Archived General News - 2007

New VTM260 and MTM Series Matrix systems complete ACG range of Next Generation low pressure moulding systems - October 2007

With two America’s Cups and a Volvo Round the World race in the bag, the Advanced Composites Group’s (ACG’s) Variable Temperature Moulding VTM®260 series must be ‘the’ resin system of choice for the performance boat builder.

ACG, based in Heanor, UK, part of the Composites Division of Umeco plc, offers this notable series of prepregs with a blend of features. Ease of handling in the workshop, long freezer outlife and controlled flow combine with a broad processing window - offering 65°C low temperature initial cures or reduced total cycle, to make ACG’s VTM®260 series resins one of the most user-friendly prepreg systems available. Process innovations, such as ZPREG® partial impregnation technology for both surface and structural plies, plus a supporting range of adhesives and gelcoats, have further enhanced the usability of these products.

Experience gained working with the world’s premier boat builders has highlighted how ACG’s resins can be further improved. Late 2007 will see the launch of a new range of enhanced, next generation prepregs. VTM®267 and its variants will offer improved workshop handling through reduced temperature sensitivity and controlled tack levels, while optimised flow profiles will improve fibre wet out. This will reduce void levels to improve laminate quality and also allow the impregnation of much heavier reinforcement fabrics.  

For applications where the flexible cure profile of the VTM® system is not required, new 120°C curing matrix systems will also be made available. These will offer the same enhancements in ACG’s Medium Temperature Moulding (MTM®) systems, which are already popular with spar makers. The MTM®257 and MTM®58 variants complete the range of next generation of ACG out-of-autoclave, low pressure moulding systems now offered across the composite industry, including the aerospace, automotive and marine sectors.

For further details contact ACG Sales Department.

ACG successfully develops high performance carbon fibre composite MTM59 - October 2007

Advanced Composites Group (ACG) Ltd (Derby, UK), part of the Composites Division of Umeco plc, is proud to announce that it has successfully developed MTM®59, a revolutionary carbon fibre composite material that is set to benefit the medical sector.

MTM59, a 120°C curing matrix system has been combined with a recent development from ACG to provide a high performance composite system in addition to enhanced clarity, which is required for X-ray tables and plates.

The development of this carbon fibre composite not only represents a new hallmark of quality, but beneath the clear surface lustre there can be far more serious and technically demanding aspects to these exciting materials. Composite materials offer high strength, stiffness and low weight, but in the medical world it is their transparency to X-rays that makes these materials so attractive.

Surface clarity can, through innovative resin chemistry, translate into through thickness clarity and high definition X-ray images.

Presently under trial with a number of European manufacturers, MTM59 will set the standards for the construction of future medical imaging equipment.

Jon Mabbitt, Managing Director of ACG said: “We are constantly exploring new avenues for our innovative new products to service the growing needs of our customers. Until now there has never been a product like MTM59, and we believe it will prove vital to medical equipment manufactures the world over.

For further details contact ACG Sales Department.

Increasing In-Service Life with Insitu (Patch) Repairs - April 2007

The Advanced Composites Group Limited (Heanor, UK), part of the Composites Division of Umeco plc, is regularly called upon to assist in areas when direct replacement is neither feasible nor cost-effective. ACG considers this an important service to all market sectors and continues to respond to market demands, develop materials and techniques, and service this important aspect of composites applications. It is ACG’s philosophy is to keep an open mind on all composites applications and welcomes the opportunity to embark upon further projects of the nature and magnitude described herein.

Composite wet lay-up systems have their applications and associated advantages. When compared to prepregs, materials are relatively cheap and equipment requirements are minimal. However, the process attracts high labour costs, exhibits poor control of fibre fraction, has the potential for high void content, thickness is difficult to control, it is regarded as a ‘dirty process’ and has associated health and safety and environmental issues.

On the other hand, prepregs can, in certain circumstances, offer a more attractive solution, boasting better control of fibre fraction, low void content, superior control of laminate thickness, and definite improvements in quality and repeatability. From a heath and safety angle, prepregs offer a relatively ‘clean’ process, minimising the risks to laminators. Material and additional equipment costs are higher, but this is generally offset by a marked reduction in labour costs.

