Although there are a number of variations of drive technologies for motion applications, there are a few that are used for the majority of systems being built today. These most common drives do take a bit of understanding before applying.

Kinematic Analysis of a 6DOF Gantry Machine

2015-01-04974/14/2015

Gantry robots are mainly employed for applications requiring large workspace, with limited higher manipulability in one direction than the others. The Gantries offer very good mechanical stiffness and constant positioning accuracy, but low dexterity. Common gantries are CNC machines with three translational joints XYZ (3DOF) and usually with an attached wrist (+3DOF). The translational joints are used to move the tool in any position in the 3D workspace. The wrist is used to orient the tool by rotation about X, Y and Z axis. This standard kinematic structure (3T3R) produces a rectangular workspace. In this paper a full kinematic model for a 6DOF general CNC (gantry) machine is presented, along with the Jacobian matrix and singularity analysis. Using Denavit-Hartenberg convention, firstly, the general kinematic structure is presented, in order to assign frames at each link. The forward kinematic problem is solved using Maple 17 software. Differential kinematics describes the analytical relationship between the joint motion and the end-effector motion in terms of velocities, through the manipulator Jacobian matrix. The configuration at which the manipulator Jacobian matrix drops rank is called singular configuration. In this paper the Jacobian matrix is derived using the vector cross multiplication method. The singularity conditions are examined and validated. The fully reachable workspace is plotted with Matlab tools using specified joint limits. The presented solutions are expressed in parametric manner and can be used for analysis of the existing gantry type machine as well as a design tool for new machines.

Filiposka, Monika, Djuric, Ana M., ElMaraghy, Waguih

Optimization of Multiple Quality Characteristics for Dry Drilling Ti-6Al-4V Using TiAlN-Coated Carbide Tool

2014-01-91051/1/2015

The present paper aims at optimization of multiple quality characteristics (dimensional accuracy and surface roughness) in dry drilling Ti-6Al-4V using TiAlN-coated carbide tool while the controllable factors are spindle speed and feed rate. To do so, desirability methodology is used to explore optimum conditions for concurrent optimization of the addressed quality characteristics. Central composite design (CCD) is used for experimentation. In order to create reliable models describing the process behavior, response surface methodology (RSM) is used.

Faqeeh, Akram, El-Gizawy, Ahmed Sherif

Tribological Characteristics of Yttria Stabilized Zirconia Nanolubricants

2014-01-279010/13/2014

Nanolubricants are suspensions of nanoparticles in base fluids, a new challenge for thermal sciences provided by nanotechnology. The objective of this work is to analyze the thermal and tribological properties of yttria stabilized zirconia (YSZ) nanolubricants. Nanosized YSZ particles were prepared by milling YSZ (10μm) in a planetary ball mill equipped with vials using tungsten carbide balls. After 40 hrs, milled YSZ nanoparticles of sizes ranging from 70-90nm were obtained. The nanoparticles were characterized by Energy Dispersive X-ray analysis (EDXA), Scanning Electron microscope (SEM), Transmission Electron Microscope, Thermo Gravimetric-Differential Scanning Calorimeter and non contact 3D surface profilometer and the images of the same were obtained. The heat transfer properties of automotive engine lubricants were determined by utilization of measured thermal conductivity, viscosity index, density, flash point, fire point and pour point, which revealed that lubricants with additive constituents have a significant effect on the resultant heat transfer characteristics of the lubricants. The YSZ nanoparticles incorporated lubricants were evaluated for their potentials as effective solid lubricants at room temperature by using ball-on-disk tribometer. The lubricant without nanoparticles has a co-efficient of friction of 0.08-0.1 and a wear rate in the order of 10-4 mm3/Nm, while the lubricant with yttria stabilized zirconia nanoparticles exhibits a steady state co-efficient of friction of less than 0.07 and a wear rate in the order of 10−6 mm3/Nm at room temperature. Scratches and furrows are considered as the dominating wear mechanism of the disc applied with lubricants. However, for the disc applied with YSZ nanolubricants, the formation and effective spreading of the YSZ lubricating films are the most important factor to reduce the friction and wear rate.

