MANUFACTURING hybrid structures Fig. 3: Principle of the WARM-Bond process using induction Tab. 3: SWOT matrix for the WARM-Bond process using induction Strengths - Texture fixed in the fibre composite material - No fibre rupture - Ability to create stronger links than bonding within 30 to 60 s - Limited heating of parts Weaknesses - Only resists to shear mode - Limited peel strength - Freezing time of the thermoplastic polymer To improve the mechanical assembly and include shear, CETIM developed and patented a coupling system with metal surface texturing. These tests were conducted on PA66glass/aluminium assemblies with the following results (Table 4). Opportunities - Optimized textures, so that more fibres can be integrated in the metal - Optimized texturing process Threats - Texturing time can be long, depending on the process Tab. 4: Single lap shear results on joints Condition being metal induction heating. The temperature is regulated to exceed the melting temperature of the polymer matrix and then the parts are kept in contact for hot bonding. A hold time is needed after heating to cool the assembly and freeze the thermoplastic matrix (Table 3). SLS-test (MPa) AR: Adhesive rupture CR: Cohesive rupture Standard deviation Sandblast aluminium 8.6 MPa (AR) 2.9 Texturing - Without ageing 26.0 (CR) 0.4 Texturing - Ageing H7 15.7 (CR) 0.5 What should be remembered for WARM-Bond assembly: - Only suitable for thermoplastic composite materials; - Metal surface texturing yields a higher SLS strength than bonded joints with a shorter process time; - WARM-Bond resists H7 automotive ageing. CMT pin and thermostamping assembly The pins are produced using the CMT process developed by FRONIUSĀ®. The Fig. 4: Examples of pin thermostamping 30 jec composites magazine / No107 August - September 2016 metal is then placed in the mould and stamped to insert the pins into the composite part (Figure 4). CETIM coupled these metal pins with thermostamping assembly of the composite part on the piece of metal and filed a patent together with its partners in the LIMECO project supported by IRT Jules Verne. A number of issues still need to be solved, especially the optimization of the pin construction time and of the distribution and quantity of pins. What should be remembered for CMT pin and thermostamping assembly: - The distribution and geometry of the pins are the parameters that have the most influence on the assembly's mechanical resistance; - Time is saved as assembly takes place while forming the composite part (Table 5). Self-piercing rivet assembly The self-piercing rivet process is used to fasten together two sheets of material by pushing a rivet without predrilling. This technology was tested on alu-