ACG has always manufactured ‘standard’ 120°C curing prepregs, but an early advancement was the development of a unique technology known as ‘step ahead’ curing. Prepreg technology is centered on ACG’s Low Temperature Moulding (LTM®) processing resins. These resins, which are formulated to cure at low temperature, can, in terms of mechanical and thermal characteristics, develop a state of cure that exhibit a much higher level of performance than can be expected from a particular curing condition. This enhanced stability allows hot curing to take place at 50 to 60°C. This concept was first exploited in Low Temperature Moulding (LTM®) tooling systems. The resins developed for this purpose exhibited resistance to extremely high temperatures. ACG’s determination to move forward in other arenas brought about further developments to this pioneering system, enhancing toughness and allowing low pressure processing, essential characteristics that have made prepreg technology a reality for repair systems.

That’s not to say these materials were not without their foibles; material is stored frozen to maximize life, but the reactivity of a particular prepreg system and its minimum curing temperature are inextricably linked. Therefore, low temperature curing means a short working life, which in turn limits the project size and complicates site logistics. This was less than ideal, but some projects have shown the potential for prepreg technology as the basis of a site repair.

With Low Temperature Moulding (LTM®) systems (Boots building project - discussed herein) having a limited outlife of 2 to 3 days, ACG developed its range of Variable Temperature Moulding (VTM®) systems, which have extended outlife of 30 days and a 65°C minimum cure temperature (Macintosh building and Cutty Sark projects - discussed herein). Obviously, there are benefits with both systems, each having their own particular applications.

Taking the civil and military aerospace, and Formula One industries as specific developments for composite repair, ACG has offered several methods of executing on-site repairs.

• Bonded pre-cured patch of doubler using paste adhesive.

• Scarf on repair using the same prepreg as the parent component. Typically performed using +120°C curing film adhesive co-cured with the patch.

• Scarf on repair using lower-temperature cure prepreg than originally used in manufacture. Applicable in repairs where it is not desirable to subject the parent material to high temperatures, e.g. composite repairs to civil airliners performed <30°C of the original component cure. Typically bonded with room temperature paste adhesive. Repairs using wet-resins make it particularly difficult for the user, especially for in-situ repairs on hard to reach areas.

Traditionally, to achieve the physical properties provided by the parent fibre reinforced composite, high temperature curing (+120°C) film adhesives need to be used; lower cure temperature adhesives fail to meet the physical performance requirements. ACG’s goal was to develop a high performance, rapid low temperature cure film adhesive.

The patch repair technology developed by ACG has the potential to replace two of the current scarf repair methods previously described.

• Low temperature rapid repair for in-situ repairs (in the field), where out-of-service time must be minimal. 

• For structural repair where it is not desirable to subject +120°C curing temperatures, but service temperature provided must be adequate.

A range of ACG prepregs and adhesive materials have been formulated and developed under two collaborative, funded projects, namely Patch Repair and FILMBOND.

Screening and data generation for these projects was handled by ACG, while durability and validation was performed by Aerostructures Hamble (now Smiths), with patch repair efficiency performed by QinetiQ.

A range of repairs was carried out on different components in a variety of market sectors:

• Formula One sector - low temperature repairs were carried out on several structural components (upper engine mount, front wing, and chassis) for Jordan GP.  

• Military aerospace sector - rapid low temperature repairs were carried out on the Eurofighter undertake scoop.  

• Civil aerospace sector – rapid low temperature repairs were carried out to a B747 rear underbelly fairing, where the patch accumulated >16K flying hours.

The patch repair process is outlined in the following simple sequence diagram.

Other areas where composite patch repairs have played a vital role in general preservation include ACG’s involvement in the Macintosh and Boots building projects and, more recently, an in-situ repair to the famous and faster ever tea clipper, the Cutty Sark, which is in dry dock in Greenwich, UK.

Cutty Sark

As part of the refurbishment of the structure of the Cutty Sark, the corroded inner wrought iron structure must be reinforced and, in some cases, totally re-established. Composite materials, comprising a combination of glass and carbon fibres in a polymer matrix, were proposed for this purpose and ACG personnel carried out a trial on the ship to demonstrate the technique using a low temperature curing prepreg method.

