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Technical Paper

Surface Treatments and Characterization of Electroplated and Hot Dip Galvanized Steel Sheets

1996-04-01
91A126
Protection of surfaces is a critical factor in determining the extended service life of a structure in polluted and aggressive environments. In particular, a rapid growth of the technology for the protecting coating of cold rolled steel is experienced, for the use in transport, electric housewares, building and industrial plants. Numerous changes have taken place in the production of zinc coatings on steel in order to improve the corrosion resistance using zinc alloy platings. Our research group collected from the international production a number of selected galvanized steel samples, including electrodeposited zinc alloys, multilayer coatings, hot dip galvanized steels. On the selected materials we established and analyzed morphology, composition, crystal structure, impurity content and distribution, using many surface microanalysis techniques.
Technical Paper

State of the Art in the Use of Stainless Steel for Bus and Car Parts Manufacture

1996-04-01
91A127
The paper describes recent developments in the use of stainless steel to make the parts of buses which are most liable to corrosion. Sheet metal is used for the outer panelling, and square and rectangular tubes for the body. The types of steel used and their fabrication are analyzed. Finally, a brief description is given of the stainless steels used to make car exhaust systems.
Technical Paper

The Modeling of Mold Filling in Structural Reaction Injection Molding

1996-04-01
91A118
The main use of FRC in automobiles, with the exception of a few specialized low volume vehicles, has been until now in semistructural parts. One of the most promising process in development today, that may play major role in future structural composite fabrication, is based on SRIM technology. The rapid and extensive introduction of this process goes also through the development of deeper theoretical knowledge of the process and the development of computer simulation to aid mold design and choice of proper processing parameters. To contribute SRIM advancement, a preliminary model has been developed for viscosity changes, extent of the reaction and temperature rises, associated with the mold filling stage, as well as a simple software to evaluate the pressure drop through different combinations of reinforcements.
Technical Paper

Simulors, An Innovative Tool for Molds Development

1996-04-01
91A117
Mold designers and foundrymen spend a lot of time in developing molds without knowing exactly the phenomena which take place inside. Simulor, which has been used in an industrial environment for two years, offers the solution to make foundrymen understand what happens during the filling of the mold and the solidification of the part. Based on navier-stokes and heat transfer equations, simulor provides speed distribution and metal front evolution in the cavity and thermal map in the mold and the part. Some examples with different metals (cast iron, aluminum alloy) cast with various processes (sand or die casting, low pressure or gravity casting) will be given. This new tool will given foundrymen the opportunity to test the mold before having it machined and will also allow reduction in development delays.
Technical Paper

Integration and Validation of Sheet Metal Forming Simulation Computer Programs Into the Design Process

1996-04-01
91A121
In order to improve the design of drawn parts and to reduce the number of trial and error tests, Renault has undertaken the development and the validation of various finite element procedures and codes. This paper describes the function of each software and its level of integration into the design process. One of them is already an operational tool used be planners whilst the others are still in the validation phase. Selected examples show typical applications of the computer programs on automotive parts.
Technical Paper

Glass Reinforced Thermoplastic Composites: Effects of Ribs and Different Types of Reinforcement on the Characteristics of the Molded Part

1996-04-01
91A119
Compression molding of thermoplastic sheets, consolidated or non- consolidated, reinforced with glass fibers (GMT, GRT) is applied as an economic production process in the automotive industry. The aim of this work is to evaluate how the physical and mechanical strength characteristics depend on the presence or absence of ribs and how component performance may be changed by modifying the molding parameters, altering the content and orientation of the reinforcement fibers in the ribbed areas. For this purpose, two statistical designs will be considered, the first carried out on a box type component without ribs, the second on the same component with a set of internal ribs. Two different materials with a PP matrix will be tested, a GMT reinforced with continuous random glass fibers and a 12 mm random glass fibers composite.
Technical Paper

Thermomechanical Behavior and Wear Resistance of Whisker Or Particle Reinforced Ceramics

1996-04-01
91A107
Ceramic composite materials have been intensively studied during the last years. Particles and whisker reinforcement have shown the simultaneous advantage to allow the preparation of composite materials by conventional processing and to lead, when under optimum conditions, to dramatic toughening and strengthening. Since wear resistance of brittle material have been shown to be related to both hardness and toughness, composite materials with improved were resistance have been developed for cutting tools or bearing applications. However the mechanism responsible for toughening is of major important for wear resistance effectiveness. We have therefore reviewed the main mechanisms before presenting some examples of composites materials for wear resistance applications.
Technical Paper

