LFT pellets

ProTec can supply a complete production line for producing long fiber reinforced thermoplastics (LFT) in pellet form and as UD (unidirectionally reinforced) tapes. The line is highly flexible and is designed for variable formulations.

LFT plant engineeringInnovative solutions for lightweight construction

ProTec's LFT-pultrusion line is tailored to economically produce high-quality thermoplastics with fibers along the length of the pellets. In practice, LFT materials with fiber lengths of 7 mm to 25 mm are conventional. When injection molded, LFT compounds result in components combining high strength and light weight with very good surface quality, as is most particularly required in the automotive industry. ProTec's LFT technology is suitable for producing a wide range of materials with differing levels of fiber reinforcement and many different polymer matrix materials which may also be directly compounded during LFT manufacture. Even the challenging pairing of carbon fibers with PP can be reliably processed. ProTec has a well equipped, versatile pultrusion line in its technology center for carrying out application-specific customer testing as well as fundamental process and materials development.

Custom concepts and formulations

ProTec is a one-stop shop capable of designing and supplying complete bespoke turn-key lines going from materials development right through to testing and commissioning on the customer's premises. LFT-lines may be as long as 40 m and are capable of handling fiber contents of up to 60 wt.% and throughputs of up to 1,000 kg/h. Any conventional thermoplastics or even biopolymers such as PLA (polylactic acid) can be used as the matrix, while glass, steel or carbon fibers can be used as the reinforcing fibers.

A keystone of the line is a high-performance compounding extruder equipped with a SOMOS® Gramix S gravimetric dosing system capable of accurately dosing and mixing up to nine components. As a result, a very wide range of individual formulations of the polymer matrix can be produced very flexibly directly in the process. Recycled material and additional fillers may likewise be included in the material formulation.

Flexible plant engineering

Producing LFT compounds by pultrusion involves continuously drawing fiber strands through a polymer melt, so embedding the individual fibers in, i.e. impregnating them with, the polymer matrix and, once the resultant fiber/polymer strands have cooled, pelletizing them. In order to be impregnated, in the first process step, the fiber strands are guided from the creels by a specially designed guide into the impregnation die.

Downstream from the die, the hot fiber/polymer strands are then finally shaped, for example into round strands or flat tapes, in a profiling system. After cooling in a cooling unit adapted to the polymer, they additionally pass through a puller which controls the continuous passage of the strands through the line. Changes in formulation are quick to make by adjusting just a few components.

The LFT-line and all its modules are operated from the central line controller. Variable parameters include line speed, extruder throughput and pellet chopping length. Additional functions, located upstream or downstream depending on application, may also be incorporated into the controller. These include drying, conveying, dosing and mixing of the feed components.

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