Cutty Sark in Dry Dock

Damaged Area

The ACG repair patch was successful and Cutty Sark Trust was left to carry out a series of tests on this patch to evaluate bond strength, etc.

The surface profile achieved by ACG reflected that of the original surface. In fact, the surface was improved where it was filled and faired.

Initially, the vacuum bagging process proved quite difficult, but initial obstacles were overcome and a vacuum tight surface to seal was achieved. Infrared heaters proved successful, but needed a higher level of control for large-scale usage. Heated rubber mats, used for drum heating or weld pre-heating, would be the easiest way to cure prepreg on a large scale. A number of mats of different sizes could be interlaced to accommodate varying structural geometry and would then only require simple insulation during the curing process.

The format of the prepregs used can be further optimised, perhaps with a VTF type surface ply, which would offer the benefits already highlighted, but also reduced tack and a higher level of adhesion. Similarly, a lower tack variant resin in the structural plies would make placement easier.

The Boots Building

The Boots building, which is located in Nottingham, UK, is an important Grade II listed building in pedestrianized area. Initially considered to have a zero-value asset on pension fund’s books, it was transformed, in collaboration with Taylor Woodrow, using ACG’s Low Temperature Moulding (LTM®) prepregs and is now valued at £8M.

Curved-in-plan rolled steel ‘I’ beam

The key features of this project were:

• Beam sizes not identified until Terra Cotta cladding was removed.

• Scaffolding would hinder crane access, which could only be granted for Sundays.

• Large crane required to access the damaged areas.

• Beam fabrication time 12 weeks, but strengthening with composites only 6 week.

• Bolted detail to be released for replacement, hence need to support adjoining members.

The solution was to wet lay-up ACG’s LTM® prepreg.

• Beam locations presented limited access, but application of the lightweight composites suited this.

• Only a small section of cladding had to be removed to gain access to the beams. Extensive dismantling would have been necessary for beam replacement.

• Based on experience, ACG selected the most appropriate composite material, thereby reducing the number of layers to be laminated.

The composite was vacuum-consolidated and heat-cured at just 65°C. ACG worked with its research partners to develop a low temperature moulding resin suitable for construction site applications.

The finished thickness of material added to the steel section was just 5 mm. Therefore, the Terra Cotta cladding was not displaced after restoration.

This award winning project, which was hailed as a resounding success, was based on the application of innovations from other industries, it fully demonstrated a new application of a particular format of composite, it used research and development to close knowledge gaps, restored rental income capability of the asset, and developed added value solution by shortening programme and saving time-related costs.

Column Repair

To facilitate a change of use to an old mill in Manchester, UK, a number of damaged structural, cast iron columns required repair and reinforcement.

The Scale of the Problem

A Fully Repaired Column

It was proposed that a carbon/glass fibre composite over wrap system be adopted for this purpose. A single column was then over-wrapped by ACG personnel to evaluate the process and demonstrate the technique to the client.

Building on the experience of the Boots project, and exploiting the material gains of VTM® systems technology, ACG’s Variable Temperature Moulding (VTM®260) series prepregs, the next generation of ACG’s prominent Low Temperature Moulding (LTM®) technology, were selected for this project. The extended, 2 to 30 day out-life of these prepregs removed the need for on-site refrigeration and simplified on-site logistics. Whilst the very low curing temperatures of the LTM® range are not available with VTM®260, it was felt that achieving the minimum cure of 65°C would not be difficult and this preliminary wrap was used to demonstrate the viability of on-site fabrication with the VTM®260 series.

The VTM®264 resin utilised for the prepreg materials mixed glass and carbon reinforcements. The glass offered electrical insulation between the column and the carbon reinforcement (carbon is galvanically active) resisting corrosion and providing some hoop strength through the thickness of the carbon reinforcement over-wrap, while also providing a final surface for subsequent over coating. An adhesive film was pre-laminated to some of the glass prepreg, which was then applied to the cast iron to ensure effective bonding and act as a compliant interlayer once curing was complete.

Bridge Repair

Surrey University carried out some research on the application of VTM® prepreg systems for bridge repair work. Further information on this project can be found in the research paper ‘ADVANCES IN ADHESIVE JOINING OF DISSIMILAR MATERIALS WITH SPECIAL REFERENCE TO STEELS AND FRP COMPOSITES, by L.C. Hollaway - School of Engineering - Civil Engineering, University of Surrey, Guildford, Surrey, UK.