Manufacture of Automotive Components By Semi-Liquid Forming Process

1996-04-01
91A113
Semi-liquid forming process, applied to pressure die-casting, permits to obtain low cost components with high qualitative characteristics and adequate mechanical performances. The technology is based on the employment of material with globular microstructure (flow-cast alloys) obtained subjecting a metal alloy at the time of solidification to an elevated shear rate. Such microstructure permits the accomplishment of conventional forming processes at temperatures in solidification range. The particular fluid-dynamic properties of the semi-liquid slurry and the lower injection temperature allow to obtain casting with improved soundness, without need of impregnation, and to extend die life. The present work describes the Weber (Magneti Marelli) activity of the process industrialization and some applications for the manufacture of automotive components.
Technical Paper

Devleopment and Industrial Realization of Glass Mat Preforming Equipment for Rtm and Shim

1996-04-01
91A101
As a result of the rapid expansion of liquid molding in closed mold, fiberglass mat performers have rapidly changed in order to meet the high production requirements. The reasons for this interest in RTM and SRIM can be found in the considerable benefits offered by this technology which include: 1) ability to produce very large parts (weights up to 70 kg are currently being prototyped); 2) continuous and homogeneous reinforcement or even predetermined distribution of the reinforcement in the mold; 3) the ability to produce structures using cores of various types; and 4) the ability to use large inserts, even if they are metallic. The creation and development of this technology has been possible thanks to the introduction of very low viscosity reactive polymers. These materials permits very fast impregnation of the reinforcement in the closed model, thereby decreasing the cure time and the overall cycle time.
Technical Paper

Advances in Thermoset Injection Molding

1996-04-01
91A102
Injection molding of thermosetting materials such as low profile SMC/BMC composites found increasing application in the transportation industry in the eighties. Such automotive parts as front end panels and rear/hatchback doors have grown in usage. The rear doors have reached exceptional production levels of 2600/day in a single plant. The injection process offers the advantages of greater automation for the mass production of body panel parts compared in compression molding. However, the injection molding of fiber reinforced low profile composites suffers from a severe reduction in physical properties. This is particularly true for impact strength which can be one-third that of similar compression molding materials. A primary reason for this is due to the degradation of the reinforcement during the processing/molding. Efforts at increasing the physical properties through processing changes have many times caused problems with the surface smoothness of the moldings.
Technical Paper

Actuation and Fastening With Shape Memory Alloys in the Automotive Industry

1996-04-01
91A103
As a result of a phase transformation, shape memory alloys can change their shape when the temperature changes. This unusual effect can be utilized in actuation and fastening components for automotive applications. Springs made from Ni-Ti shape memory alloys change their rate in a predetermined temperature range due to a significant change in the elastic modules of the material. They can be used as sensor-actuators in pressures control valves or oil cooler by-pass valves in automatic transmissions or to compensate for oil viscosity changes in shock absorbers or thermal expansion of dissimilar materials in gear boxes. If the recovery is constrained, i.e., shape memory element is physically prevented from returning into its original shape, a potentially high stress is generated. This effect is used in fastener rings. Fasteners made from Ni-Ti alloys provide high reliability and easy installation for braid terminations, locating of shaft mounted components, connectors and hose clamps.
Technical Paper

Structual Problems in the Design of a Car-Component in a Composite Material

1996-04-01
91A096
The paper summarizes the results of an experimental and numerical study performed on the rear door of a car of large production. It was carried out with a DMC ("dough molding compound") plastic material with short glass fibers. This technology makes strong the link between the production process and the mechanical properties of the component. Such properties really vary according to the fibers orientation, the distance from the injection points and the geometrical complexity of the different regions of the molded component. In some regions the fibers orientation is well defined, in others the orientation can be expressed only in average tendency terms, with a large scatter band. It is natural to think that the material modifies its behavior from region to region, showing marked orthotropic properties or, on the contrary, a compensation isotropic trend.
Technical Paper

Pultrusion Technology for the Transportation Industry

1996-04-01
91A099
The utilization of the pultrusion process for the manufacturing of components and structures for the transportation industry is discussed. Both the characteristics and capabilities of the process and the properties of pultruded composites are reviewed. The most important characteristics of this process is its capability of producing cost effective composite products which exhibit all the features of other composites. The benefits of this technology are demonstrated by a variety of applications for different industries together with the more recent developments for the transportation industry.
Technical Paper

Finite Modeling of Sheet Stamping Operations

1996-04-01
91A089
A wide variety of choices confront the potential user of finite element modeling (FEM) for sheet forming analysis. In the first part of this paper, a brief summary of the basic formulations available and sample references to them are provided. Several kinds of finite element models have been developed for analyzing sheet forming operations at OSU and in the Center for Net Shape Manufacturing. These variations began with in-plane FEM and grew into 3-D versions. In the second part of this paper, some key conclusions from these developments will be summarized. More recently, a section analysis program (SHEET-S) has been prepared and transferred to industry. The capabilities and limitations of SHEET-S will be presented in greater detail, including comparisons with experiments and industrial trials.
Technical Paper

