Long-term glass fiber online compounding technology

The technology of directly compounding glass fiber fibrils into thermo-plastic molded parts is rapidly developing in Europe and is now expanding. D-LFT, long-fiber "direct" compounding, as its literal meaning, can produce cheaper, more robust components, but to take the risk of new technologies and assume higher upfront investment costs.
In-line compounding and molding of long fiberglass-reinforced thermoplastics is a new alternative to long fiberglass particle preforming and glass fiber mat thermoplastic (GMT) sheet injection or compression molding. D-LFT is still in the early stages of commercialization. According to a survey by BRG Townsend in the United States, D-LFT accounts for 16% of the global market for long glass fiber-reinforced thermoplastics, which is approximately 0.44 billion. lb. GMT accounted for 52%, which was 277 million pounds, and long glass fiber pellets accounted for 32%, which was 89 million pounds. In addition to GMT, it is said that the LFT market will grow at a rate of 30%, while D-LFT will grow faster.
In addition to material costs, D-LFT's molding accounts for 50% of the cost. This technology was developed in Europe long ago. For example, GMT molding manufacturer RKT has produced dashboards for VW vehicles.
There are at least six methods for the molding of long glass fibers that are in use, some have been commercialized, and some have not been disclosed. The oldest method has been around for 10 years. It is to cut off about 0.5-2 inches of glass fiber into a special extruder. In the last three to five years, a newer technique was to add continuous glass rovings to the extruder and shear the glass rovings with a shear or extruder screw.
The latest D-LFT feed method uses a two-stage screw/plunger injection molding machine, in which a twin screw compounding extruder replaces the usual single screw extruder. There are some D-LFT equipments that are used for extrusion of raw materials, logs, slabs, etc., but the sheet is still pressed in the press under hot conditions. A variant of the latter method is to directly extrude the log into the lower mold half of the press (however, due to the slower manufacturers have stopped using this method).
The definitive features of all D-LFT technologies are that they require the processor to master a full set of compound processing, which combines the compounding of resin and glass fiber fibrils with compression and injection molding. A large number of pounds are needed for glass fiber compounding. Molders need high technology. However, there is a possibility that it will change from a pellet supplier to a molding manufacturer. If someone wants to try this method, it will find it too complicated. Heating the sheet and then tapping it into the mold is much simpler than the compounding and molding process.
Molding manufacturers not only have to take responsibility for their own raw material formulas, but also have to take responsibility for the significant increase in costs. Salisbury Meridian Motors plans to spend $1 million to purchase three D-LFT molding machines, just for the purchase of compound and automatic feed presses, not including the press itself. Each piece of equipment covers an area of ​​1500 square feet and does not include a gravity metering and mixing plant. D-LFT injection molding machines are also 80% more expensive than standard injection machines.
There are two main advantages of long glass fiber online compounding. One is to reduce costs, and the other is to have excellent overall performance. The large structural parts produced by D-LFT are 20% to 50% less expensive than GMT compression molded parts. For example, the GE GMT trademark of Azdel is sold at US$1.3/lb, while the cost of D-LFT components is less than US$1/lb.
The impact properties of the D-LFT compression molded parts are slightly lower than those of the GMT, and the average fiber length is 19 mm to 50 mm. D-LFT compression molding has been commercialized in the United States and Europe and is mainly used to produce large and flat structural components. Currently, six European automotive molding manufacturers use 25 compression molding equipment and have also signed orders for 10 to 15 equipment. So far, only two molders in the United States are conducting D-LFT compression molding trials, there is one in the installation phase, and there are some R&D equipment used for testing and product research.
D-LFT injection molding is much newer than compression molding, which means that it saves more than long glass fiber, but its main advantage is that the ultimate fiber length is much longer than that of the commonly used long glass fiber injection molding. One of the reasons is that the continuous glass fiber roving is drawn into the extruder barrel where it is mixed with the already melted resin. A large number of studies have shown that the productivity of D-LFT injection molding is higher than that of standard long glass fiber pellets. Because of the low plasticization required to avoid fiber breakage of long glass fiber pellets. Parts with a molding cycle longer than 1 minute can be completed within 30 s using D-LFT injection molding equipment. However, injection molding requires that the melt flow of the D-LFT material is higher than that of the compression-molded material. Another advantage of D-LFT injection molding is the ability to avoid large punching of parts and the resulting scrap. The limit fiber length of D-LFT injection molding is 7mm~12mm, which is shorter than that of compression molding, but longer than the length obtained by standard machine injection molding of long glass fiber.
The D-LFT compression molding process has developed the fastest in Germany, while in France and Germany where the development of thermoplastic compression molding is not very good, the long-glass fiber injection molding products for automobiles have high impact strength, but with long glass fiber aggregates, Regardless of the length of the glass fiber at the beginning, it will reach 3.2 mm to 6.4 mm in the final product, and the result is shorter than that of the D-LFT injection or compression molding.
Any of D-LFT's injection molding or compression molding has the advantage that it can easily recycle the punching scraps and waste that traditional GMT can't recycle, and D-LFT can even recover the traditional GMT chipsets. Molders from both processes are a big advantage.

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