SPE Library

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.

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Conference Proceedings

High-Pressure Compression RTM — A New Process for Manufacturing High Volume Continuous Fiber Reinforced Composites

Raman Chaudhari, September 2013

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 Process

Jack Van Ert, September 2013

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.

Active Thermal Management using the PtFS Process for Rapid Processing of Composite Structure

Ben Halford, September 2013

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).

Temperature Control in Manufacturing Self Reinforced Polymers (SRPs): A Smart Way to Keep Cool

David Lowe, September 2013

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.

Progressive Forming of Thermoplastic Laminates

Uday Vaidya, September 2013

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.

Thin Wall and Superior Surface Quality Processing Method of Fiber Reinforced Thermoplastic for Cosmetic Applications

José Feigenblum, September 2013

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

Process Material & Part Characterization of the Innovative Direct SMC Process

Tobias Potyra, September 2013

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.

New Molding Process Offers Unique Levels of Design Complexity Mechanical Strength Cost Reduction for Long-Fiber Thermoplastic Composites

Werner du Toit, September 2013

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.

Aerospace Process Control for Automotive Composites: Defect Prevention Data Collection and Documentation

Scott Blake, September 2013

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.

Production of a Class 8 Truck Trailer Bed Using c-PBT Thermoplastic Prepreg and Vacuum Bag Processing

James Mihalich, September 2013

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.

Dielectric Sensing Technology: Key to Productivity & Product Consistency

Tom Trexler, September 2013

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.

Adhesive Technology for Automotive Multi-Material Substrate Bonding

Frank Billotto, September 2013

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.

Precision Waterjet Cutting in the Composites Industry Utilizing Robots for High Quality Accurate Machining

Duane Snider, September 2013

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.

Heatpipe / Thermosyphon Augmented Mandrels to Improve Cure Quality and to Reduce Cure Time in the Thermoset Pipe and Tube Filament Winding Process

Joseph Ouellette, September 2013

Filament winding as a composite process for fabricating highstrength reinforced thermoset hollow structures is well documented. Traditionally cure was accomplished in a convection oven and this cure sequence was the most time consuming portion of the overall process as well as the least predictably controlled. This paper will define and detail a new method for curing filament-wound composites. Here a closed-loop controlled heatpipe thermally enhanced mandrel heated by induction heating replaces a cure oven allowing for very-rapid cure and permitting the escape of volatiles and water vapour that normally are trapped interstitially.

Continuous Fiber Reinforced Thermoplastic (CFRT®) Inserts for Injection Over-Molding in Structural Applications

Thomas Smith, September 2013

A primary goal in automotive structures is reduction of weight while maintaining or improving other desirable attributes. Composite materials offer solutions to weight reduction in comparison to metal structures and thermoplastic composite materials offer the added benefits of improved cycle times high impact resistance cost-effective solutions and a path for sustainability. Developments in the area of injection over-molding of structural inserts produced from continuous-fiber-reinforced thermoplastics (CFRT ®) are an example of this and combine the advantages of injection molding with CFRT properties. Typical applications are in seat structures airbag housings front-end modules and crash beams that take advantage of the excellent strength and impact characteristics of the materials. A seat back application produced with injection over-molding of CFRT inserts is used as a demonstration case study.

High Pressure Resin Transfer Molding—Process Advancements

Matthias Graf, September 2013

The resin transfer moulding (RTM) process is well established for low-volume manufacturing and has recently gained interest for manufacturing higher volumes particularly in automotive to produce lightweight composite structures. However the process is currently limited by the low-volume production capacity of the preforming processes long impregnation times and lack of robust processing equipment all of which limit RTM’s use for continuous manufacturing of components. This presentation addresses recent developments in the RTM process and RandD strategies of a trilateral collaboration working to address these issues.

Robotic Trimming Cutting & Sanding of Carbon Fiber Body Structures

Mark Handelsman, September 2013

Stamped steel body structures set a benchmark for construction and aesthetics that any alternative including carbon fiber body structures must meet. The challenge to carbon fiber body structure manufacturers is to achieve the traditional body structure standards while maintaining the most competitive possible per part manufacturing costs. Fortunately for these manufacturers there is a great deal of accumulated experience in composite manufacturing including the finishing and trimming processes that can be among the most challenging to automate. This paper will discuss some of the robotic technologies that have been adopted from other composite finishing and trimming processes to meet the needs of carbon fiber body structure manufacturers. Specific examples will be discussed including robotic sanding of Class A surfaces and abrasive waterjet cutting of holes and features on various carbon fiber body structures both of which are or will soon be in full production. For abrasive waterjet cutting this paper will elaborate on a unique approach that was developed using robots to manipulate parts while secondary robots manipulate the abrasive waterjet media.The paper will also discuss the advantages of these robotic solutions vs. other approaches including lower running costs and the flexibility to quickly adapt to product or model changes.

Engineering Software for Designing Cost Effective Mixed Material Vehicles

Edward Bernardon Siemens PLM, September 2013

This presentation discusses issues that must be addressed by engineering software tools currently used for metal structures and based primarily on geometry so that engineers can efficiently make the tradeoffs required to design mixed-material vehicles. Engineering software must help identify optimal combinations of materials assembly methods and joining technologies by allowing engineers to efficiently conduct tradeoffs. These tradeoffs include assembly complexity vs. part complexity the appropriate mix of material (metals plastics composites) the impact of alternative joining methods and assessment of part manufacturing and assembly alternatives while concurrently conducting an integrated design cost and performance assessment as design features are changed.

Continuing Evolution of Low Density SMC for the Automotive Market

Ian Fellows, September 2013

This presentation will showcase some examples of the current market for low-density sheet-molding compound (SMC) and will provide a brief history of weight reduction initiatives and benefits in the automotive industry. One specific development program will be described in detail. This program focused on improving stiffness-to-weight ratio maximizing the benefit of microsphere technologies and creating a paint-ready surface suitable for high-appearance applications. The result was a new low-density SMC with an industry-leading density of 1.18 sp.gr. — 9% lower than the previous industry best. The discussion concludes with a peek at future opportunities for thermoset composites in this specific marketplace.

High-Volume Automotive Structural Composites: Novel Thoughts on Key Enabling Materials and Manufacturing Technologies

Donald M. Lasell, September 2013

Fiberglass-reinforced epoxy (FG/epoxy) and carbon fiber-reinforced epoxy (CF/epoxy) composite components are known to be produced in high volumes using the compression-molding process. This same molding technology can reasonably be expected to produce high volumes of CF/epoxy automotive body structure and chassis components. The author discusses unique epoxy chemistry forming and molding processes possible due to the thermoplastic stage-of-cure referred to as the epoxy “B-stage.” B-staged epoxies are discussed and then compared to what is commonly referred to as a B-staged sheet molding compound (SMC). A progression-molding assembly line concept similar in configuration to existing automotive sheetmetal forming lines is discussed. This conceptual molding operation would be capable of producing complex CF/epoxy structural composite components at a rate of at least 120 / hour.