Hand Laid Glass Reinforced Polyester is still one of the most cost effective methods of manufacturing your composite or fibre glass mouldings, especially where low to medium volume and long term production are applicable. It has been the preferred method of production for many of our customers and we’ve been producing GRP mouldings in this way since inception 30 years ago.
This method is generally limited to the manufacture of fibreglass mouldings with relatively simple shapes that require only one face to have a smooth appearance (the other face being rough from the moulding operation). Norco GRP however are specialist GRP manufacturers of double finished surfaces and split GRP mouldings so if your part has 5 or 6 split sections for mould release necessity or is a complex form and shape, we can offer our many years of experience, knowledge and practical approach to produce your product utilising this cost-effective production method.
By drawing the resin through the stack of dry fibres under a vacuum bag you can achieve higher quality laminates than with traditional hand layup. The use of gelcoats and foam cores is still perfectly feasible and in some cases where the laminates are very thick the manufacturing time is quicker. It does require some planning at the design stage however and also some consideration on tooling as vacuum integrity of tooling is essential.
Benefits include improved consolidation, lower void content, reduced resin content and far better repeatability from part to part and it is more cost efficient than prepreg due to lower material costs. As it is a closed mould process, it virtually eliminates potentially harmful volatile organic compound (VOC) emissions and is also a very clean process. Hence the resultant mechanical properties of the cured part are markedly higher than would be the case with hand laminating, and part to part consistencies are greatly improved.
Resin Transfer Moulding
This is broadly similar to infusion but instead of using a vacuum bag, the upper surface of the tool is produced using a solid GRP mould. This way you can achieve matched A and B surface finishes with tight control of finished dimensions, and rapid part production rates from a single mould as the injection process is much quicker. Careful tool design is required and it’s something that Norco can assist with. Generally, you would consider RTM for +100 parts due to the investment in tooling.