The SPE Library contains thousands of papers, presentations, journal briefs and recorded webinars from the best minds in the Plastics Industry. Spanning almost two decades, this collection of published research and development work in polymer science and plastics technology is a wealth of knowledge and information for anyone involved in plastics.
Lightweight design with CFRP is not just a catch phrase. A South German car maker has installed a total of ten lines for the large-scale series production of CFRP-parts used in a passenger cell for e-cars made of CFRP. On these lines the vacuum-assisted high pressure RTM-method is applied on parallelism-controlled 36000 kN presses equipped with twin-shuttle moving bolsters. This presentation begins by exploring the motivation for CFRP lightweight design continues with an explanation of the applied vacuum- assisted high-pressure RTM method including both press and automation technology that complies with the special requirements of the RTM process and the logistics of both preformed and final parts. The presentation ends with a systems overview of the complete RTM process chain leading from the production of preform parts via automation to the final pressed CFRP part and the introduction of a new development in press technology.
This presentation will discuss the design development and performance refinement of the 2013 SRT Viper carbon fiber-reinforced plastic (CFRP) X-brace. The single-piece all CFRP X-brace was developed from lightweight carbon fiber composite material to maximize weight reduction opportunities and meet the stringent vehicle performance targets of the all-new Viper. The design process was driven extensively by virtual engineering which applied computer-aided engineering (CAE) analysis and results to optimize the design and improve the design efficiency. A close partnership between Chrysler Body Engineering Chrysler Product Design Office and tier 1 Plasan Carbon Composites lead to the completion of this part which will be sold in the aftermarket by Chrysler’s Mopar parts division.
The primary focus of this presentation will be the use of lightweight carbon fiber-reinforced thermoset compounds (AMC®Advanced Molding Compounds) for a comprehensive approach to design and validation of structural components. Discussion will include the use of discontinuous carbon fiber sheet molding compound (CF- SMC) for light weighting structures. The presentation also will cover variations in high-flow vs. low-flow compression molding mechanical properties and variation in carbon fiber tow size as it relates to mechanical properties and notch sensitivity. Also covered will be applications for CF-SMC and how they compare with competitive technologies.
Development of Particle-Core Compression Molding CFRP (Carbon Fiber Reinforced Plastic) is a proven material that can significantly reduce vehicle weight although it has not been widely used for automotive applications due to the lack of a high-cycle production process. Recently PCM (Prepreg Compression Molding) based on rapid-cure prepreg suitable for compression molding was introduced as a high-cycle compression molding process. The PCM process can produce high quality parts like the autoclave process with equally high efficiency as compression molding which has long been used for high volume production in automotive applications. The PCM process can also provide high mechanical properties required for automotive structural applications. Hollow sections can effectively stiffen structures without adding much mass. but it has traditionally been difficult to mold hollow sections by compression molding because of high molding pressures. This presentation discusses development of removable particle core technology a new molding technology to produce parts with hollow sections by the PCM process which enables molding of hollow section by high-cycle compression molding greatly increasing the stiffness of PCM parts.
Lightweight design is an essential part of the overall Volkswagen strategy for reducing the CO2 emissions. Carbon fiber-reinforced polymers (CFRP) offers an enormous lightweight potential. The use of CFRP is limited in mass series applications by the costs of the conventional C-fiber precursor Poly-Acrylic-Nitrile (PAN). The investigation of novel alternative precursors enabling a significant reduction in the costs of CFRP automotive parts is essential to make carbon fibers ready for a mainstream use within the automotive industry
The increasing need to reduce mass in automobiles is driving interest in newer materials like carbon fiber composites. While the use of prepregs and autoclave processing is acceptable for racing cars and high cost supercars a need exists for processes that can deliver higher volumes in much faster cycle times and lower costs. Compression molding and high-pressure RTM are options for highest volume applications that can justify the high equipment and tooling cost. For volumes in the 2000 to 25000 vehicles per year segment Resin Spray Transmission (RST) offers a balance of low material costs low tooling costs and cycle times under twenty minutes per part while delivering a Class A finish straight out of the mold for thin carbon fiber body panels. This presentation will cover materials and process development associated with the novel RST solution.
There have been several technologies used to bring mold surface temperatures above/to a polymer’s glass transition temperature (Tg) in order to improve part finish appearance and mechanical properties. Steam cartridge heaters induction and high-temperature pressurized water have all been successfully applied. Due to the inherent energy savings high-temperature spectrum precise temperature control and fast ramp rates pressurized water offers numerous advantages over these systems when applied to composite and injection molding of various materials.