Ganapathy Pandian, Sakthinathan

Some Considerations on the Role of Third Bodies during Automotive Braking

2014-01-24909/28/2014

Third bodies, also termed friction layers, tribofilms or secondary contact patches, are layers of more or less compacted wear debris between pads and rotor of a disc brake. Our approach of assessing the sliding behavior and friction properties induced by third bodies has been: i) structural characterization after AK-master test procedure, ii) sliding simulation of model structures similar to the observed ones but with simpler and well defined compositions, and iii) verification of simulation results by pin-on-disc tests with artificial third bodies showing the same microstructures and compositions as the model structures. The idea was to simulate structure formation during real braking conditions by high energy ball milling of appropriate powder blends. The final outcome of numerous parameter studies was that a third body containing 15 vol% soft ingredients and 0-20 vol % hard ingredients, both distributed homogeneously in a nanocrystalline iron oxide matrix, should be most desirable for braking. This general description of the optimum third body structure and several parameter studies performed by modelling enabled us to interpret a number of features of the AK-master test procedure, such as i) friction evolution during bedding, ii) the role of solid lubricants in respect to the initiation of smooth sliding behavior, and iii) friction evolution during a single braking event (in-stop behavior).

Oesterle, Werner, Dmitriev, Andrey I.

A New Robotic Vibration-Drilling Process

2014-01-22589/16/2014

In today's aircraft assembly process several new features make drilling operations very challenging according to production requirements. Parts are made of thin or thick multi-material stacks with a large scope to cover and complex assembly sequences. In addition, the current ramp-up in aircraft programs involves to improve productivity while keeping process quality and reliability. In this context robotic solution meets perfectly all these requirements as it is flexible, reconfigurable, fast and agile. Among the possible end-effectors, the Barrel Multi-Function End Effector (BMFEE) appears to be the most flexible solution to allow many different process configurations. The latest developments have been focused on the drilling equipment of this BMFEE. In fact the drilling process efficiency can be constantly improved especially in terms of reliability, quality and productivity. Therefore vibration-assisted drilling system has been integrated into the BMFEE drilling module. This innovative drilling process allows breaking up the metallic chips in such a way that jamming is avoided. Thus peck-drilling cycles are avoided and the global process offers more reliability and productivity while fulfilling quality requirements. This article presents the work of this integration. Benefits of this new robotic vibration-drilling process are shown on the basis of an industrial example.

Laporte, Sylvain, Gueydon, Etienne, Auffret, Alain, De Castelbajac, Cosme

Improving AFP Cell Performance

2014-01-22729/16/2014

The Automated Fiber Placement (AFP) machine layup run time in large scale AFP layup cells consumes approximately 30% of the entire part build time. Consequentially, further reductions to the run time of the AFP machine part programs result in small improvements to the overall cycle time. This document discusses how Electroimpact's integrated system and cell design reduces the overall cycle time by reducing the time spent on non-machine processes.

Rudberg, Todd, Nielson, Justin, Henscheid, Mike, Cemenska, Joshua

An Experimental Analysis of Ultrasonic Vibration Assisted Tapping of Ti-6Al-4V

2014-28-00244/28/2014

Tapping is an important process in assembly of aircraft structures because on an average one millions of tapped holes are made on an aircraft structure. However, sudden breakage of the tap is the most undesirable event frequently encountered during the tapping process. In particular, this can mostly occur when small diameter internal threads are made in a ‘difficult-to-cut’ material like titanium. For this reason, it has been a topic of industrial interest in the manufacturing sector for many years. The ultrasonic vibrations assisted tapping (UVAT) is a novel manufacturing technology, where ultrasonic vibrations are provided to the work piece in the axial direction. The present work is a comprehensive study involving experimental characterization. The experimentation shows that UVAT reduces the torque during tapping as compared to that of in conventional process. There is a 19.1% reduction in torque and about 20.3% reduction in cutting temperature in UVAT over that of in CT. The experimental analysis of UVAT process also shows that the superior surface and better machinability in UVAT over that of in CT.