Potential Future Work

ACG has performed investigative work on some major projects that would benefit, commercially, from the application of composites patch technology. One in particular is that of the repair of corroded train pillars.

Alstom Train Services, Eastleigh, UK (AKA Angel Trains) identified a number of corroded pillars on their fleet of Class 314 trains that could be repaired using advanced composite materials. With minimal disruption to service, simple pre-cured composite patches could carry service loads from the pillars into the train chassis. The application of such a patch would be a faster, more cost effective solution than a standard repair that involves the removal of surrounding panelling and flooring, followed by removal of the effected pillar and the subsequent manufacture of replacement ‘U’ shaped channel extensions that would be welding into position. Obviously, there are major issues associated with this technique. In particular, welding generates heat so there is potential for local distortion and heat damage to surrounding materials.

Corroded Interface Between Vertical Pillar and a Shear Plate

The composites patch option would enable the repair to be undertaken with minimal additional work. Following simple grit blasting and cleaning operations, the patch would then be fitted directly to the affected area, moulded into position and held there using a suitable clamping fixture for the duration of the curing process.

ACG’s Variable Temperature Moulding fire-retardant prepreg, VTM®264FRB, is ideally suited for this application. Material quantities are negligible, with calculations based on the pillar being corroded to a level of 25mm above the point at which it was originally welded to the chassis.

For further details contact ACG Sales Department.

Update on Out-of-Autoclave Processing - April 2007

ACG’s first generation of out-of-autoclave composite prepregs were developed to cure and de-mould in a stable condition after initial cure at temperatures as low as 60°C using low cost tooling and oven vacuum bag processing, but without need for the high temperatures and pressures of the autoclave normally associated with aerospace prepreg processing. One typical application of these prepregs is LTM®45EL, which was used in the construction of Scaled Composites’ SpaceShipOne space vehicle and its carrier plane WhiteKnightOne. Parts made from ACG’s LTM® prepregs are then post-cured, in a freestanding state, away from the mould to a higher temperature, thus completing the curing reaction and generating the required mechanical and thermal resistance properties.

In contrast, traditional composite prepreg materials, such as those typically used on the Lockheed/Boeing F-22 ‘Raptor’ stealth fighter aircraft or the Boeing 787 commercial airliner, require autoclave pressures of 6 or 7 atmospheres and high temperatures - typically 180°C - to bring about the cure. The composite or Invar mould tools required to withstand these conditions are expensive. This presents particular problems for one-off prototypes or limited production aircraft with only a small number of parts over which to amortize costs. This could result in the tooling constituting 75% of the airframe costs. A low temperature, oven vacuum bag cure resolves this problem, allowing the use of low cost tooling materials, as well as removing size limitations imposed by an autoclave.

First generation out-of-autoclave systems, developed during the 1990’s, had some success, but were deficient when compared to high temperature autoclave cured materials in a number of areas, specifically:

• mechanical performance.

• laminate quality

• damage tolerance.

Next generation out-of-autoclave prepregs and infusion systems exhibit none of these deficiencies and offer levels of performance, toughness and laminate quality comparable with high temperature/pressure systems, as well as improved handling and work-life at room temperature when compared to their predecessors.

MTM®44-1, MTM®45-1, MTM®46 and MVR444 (detailed below) form ACG’s new generation out-of-autoclave processing systems currently in use or under qualification for a variety of civil and military applications.

MTM®44-1 is a dual cure temperature (130°C / 180°C [266°F / 356°F]), high performance epoxy matrix developed for both resin film infusion (RFI) and prepreg processing. It has been optimised for low pressure vacuum bag processing and, in addition to resin film and prepreg formats, it may be supplied in partial or selectively impregnated (ZPREG®) formats to reduce lay-up time, minimise surface defects, and ensure very low internal void content. After a freestanding postcure, the system is capable of 150°C (302°F) wet Tg and exhibits a high level of damage tolerance. This, together with its low density, makes it a strong candidate for primary structures on aircraft, produced out of autoclave. The process cost savings can equally be applied to many less critical structures, such as fairings, which have, historically, been designed for autoclave processing.