The current paper addresses High Pressure Compression Resin Transfer Molding (HP-CRTM) for the manufacturing of continuous fiber reinforced composites with high fiber volume content. The HP-CRTM process is a combination of resin transfer molding (RTM) and compression molding. In this process the preform is placed into the mold cavity and then the mold is closed partially to obtain a small gap between the mold surface and the fiber preform. The resin is introduced through a suitable injection point into the gap and flows easily over the preform and may partially impregnate the preform as well. Once the required amount of resin is injected into the gap and the injection point is closed the mold closes further and applies high compression pressure to squeeze the resin into the preform. In this step the preform is compacted to achieve the desired part thickness and fiber volume fraction. The objective of the proposed study is to investigate the effects of parameters such as mold opening distance and fiber orientation on the quality of the HP-CRTM components. The influence of these process variables on the component quality and the mechanical properties is analyzed. Finally the applicability of the HP-CRTM process for high volume manufacturing is discussed.
Differential pressure molding (DPM) is a new patented process that was developed to meet the auto industry’s need to produce interior-trim products at remote sites. The process was developed to incorporate low-cost tooling minimum support equipment and simple energy-efficient work cells. The process uses low-pressure compression molding to shape thermoplastic and some thermoset materials. It makes use of thinshell composite molds and applies pressure across the entire tool surface -- either by placing a vacuum inside the tool or placing the mold in a pressure chamber -- which saves on capital equipment and the energy required to run a hydraulic press and cooling system.
This presentation will outline the technical commercial and legal requirements for manufacture of high-volume fibre- reinforced structures in the context of fully automated lights- out production environments. Fusing of discrete technical elements will be shown to deliver order of magnitude gains in cycle time precision energy efficiency and quality for thermoset and thermoplastic components. With reference to prismatic and fully developed forms the presentation: identifies methodologies for using fully integrated production solutions to achieve 95% reductions in cycle time and 50% - 95% reductions in energy consumption; outlines benefits whereby highly integrated composite structures with varying section thicknesses can be processed optimally using local thermal control; explores opportunities for in- mold residual stress correction reductions in ply count increased feedstock tolerance and optimisation of part surface finish; and examines the benefits of 100% in-process quality assurance from a production and legal perspective (i.e. insurance crash & repair).
Self Reinforced Polymer (SRP) composites use a reinforcement and matrix from the same polymer group to make lightweight impact-resistant and easily recyclable products. However the processing requires very tight process control and in some cases an in-tool cycle of cool-hot-cool (so-called isobaric or variotherm processing). To achieve optimum cycle times when heating and cooling tools the European Esprit project used the Regloplas dual-channel heating system which utilizes advanced valve systems pressurised circuits and a novel ‘energy battery’ to mold SRP composite parts.
Thermoplastic composite laminates can be post-manufactured by progressively thermoforming them to generate contoured parts from prior flat panels. This process is attractive for expanding the potential usage of composite materials in next generation transportation infrastructure marine and military sectors for part replacement and structural applications. Thermoforming has proven to be an efficient means for creating parts of complex geometries. Accurately predicting material properties and temperatures prior to forming is of utmost importance to minimize waste and reduce cost for mass-production applications. This paper presents a finiteelement modeling approach to establish the manufacturing parameters for locally formed thermoplastic composite plates.
The induction heating capabilities allow high-heat molding of the tool to obtain a resin-rich surface of the final part and avoid forming issues or surface defects while also keeping cycle time and energy consumption at acceptable levels. This presentation will discuss some design rules describing key points such as: steel selection inductive integration thermal expansion H&C performance and energy consumption. Finally examples of tool design and associated cycle time will be shared along with trends for large parts in order to propose an out-of-autoclave process
For manufacturing of compression moulded parts with long fibre reinforcement and thermoset matrix the Direct Sheet Moulding Compound Process (D-SMC) has been developed. In this process the compound is being inline manufactured and subsequently directly moulded. In that way a consistent compounding process with constant material treatment is achieved with very short processing times of minimum 15 minutes from mixing to molding. A prototype manufacturing D-SMC line has been set up in full industrial scale in conjunction with a 3600 tons press. The process control is fully integrated from raw material dosing over compound manufacturing until compression moulding of parts. In this paper the characteristics of this new and innovative process have been investigated with respect to the achievable material and part properties.