Pawar, Swapnil, Patil, Sandip, Joshi, Suhas, Singh, Rajkumar

Advanced Automated Milling, Drilling and Fastening Utilizing Parallel Kinematic Machines

2013-01-21529/17/2013

The improvements in Parallel Kinematic Machines (PKM) coupled with new innovative technologies, allow for Advanced Automated Milling, Drilling and Fastening in the Aerospace industry. Providing economical alternatives to processes that currently utilize highly customized machine tools, sacrificing flexibility and dynamics, or complex robotic cells sacrificing system capabilities with the rigidity and accuracy limitations of serial robots. The latest in PKM technology eliminates the ball joints that were mandatory in all previous PKM machines, as well as the heavy platforms or structures supporting the actuators. This allows for the strength and rigidity common to machine tools, but with the flexibility and high dynamics associated with standard serial robots. The new use of Auto-Calibration and cross lasers allow for highly accurate positioning, adaptation to a material surface, edge, datum, hole, etc. or to reference the machine to the adjacent work zone. Specific advanced automated applications will demonstrate the applications of drilling, milling, orbital drilling and fastening. Implementation of Multifunction End Effectors, using the rigidity, flexibility and accuracy of the PKM to position the Multifunction End Effector while providing the forces required, as well as high speed spindles. These advanced automated applications will include; drilling & fastening for wing assemblies, milling and trimming of wing panels, milling/drilling for wing root ends and stringers. These systems provide for flexible solutions that, in the past, have been difficult (if not impossible) for serial robotic systems, and very expensive and slow for dedicated custom machine tools to achieve. As the aerospace industry demands greater flexibility, and cost reduction, the implementation of parallel kinematics will be key in bridging the gap between serial robots.

Neumann, Karl-Erik, Reno, Robert

Defining Environmental Indicators at Detail Design Stage as Part of an Ecodesign Strategy

2013-01-22769/17/2013

Implementing Design for Environment (DfE) into the design process requires a strategic integration. Furthermore, as DfE is continuously evolving, flexible processes need to be implemented. This article focuses on the integration of DfE into an optimization framework with the objective of influencing next-generation aircraft. For this purpose, DfE and Structures groups are developing together a set of new environmental indicators covering all life cycle stages of the product by coupling a list of yes/no questions with an environmental matrix. The following indicators are calculated: Regulation risk, Impact of manufacturing the part, CO2 emissions and Recyclability potential. These indicators will be used as constraints in the multi-disciplinary design optimization (MDO) framework, meaning that the structure will be designed while complying with environmental targets and anticipating future regulation changes. To illustrate this new methodology, it is applied to three common processes used in structural design on a generic part: aluminum with chemical milling, aluminum with mechanical milling and composite produced by automated fiber placement process. Through this initiative, it is believed that in the mid-term, manufacturing processes selection will not only be influenced by technical and cost requirements, but also considering their environmental impacts.

Doudrich, Greg, Corriveau, Guillaume, Walch, Denis, Oudjehani, Kahina, Dervault, Franck

Increasing Machine Accuracy by Spatially Compensating Large Scale Machines for Use in Constructing Aerospace Structures

2013-01-22989/17/2013

Starting in 2003 Electroimpact began development on a comprehensive kinematic and compensation software package for machines with large envelopes. The software was first implemented on Electroimpact's Automatic Fiber Placement (AFP) equipment. Implementation became almost universal by 2005. By systematically collecting tracker measurements at various machine poses and then using this software to optimize the kinematic parameters of the machine, we are able to reliably achieve machine positional accuracy of approximately 2x the uncertainty of the measurements themselves. The goal of this paper is to document some of the features of this system and show the results of compensation in the hope that this method of machine compensation or similar versions will become mainstream.

Rudberg, Todd

Portable 2 Axis Milling Machine for CFRP

2012-01-18799/10/2012

As part of a Composite Wing Manufacture Program, Electroimpact was asked to design and develop a small portable milling machine for machining CFRP. The machine needed to be light so it could be lifted by two operators, robust to the production environment, and stiff enough to allow it to cut a 15 mm deep 3/8\mi slot through composite material (CFRP), in one pass, with no delamination. The machine also needed to be capable of performing a 30 mm deep finishing cut, in one pass, with 3 μm or better surface finish. Specialist Polycrystalline Diamond (PDC) roughing cutters were developed for the cutting process to reduce cutting loads and vibration while maximizing cutter life. The machine also needed to be capable of cutting along a 2 axis path. Electroimpact successfully introduced the machine in to the production environment in October 2011, within a 12 month development window. PCD Cutters were developed with the assistance of Cruing UK Ltd who supplied the final roughing and finishing cutters.

