Quality assurance standards for adhesive bonding technology and fibre-reinforced plastics technology

In accordance with the Product Safety Act (ProdSG), in order to be able to use a material, a product made from it or a process safely, work must be carried out in accordance with the »state of the art«. A product may only be placed on the market »if it does not endanger the safety and health of persons when used as intended or in a foreseeable manner«.

Fulfilment of this legal requirement must be verified.

If this verification cannot be provided purely non-destructively and with one hundred per cent certainty on a process and product-specific basis, these are so-called »special processes« in accordance with ISO 9001. In order to fulfil the legally required »state of the art«, errors must be avoided from the beginning of the product development phase through production, maintenance and repair to the end of the product's life. This is done by verifying the processes, their description, control and documentation. 

Application processes of adhesive bonding technology or fibre composite technology, as well as products manufactured using these technologies, cannot be tested one hundred percent non-destructively for freedom from defects - as is the case with welding, for example. Both technologies (as well as welding techniques) are therefore »special processes«, along with countless others.

Consequently, the »state of the art« for both technologies is the avoidance of possible process defects and product defects through an end-to-end quality management system (QMS) in accordance with ISO 9001 (see illustration).

However, the logically broad-based ISO 9001 can only define the basic QM framework conditions for a quality management system (QMS). This therefore requires technology-specific concretisation.

These specifications are made - also comparable to the corresponding welding standards - by means of quality assurance standards for adhesive bonding and fibre composite technology. They specify an existing QMS and the ISO 9001 core concept of comprehensive error prevention on a technology-specific basis and help the user companies to work safely with the respective technology in accordance with the legally required »state of the art«.

In this way, QA standards holistically complete the legally required »state of the art« for the professional, error (source) avoiding planning, organisation and implementation of adhesive bonding and fibre composite processes and corresponding products in all areas of industry and handicraft.

Consequently, the required »state of the art« for adhesive bonding technology and fibre composite technology is the inseparable link between product safety law, quality management system and adhesive bonding and fibre composite QA standards (see illustration). By implementing the standards, the user makes adhesive bonding technology and FRP processes robust and reproducible.

The quality assurance standards for adhesive bonding and fibre-reinforced composites (see below) define the requirements for quality-compliant development and design as well as the general organisational, contractual and production-related principles for development, manufacture, maintenance and repair across all cross-industry sectors, from the initial idea to the end of the product's life.

Standards for adhesive bonding technology

Standards for fibre composite technology

As with the welding standards, all QA standards contain the same core elements and are therefore structurally compatible with each other. 

Core element 1: Classification according to safety classes 1 - 4
 

In accordance with the standards mentioned, all adhesively bonded joints are classified by the user into the safety classes Level 1 - Level 4. Put simply, this categorisation is based solely on the question:

What happens if the adhesively bonded joint/composite component fails?

The answer to this question is unalterably the responsibility of the company using the adhesive or fibre composite and can under no circumstances be delegated to other (contractual) partners such as adhesive or resin/fibre manufacturers. Classification is the responsibility of the responsible designer or component manager of the user company, with the involvement of the supervisory personnel appointed by the company in accordance with Core Element 2 (see below) (adhesive bonding technology: Adhesive Bonding Coordinator - ABC / fibre composite technology: Composite Coordinator - CC).

Basic presentation of safety classes in adhesive bonding technology and fibre composite technology

Core  element 2: -        Objective verification of the respective technological personnel competence  (Competence level 1 - 3)

The user company must have sufficient personnel with adhesive bonding or fibre composite qualifications that can be objectively verified to third parties at the technical decision-making and supervision level as well as at the execution level.

The supervisory personnel to be appointed by the user company (adhesive bonding technology: ABC/fibre composite technology: CC) are employees who are responsible for the respective technology and associated activities in the company. Their suitability and specialised knowledge, e.g. through training, education and/or corresponding experience, must be verified and documented.

