Adhesive Bonding – the Right Way

Tips and information for effective adhesive bonding, quality management and quality assurance

Adhesives nowadays have a multitude of uses, from sticking plasters used in the home to bonded joints in cars and rail vehicles that must meet the highest safety requirements. For this reason, it is not possible for adhesive manufacturers to take account of all and in particular very special uses of their products in their product data sheets.
Adhesive bonding is one of the “special processes” defined in DIN ISO 9000 ff., meaning that non-destructive tests do not allow quality statements of 100% certainty to be made. This is why users of adhesives must have a fundamental knowledge of bonding so that they are aware of the special requirements for making bonded joints.
Making an effective bonded joint involves much more than merely selecting the right adhesive. Indeed, the whole adhesive system must be considered and quality assurance is vital during all phases of the product life-cycle.
The carrying out of all necessary process steps in the correct sequence involves a not inconsiderable amount of quality assurance work. At the outset it is important to create awareness of all the steps in the planning and production phases.

These guidelines therefore describe the development and manufacture of a fictitious product in various steps. The guidelines are directed at small and medium-sized companies, including those in the handicrafts sector, that already use adhesives and perhaps require additional specific information and also at companies that wish to start using adhesives and so require more fundamental background information.

These guidelines have been prepared for both these situations and so present a variety of topics which can either be referred to individually or which can be studied in sequence. A full picture of adhesive bonding technology is presented here, covering all key practical aspects. Unfortunately, specific adhesives and specific bonded joints cannot be discussed. Specific questions should be directed at the adhesive manufacturers and external experts.

The starting point is the product idea. The planning and production phases for the product are considered in the following sections.

0. Fundamental principles of adhesive bonding
1. Planning to manufacture bonded joints
2. Substrate selection and properties
3. Bonded joint design
4. Adhesive selection
5. Surface treatment
6. Demonstration of usage safety
7. Preparations for production
8. Production of bonded joints

Section 0 (Fundamental principles of adhesive bonding) outlines fundamental principles of adhesive bonding that are essential for understanding the subsequent sections. Terms such as “adhesion” and “wetting” are explained.

Section 1 (Planning to manufacture bonded joints) covers the key points that have to be considered when planning to manufacture bonded joints. The importance of “quality management” is also outlined.

Section 2 (Substrate selection and properties) describes the selection of substrate materials. The most common material groups such as metals, plastics, glass, wood and fibre composites are presented.

Section 3 (Bonded joint design) considers aspects of bonded joint design. The complex process of adhesive selection is covered in detail in Section 4 (Adhesive selection). A variety of adhesives are presented. Special focus is put on processing and curing and on the properties of the cured or hardened adhesive.

Once the substrate and adhesive have been selected, suitable surface treatment has to be considered. Section 5 (Surface treatment) outlines a variety of surface treatment methods for different substrates.

Once the substrate, adhesive, and surface treatment have been chosen, the usage safety of the bonded joint must be demonstrated. This aspect is covered in Section 6 (Demonstration of usage safety).

After all the planning steps have been successfully completed, practical implementation must be initiated. These activities are summarized in Section 7 (Preparations for production).

Finally, Section 8 (Production of bonded joints) presents aspects that must be taken into account to manufacture effective bonded joints and to prevent errors occurring.

If you wish to acquire a full picture of adhesive bonding or if you have little or no experience working with adhesives, then it is best to go through these guidelines in full and in the given sequence.

If you wish to only acquire information about specific aspects, then specific sections can be referred to. It is possible to switch between sections at any time. Technical terms are summarised in the glossary. The relevant information is displayed on clicking the term.

We hope you find these guidelines useful!