Richards, Barry, Turnbull, Craig

Cutting Tool Technology for Machining Composite Curing Tools

2012-01-18759/10/2012

In the present study, a fully controlled experimental protocol is used to investigate the difference in milling Invar and HexTool® for composites curing tools. The main difference is the use of the different strategies: conventional milling is better than climb milling, high feed/low speed better than low feed/high speed, high depth of cut better than low depth of cut, air coolant better than water coolant, diamond coating better than solid carbide, sand finishing better than chip removal, torus tools better than ball nose tools. Therefore, using metal machining strategy on composite curing tools leads to cracking and delaminations in the composite surface which causes the resin flow to infiltrate these cracks during the molding process. Consequently, parts demolding will destroy the surface of the curing tool and make it unusable without repair. The new technology approach will lead to a higher integrity of the composite surface and enhance the life cycle of the curing tool.

Mueller-Hummel, Peter

Synthesizing Metrology Technologies to Reduce Engineering Time for Large CNC Machine Compensation

2011-01-278010/18/2011

Very large multi-axis CNC machines offer a special challenge for efficient and accurate machine compensation. Aerospace applications demand tight tolerances, but conventional compensation methods become expensive for large machines. Volumetric compensation offers an approach for reducing costs and improving accuracies. A unique control architecture enabled by volumetric compensation enables the use of a single part program by multiple machines. Combining multiple technologies (a proprietary volumetric compensation solver program, Spatial Analyzer, API's Active Target, a laser tracker and bespoke CNC-Tracker communication software for measurement triggering) significantly reduces machine compensation time. Available analysis tools also enable the engineer to evaluate measurement uncertainties and determine the best locations for additional stations as well as quantify the accuracy benefits such stations would offer.

Flynn, Robert

Single, Stationary Lens Able to Create Microscopic 3D Images

TBMG-99235/1/2011

A lens that enables microscopic objects to be seen from nine different angles at once to create a 3D image has been developed. Other 3D microscopes use multiple lenses or cameras that move around an object; the new lens is the first single, stationary lens to create microscopic 3D images by itself.

Nozzles for Focusing Aerosol Particles

TBMG-884712/1/2010

Several nozzles have been designed to aerodynamically focus aerosol particles into a small-diameter jet, so that individual particles can be illuminated by a laser beam and their light scattering and/or laser-induced fluorescence (LIF) spectra can be measured. An additional nozzle can aerodynamically puff selected particles out of the airstream so that they can be sorted and collected.

Is It Time to Try Direct Digital Manufacturing?

TBMG-84589/1/2010

Over the past 20 years, additive manufacturing technology has migrated from use in rapid prototyping to a full-fledged manufacturing solution, which is referred to as “direct digital manufacturing” (or rapid manufacturing). Increasingly, companies are applying it to manufacturing applications, and with each success, they prove that it is a viable alternative. While the general concept of additive manufacturing is the same as when it was introduced 20 years ago, the change is in its intended use — production, not just prototyping. So while the concept has been around for a while, in the minds of many, direct digital manufacturing (DDM) is a new and difficult concept to understand.

Chemical Machining of Microscopic Holes and Grooves in Glass

TBMG-73392/5/2010

A technique for making precise, microscopic holes and grooves in glass workpieces has been invented. The technique differs from both (1) traditional macroscopic mechanical drilling and milling and (2) conventional micromachining that involves etching through photolithographically patterned masks. The technique can be used, for example, to make holes between 20 µm and 1 mm in diameter.

Making Complex Electrically Conductive Patterns on Cloth

TBMG-28626/1/2008

A method for automated fabrication of flexible, electrically conductive patterns on cloth substrates has been demonstrated. Products developed using this method, or related prior methods, are instances of a technology known as “e-textiles,” in which electrically conductive patterns are formed in, and on, textiles. For many applications, including high-speed digital circuits, antennas, and radio frequency (RF) circuits, an e-textile method should be capable of providing high surface conductivity, tight tolerances for control of characteristic impedances, and geometrically complex conductive patterns. Unlike prior methods, the present method satisfies all three of these criteria. Typical patterns can include such circuit structures as RF transmission lines, antennas, filters, and other conductive patterns equivalent to those of conventional printed circuits.

