One of the parameters that has the most impact on the structural and quality performance of manufactured components is bonding, which often has hugely challenging requirements. In order to consolidate the construction process, as well as implement a new production line, Ferretti and Mastikol explored the possibility of replacing classic polyester-based adhesives with Scigrip’s innovative methacrylate adhesives, and following an intense collaboration and an extensive period of testing and validation, Scigrip methacrylate adhesives were approved for use in Ferretti’s moulding yard.
The production lines at the M&S Composite Manufacturing Yard – Ferretti’s assembly department – are based on the concept of bonding together structural elements that are built off-site to maximise repeatability in the building stages, resulting in shorter production cycle times. The yard requires the very high performance structural bonding (in terms of both mechanical bond strength and fatigue performance) offered by Scigrip’s MMA adhesives, when bonding the fibre-glass hull shell and the structural elements, specifically those of the engine room and other key load bearing parts, that are laminated off-line. Adopting a solid and reliable process and using materials that were independently certified for marine use were key requirements for the bonding process.
The product specified by Mastikol was Scigrip’s Lloyd’s approved SG230 HVA adhesive, supplied in 189 litre drums. This high viscosity, thixotropic adhesive can also be applied in void free bead sizes up to 80mm in thickness without sagging or any reduction in bonding performance. Different hardener speeds were supplied allowing customised working times to match the required joining times.
Given the large bonding surface area, it was necessary to use an application system that dispenses a large quantity of product in the shortest possible time. Mastikol and Scigrip also specified a special drum extruder to dispense the product. The large drum product format makes it possible to apply the product without any production stoppage time for changing the drums and using a machine optimises the accuracy of the component mixing.
Further optimisation of the production process is being studied for the future, which will greatly reduce the surface preparation stage and make full use of another feature of Scigrip’s SG230 HV adhesive: its high capacity to adhere to smooth, gel-coated and moist surfaces makes it possible to avoid/reduce preliminary abrasion of the composite. This will further reduce the production cycle time, while also reducing the production of dust that is often produced by this sanding and grinding. This latter aspect is also strategic for the M&S Composite Manufacturing department, as the dust is not only harmful to personal health but is also extremely detrimental to the quality of the production processes in the moulding department (additional material cleaning costs are required). The impact on operating costs linked to management and disposal of the dust particles generated by all of the surface abrasion processes is also far from being negligible.
“Scigrip is delighted with the results of this latest qualification, it’s a great example of how we work with our customers and our highly experienced distributors, like Mastikol, to develop an optimised bonding solution for each individual customer” comments Tim Johnson, European Sales and Marketing Manager, Scigrip.