Long fibre reinforced thermoplastics (LFT) is the most commonly used base resin for LFT, by PP, PA and also PBT, PPS, PPA, TPU and other resins. It is worth mentioning that different fibers are needed for different resins to achieve better results.

Development of LFT

In 1980, Polymer Composites Corporation (PCI), USA, was the first to propose the theoretical design concept of LFT, and conducted preparation research and product development.

In 1990, the British composites company (ICI) first successfully developed LFT particles with the trade name of Verton. It began to be applied to the design and preparation of automotive parts.

In 2000, 80% of LFT products were used in automotive parts. It has made outstanding contributions to the lightweighting of automobiles.

LFT in automotive applications

Front-end module: For automotive front-end module, PP-LGF40 material can be used to integrate more than 10 traditional metal parts such as radiator, horn, condenser, bracket, etc. into a single unit; compared with metal parts more corrosion-resistant, less dense, weight reduction of about 30%, with higher design freedom, can be directly recycled without sorting and disposal; reduces manufacturing costs, with obvious cost reduction advantages.

Dashboard body skeleton: For soft dashboard skeleton material, the use of LGFPP has higher strength, bending modulus change and better flowability than filled PP material. Under the same strength, the dashboard design thickness can be thinned thus reducing the weight, generally the weight reduction effect is about 20%. At the same time, the traditional multi-part dashboard bracket can be developed into a single module. In addition, the dashboard front defrost air duct body, dashboard middle skeleton material selection, generally with the dashboard body skeleton using the same material, can further enhance the weight reduction effect.

Door module (door center panel skeleton)

The Hyundai Sonata plastic door module, which once used SABICSTAMAX long glass fiber polypropylene, won an innovation award at the Society of Plastics Engineers (SPE). The new Ford Fiesta front door module integrates a variety of functional components such as door locks, door glass lifters, speakers, anti-theft devices, etc. The Mazda6 inner door panel and FAW Pentium B70 are made of LGFPP.

Door module for VW A5
Gearshift mechanism (shifter pivot)

The gearshift mechanism mainly uses metal material and short fiber nylon material. At present, a few foreign models have tried to use long glass fiber reinforced polypropylene material instead of short glass fiber nylon material for the gearshift mechanism skeleton. Nylon material is easy to absorb water, and the water absorption rate of finished parts is generally above 0.7%. In the high temperature and high humidity environment, there is a risk of failure; if changed to long glass fiber polypropylene material, which is not easy to absorb water, such problems can be avoided. At the same time, the use of long glass fiber reinforced PP material can play a role in weight reduction and cost reduction.

Electronic throttle pedal:
Electronic throttle pedal arm needs to withstand a large force, therefore, its selected material needs to have excellent mechanical properties, better toughness, and the material properties should not have big changes under high and low temperatures. At present, the electronic accelerator pedal arm is mainly made of glass fiber reinforced PA material. Tekona Material has successfully used long glass fiber plastic (grade CelstranPP-LGF40/50) for electronic gas pedal, which has good performance of low odor and high strength, and lower cost than reinforced PA material.Long glass fiber plastic can be used in the seat back, replacing the traditional steel frame to achieve a 20% weight reduction, and excellent design freedom and mechanical properties, expanded passenger space, etc.

Sunroof Drainage Channels

In addition, long fiberglass plastic can be made into a battery tray, sunroof frame, spare tire compartment and spare tire compartment cover. The Ford KUGA (2010) uses PP-LGF40 for the inner rear back door panel.


Current status and focus of LFT material parts development

Weight reduction and cost reduction has always been a topic of more concern for the whole vehicle, compared with the successful application of foreign car companies to PP-LGF as a new lightweight material, there are still many difficulties to be overcome in the implementation process of independent brands. For example:

(1) the establishment of reason EVI (EarlyVendorInvolvement abbreviation) concept: that is, the material supplier system parts suppliers, in the concept development stage to intervene in the new model project, fully understand the host plant user demand for materials, so as to improve the performance of the products and services to change; if only the benchmark car enterprises with materials as the basis for material selection, the model listed with the benchmark car has about 5 The material selection gap of about 5 years.

(2) cost analysis: if purely from raw material cost considerations, the price per kilogram of plastic is higher than metal materials; but the preliminary mold costs less investment, plastic parts injection mold only 50% of the same part steel mold, molded mold only 30 ~ 40% of the same part steel mold; integrated peripheral components, modular supply, can further save the host plant assembly and other costs, reduce assembly tools, save space.

(3) Other aspects: changes in the type of materials used for components, changes in material shrinkage require the development of new molds; at the same time, for long glass fiber special materials, the need to use different processing equipment such as conventional injection molding machines. Although, as outsourced parts most of the technical research is undertaken by the first-tier suppliers to carry out, but in the host plant need to do a good job in the industrialization of long glass fiber materials in the process of various technical issues to deal with measures.

In the application development of long glass fiber reinforced plastics, foreign car companies in the application development is more in-depth and ahead of the domestic independent brand is more to learn from the application of foreign car companies to absorb the mature application cases and advanced technology.

Among the domestic brands, Great Wall Motor and SAIC passenger cars are in the forefront, while Geely, Chery and Changan passenger cars have also carried out a lot of application development work. Great Wall Motor has carried out comprehensive research work on plastic parts and components, and some of them have been applied in mass production; with the support of national projects, SAIC has researched and used many LGFPP parts in pure electric vehicles such as E50. In the industry, based on the Automotive Lightweighting Alliance, the exchange and communication of lightweighting technology (including lightweighting material technology) is carried out; in the company, a platform for the application of lightweighting technology for whole vehicles is built, and new materials and technologies are introduced into the development of whole vehicles in a timely manner.

In terms of material substitution, long glass fiber plastic products can play the role of weight reduction and cost reduction at the same time. In recent years, with the development of lightweight material application, long glass fiber reinforced polypropylene material has gradually replaced short glass fiber nylon plastic in more and more automobile parts, which further promotes the research and application of LGFPP material in automobiles.