What adhesive strength do you actually need? A practical guide for industrial applications

Adhesives are used across countless industrial applications - from electronics assembly and automotive manufacturing to construction and product design. Yet one of the most common mistakes when selecting an adhesive is assuming “stronger is always better.”

In reality, choosing the right adhesive strength is about matching the adhesive’s properties to the application. Too little strength can lead to joint failure, but excessive strength can introduce unnecessary cost, curing time, or even stress within the materials being bonded.

In this practical guide, we’ll explain how adhesive strength is measured, what factors influence it, and how to determine the level of performance your application actually requires.

What is adhesive strength?

Adhesive strength refers to the force required to break the bond between two materials. It indicates how well the adhesive holds under load or stress.

Different tests measure adhesive performance in different ways, including:

• Shear strength – resistance to sliding forces between bonded surfaces
• Tensile strength – resistance to pulling forces that separate the joint
• Peel strength – resistance to forces that peel materials apart
• Impact resistance – ability to withstand sudden forces or shocks

These values are typically measured according to standards such as ASTM D1002, which evaluates lap shear strength for adhesives used in structural bonding.

Understanding these different strength types is essential because the forces applied to a bond rarely occur in just one direction.

Why “maximum strength” isn’t always the best choice

A common assumption in industrial design is that selecting the strongest adhesive available will guarantee reliability. However, this approach can create several issues.

1. Material stress

Very high-strength adhesives can transfer stress directly into the materials being bonded. If the materials are relatively weak or flexible, such as plastics, the substrate may fail before the adhesive does.

2. Difficult disassembly

Some applications require maintenance, servicing or recycling. Extremely strong adhesives can make disassembly impossible without damaging components.

3. Longer cure times

Structural adhesives often require longer curing periods, elevated temperatures or specialised equipment, which can slow down production processes.

4. Increased cost

High-performance structural adhesives typically cost significantly more than general-purpose alternatives.

Selecting the appropriate strength rather than the highest strength helps balance reliability, cost and manufacturing efficiency.

Key factors that determine the adhesive strength you need

Several practical factors influence the adhesive performance required for an application.

Load type

The direction and nature of the load applied to the joint are critical.

Common load types include:

• Shear loads – forces acting parallel to the bond line
• Tensile loads – forces pulling directly apart
• Peel loads – forces lifting one material from another
• Dynamic loads – vibration or repeated stress

Adhesives typically perform best under shear loading, while peel stresses often cause failure more easily.

Surface materials

Different materials bond differently with adhesives.

Examples include:

• Metals – typically provide strong adhesive bonding
• Plastics – may require surface treatment or specialised adhesives
• Glass and ceramics – often require adhesives with excellent adhesion and low shrinkage
• Composites – may require flexible adhesives to handle stress

Surface energy, texture and cleanliness all affect bond strength.

Environmental conditions

Industrial adhesives must often withstand demanding environmental conditions.

Important considerations include:

• Temperature extremes
• Moisture or humidity
• Chemical exposure
• UV exposure
• Vibration

For example, adhesives used in outdoor applications may require UV resistance, while those used in electronics assembly must tolerate heat from components.

Bond area and joint design

A well-designed joint can dramatically increase effective bond strength.

Factors that improve performance include:

• Increasing bonded surface area
• Designing joints for shear rather than peel loading
• Ensuring consistent adhesive thickness
• Avoiding stress concentrations

Mechanical design often plays just as large a role as the adhesive itself.

Typical adhesive strength ranges

Different adhesive families provide varying levels of strength and flexibility.

Here are typical examples.

Cyanoacrylates (instant adhesives)

Often associated with products like LOCTITE instant adhesives, cyanoacrylates provide:

• Very fast curing
• High tensile strength
• Best performance on small bonding areas

Typical applications include electronics, plastics and small component assembly.

Epoxy adhesives

Epoxies offer some of the highest structural bond strengths available.

Key characteristics include:

• Excellent shear strength
• Good temperature resistance
• Strong bonding to metals and composites

They are widely used in structural bonding and industrial manufacturing.

Acrylic adhesives

Acrylic adhesives balance strength and flexibility.

Advantages include:

• Good environmental resistance
• Fast curing
• Strong bonding to metals and plastics

These are commonly used in automotive and general industrial assembly.

Polyurethane adhesives

Polyurethane adhesives offer flexibility and impact resistance.

Typical uses include:

• Construction
• Automotive panels
• Bonding dissimilar materials

They are particularly useful when joints must absorb vibration or movement.

Brands like Gorilla Glue offer tough, gap‑filling polyurethane adhesives built to bond almost anything and stay stuck, even under the harshest conditions.

A simple method to estimate required adhesive strength

A basic engineering approach can help determine the adhesive strength needed.

1. Identify the maximum load the joint will experience.
2. Calculate the bonded surface area.
3. Determine the stress applied to the bond.

Example:

If a joint experiences 500 N of force and the bonded area is 50 cm², the required strength is:

Engineers then typically apply a safety factor, often between 2× and 5×, depending on the criticality of the application.

Surface preparation: the most overlooked factor

Even the strongest adhesive can fail if surfaces are not prepared properly.

Effective surface preparation may include:

• Cleaning oils and contaminants
• Abrading smooth surfaces
• Applying primers or activators
• Controlling moisture

In many cases, surface preparation has a greater impact on bond strength than the adhesive itself.

Practical tips for choosing the right adhesive

When selecting an adhesive for industrial applications, consider the following guidelines.

• Focus on application needs rather than maximum strength
• Design joints to minimise peel forces
• Prepare surfaces thoroughly
• Test adhesives under real operating conditions
• Consider curing time and manufacturing workflow

These steps help ensure reliable performance while avoiding unnecessary cost or complexity.

Making the right choice

Choosing the right adhesive strength is not about selecting the strongest option available - it’s about understanding the mechanical loads, materials and environmental conditions your application will face.

By evaluating factors such as joint design, load type, surface preparation and curing requirements, engineers can select adhesives that provide the right balance of strength, flexibility and efficiency.

When matched correctly to the application, adhesives deliver reliable bonding performance across a wide range of industrial environments.