What is Adhesive Strength?
Adhesive strength refers to the strength of the bond between adhesive coating and the substrate. Cohesive strength is another component which refers to the internal strength of the adhesive and its ability to hold itself together under stress.
How is Adhesive Strength Measured?
Adhesive strength measurement is calculated using three tests; a tensile strength test, shear strength test, and peel strength test which all determine the effectiveness of an adhesive and its ability to bond to certain substrates.
Tensile Strength
Tensile strength is measured by stretching apart two sample substrates that are bonded with the adhesive. The point at which the adhesive breaks indicates the peak tension force it can withstand; this amount is then divided by its cross sectional area and the total figure is its tensile strength. This measurement is the most widely used for adhesive strength and refers to the adhesive’s ability to resist loads under stress without failure.
Shear Strength
Shear strength is measured by pulling two sample substrates that are bonded with the adhesive in a sliding motion and in opposite directions. The peak shear force that is sustained before failure is then divided by its cross sectional area resulting in the shear strength of the adhesive. This measurement represents the adhesive’s ability to resist forces that can potentially cause their internal structure to slide against itself.
Peel Strength
Peel strength is measured by pulling back two sample substrates that are bonded with the adhesive in a peeling motion. Commonly peeled at 90° and 180° angles and at a constant rate, the peak peel force that is sustained before failure is then divided by its cross sectional area resulting in the peel strength of the adhesive. This measurement is used to identify the adhesive’s resistance to localised stresses.
Why is Adhesive Strength Testing Important?
Adhesive strength testing and calculation is important for quality control purposes. This is not just for meeting customer specifications, but for adhering to industry standards too. Different industries and applications have various adhesive strength requirements, so it is vital to test according to those parameters.
Adhesion failures are economically costly and risk reputations; adhesive bond strength analysis can avoid these pitfalls along with other testing and prototyping during the design process. Identifying adhesive capabilities and the impact of variations on its performance is a significant part of the manufacturing process and one that needs meticulous attention to detail, especially medical adhesives.
At BDK, we provide comprehensive project management which consists of design, materials, prototyping and development, process validation and production. During our prototyping and development stage, we undertake adhesive strength testing to provide a solution that meets your specification.
Contact us today to find out more information and to discuss your project with BDK.