Spot Friction Welding of Mg-Mg, Al-Al and Mg-Al Alloys

2008-01-01444/14/2008

Spot friction welding is considered a cost-effective method for joining lightweight automotive alloys, such as magnesium and aluminum alloys. An experimental study was conducted to investigate the strength of spot friction welded joints of magnesium to magnesium, aluminum to aluminum, magnesium to aluminum and aluminum to magnesium. The joint structures and failure modes were also studied.

Agarwal, Lavish, Mallick, P. K., Kang, H. T.

Split-Block Waveguide Polarization Twist for 220 to 325 GHz

TBMG-26503/1/2008

A split-block waveguide circuit that rotates polarization by 90° has been designed with WR-3 input and output waveguides, which are rectangular waveguides used for a nominal frequency range of 220 to 325 GHz. Heretofore, twisted rectangular waveguides equipped with flanges at the input and output have been the standard means of rotating the polarizations of guided microwave signals. However, the fabrication and assembly of such components become difficult at high frequency due to decreasing wavelength, such that twisted rectangular waveguides become impractical at frequencies above a few hundred gigahertz. Conventional twisted rectangular waveguides are also not amenable to integration into highly miniaturized subassemblies of advanced millimeter- and submillimeter- wave detector arrays now undergoing development. In contrast, the present polarization-rotating waveguide can readily be incorporated into complex integrated waveguide circuits such as miniaturized detector arrays fabricated by either conventional end milling of metal blocks or by deep reactive ion etching of silicon blocks. Moreover, the present splitblock design can be scaled up in frequency to at least 5 THz.

Flexible Template for Drill Feed Units

2007-01-38509/17/2007

Flexi-Temp is the name give to the revolutionary design of drill jig that enables the drilling of holes that are normal to an exposed surface, without the need of a 5 axis machined drill jig. The Flexi-Temp jig is essentially a series of loose laminates that are held together using a 2-part drill jig bush. The loose jig can be pinned into piloted datum holes, allowing the jig to find the form of the work piece. The bushes / sleeves can be tightened / locked which creates a rigid jig, capable of withstanding applied forces during the drilling machine medium of your choice. Once set, the jig can be removed and refitted over and over, only requiring resetting for recertification purposes.

Wiemann, Axel, Leverington, Scott

Lug Cutting and Trimming of the Carbon Fibre Wing Panels of the Airbus A400m with Portable Hand Positioned Tools

2007-01-37959/17/2007

The Airbus A400m has carbon fibre wing panels on both the upper and lower surfaces. When manufactured, these panels come supplied with various lugs on the periphery of the panel. Some are used for lifting the panel, some are used for indexing the panel; however, all lugs must be removed at some time during wing build. Lug thickness varies from 4mm to 14mm; in addition, many lugs must be cut to a 2D profile rather than just straight. The main challenge of the project was to deliver a tool that was small, portable and compact, but that could also accurately slot thick carbon fibre panels, without de-lamination, leaving a good surface finish. The solution was an air powered routing hand tool that was mechanically guided along a 2D path using a cam profile. Special diamond grit cutters were used to cut the initial slot and reduce the machining forces to a bare minimum, with the finishing cut done using a PCD router bit to obtain a good surface finish.

Richards, Barry, Howard, Kenny, Williams, Stephen

Mechanical Alloying for Making Thermoelectric Compounds

TBMG-21869/1/2007

An economical room-temperature mechanical alloying process has been shown to be an effective means of making a homogeneous powder that can be hot-pressed to synthesize a thermoelectric material having reproducible chemical composition. The thermoelectric materials to which the technique has thus far been applied with success include rare-earth chalcogenides [La3–xTe4 (0 < x < 0.33) and La3–xYbyTe4 (0 < x < 1, 0 < y < 1)] and Zintl compounds (including Yb14MnSb11 and Yb14BiSb11). The synthesis of a given material consists of the room-temperature thermomechanical- alloying process followed by a hot-pressing process. Relative to synthesis of nominally the same material by a traditional process that includes hot melting, this synthesis is simpler and yields a material having superior thermoelectric properties.

