As part of a drive towards a green economy across Europe, the European Environment Agency (EEA) has established new EU environmental policy targets and goals to be met by the year 2050. Mandatory emission reductions are part of this directive.
Under the 443/2009/EC directive (EU, 2009f) a 130 g CO2 per kilometer limit has been set for new cars by 2015 and a 95 g CO2 per kilometer limit has been set by 2020. In response to these new emission targets, the automotive industry will focus on multi-material platforms and start to develop new vehicles that are more lightweight.
One way to produce lightweight vehicles is to substitute black metal body panels and components with carbon fiber reinforced plastic (CFRP). This method of weight reduction can help to significantly reduce carbon emissions.
However, the use of CFRP involves a number of complications, including the lack of suitable methods of bonding CFRP panels for high-volume manufacturing. In the existing CFRP panel development process, an advanced 6 axis robotic system is used to apply polyurethane (PU) adhesives and a liquid epoxy to the panel and this is followed by fixing the structurally bonded CFRP panels by adding rivets or jig fixtures.
The adhesive has low green strength and hence, temporary mechanical fixings are added to hold the bonded panels together so that they remain properly aligned throughout the curing time. While the adhesive cures, the components are either shifted to a storage area or cycled via an extra heat source to speed up the curing time. The addition of fixtures and jigging further increases the infrastructure costs involved in the manufacture of CFRP components.
Other areas of importance include careful monitoring and control of the thickness of the bond-line across the entire panel. This is necessary to improve the performance of the adhesive. In the case of parts and components that have intricate shapes and sizes, controlling the thickness between 0.2 and 0.3 mm can be difficult and hence, this aspect has to be mechanically controlled through complicated jigging arrangements and stand-offs.
On the whole, high infrastructure costs together with a large carbon footprint can lead to unaffordable costs.
DAAT® Dual Action Adhesive Tape (DAAT-02)
In order to develop highly sophisticated bonding systems, Tecman Speciality Materials is presently manufacturing the DAAT® Dual Action Adhesive Tape, (Figure 1) a patented composite adhesive tape. This development project is partly being funded by the Innovate UK Technology Strategy through a SMART Grant as the company has recognized the significance of the research.
DAAT® Dual Action Adhesive Tape Technology can help to resolve the issues of structural bonding of composites in the automotive industry.
The DAAT® Dual Action Adhesive Tape can redefine the way CFRP panels are developed, because it integrates the rapid adhesion advantages of pressure sensitive adhesives (PSA), the impact/contact resistance of structural polyurethane adhesives and the excellent bond performance of a structural epoxy.
This composite adhesive tape displays high impact reinforcement and the bond line further increases its structural performance. By using DAAT® Dual Action Adhesive Tape technology instead of existing bonding techniques, the manufacturing process can be accelerated and streamlined thanks to the rapid adhesion properties of the composite adhesive tape.
In addition, when DAAT® technology is used, there is no need to employ mechanical fastenings like self-piercing rivets or heavy and complex jigs. The tape controls the bond-line, resulting in a consistent adhesive layer, and it contains a reinforcement fiber layer to improve the impact resistance properties of the composite adhesive tape.
DAAT is a dual action, double sided adhesive tape that includes a flexible structural carrier with a thick coating of customized epoxy adhesive. It offers a number of features such as a high initial adhesion, high impact resistance and high fatigue resistance. It can bond with different materials.
DAAT-02 can be used for assembling body shell panels, structural composite parts, and internal structures.
Features of DAAT® - Dual Action Adhesive Tape
- Quick adhesion
- Simplified application
- Rapid processing
- High green strength
- Low cost curing
- Multi substrate bonding
- Improved impact resistance
- Application can occur at different stages
Benefits of DAAT® - Dual Action Adhesive Tape
- High green strength allows quick adhesion.
- Low cure temperature with fast cure times.
- Can be applied quickly using robotic applicators and offers immediate adhesion between surfaces
- There are no problems related to open time or handling the adhesive slump. The product can be manually applied to the substrate on low- to-medium volume applications.
- DAAT can be applied at a Tier 1 or off line and can be transferred to the subsequent assembly point at the OEM. Alternatively, it can be transported to another location or kept in storage for the next assembly step.
- Thanks to a high green strength, parts can be bonded with adequate adhesion strength so that they can support their own weight. This facilitates the manufacturing process to carry on without the added necessity for jigging and fixing during the initial cure time.
- Addition of reinforcement fibers offers excellent tensile impact resistance.
- DAAT can quickly bond different substrates; including aluminum and carbon fiber.
This information has been sourced, reviewed and adapted from materials provided by Tecman Speciality Materials.
For more information on this source, please visit Tecman Speciality Materials.