MTM®45-1 is a variable cure temperature, high performance, toughened epoxy matrix, developed for both resin film infusion and prepreg processing. It has been designed for low pressure vacuum bag processing and, in addition to resin film and prepreg formats, it may be partially or selectively impregnated (ZPREG®) formats to reduce lay-up time, minimise surface defects and ensure very low internal void content. After a freestanding postcure, the system is capable of 150°C (302°F) wet Tg and exhibits a high level of damage tolerance. This, together with its low density, makes it a strong candidate for primary structures on aircraft, produced out of autoclave. The process cost savings can equally be applied to many less critical structures, such as fairings, which, historically, have been designed for autoclave processing. MTM®45-1 may be initially cured at temperatures as low as 80°C (176°F), allowing lower cost tooling materials to be selected for prototypes and very short production runs.

MTM®46 is a long outlife, flexible cure epoxy resin matrix for the manufacture of aerospace components using oven/vacuum bag moulding processes. The rheology of MTM®46 has been developed specifically for the production of high quality laminates using low pressure processes. The 60 day room temperature working life and excellent tack and drape properties facilitates the lay-up of very large complex structures. A full range of standard prepregs is also available autoclave processing. MTM®46 offers excellent hot/wet performance, making it the ideal candidate for the low cost primary and secondary structures in FAR23 aircraft. It is also suitable for secondary structures in civil aircraft and helicopters.

MVR®444 is a single component epoxy resin matrix for the manufacture of aerospace quality composite components using infusion processes such as VARTM (Vacuum Assisted Resin Transfer Moulding), RTM (Resin Transfer Moulding) or RIFT (Resin Infusion under Flexible Tooling). MVR®444 may be infused at temperatures as low as 70°C (158°F) and may be cured at temperatures between 90°C and 180°C (194°F and 356°F). It also exhibits excellent performance after hot/wet conditioning.

For further details contact ACG Sales Department.

New Product Development – TB720 Epoxy Tooling Block - April 2007

Following fast on the heels of the premium grade epoxy tooling block TB750, launched at the JEC Show 2006, the Advanced Composites Group Limited (Heanor, UK), part of the Composites Division of Umeco plc, announce the introduction of a new product ‘ACG TB720’.

As with TB750, TB720 has been developed in partnership with Huntsman Advanced Materials (Huntsman) as part of an on-going 5-year collaboration and distribution agreement with ACG. TB720 is an easily machined, lower-cost master model material that exhibits a good blend of mechanical and physical properties and is fully compatible with ACG's existing range of ancillary adhesives and sealers. To meet market demands, as ever, TB720 will be available in a range of sizes and on short lead-times from ACG factories in Europe and the USA.

For further details contact ACG Sales Department.

Applying Advanced Gaming Technology to Deliver Novel Composite Manufacturing Techniques - April 2007

A joint project, featuring technology transferred from the serious computer games industry, aims to develop a low-cost, high-performance physics-based software product for the visualisation and simulation of complex composites manufacturing systems.
This venture, called ‘PhysVis’ and led by AMTRI, will include the ACG and Innoval Technology, an independent materials and process technology consultancy.

The nineteen-month project, which started in October 2006, qualified for nearly 50 percent funding under the DTI Technology Programme via the Fast Track route, with the remainder being made up of contributions by the partner companies.

The PhysVis initiative promises to unlock the door to more innovation and new business for manufacturers in rapidly developing sectors such as the aerospace, motor sport, marine and automotive industries where ACG already delivers bespoke prepregs and novel material and process technologies to numerous OEMs on a worldwide basis. The proposed visualisation and simulation system is intended to offer, at far lower cost, the high levels of performance and capability only likely to be found in the application modules of far more expensive CAD suites from major vendors.

Phil Sholl, managing director of AMTRI, explained: "The high performance and low cost of PhysVis will represent a profound opportunity for a range of specialist companies in fast-growing, high-technology sectors like the production of carbon fibre-based composite components. These specialist manufacturers will be able to design 'right-first-time' production systems and assess investment and operational risks before they commit to procurement and implementation. This can only be done now with the resources available to larger companies".

AMTRI will develop the new product based on extensive work with the so-called 'serious computer games' technology developed by US company AGEIA and its new PhysX Accelerator and a low cost but sophisticated PC-based digital factory simulation system from Finnish company Visual Components.