Fabrication of Buried Nanochannels From Nanowire Patterns

TBMG-20197/1/2007

A method of fabricating channels having widths of tens of nanometers in silicon substrates and burying the channels under overlying layers of dielectric materials has been demonstrated. With further refinement, the method might be useful for fabricating nanochannels for manipulation and analysis of large biomolecules at single-molecule resolution. Unlike in prior methods, burying the channels does not involve bonding of flat wafers to the silicon substrates to cover exposed channels in the substrates. Instead, the formation and burying of the channels are accomplished in a more sophisticated process that is less vulnerable to defects in the substrates and less likely to result in clogging of, or leakage from, the channels.

Core-Cutoff Tool

TBMG-13843/1/2007

A tool makes a cut perpendicular to the cylindrical axis of a core hole at a predetermined depth to free the core at that depth. The tool does not damage the surrounding material from which the core was cut, and it operates within the core-hole kerf.

Automation for the Assembly of the Bottom Wing Panels on Stringers for the A320

2006-01-31439/12/2006

The paper details the two main phases of the research and development process which led to the current state on the stage 0 dedicated to the assembly of the A320 bottom panel on stringers and buttstraps. First phase: evaluation of the feasibility through trials on platform with a serial KUKA robot, evidence to achieve correctly 3/8" diameter and evidence of the difficulties to achieve the performances for the positioning accuracy. Second phase: development of specific solution on calibration and end effector, implementation on site, definitive performance proved during production.

Cibiel, Claude, Redman, Mike, Prat, Philippe

RASCAL Facility

TBMG-46322/1/2006

AFRL’s Radiation and Scattering Compact Antenna Laboratory (RASCAL) enables researchers to develop and evaluate advanced aperture technologies that support electronic warfare, radar, communication, and navigation— technologies supplementing a variety of applications as the “eyes and ears” of the warfighter. Current research efforts are concentrated on developing relatively small and inexpensive broadband, multifunctional antennas, as well as conformal and structurally integrated antennas for manned and unmanned air vehicles. Using the RASCAL facility, researchers can perform the necessary fabrication, simulation, testing, and measurement of aperture technologies.

Equipment for On-Wafer Testing From 220 to 325 GHz

TBMG-15421/1/2006

A system of electronic instrumentation, constituting the equivalent of a two-port vector network analyzer, has been developed for use in on-wafer measurement of key electrical characteristics of semiconductor devices at frequencies from 220 to 325 GHz. A prior system designed according to similar principles was reported in “Equipment for On-Wafer Testing at Frequencies Up to 220 GHz” (NPO-20760), NASA Tech Briefs, Vol. 25, No. 11 (November 2001), page 42. As one would expect, a major source of difficulty in progressing to the present higherfrequency- range system was the need for greater mechanical precision as wavelengths shorten into the millimeter range, approaching the scale of mechanical tolerances of prior systems.

Automated Fastening and Milling Machine for Complex Aircraft Structures

2005-01-328910/3/2005

The demands of fulfilling the continually increasing customer requirements always forces suppliers to improve their system solutions to be more-state-of-the-art. The fastening / milling machine discussed allows for the combined fastening / milling / drilling of complex aircraft structures. The equipment described fulfills high precision manufacturing requirements including economic constraints. The system provides flexibility to handle different aircraft panels and types. This paper is intended to describe and focus on the main aspects of this state-of-the-art technology in automated fastening / milling / drilling processes to meet the important customer production criteria. Furthermore, it shall explain the integration by presenting a current example of the process.

Neugebauer, Lutz, Conover, Dan

Finned-Ladder Slow-Wave Circuit for a TWT

TBMG-3811/1/2004

A finned-ladder structure has been invented in an effort to improve the design of the slow-wave circuit of a traveling-wave tube (TWT). The point of departure for the design effort was a prototype TWT that contains a ring-plane slow-wave circuit (see Figure 1). The design effort was a response to the observation that despite the high-power capabilities of the ring-plane TWT, its requirement for a high supply voltage and its low bandwidth have made it unacceptable for use outside a laboratory setting.

