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Among the various materials used today for an instrument panel application, polypropylene is one of the least expensive per kilogram and therefore one of the most attractive. Typically, different polypropylene compounds may be used in different components of the IP according to the desired performance requirements. At the same time, polypropylene is one of the most difficult thermoplastics to use properly when designing an instrument panel due to weaknesses related to its semi-crystalline nature. For some vehicles, the metal reinforcement which would be needed to overcome these weaknesses would lead to a higher overall system cost compared with engineering thermoplastics. In the last decade significant progress has been made in the development of new polypropylene compounds and processes.

In the present paper the engineering development of a structural instrument panel (IP) concept made of a Polypropylene (PP) rubber modified compound filled with 15% talc in which the metal cross car beam has been eliminated, is discussed. The design concept consists of three main injection molded shells which are vibration welded to each other to form a stiff structure. The steering column is attached to the BIW and plastic structure by means of a separate column support made of steel, aluminum, magnesium or fiber-reinforced plastic. The concept has been developed for the European market and is therefore not intended to meet the unbelted FMVSS 208 requirements. The total IP assembly has a substantially lower cost and weight than conventional cross car beam based IP structures while meeting all of the performance requirements. The concept development was supported by static and dynamic numerical analyses using well established, widely used FEA codes.

The platform strategy broadly used by OEMs across their different brands, as well as the increasing targets in terms of cost, weight and performance are driving forward since several years the modular approach for a new generation of instrument panels. An innovative hybrid concept has been developed in order to integrate the HVAC system with the structural IP components, reducing cost and weight, improving thermal comfort and structural performance, with at the meantime high style flexibility. The integration of metallic and thermoplastic components, together with a structural use of plastic parts, has driven to the development of different modular concepts. Each of these concepts has been screened and optimized using engineering tools such as finite element analysis (FEA) and computational fluid dynamics (CFD) in order to assess the structural, noise-vibration-harshness (NVH), airflow and cool-down performance.

An advanced high flow PCABS was developed for improving the efficiency of injection molding processes and cycle times. Proprietary technology was used to develop this new blend while maintaining key properties (heat resistance and impact) necessary to meet end use part requirements. Significant rheological improvements in melt flow rate (MFR) and flow capabilities throughout the entire viscosity versus shear rate range were obtained. These improvements allowed for lower cooling times (21-27% reduction) and injection pressures. Molders using this resin have the potential to improve cycle times, improve processes, and save money. This paper will document cycle time and process improvements in automotive instrument panel applications with the new high flow PCABS blend, PULSE*2000EZ.

Fully-integrated structural instrument panels (IP) have been in commercial use in passenger cars, light trucks, and sport utility vehicles for some years now. They offer a cost-effective alternative to the more traditional IP construction that utilizes full-size cross car beams to achieve the structural stiffness and energy management required to meet Federal Motor Vehicle Safety Standard (FMVSS) 208 and corporate performance requirements. The natural evolution of interior designs demands an increasing level of integration of the different components in the interior of the vehicle. Therefore, the natural extension of current structural IP technology is to integrate the steering column subassembly, i.e., steering column and column support, and the heat, ventilation, and air conditioning (HVAC) unit into a modular pre-assembled system.

The drive to reduce costs and increase efficiency in the automotive industry is often the driving force for development of new technologies and methods of engineering. Polypropylene (PP) is widely used as a low cost alternative to “engineering” thermoplastics. This paper outlines the characterisation methods used to develop material models for talc-filled impact-modified PP, which are then used to increase the efficiency of the development process, by using engineering analyses to reduce the prototyping costs and potentially the development time for an application. Instrument panels (IPs), door panels and trim parts are usually subjected to heat requirements and must maintain dimensional tolerance levels for each application. This necessitates extensive prototype testing and often several design iterations in order to reach the requirements. This paper deals with the characterisation of PP creep behaviour and development of a model for use in Finite-Element (FE) - based codes.

In a joint effort between Ford Motor Company, Visteon Automotive Systems, Textron Automotive Company, and Dow Automotive the 1999 Mercury Cougar instrument panel (IP) was designed and engineered to reduce the weight and overall cost of the IP system. The original IP architecture changed from a traditional design that relied heavily upon the steel structure to absorb and dissipate unbelted occupant energy during frontal collisions to a hybrid design that utilizes both plastic and steel to manage energy. This design approach further reduced IP system weight by 1.88 Kg and yielded significant system cost savings. The hybrid instrument panel architecture in the Cougar utilizes a steel cross car beam coupled to steel energy absorbing brackets and a ductile thermoplastic substrate. The glove box assembly and the driver knee bolster are double shell injection molded structures that incorporate molded-in ribs for added stiffness.