A new technology has emerged that offers significant advantages vs. traditional molding processes through rapid cycles excellent surface finish and 3D design possibilities in a closed molding process similar to injection molding while producing parts with material properties similar to compression molding by keeping post-mold fibers longer – typically 10 mm / 0.4 in. in very-complex designs and up to 50 mm / 2 in. in simpler structures. This paper summarizes the research and results of a comprehensive 10-year study on the effects and benefits demonstrated by this new molding process through an analysis of its design flexibility material formulation cycle-time reduction strength improvement aesthetic enhancement and weight-saving capabilities.
As the automotive industry makes the transition from metal parts to high-performance composite materials in critical structures it will encounter many of the problems that the aerospace industry has already grappled with and resolved. The systems used in aerospace composites to verify and document acceptable fiber orientation absence of FOD (Foreign Objects or Debris) accurate vacuum and debulk out time and material batch are described. Current development efforts to extend capabilities to automatically address wrinkles and other forms of fiber distortion are also discussed.
An ambitious multi-year program was recently undertaken in Europe to improve the sustainability of composites used in transportation – particularly with respect to the ability to develop thick parts with large surface areas economically. The program worked with a novel highly reinforced thermoplastic composite based on cyclic oligomers of polybutylene terephthalate (cPBT) which were used to produce thermoplastic prepregs that were then evaluated in vacuum bag processes while liquid cPBT / fiberglass systems were assessed in vacuum infusion and vacuum-assisted resin-transfer molding – all forming processes traditionally used for composites with thermoset (not thermoplastic) matrices. Once the best material / process combination for the program was determined and small-scale testing confirmed the finished composite provided sufficient mechanical performance the prepreg / vacuum bag process was selected to mold one of the largest thermoplastic parts ever produced: a 3-piece structural floor for a flat-bed trailer for a Class 8 truck which is the focus of this paper.
Breakthroughs in dielectric sensor design have resulted in the development of durable in-mold sensors that can operate on the production floor and in the laboratory. Thermoset molders can now “see” changes in flow and cure inside their production tools and in spiral flow tools allowing automatic “real-time” adjustments for process variation and enabling significant gains in productivity and quality. Dielectric cure monitoring has been used in thermoset laboratories for decades to characterize materials. Historically attempts to take the technology to the production floor where the benefits can be maximized in production tools have failed due to shortcomings in sensor durability and system re-liability. Signature Control Engineering has made significant advances in sensor design cabling and hardware to provide molders with a robust system capable of operating in the harsh production envi-ronment. Additionally advances in spiral flow tool design coupled with the SmartTrac technology have opened a window of opportunity to optimize thermoset compound processes. Production and laboratory dielectric cure control uses in-mold sensors to measure the electrical impedance across the mold cavity during curing of the thermoset materials. The dielectric properties of thermosets vary dramatically during cure due to the changing ability of dipolar molecules to oscillate in the applied electrical field. An impedance “signature” is created for the material during the cure which is correlated to adequate cure state by a computer control system. Benefits to compression and injection olders include:5-20% reductions in cycle time due to the elimination of safety factors built into the process to accommodate for process variation Improvements in quality because you are curing to a fixed cure state rather than a fixed cure time. Fixed cure states mean consistent finished part properties and the elimination of cure related scrap better understanding of flow and cure rates inside the mold.
The global trend towards improved fuel efficiency and reduced environmental impact is driving the use of new and dissimilar substrates for lightweight vehicle construction. Modern lightweight designs require new joining technologies to support the use of new materials as well as an increased use of mixed material substrates. Adhesive bonding is an enabler for lightweight and mixed substrate construction — allowing joining where traditional methods are not feasible — and takes advantage of structural bonding benefits such as improved load bearing capability enhanced NVH performance ride and handling and safety. This presentation will focus on the available adhesive-bonding solutions and will give an outlook into future adhesive-development directions.
5 Axis Gantry robots and 6 axis Articulated arm robots have been used with plain waterjets for many applications especially in the automotive industry. This paper is on extending the use of these robots to abrasive waterjets and for a much wider range of applications primarily in the composites market. This paper discusses the cutting process of the ultra high pressure waterjet and its technical advantages over conventional mechanical cutting tools. The integration of the abrasive waterjet process on robotic arms has been successfully developed to address the end effector supply of high pressure water and abrasives to the cutting head and operational safety. Off line programming calibration and inspection are discussed. Advanced software packages typically used in the aerospace industry have been successfully adapted. A few case studies are presented in this paper addressing composite trimming for wing skins used in aircraft and wind turbines small airframe composite parts glass trimming for high efficiency solar panels and three dimensional machining of relatively small parts used in jet engines.
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