ASTM D6862

90 Degree Peel Test Fixture

Standard Test Method for 90 Degree Peel Resistance of Adhesives - PDF

 

ASTM D6862 is the standard test method used to determine the peel resistance of adhesives by pulling one adherend away from another at a 90-degree angle. This test is particularly useful for structural adhesives, pressure-sensitive adhesives, and laminated materials bonded to rigid substrates.

It is widely used in industries like:

• Aerospace

• Automotive

• Electronics

• Consumer goods

• Packaging and labeling

• Composite bonding and metal-to-metal adhesion

What Does ASTM D6862 Measure?

• Peel strength (expressed in N/mm or lb/in)

• Failure mode (adhesive, cohesive, substrate failure, or a combination)

• Uniformity of adhesion along the bond line

• Repeatability and durability of bonded joints over time

Key Features of ASTM D6862

• The test is performed at a constant speed, typically 254 mm/min (10 in/min), though other rates may be specified.

• The angle between the pulling force and the substrate is fixed at 90 degrees throughout the test.

• It differs from ASTM D903 (which tests at a 180-degree angle) and is more appropriate when bonded materials are adhered to rigid substrates.

Equipment Required

1. Universal Testing Machine (UTM)

• Load capacity: 1–5 kN typically sufficient, depending on adhesive strength

• Must have a constant crosshead speed control

• Capable of real-time data collection and graphical output (force vs. displacement)

2. 90-Degree Peel Test Fixture

This is the core component of the ASTM D6862 setup.

Features of the 90-Degree Peel Fixture:

• Rigid base with a low-friction sliding table or roller platform to support the substrate

• Clamping mechanism to hold the rigid substrate in place during the test

• Guide system to maintain the peel angle at exactly 90 degrees

• Some systems include bearings or air slides to ensure smooth, low-friction movement

Function:

• As the flexible adherend is pulled upward by the UTM, the rigid adherend remains on the low-friction platform and slides horizontally, maintaining a consistent 90-degree peel angle throughout the test.

3. Grips

• Pneumatic or mechanical grips to securely hold the free end of the flexible adherend

• Must prevent slippage without damaging the material

• Often lined with rubber, cork, or serrated metal surfaces for better gripping

4. Extensometer (optional)

• Typically not required for peel tests, but may be used if measuring elongation or displacement with high accuracy is needed

ASTM D6862 Specimen Preparation

Typical Dimensions:

• Bonded area length: 150 mm (6 in) or longer

• Bond width: 25 mm (1 in) standard

• Flexible adherend thickness: variable; often thin films, tapes, or foils

• Rigid adherend: metal, plastic, composite panels, etc.

Guidelines:

• Bond line must be uniform and free from air bubbles or voids

• Adhesive should be fully cured before testing

• Conditioning: 23 ± 2°C and 50 ± 5% RH for at least 40 hours (unless otherwise specified)

Test Procedure: ASTM D6862

1. Mount the specimen in the peel fixture so that the flexible adherend points upward and the rigid adherend lies flat on the sliding table.

2. Secure the rigid adherend to the 90-degree peel fixture, ensuring it moves smoothly in the horizontal direction.

3. Secure the flexible adherend in the upper grip of the testing machine.

4. Set the crosshead speed to 254 mm/min (10 in/min) unless another rate is specified.

5. Begin the test and record the peel force as the flexible adherend is pulled upward at 90 degrees from the bonded interface.

6. Continue peeling for a defined length (often 75–100 mm) to collect steady-state peel force data.

7. Record and report:

   • Average peel force

   • Maximum and minimum values

   • Peel strength (force divided by specimen width)

   • Type of failure (adhesive, cohesive, substrate, or mixed)

Failure Modes to Observe

ASTM D6862 encourages recording qualitative failure modes, such as:

• Adhesive failure – separation at the adhesive-adherend interface

• Cohesive failure – failure within the adhesive itself

• Substrate failure – failure of one of the adherends

• Mixed failure – combination of the above

Photographs or video of the peel process are helpful for detailed failure analysis.

Data Reporting Requirements

• Full description of materials (adhesives and substrates)

• Curing conditions and times

• Specimen geometry and preparation method

• Crosshead speed

• Peel strength (N/mm or lb/in)

• Failure type and any anomalies

• Test environment (temperature, humidity)

• Number of replicates and statistical analysis (if performed)

• Force vs. displacement curve (recommended)

Related Standards

• ASTM D903 – 180 Degree Peel for Adhesives

• ASTM D3330 – Peel Adhesion of Pressure-Sensitive Tape

• ASTM D1876 – T-Peel Test of Adhesive Bonds

• ASTM D3167 – Floating Roller Peel Test of Adhesives

• ASTM D1781 – Climbing Drum Peel Test (composite laminates)

• ISO 8510-2 – Peel test for rigid-to-flexible bonded assemblies

Best Practices for Accurate Testing

• Use a high-quality 90-degree peel fixture with minimal friction.

• Ensure precise alignment of grips and platform to maintain a consistent angle.

• Use anti-slip gripping surfaces to prevent specimen slippage.

• Cut specimens with clean edges to avoid stress concentrations.

• Conduct at least 3–5 replicates for statistical significance.

• Monitor adhesive and substrate conditioning environment closely.

Summary

ASTM D6862 provides a reliable and standardized method for measuring the peel resistance of flexible adherends from rigid substrates at a 90-degree angle. When paired with a quality 90-degree peel fixture and a precision UTM, this method delivers repeatable and valuable data for adhesive selection, process validation, and quality control. It is particularly useful when the 180-degree peel method (ASTM D903) is unsuitable due to stiffness or rigidity of one of the bonded materials.