Small preforming and moulding equipment is available for laboratory and development use.
Large Cannon preformers are currently being used for Automotive Composites by leading OEM and Tier One suppliers.
This Cannon Patented solution allows for an efficient draping of the Prepreg sheet in the various sections of the mould cavity, avoiding the formation of wrinkles in the formed sheet. The grippers, mounted on a shuttling frame, travel the whole distance from the heating press to the forming press and can transport efficiently the whole range of sheets dimensions. The Cannon preformer can handle – with the units supplied up to now – preforms up to 2.5 by 2.5 metres, with a clamping force of 3,000 kN, but larger solutions can be provided on demand. The preforming press is a high-speed hydraulic clamp, with a thermoregulation system that keeps the tools at the temperature specified by the Prepreg suppliers to achieve the shortest preforming time. Additional grippers are installed inside the forming press to increase the active control during the forming of the parts, by holding and draping the material from all four sides. In less than a minute a complex preform is made, which is then extracted by a robot as the next hot Prepreg comes in from the heating station. The automatic unloading of the formed parts at the end of the cycle avoids any manual intervention of the operators within the press area. At this point the part can be extracted and trimmed to final size, using either a punching press or a robotized contour cutter, both trimming solutions available from Cannon.
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This step is necessary to obtain a finished part after the following operation.
Prepreg Compression Moulding: a Cannon Specialty For the compression moulding process of Prepregs Cannon Ergos designed a press with dedicated features to combine the main requirements of a fast cycle with the specific processing needs specified by each Raw Material Supplier for their materials:
· One or two lower mould halves shuttling on the front, which allows for a fast loading of the Prepregs and the unloading of moulded parts,
· A revised hydraulic pack which provides both a fast approaching speed and a highly accurate control of the slower working speeds and p re s s u re s o n t h e m a t e r i a l. T h e t w o characteristics can be, when needed, combined with the use of a fifth central piston in addition to the traditional four on the press corners, which are equipped with a very precise Active Parallelism Control that guarantees perfect planarity to the mouldings.
For this technology a press with 25,000 kN of clamping force is available, usually with 3.6 by 2.4 m platens and 2.8 m daylight, with one or two lower platens shuttling on the sides.
A typical thickness of 2-4 mm characterizes most of the Composite parts made from Prepregs, that can be moulded in the largest sizes demanded by an automotive OEM. To ensure the full control of the mould, Cannon Ergos suggests the use of two additional dedicated devices: a sophisticated vacuum-control system for the accurate control of the in-mould vacuum and a thermoregulator able to keep the moulds at the high temperatures demanded by this process. By using different resin grades, that demand typical mould temperatures of 150-160 ° C or 190- 200 ° C, the current demoulding times for an average part vary from 15 to 5 minutes: an intense R & D activity is currently undergoing on new Prepregs, that aims to speed-up the curing, maintaining structural characteristics in the same range of moulded steel sheet or Aluminium. The Cannon press is already designed to perform a 3 minutes part-to-part cycle, including the service time on the shuttled lower mould half. When, at the end of the curing, the mould opens, the part is extracted automatically and it ' s ready for use. Its surface has acquired high gloss and the Carbon reinforcement is visible through a perfectly transparent layer of migrated resin. The only way to get an aesthetically perfect part is to respect the combination between mould temperature, clamping pressure and curing time. Each type of commercial Prepreg provides a nice result only if all parameters are kept under the strictest control!
Cannon, being able to supply all the required technologies and equipment with a“ single responsibility” contract, provides a One-Stop- Shop approach to the Companies that decide to invest in complete manufacturing solutions for Prepreg-type as well as for HP-RTM Composites. This is a unique offer, in a competitive field where several producers of single pieces of equipment are simply not able to guarantee the success of the final result when a complex plant has to be put together!
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