Evaluation and Analysis of Strength of All-Ceramic Swirl Chamber for Diesel Engines

1988-03-01
871205
An all-ceramic swirl chamber has been developed and analyses and evaluations concerning the strength of silicon nitride ceramic (Si3N4) have been performed with a view to using it for the entire internal wall surface of the swirl chamber. The strength characteristics of Si3N4 and their effect and variation have been determined. On the basis of measurements and analyses of thermal stresses, assembling stresses, etc., investigation of the most suitable construction and assembling methods to reduce load stresses on ceramic, and various kinds of duration tests, the swirl chamber has been confirmed to have the required durability. This engine was found to comply with the 1987 U.S. diesel particulate regulation.
Technical Paper

The Next Step in Acoustical Part Weight Reduction

1999-05-17
1999-01-1685
Weight reduction with maintained part performance is a continuing trend throughout the automotive industry. Acoustical insulation parts (carpet underlay and dash insulators) are no exception. Several years ago, ICI Polyurethanes led the industry in establishing a molded density standard of 48 kg/m3. Although this is the current production standard, the technology drive is toward even lower weights. Recent technological demonstrations show that molded densities of 35-38 kg/m3 are achievable. In addition to removing weight, acoustical performance can be maintained with no deficiencies in physical characteristics.
Technical Paper

A Novel Method and Product to Damp Cylindrical Articles: Constrained Layer Damping Tubing

1999-05-17
1999-01-1676
Constrained layer damping (CLD) is a well known technique to efficiently damp low frequency vibration. CLD employs a viscoelastic material sandwiched between two very stiff, typically metal, layers. While effective over essentially flat surfaces, CLD has not been applicable to cylindrical shapes. In order to damp low frequency vibration in metal pipes, users have been forced to rely on extensional layer damping, typically consisting of thick layers of extruded or molded rubbers. This paper discusses a novel product to damp cylindrical articles such as metal pipes with a constrained layer heat shrink tubing. This product utilizes a stiff heat shrinkable polymeric jacket bonded on the inside with a viscoelastic layer. When shrunk on a metal pipe or rod, a CLD system is produced. The product is typically thinner than an extensional layer damper and is more effective. It also meets the other physical and environmental requirements for a pipe covering.
Technical Paper

Objective Detection Ranking Guidelines for Performing Process Failure Mode and Effects Analysis

1999-05-10
1999-01-1625
Process Failure Mode and Effects Analysis (FMEA) has become an important tool for identifying potential weaknesses in manufacturing processes. The Automotive Industry Action Group (AIAG) has published guidelines that help ensure that Process FMEAs are developed and interpreted in a consistent fashion. These guidelines, while very helpful, are still open to broad interpretation, and need further development and improvement, especially in the area of detection rankings. The current detection ranking criteria are very subjective, difficult to apply in a consistent fashion, and can easily be used to skew Risk Priority Number results. This paper will describe revisions to the guidelines for detection rankings that have been successfully used in developing Process FMEAs for automotive manufacturing processes.
Technical Paper

Error/Mistake Proofing During New Vehicle Launches

1999-05-10
1999-01-1632
The engineering community is becoming increasingly aware of the significant benefits of performing error proofing on product and tooling designs. If a part or tooling can be designed or redesigned to allow for one-way assembly, the option of incorrect assembly at the plant is eliminated, making the process more robust. The goal of the error proofing exercise is to reduce operator decisions, eliminate misbuilds, and improve quality. Through participation in this type of exercise, all key stakeholders, including product, process, tooling, and production personnel, have greater opportunity to identify, prevent, and resolve potential production issues well in advance of launch.
Technical Paper

Staking Design and Process Parameter Study of Hot-Air Cold Staking Process

1999-05-10
1999-01-1629
An experimental evaluation to systematically study a hot air cold stake joining process was conducted with injection molded samples. Twelve material combinations consisting of six stud plate materials were matched with two hole plate materials (GDT 6400 and 18% talc filled PP). Seven stud designs with variations in size and geometry were used for each material combination. A proper heating temperature was first determined by heat characterization trials. Different heating times and stake heights were studied in the staking experiments. Pull tests were conducted to determine the strength of the joints and their failure mode. Results showed that material characteristics, material combinations, and process parameters all could contribute to variations in pull strength and different failure modes.
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