The role of ACG in the project is that of end user or the first customer for PhysVis. ACG will provide the application domain, i.e. that of aerospace composite manufacture. Innoval's role is to categorise the material (carbon fibre) using their fabric modelling approach. The simulations start with an individual fibre and model the fabric weave in all its detail to create an accurate mechanical representation of the woven carbon fibre material. The output of the simulations is a constitutive material model that represents a 'unit patch' of the material; AMTRI will then map the unit patch to AGEIA's PhysX Accelerator and simulate both the material and the robotic manufacturing system to achieve accurate process and product interactions so that the best manufacturing techniques may be determined.

For further details contact ACG Sales Department.

OASIS in Sight for ACG and Partners to Optimise Materials Processing and Modelling - March 2007

ACG and its partners, Airbus UK, QinetiQ and the University of Manchester, recently embarked on a two year, DTI funded, collaborative research programme entitled ‘OASIS’ (Out-of-Autoclave Simulation of Induced Stress).

Briefly, Oasis will apply multi-scale materials and processes modelling to optimise cure schedules for an innovative out-of-autoclave fibre reinforced polymer composite fabrication process called ‘Quickstep’.

In addition to validating this process for the manufacture of typical aerospace components, manufacturing costs relative to conventional autoclave cure will be reduced by predicting and minimising residual stress and distortion, thereby reducing the need for expensive reworking of parts, while also lowering waste generation through ‘right first time’ manufacture.

The multi-scale modelling will start from the fundamental resin chemistry and proceed to structural finite element analysis of a generic component.

In addition to providing process and property data and supporting the predictive modelling work at QinetiQ, ACG will supply the selected prepreg material (MTM®44-1) for the programme.

For further details contact ACG Sales Department.

New Commercial Director Appointed - January 2007

ACG is pleased to report the appointment of Nigel Blatherwick as Commercial Director for the Group over-viewing the strategic sales and marketing direction of the company by co-ordinating the divisional commercial activities.

Nigel joined the Sales department in 1991 as Sales Engineer and has progressed, through UK Sales Manager to Group Sales and Marketing Manager, the position he has held for the past 6 years.

Jon Mabbitt, Managing Director, and the rest of the company wish Nigel every success in his new appointment.

For further details contact ACG Sales Department.

New Managing Director Appointed - January 2007

Advanced Composites Group (ACG), a Umeco Composites company, which manufactures a range of advanced composite materials for use predominantly in the aerospace, motorsport, automotive and wind energy markets, announces that Jon Mabbitt will succeed Alan Moore as Managing Director with effect from 1st January 2007. Alan Moore will remain on the Board until his retirement on 30 June 2007.

Alan Moore has been Managing Director since December 1998, during which time the business has developed into a highly successful industry leader. In 2004 he managed the sale of the business and its subsequent integration into Umeco Composites. Alan has led the recent major investment programmes both in the USA and UK, culminating in the newly-opened £7m technology centre in Heanor, Derbyshire.

Jon Mabbitt joined ACG in a sales position in 1988 and, following a number of management roles, became General Manager of the UK operations and subsequently joined the ACG board in 2001. Earlier this year he was promoted to the role of Director and General Manager of ACG and became responsible for both the UK and US operations.

Andrew Moss, Chief Executive of Umeco Composites, said:

"I am delighted that Jon is assuming this new role. In his various positions he has played an integral role in ACG's development and is a well respected figure in the industry. He will undoubtedly continue the success that ACG has enjoyed under Alan's leadership.

"When Alan retires, it will be with our wholehearted good wishes. He has been an inspirational force behind ACG's growth, and the market leading position that the company now enjoys is very much his legacy. Everyone at ACG and at Umeco Composites is grateful for the tremendous energy and enthusiasm that he has put into the business."

For further details contact ACG Sales Department.

European Sales Manager Appointed - January 2007

ACG is pleased to announce the appointment of Rob Wilder as European Sales Manager effective as from 1st December 2006.

Rob will be responsible for the Management of the ACG employed European Sales Team and will also continue in his role as Market Sector Manager for the Marine market.

Rob is wished every success in his new role.

For further details contact ACG Sales Department.