Adaptive Feedforward Chatter Suppression in Machining

2003-01-29159/8/2003

This paper presents a novel approach for active, on-line suppression of chatter in machining operations. The presence of chatter limits the material removal rate and therefore, lowers the productivity of machining processes. The goal of chatter suppression is to minimize the chatter amplitude and therefore extend the chatter stability boundary. Once the presence of chatter is detected the suppression system will be activated. A neural network model is used to calculate current gradient values with respect to the parameters of the active vibration source. These gradient information will be used by an optimization module to find the optimal set of parameters for the active vibration source. The overall result is an on-line, adaptable chatter suppression system. The methodology described is evaluated through simulation studies. The results show that the system is capable of suppressing chatter in single point cutting process.

Ghasempoor, A., Siddiqui, I.

Automated Serial Sectioning for 3D Reconstruction

TBMG-14428/1/2003

Figure 1 depicts some aspects of an apparatus and method for automated serial sectioning of a specimen of a solder, aluminum, or other relatively soft opaque material. The apparatus includes a small milling machine (micromiller) that takes precise, shallow cuts (increments of depth as small as 1 μm) to expose successive sections. A microscope equipped with an electronic camera, mounted in a fixed position on the micromiller, takes pictures of the newly exposed specimen surface at each increment of depth. The images are digitized, and the resulting data are subsequently processed to reconstruct three-dimensional (3D) features of the specimen.

Preparation of Regular Specimens for Atom Probes

TBMG-76506/1/2003

A method of preparation of specimens of non-electropolishable materials for analysis by atom probes is being developed as a superior alternative to a prior method. In comparison with the prior method, the present method involves less processing time. Also, whereas the prior method yields irregularly shaped and sized specimens, the present developmental method offers the potential to prepare specimens of regular shape and size.

Deforming Fibrous Insulating Tiles To Fit Curved Surfaces

TBMG-101012/1/2002

A curved tile of refractory silica-fiber-based or alumina-fiber-based thermal-insulation material can be formed from an initially flat billet in a process that includes pressing against a curved mold surface during heating. The mold or tile curvature can be concave or convex. Curved tiles are needed for thermal protection of curved surfaces of spacecraft reentering the terrestrial atmosphere; curved thermal-protection tiles may also be useful on Earth in some industrial applications.

Die Development and Manufacturing Through Standardization, Geometric 3D Data, and Computing Resources

2002-01-349711/19/2002

This paper presents an efficient methodology for the development and manufacturing of production resources for the trimming and shaping of sheet-metals, also known as trim, fold, forming, and flanging dies, among others. This methodology is synthesized in the standardization and structuring concept of the items that make up the stamping tool set. By means of computing resources, such as CAD systems, and the adoption of this method, it is possible to generate solid tridimensional models, even from a complex set of tools for stamping. This information will be essential to reduce time and cost at the tool design and manufacturing stages.

de Paula, Flavio Gesca Verissimo

Lightweight Foam Pads for Helmets

TBMG-725211/1/2002

Special foam pads have been developed for use in helmets. The foams in these pads have been formulated to obtain a combination of light weight, resistance to oxidation, flame retardance, superior shock-absorbing properties, and physical comfort during long use. In the original application, the pads are intended especially for use in supporting the heads of reclining astronauts during launch, providing a slight upward tilt so that the astronauts can see critical panels, switches, and checklists more easily. Modified versions of the pads and foams may be useful on Earth in helmets for motorcyclists, athletes, and others.

Millimeter-Wave Dichroic Plates for High Angles of Incidence

TBMG-73978/1/2001

Dichroic plates for cutoff wavelengths down to about a millimeter and high angles of incidence can be fabricated by numerically controlled milling of rectangular arrays of waveguide slots in half-wavelength-thick metal plates. A plate of this type is used to separate higher- and lower-frequency components of incident electromagnetic radiation linearly polarized along a specified axis; the plate is designed to reflect most of the incident electromagnetic radiation at frequencies below its cutoff frequency while allowing most of the radiation at higher frequencies to pass through.

Making Submicron Features by Ion Etching Through PMMA Masks

TBMG-2964810/1/2000

Experiments have shown that a substrate can be patterned with submicron features by the following procedure:

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