The supervisory personnel are the central point of contact in the company for all quality-influencing factors of the »special process« of adhesive bonding or fibre composite technology - from planning and production to maintenance and repair. In accordance with the QA standards mentioned, the user company must have sufficient and verifiably qualified personnel for the tasks mentioned and document their appointment.  Depending on the classification, professional training (carpenter, floor layer, painter, etc.) or extra-occupational training can be used as verification of adhesively bonded or fibre composite-specific qualifications to justify the designation as supervisory personnel (adhesive bonding technology: ABC/fibre composite technology: CCC) as follows: 

Core element 3: -        Verification of product and process safety

The fact that an adhesively bonded joint or a fibre composite component must be designed in such a way that its real loading is always less than the maximum load capacity is the »state of the art«. What is new in the context of the aforementioned QA standards for adhesive bonding technology and fibre composite technology is that this must be ensured with the involvement of the supervisory personnel (adhesive bonding technology: ABC/fibre composite technology: CC) and the verification process must be documented in a traceable manner.

The supervisory personnel (adhesive bonding technology: abc/fibre composite technology: CC) must be involved in the release process.

The verification itself can be carried out in the following four ways:

1. Calculation verification
   In computational verification, the loading of the adhesively bonded joint or the fibre composite component is determined using calculations, standards or real data. The load, environment and manufacturing conditions are transferred to a model, the loading is calculated and compared with the load capacity. This method is particularly suitable if the real conditions can be easily modelled. However, this verification method entails uncertainties due to computational abstraction and could involve a great deal of effort in determining the characteristic values.
   
   
2. Component testing
   In component testing, adhesively bonded joints or fibre composite components are tested in a test bench under real conditions or conditions modelled on reality. Loads and environments as well as manufacturing influences are applied. The global/local failure of the adhesively bonded joint or the fibre composite component is observed and measured and the reserve and safety are shown, for example, with the help of overload or a longer load duration. This method offers direct verification on the structure without the uncertainty of mathematical abstraction and represents a cost-effective method for small test components. However, the verification of low failure probabilities is rather difficult, as is the realisation of complex test conditions (e.g. temperature changes for large components; possibly also zero series production or production of only one product).
   
   
3. Documented experience
   This method requires verifiably verifying the load capacity based on empirical values that show that the design has already proven itself in the past. In addition, the transferability to the adhesively bonded joint or fibre composite component in operation must be documented. This approach is cost-effective due to the existing experience and there is no uncertainty due to mathematical abstraction. In addition, direct verification can be provided on an existing construction under real conditions. However, the documented experience is only applicable if the design and operating conditions are comparable.
   
   
4. Combination of paths 1 - 3
   The safest way to verify adhesively bonded joints or fibre composite components is to combine the first three methods. All requirements can be assessed in a suitable manner and documented in a comprehensible manner. The combination enables a mathematical verification that is experimentally supported and validated. Compared to path 1 and 2, the environmental conditions including ageing are easier to visualise. In addition, experience is systematically built up - which in turn makes route 3 possible in the first place. Although this approach initially involves a relatively high level of effort, it later proves to be profitable in terms of data, experience and transferability.

Presentability of the verification process

Load and temperature, adhesion, media resistance and manufacturing influences play an important role in the verification process. The table shows the presentability of the individual factors for each verification path. Here, too, it is clear that a combination of paths 1-3 offers the best option for both small and large components. Under certain conditions, however, it is sufficient to give preference to individual paths (e.g. component testing for small components or documented experience with verified transferability to the operating behaviour).

In addition to the three core elements mentioned, the following areas are taken into account in the standards:

• Contract review and subcontracting
• Development process and process planning
• Infrastructure
• Production and maintenance
• Storage and logistics
• Monitoring of measuring, testing and production equipment
• Quality management

User companies can be certified according to the above standards by our DIN EN ISO/IEC 17065 -accredited co-operation partner

TBBCert (www.tbbcert.com)

Contact: Frank Stein (stein@tbbcert.de)

More than 1,1,50 companies worldwide (as at 01/02/2024 / (www.en17460.com / www.din2304.de / www.tla0023.de) are already certified to one of the above standards.

Outlook on the internationalisation of standards:

After a three-year transition period, the DIN 6701 series of standards for rail vehicle construction will be withdrawn in 09/2025. From then on, DIN EN 17460 will apply worldwide. Ausblick zur Internationalisierung der Normen:

The same applies to DIN 2304-1: It will be withdrawn in 06/2026 and replaced by DIN EN ISO 21368.

Companies that are already certified in accordance with one of the national standards mentioned will be audited in accordance with the future standards in the course of regular recertification or surveillance in consultation with the certification body. You will receive further information on this in the course of audit planning.

Companies in the rail vehicle construction sector that are seeking new certification are advised to obtain certification to DIN EN 17460 straight away.