exact dimensions are defined in the standard). A surface layer is partially pre-cut or loosened at one end to ensure adhesion.
• Setup: The sample is positioned so that the loosened surface layer is wound and compressed around the center of a cylindrical drum. The drum has flanges or end plates to guide the winding. Flexible loading straps or bands are fitted under the drum fixture and connected to the lower crosshead of a universal testing machine.
• Procedure: The other end of the sample (still attached) is held from above. As the testing machine belts pull upwards, the drum rotates and climbs along the length of the sample. This process peels the surface layer from the core in a controlled manner, simulating a 180-degree peeling operation with moment loading instead of pure tension.
• Measurement: The force required to peel the surface layer is continuously recorded. The basic result is usually the average peeling moment over a defined peeling length, calculated from the torque generated by the applied force and the drum radius. The climbing drum method is advantageous because it applies a relatively constant peeling angle and reduces the effect of bending stiffness of the surface layer compared to simpler planar peeling tests.

The DIN 53295 standard is closely related to, and often cited alongside, other international standards for the same or similar climbing drum peeling test:

• EN 2243-3 Aviation series - Structural adhesives - Test methods - Part 3: Climbing drum peel test
• ASTM D1781 Climbing drum peel test method for adhesives

Many modern test setups are designed to comply with all three standards simultaneously.

The DIN 53295 standard continues to be actively referenced in recent years in test equipment specifications, research papers (e.g., on aluminum foam cores or reinforced fabricated truss sandwiches), and industrial applications.

In short, the DIN 53295 standard is based on measuring the force required to peel the coating layer from the core at a specific angle and speed.

A sandwich structure typically consists of three layers:

• Top coating: Metal, composite, or plastic sheet.
• Core: The core is honeycomb, foam, or lightweight filler.
• Undercoat: Provides bending resistance together with the topcoat.

This structure provides the advantage of high rigidity/low weight in aerospace, automotive, construction, and marine applications.

The DIN 53295 standard is used to evaluate the following characteristics:

• Coating-core adhesion strength
• Adhesive performance
• Production quality
• Delamination resistance

It is particularly important in quality control and research and development activities.

The testing process essentially follows these steps:

• The coating layer is prepared so that one end is separated from the core.
• The sample is placed in the sample extraction testing machine.
• The coating layer is typically peeled off at a 90-degree angle.
• Pulling is applied at a constant speed.
• The force required during peeling is measured.

The result is usually expressed as: Peel strength = Force / Sample width.

The standard typically specifies the following sample characteristics:

• A sample of a specific width (e.g., 25 mm)
• Defined peeling length
• Controlled test speed
• Environmental conditions (temperature and humidity)

The following information is reported after the test:

• Average peeling force
• Maximum force
• Fracture type:
• Adhesion rupture
• Cohesive rupture
• Nuclear rupture

The type of fracture is critical in determining whether it is due to a manufacturing defect or a material weakness.

The DIN 53295 standard is used particularly in the following areas:

• Aviation panels
• Lightweight building elements with composite cladding.
• Glued aluminum honeycomb panels
• Automotive interior trim parts

The DIN 53295 standard is considered important for the following reasons:

• It improves product reliability.
• It helps predict long-term performance.
• It makes the results of different manufacturers comparable.
• It forms the basis for international quality requirements.

For many years, our organization, with its competent and experienced staff, has been understanding the needs of its clients, providing the advanced testing services they require, and assisting them in the establishment, implementation, and improvement of management systems. Within this framework, we also provide testing services in accordance with the DIN 53295 standard.