Currently, throughout the automotive industry, a major emphasis is being placed on reducing costs of plastics part manufacturing. For example, manufacturers of plastics parts used for interior trim applications have traditionally painted parts, to improve part aesthetics and cover over such surface defects as weld lines. Part painting can typically add from $.60-$2.00 to the part costs for these applications. Furthermore, due to the loss in mechanical properties found at weld lines, structural integrity can also be sacrificed. This paper discusses the use of the multi-live feed molding process as a solution to minimize weld lines, improve mechanical properties and part aesthetics, and potentially reduce costs by eliminating steps in manufacturing operations such as painting.

The trend in the automotive industry to establish higher quality, comfort and safety levels, while at the same time reducing cost and weight, is pushing production techniques, materials and the development cycle to become as efficient as possible. The automotive supplier has to choose from a broad range of fabrication technologies and material alternatives to achieve the highest performance level at the lowest possible cost. This paper outlines the process followed by a multi-functional team to design and develop the interior door panels for the VW Golf, in ABS resin for large scale production. The team effort, headed by the Tier 1 (Sommer Allibert Industrie), with extensive interaction with the OEM, and the support of the material supplier and tool-maker, led to a thin-walled part with integrated mountings, high quality appearance and excellent dimensional stability.

The passing of the federal regulation for head impact protection for upper interior components (FMVSS 201U) has led to the use of a variety of foam materials in interior trim pillar and headliner reinforcement applications. Polyurethane foams and expanded bead foams are some of the commonly used foams in these applications. However, the low energy absorption efficiency (35% - 55%) of the current foams requires the use of 20 mm - 40 mm of packaging space to integrate the countermeasures that make it possible to meet the regulations. A newly developed high efficiency olefin based foam is able to meet the performance requirements at a reduced packaging space. A combination of physical structure and superior mechanical properties provides the much needed higher efficiency (80% - 90%) of the olefinic foam. This paper discusses the foam architecture and performance benefits for many interior applications, such as energy absorbing countermeasures in pillar trim, headliners, and door panels.

The major element of contact between the occupant, the vehicle and the road surface is the automobile seat. Flexible polyurethane foams are the material of choice for this application, not only because of the economies offered by large-scale molding operations, but also because the cushioning characteristics of the foam/seat assembly can be adjusted. The automotive original equipment manufacturers (OEM’s) worldwide are looking for optimization of the balance between foam weight and foam specifications, with more emphasis than ever on comfort and durability. This goes with specific requirements for the various foam pads, i.e., front cushion, rear cushion, front backrest and rear backrest. Commercially useful foams can be made from a variety of polyurethane molding chemistries.

Many studies have been done to objectively measure car seat foam properties and correlate them to comfort performance. Typically, the vibration characteristics (namely transmissibility) of the foam cushion are measured. It has been generally accepted that low natural frequency equates to better comfort. However, no subjective studies have been done to verify that humans can feel the vibration differences that are measured. Also, the measured differences of the foam may not be detectable once the foam is built into a complete seat. Three different foam formulations utilizing MDI (methylene diphenyl diisocyanate) and TDI (toluene diisocyanate) technology were evaluated for vibration characteristics. The foams were then submitted to subjective human testing and objective lab testing after being built into seats. The subjective testing was done using a typical ride and drive evaluation where people were interviewed about the comfort of the seat while driving over various road conditions.

Field cracking in some instrument panels (IP) manufactured with a competitive grade of polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS) material was observed in high temperature/high humidity geographies. OEMs and tier molders are: 1) questioning the thermal and hydrolytic stability of the various suppliers' PC/ABS resins, and 2) converting to grades with advantaged stability. A study was undertaken to compare the thermal and hydrolytic stability of two suppliers' high flow PC/ABS resins. Materials were aged at 90C/95% relative humidity up to 1000 hours. Samples were tested to compare the retention of properties. This paper will discuss the experimental procedures, resulting data, and the common factor in the PC/ABS resins showing the best stability.