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The current lightweight solutions for the automotive industry must meet a wide range of requirements – not only for the weight reduction of the final part, but also for the cost reduction of the final part. Therefore, they need to use cost-effective materials, and these materials have the potential to be recycled.

While thermoplastic composites meet these requirements, processing challenges have hampered their application.

A new thermoplastic composite preforming technology called "QEE-TECH" developed by Korea EELCEE and corresponding processing equipment is said to provide a lightweight solution to these challenges.

QEE-TECH technology can shape the complex three-dimensional preforms required for thermoplastic composite parts and reduce the cost and time required to produce thermoplastic composite parts in large quantities. The equipment used was manufactured by QEESTAR, a joint venture between EELCEE and Robostar, a robotics company based in Gyeonggi-do, South Korea.

To demonstrate the ability of the joint venture to continue to improve the technology, EELCEE implemented a demonstration project with a car supplier that supplied the door module.

Too much viscosity and difficult to process

The relatively high viscosity of thermoplastic polymers is a major cause of processing problems compared to corresponding thermoset materials.

“The high viscosity of the thermoplastic resin imposes stringent requirements on the impregnation method, and subsequent molding operations place stringent requirements on the integrity of the preform and the mold,” said EELCEE CEO Queein Chang-Manson.

To solve this problem, the company is forming a pre-impregnated fiber structure, then placing the pre-impregnated preform (prepreg) into a mold and overmolding it to impregnate the continuous fiber, This prepreg is then placed in a mold to solve the problem of poor impregnation of continuous fibers in injection or molding dies.

“By encapsulating unidirectional fibers and fabric composite inserts in injection molded and molded parts, QEE-TECH technology brings significant advancements in the design space for high-volume production of thermoplastic composites, and is easy to use in a single "Multiple functions are integrated into the components," she explained. "This gives designers the freedom to design, allowing them to lay expensive, high-performance continuous fiber materials where they are needed, while at the same time using lower cost, Low performance, flowable materials to ensure shape freedom to optimize cost and performance."

In a range of applications, EELCEE has proven to be able to reduce weight by 20% to 30% (up to 50% in special cases) and can reduce costs by 10% to 20%.

In 2013, EELCEE won the JEC Innovation Award during the JEC Asia Show. The award-winning product was a thermoplastic bumper system produced by the molder Hanwha Group for the Hyundai-Kia Motors Group using 3D QEE-TECH technology.

Automated process

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Automated layup, forming, cutting and wetting. The fully automated QEE-TECH unit uses a clamp that is attached to a rotatable, sliding and/or tilting table. The device is capable of rapidly laying the material into a desired three-dimensional shape, whereby the preform obtained is subjected to an automatic or advanced impregnation into an injection molding or compression overmolding operation.

This three-dimensional preforming process can be completed in a 60s cycle time (picture from EELCEE)

The QEE-TECH 3D pre-forming equipment is designed to produce complex-shaped parts with multiple functions and custom structural properties in a single operating step.

This fully automated process begins by pulling a plurality of continuous carbon or fiberglass rovings or tows from a creel and passing them through a series of dies for use with suitable resins (eg PA, PP, ABS and PEEK, etc.) started by infiltration.

“When strength is the focus of consideration, glass fiber has proven to be the preferred alternative, but carbon fiber may be the preferred material if high stiffness is a primary requirement,” says Chang-Manson.

During the infiltration process, the material passes through a preheating furnace. Next, a uniform molten tow is deposited onto a fixture that is attached to a rotatable, sliding or tilting table robot. A pressure roller applies pressure to the tow during the deposition process.

In summary, the production unit uses three robots – a head robot system for depositing materials, and a desktop robot system and a supporting robot system.

An open, custom three-dimensional skeleton (prepreg) is prepared by rapid placement into an ideal three-dimensional shape. The laid material is cooled by a jet system. This finished solid composite preform is then subjected to an overmolding operation after being automatically cut.

This fully automated preforming production facility synchronizes with the integrated overmolding operation to achieve efficient layup at temperatures up to 400 °C. This three-dimensional preforming process can be completed in 60s of the beat time.

“QEE-TECH technology is designed for mass production of structural components.” Chang-Manson emphasized, “Each production unit provides less than 1 minute of takt time and can produce 10,000 to 300,000 parts per year.”

In general, conventional regular or short fiber reinforced polymers (PA, PP, PET, ABS, etc.) are used in overmolding operations, particularly injection molding or compression molding.

“This is a non-isothermal process,” explains Chang-Manson. “The insert is preheated to just below the melting temperature, and the overmolded material is heated above the melting temperature. Thus, the injection pressure is achieved. Low porosity and good adhesion between the insert and the overmolded polymer, the cycle time is the same as ordinary injection molding."

According to reports, this preforming process does not have a negative impact on the cycle time of overmolding (as with injection molding) when integrated into a production line. The preform production unit can also be integrated into other composite production technologies such as RTM and thermoforming.

Composite door module

Assemble the "skeleton" of continuous fibers. QEE-TECH equipment is capable of quickly laminating the main structural strength components of the door module (top left) to create pieces that can be combined into an open, custom three-dimensional skeleton in the mold. When incorporated into an integrated production line, this preforming process does not affect the cycle time of the overmolding process (picture from EELCEE)

EELCEE has teamed up with South Korean auto parts manufacturer Duckyang Industrial Co., Ltd. and MSAutotech to develop a composite door module. The research was supported by the Ministry of Trade, Industry and Energy (MOTIE) and the Korea Institute of Science and Technology (KIAT).

“The value of this concept lies primarily in the opportunity to reduce weight, reduce costs and reduce the number of sub-components for metal door modules of the same price range. By using continuous fiber preforms to locally strengthen the doors of thermoplastic composites, Achieve up to 20% weight loss," she added.

For this module, EELCEE uses a so-called "M-Tow" proprietary system. This is a weaving system that encloses a unidirectional ribbon tow with a suitable fiber braid and/or polymer to allow the tow to be thermally deformed during subsequent automated layup. It does not cause any loss to the consolidation of the composite, nor does it cause bleed out of the polymer. It also allows the braided tow to be self-supporting in any form of three-dimensional layup.

Use continuous fibers only where needed. The thermoplastic composite door made of QEE-TECH three-dimensional preforms consists of only six parts, compared to 17 parts for steel doors. This overmolded preform can be seen on the open door frame (picture from EELCEE)

The QEE-TECH process also allows customers to lay out a wide variety of 3D preforms for specific load introduction and load distribution. With proper design, it is also possible to reduce the number of sub-components - this thermoplastic composite door module consists of only six components, compared to a traditional steel door module consisting of 17 components.

“When developing this part, all the factors of the entire value chain need to be considered, including: production process and mold design, assembly and end of life.” Chang-Manson points out, “Introducing inserts locally can improve performance, but it is inevitable. It adds complexity. Therefore, it is very important to define the 'what aspect of performance is prioritized to minimize complexity'."

The redesign of the doors is not only focused on weight reduction, but also on engineering strength. To verify the reliability of the process and the performance of the product, EELCEE has conducted extensive tests on various preforms with different material combinations and shape configurations.

“Our partners are very satisfied with the prototype parts produced,” says Chang-Manson. “They are dimensionally stable and seem to be good for mass production.”

It is said that Hyundai Motor Co., Ltd. is closely following the door project and is considering using this technology in production.

After the test is completed, EELCEE plans to contact other OEMs.

Editor in charge: Honor

Carbon Steel Balls

Low Carbon Steel Ball: AISI1010/ AISI1015/ C15/ 1.0413/ JIS SWRM 12/ EN32 ASTM A/29