A strong upward trend is still being seen in the use of fiber-reinforced composite in automotive engineering. Realizing this, Dieffenbacher has developed new line technology that allows components to be manufactured from long fiber-reinforced thermoplastics via direct compounding (known as LFT-D) with additional reinforcement provided by unidirectional fiber tape (UD fiber placement).

Body components are made from long fiber-reinforced thermoplastics featuring greater structural rigidity thanks to the addition of UD fiber tapes. With the development of tailored fiber placement LFT-D technology, it is now possible to discontinue inline, component-specific unidirectional fiber reinforcement and integrate the reinforcements into the component structure itself.

In order to carry out this process, the tape fiber placement step is introduced upstream of the LFT-D line. The UD fiber tapes consist of glass or carbon fibers embedded in a matrix of thermoplastics and are available as reels of material. The entire procedure required to process the UD fiber tape into the tailored blank has now been integrated into the LFT-D line technology as a fully automated step.

The combination of both materials allows the high strength and structural rigidity features of the fiber tape to be combined with the benefits of the LFT-D compound. Thanks to this plant technology, there is scope for great flexibility in the design of the components. In each plant, a wide range of materials can be manufactured, including pure LFT-D components, pure fiber-tape components, LFT-D components with local endless fiber reinforcement and LFT-D components with all-over fiber-tape reinforcement.

Various material strengths can also be achieved within a single component. Aside from the high degree of flexibility for material combinations, thermoplastics with endless fiber reinforcement offer an affordable, lightweight alternative.

The cost-effective nature of this solution is significantly lower material costs and higher plant productivity resulting from shorter cycle times of less than one minute. Another key advantage is the fact that this group of materials is ideal for recycling, meaning production waste can be recycled within the LFT-D line itself.

Fully Automated Processes for Producing Lightweight Carbon Components

Large-scale batch production and automation for the cost-efficient production of CFK components have been key topics in the automotive, aeronautical and wind energy industries for some time now.

Dieffenbacher has developed a fully automated production line for the production of carbon fiber-reinforced plastic components using the high pressure resin transfer molding process (HP-RTM). The entire production system covers the system units for preform production, the press process and the subsequent reworking of components.

The key technology in this production system is that for producing preforms. The development aimed at fully automating the preform process. This involved looking at the processes for cutting the carbon fiber material, incorporating the cuts and applying the binder material, processing from 2D into a dimensionally stable 3D preform and the subsequent storage in load carriers.

The focus was on meeting the demands of the industry with regard to process reliability and productivity. Work that previously took two to three hours to complete by hand, resulting in high costs, has now been reduced to cycle times of two to three minutes.

As part of a complete production line in the high pressure RTM process, the PreformCenter can be configured for use in both large and small-scale series production. In addition to preform production, the HP-RTM line also includes the compression process and the related steps for reworking the finished lightweight components. Dieffenbacher delivers the HP-RTM line such that it is ready for immediate use.

The complex development of the HP-RTM line is now paying off for Dieffenbacher. After a testing phase lasting several months, the first PreformCenter was commissioned by a major German automobile manufacturer in the spring of 2012. Further commissions from the automotive industry were received shortly afterward.

D-SMC Line: Just-In-Time Manufacturing of Semi-Finished Parts

The advanced D-SMC direct process opens up new potential applications for thermosetting plastic composites as part of lightweight construction in the automotive industry.

Mat-like semi-finished parts are traditionally transformed into molded parts by means of a flow process. However, the process for maturing and storing semi-finished parts, as well as the related logistics, is both time-consuming and cost intensive. Dieffenbacher has developed a fully automated production line for fiber-reinforced thermosetting plastics that helps avoid these costs.

As part of the direct process for SMC, the semi-finished SMC part is manufactured immediately before being sent on for further processing.

A particular composition of resin, filler and glass fibers is added to a compounder and molded into a flat material that can then be processed in the same way as a conventional semi-finished SMC part. An integrated SMC sheet cutter creates stacks of sheets, which are automatically fed to the press.

The high level of automation and continuous control of the production line from the SMC compound to the finished component mean that the process is fully reproducible and can be monitored at all times, making it possible to manufacture products of a consistently high quality. In addition, the continuous manufacturing process cuts the processing time from raw material to end product down to just a matter of minutes, offering a huge advantage both in terms of time and expense.

Compress Eco: The Economical Press Series

The COMPRESS ECO is Dieffenbacher's cost-effective forming press for small and large components.

The standardized Compress Eco press series is a response to the high levels of cost pressure the industry is witnessing, offering an attractive price-performance ratio.

The series is supplied in variants delivering press forces from 4,000 to 25,000 kN, with a controlled closing unit available from 10,000 kN. Compress Eco meets all the requirements for processing fiber-reinforced plastics and is primarily used for SMC, LWRT and RTM applications.

A modular system offering flexible expansion options means the unit can be adjusted for different component sizes. The use of mature technologies, a practical operating concept and ease of maintenance deliver a high level of process reliability and ensure a continuous production process. This is additionally supported by a global service network.

Proportional valve technology ensures infinitely variable control of the press force and a speed optimized for the process in question. Thanks to customized control technology, the press can fulfill the quality demands placed on components. Quality control through process data acquisition and archiving makes the manufacturing process transparent and guarantees reliable production.

Compress Lite: The New Press Series

Flexible press and automation systems are crucial to ensuring that fiber-reinforced plastic components can be produced in a cost-effective manner. Dieffenbacher has developed the new Compress Lite press series in order to satisfy this requirement.

The press, which is available in an upstroke and short-stroke design, boasts a low construction height and an energy-saving drive. The identical deflection of table and ram, which provides an even bend flow of the upper and lower tool, and high-precision parallel-run behavior ensure a consistent component thickness and increase the quality of the component.

The exceptional ease of access on all four sides of the press enables rapid, flexible die changes using moving bolsters as well as optimum clearance for automation tasks.

The press series is designed for pressing fiber-reinforced thermoplastics and thermosetting plastics, as well as carbon fiber-reinforced plastics.

The Compress Lite is available in variants delivering press forces from 4000 to 12,500 kN. The new press design compliments Dieffenbacher's existing press range, which includes the Compress Plus and Compress Eco series.

Compress Plus: The Energy-Saving Press Series

Constantly increasing energy prices are calling for energy requirements to be reduced through the efficient and economical use of valuable resources. Ecologically sound production processes protect the environment and reduce costs. The energy-saving Compress Plus press series is Dieffenbacher's response to changes on the market and safeguards customers' ability to compete.

The Compress Plus is primarily used for LFT-D and SMC applications and allows top quality components to be produced thanks to high-precision dynamics and process reliability. The series is supplied in variants delivering press forces of 15,000 to 50,000 kN and bolster sizes from 2400 x 1800 mm to 4000 x 3000 mm.

The short-stroke cylinder system allows energy requirements to be cut by 50%, making it possible to achieve closing speeds under load of 80 mm/s and therefore cycle times of approx. 20 secs., depending on the press force.

A variable control system means the press can be adjusted to different material characteristics, ensuring process-optimized parts production that can also be documented. Speed, low energy requirements and optimum control allow for an efficient, and therefore economical, production process.