Time for Face Lift For Composite Industry

Light RTM

May 30 2022 at 07:41am

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Time for Face Lift for Composite Industry

The composite industry has, during the past few years. improved and changed substantially, changing from the Hand Lay-up system increasingly to using machines such as Spray up to Resin Transfer Mold. However, the system in the early stages of development involved very high expense as it required strong mold that could withstand the pressure when resin is injected into the mold. This necessitated the mold to be very strong, thus being very expensive as well.

Still, today, the composite industry has developed its manufacturing process to using the LRTM (Light Resin Transfer Mold) which is a Closed Mold system that enables the entrepreneur to reduce his mold investment and lower his machine costs while still being able to produce a big quantity of work pieces with quality that is still accepted in the market.


Mr. Nattawut Chaiyakunapruk, Managing Director, Neotech Inspection & Chemical Co., Ltd., an importer of a complete range of raw materials for use in the composite industry and as the introducer of the LRTM technology to raise the level of composite production in Thailand to be more advanced said that, the LRTM system is a resin injection system that is used by leading manufacturers throughout the world such as in Europe and America. The technology was developed about 4-5 years ago, but has only become well-known in Thailand about 2-3 years ago. Prior to this, the RTM system was popularly used for injecting resin which required a lot of pressure for the resin injection resulting in a thick and heavy mold a sit had to be able to withstand the pressure from the injection to allow the resin to pushed through into the work piece.


The problems of heavy weight, mould thickness and high price, other countries therefore conducted research and developed the LRTM system that enabled the size of the mould to become less thick, lighter in weight and uses a machine with lower pressure injection. This is possible because the LRTM uses the vacuum system technique to suck air out of the mould while simultaneously injecting the resin inside. Therefore, during the process there is a pulling pressure that helps the resin to pass through into the mould much easier. As such, the mould does not have to be very thick or heavy like before, making injection of the work piece needing only low pressure and making the injection much more easier. This results in lower cost of mould as well as lower cost of the machine which previously used high pressure that is more expensive to a low pressure machine that is cheaper.



Advancing with LRTM injection system

Special qualities of the LRTM system when compared with the traditional system such as RTM that only uses pressure to push or inject the resin in until the mould is full and has to overflow out to know that it is full and only then can the system be closed off. This causes a lot of errors as sometimes the pressure is very high making it difficult to control the injection process.

However, with the advantages of the LRTM system there is a vacuum system that helps to control the injection quality well as the air is vacuumed out first. This empties the inside of the mould into a vacuum similar to taking the work piece to be injected at 100 km. outside the atmosphere, resulting in a great pulling force within the mould so that when the racing is injected into it, it is not necessary to use high pressure. Simply released low pressure of approximately 1 bar and the racing just flows into the mall to replace the air that has been sucked out. This results in the work piece that comes out to have quality similar to the RTM system but with the advantage off not having to use high pressure in the injection process. This technology uses a sensor to control and blend the injection as well as sucking out the air continuously so that when the resin is injected into the mould until completed, then the sensor automatically cuts off the system.


“The use of the LRTM system will visibly lower the cost of the manufacturer. If compared to the RTM system, for example, the price of the mould use in the RTM system, for 1 sq.m. is about 1 million baht. however the mould used in the RTM system, for 1 sq.m., the price on the average is about 40,000-50,000 baht. In particular, the injection machine that uses the RTM system usually uses high pressure of 4-5 bar, but the LRTM system uses low pressure of no more than 1 bar, resulting in the injection cylinder and injection machine becoming smaller, thus making it cheaper. at the same time, the work piece originating from the LRTM as compared with that from the RTM the accuracy and evenness of the work piece is about the same, but the quantity maybe later with the RTM system being able to inject up 15 pieces/day while the new system being able to inject 8-10 pieces/day.”


In the past, the RTM system has been widely popular in the composite industry and enables faster production as it uses higher pressure making the resident flow into the mould rapidly. RTM is therefore suitable for high capacity manufacturing ranging from 30,000-50,000 pieces/month. However, if the manufacturing has a manufacturing capacity of 1,000-5,000 pieces/month and above, then the LRTM system is more suitable and is compatible with the needs of the small and medium sized industries that RTM require production of small quantities while still being able to maintain the quality that the market requires. In addition, the operation of this system also reduces smell or odour pollution more so than the RTM system as this system is a closed system which therefore omits the smell of the mono styrene solution that evaporates throughout the factory.


Nevertheless, the original system such as the Hand Lay-up system that is popular within the fiberglass industry of Thailand is used by 90% of the manufacturers, whereas the RTM system is used by only 2-3 foreign companies that have invested in Thailand. In fact there have been many others who tried using the RTM system but were not successful and resorted back to Hand Lay-up system like before.

Yet, the LRTM system that has come into Thailand is seeing more manufacturers interested in studying the system and some have already ordered the system to try out production. The company has been conducting training seminars to advise and provide knowledge of the system via the Thai Composite Association in order to transfer the LRTM system production technology as well as servicing by making a complete range of materials, equipment, machines and related raw materials available.


Mr. Nattawut concluded that the direction of Thai composite industry development should focus on producing goods of high quality to replace imports from abroad as well as develop know-how and technical knowledge to manufacture products that differ and have higher quality. In addition, the thinking of reducing manufacturing costs and excessively competing on price should be changed to looking at development of the manufacturing process to use new technology to make it more modern in order to raise the product level. Once a product has been developed and has quality, that product will become accepted both within the local and foreign markets.




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