Modern composite manufacturing with reusable silicone technology: a smart and sustainable approach

Overview of reusable silicone technology

Reusable silicone technology involves the use of custom-made silicone membranes which now succeed the use ofconsumable traditional vacuum ‘bags’ or the B counter mould. The silicone membrane is produced to fit the precise shape of the A side (base) mould, and due to its durable material properties can last anywhere from 400-1000+ moulding cycles (with standard polyester and vinyl ester resins). Reusables work much the same as standard film infusion, yet eliminate the need for single-use consumable bagging materials, significantly reducing manufacturing operational waste over time. Indirectly, significant cost savings can be expected through reduced wastage, raw material savings, increased efficiency and lower labour cost per work carried out. Notably, the system serves as a sustainable alternative by significantly cutting manufacturing waste and reducing net weight for end-of-life disposal.

Reusables in application

Due to the similar set up, one would expect reusables to appeal explicitly to the vacuum infusion moulder. Yet, companies within hand lamination and other closed moulding operations are also reaping significant benefits from adopting reusables.

Hand Lamination

With hand lamination for instance, operators are witnessing significant reductions in part weight and consequent improvements in the glass-to-resin ratio. Attributed to the innate consolidation through a higher compaction effect that is achieved via the application of infusion under atmospheric pressure. The reusable process enables precise control over resin and glass content, resulting in uniform parts of higher-quality.

Tower Composites has been an early affiliate of AHC’s reusable silicone system. Founder Ian Flavell, who has an extensive background in hand-lamination, claims “one of the biggest advantages for us is the cost savings. Traditional hand lay or chop spray methods introduce a lot of variability and waste. With the silicone system, we can achieve precise and leaner parts. This not only reduces raw material consumption but also minimises waste, benefiting both cost efficiency and environmental sustainability.”

Another significant challenge in today’s hand-lay space is the poor working conditions and the experience of new staff. High levels of volatile organic compounds and the extensive use of personal protective equipment partnered with a messy work environment contribute to difficulties in attracting and retaining new, younger staff members. Contrastingly, reusables act within a closed moulding setup, where chemical is infused and kept under vacuum. With little training required and with a cleaner operation this process aligns with the desires of a modern workforce.

RTM/ Lite RTM

At the start of the century, Lite RTM emerged as the successor to the former heavy-duty RTM, promising advancements in composite manufacturing. However, this modern process presented its own set of challenges. Perhaps the biggest drawback is the extensive cost and significant skill level required to manufacture the second matching tool face, demanding high precision for accurate vacuum-closed moulding. Naturally, there are further challenges with manual handing of the ridged counter moulds alongside the respective storage. Needless to say, reusable silicone membranes have a far lower production time and outlay than with LRTM production, saving respective businesses an estimated third of the time and cost to do so.  Further benefits arise from the elimination of release agents, which significantly reduces downtime for reapplication. It’s therefore no surprise that many companies are transitioning from the high-cost and lengthy LRTM system to more efficient and cost-effective reusable silicone membranes.

The Dutch marine manufacturer Interboat has fully embraced the reusable closed mould system, transitioning from their previous reliance on LRTM processes. Production Manager Stuart Little highlights the significant benefits of this shift, stating, “The savings we are making in resin consumption and time compared to LRTM are massive and almost unbelievable.” Over the past three years, Interboat has completely phased out all LRTM mouldings in favour of AHC’s reusable silicone technology, with support from the Dutch distributor Advanced Plastics. This strategic move has not only reduced costs and improved efficiency but also propelled the company towards significant business expansion.

Vacuum infusion

Vacuum infusion remains a cornerstone in the composites industry, attributed to its clean, controlled, and reliable impregnation process. However, this method is inherently waste-heavy, relying on large quantities of single-use plastic consumables for each production run. The ‘bagging up’ process, which requires significant time and expertise to achieve effective sealing and infusion, further complicates the procedure.

For vacuum infusion moulders dedicated to reducing costs, saving time, and minimising plastic waste, the reusable silicone system presents a compelling alternative. This system mirrors the vacuum infusion process, but with a significant enhancement: the silicone membrane can be reused hundreds of times, drastically reducing the waste and cost managing the disposal associated with single-use materials. This includes the elimination of all single-use waste such as the resin locked into single-use flow mesh, spiral wrap runners and edge overfill. The bagging stage is also expedited, as the membrane simply aligns with the base mould’s shape, simplifying and accelerating setup.

South African Blade manufacturer Notus Fan, supported by AHC distributor Chris Scarott from Aerontec, recently published a detailed case study on their experience moving from vacuum infusion over to reusables. The company noted “We doubled our production output overnight. The silicone membrane is cleaner, lower in CO2 emissions and far more ergonomically designed for the operator to work with”. Impressively, Notus states “Setting up the infusion bag was reduced from 60 to 5 minutes. We no longer need to do a vacuum drop test on every part. Resin flow is far quicker & we never have dry spots. We now have 3 staff members making 8 very large parts a day from just 4 face moulds & the two interchangeable fiRST silicone membranes”.

Moulders can also expect improvements in part quality. Notus recorded the weight consistency measured from one part to the next was less than 0.8 %. Bringing precision balance to their 8 manufactured blades after full assembly and installation lead to an increased efficiency and reduced fatigue. Blade mass distribution differences were less than 0.6%. This also meant their budgeting & material forecasts are now very predictable. Interested parties are highly encouraged to read the full case study from Aerontec on the AHC website.

Expected reuses

Clients are often delighted by the longevity and durability of a single silicone membrane, with many achieving far more moulding cycles than initially anticipated. AHC typically suggests a baseline of 400 cycles for applications using polyester or vinyl ester resins. However, it is not uncommon for companies to exceed this benchmark. For instance, Notus documented producing 800 panels with their membranes, reporting that they still look brand new. Similarly, Tower Composites has experienced exceptional durability, with one membrane now surpassing the 1,000-cycle mark.

There are, however, some limitations when it comes to using silicone membranes with epoxy or DCPD resins, which have proven less compatible with silicone. While the number of cycles is not as impressive, AHC has collaborated closely with clients in this sector to optimise results and extend membrane life as much as possible. Businesses working with these materials are encouraged to consult with AHC to understand compatibility, set realistic expectations, and explore tailored solutions for their specific applications. This proactive approach ensures that clients achieve the best possible performance and value from their reusable silicone systems.

Embracing the future of composites with reusable silicone technology

Despite being available for over a decade, reusable silicone technology remains unfamiliar to many in the composites industry. This article highlights powerful testimonials and examples from businesses leading the way with this innovative method, aiming to inspire and foster discussion about its future.

Alan Harper Composites faced significant challenges in the early years, marked by uncertainty and scepticism. However, through relentless innovation and collaboration with forward-thinking companies, AHC has established itself as a leading expert in reusable silicone technology, boasting an unmatched portfolio and extensive experience.

As the industry evolves, the benefits of reusable silicone membranes—cost savings, efficiency, and sustainability—are clearer than ever. We encourage industry professionals to explore this transformative technology and its potential to revolutionise manufacturing processes. The future of composites production is here, and reusable silicone technology is paving the way.

Cover photo: Alan Harper Composites