Huntsman has developed epoxy resin systems that are qualified for the mass production of structural parts.
The company states these systems are proven in offering advanced properties and significant production time savings for out-of-autoclave processes such as RTM and compression moulding.
Huntsman states its latest epoxy systems, Araldite LY 3585 / Aradur 3475 allows HP-RTM parts to be made within four minutes, enabling further reductions by compression moulding, at just two minutes. With HP-RTM, for example, this includes preform set, injection, curing and de-moulding and equates to a 40% part production time reduction when compared with first generation HP-RTM.
Over the past four years, Huntsman has worked with mass-market vehicle manufacturers in various innovative projects for optimising automotive composites For example; Huntsman has a long history with the BMW Group, currently involving the supply of an Araldite binder and epoxy for manufacturing the composite parts on the BMW i3 and i8 in volume production.
Prior to this, Huntsman also provided an epoxy resin system (Araldite XB 3523 / XB 3458) used to develop roof parts for the BMW M3 which it states was the first carbon fibre reinforced part to be produced on high-pressure equipment for the series application of carbon look parts.
The company states Araldite XB 3523 / XB 3458 offers low shrinkage during curing to enable the production of high surface quality components that meet the automotive A-Class surface standard. The process also significantly reduces finishing and other preparatory work before painting. These advantages demonstrate how epoxy systems for out-of-autoclave processes can help to reduce cost, deliver excellent properties and increase the design options in carbon composites.
In the five years since BMW decided to manufacture an all-electric vehicle with a composite passenger cell, the BMW i3 has now become the first series-produced car to make extensive use of composites in primary structural components.
BMW describes the architecture of the BMW i3 as having two main elements. The aluminium Drive module, which incorporates the powertrain, chassis, battery and structural crash functions – and the Life module (or passenger cell), made from carbon fibre-reinforced plastic (CFRP). The LifeDrive concept and CFRP usage allows production time to be cut by half compared to those required for an equivalent car built along conventional lines. The process is less investment-intensive as the high costs needed for a conventional press shop and paintshop are no longer an issue and the Life and Drive modules can be manufactured alongside one another.
This is all supported by what can best be described as the largest and most sustainable composites material and fabrication supply chain ever established for a production vehicle.
Huntsman states the high-pressure RTM parts for the BMW i3 passenger cell are produced in volume production at two of BMW’s facilities in Leipzig and Landshut, Germany, which use the same processes and equipment. Within these facilities, Huntsman’s materials are used to produce the side frame and other composite parts of the i3 passenger cell in volume. Firstly, Araldite LT 3366 is used as a binder to help maintain correct fibre alignment and geometry during the automated manipulation and positioning of the dry preform in the mould. Araldite LY 3585 / Hardener XB 3458, an epoxy RTM system, is then injected at high pressure into the mould. Its low viscosity is essential to the entire process, from the dosing and mixing right through to implementation and good fibre wet-out in the mould.
Providing good thermo-mechanical performance, including a high elongation at break, this Araldite RTM system is particularly beneficial for automotive structural parts and for meeting crash test criterion. With its ability to cure in just five minutes at 100°C, Araldite LY 3585 / Hardener XB 3458 allows BMW to effectively utilise HP-RTM and meet its rate production requirements in a quick and cost-effective way. This system is also well suited to compression moulding and the production of low complexity structural parts.
Huntsman recently established four new Centres of Excellence, developing new technology platforms that support the company’s regional development teams. One of these centres, the Centre of Excellence for Composites, is building up simulation capabilities to provide consultancy on automotive composites projects. The developed simulation technology supports Huntsman’s customers in helping them to select the most ideal product and process parameters, supporting the best tooling geometries in order to ensure the most efficient processes are in place.
Photo provided by Hunstman
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