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One-piece, composite crucible with integral withdrawal/discharge section

Description: A one-piece, composite open-bottom casting mold with integral withdrawal section is fabricated by thermal spraying of materials compatible with and used for the continuous casting of shaped products of reactive metals and alloys such as, for example, titanium and its alloys or for the gas atomization thereof.
Date: July 30, 2002
Creator: Besser, Matthew (Iowa State Univ., Ames, IA); Terpstra, Robert L. (Iowa State Univ., Ames, IA); Sordelet, Daniel J. (Iowa State Univ., Ames, IA); Anderson, Iver E. (Iowa State Univ., Ames, IA); Hartman, Alan D.; Argetsinger, Edward R. et al.
Partner: UNT Libraries Government Documents Department

Manufacturing injection-moleded Fresnel lens parquets for point-focus concentrating photovoltaic systems

Description: This project involved the manufacturing of curved-faceted, injection-molded, four-element Fresnel lens parquets for concentrating photovoltaic arrays. Previous efforts showed that high-efficiency (greater than 82%) Fresnel concentrators could be injection molded. This report encompasses the mold design, molding, and physical testing of a four-lens parquet for a solar photovoltaic concentrator system.
Date: October 1, 1995
Creator: Peters, E.M. & Masso, J.D.
Partner: UNT Libraries Government Documents Department

Gelcasting of silicon preforms for the production of sintered reaction-bonded silicon nitride

Description: Gelcasting of silicon metal for the production of sintered reaction-bonded silicon nitride (SRBSN) was investigated in order to identify associated advantages over conventional forming techniques, i.e., die and isostatic pressing. Compacts were formed from identical powder mixtures by both gelcasting and pressing, and were nitrided and sintered to produce SRBSN ceramics using both conventional and microwave heating. Characterization of the samples included measurement of green density, green and nitrided pore structure, weight gain during nitridation, final density, microstructure, toughness, and flexural strength. It was found that a more uniform pore structure existed in the green gelcast samples. It is believed that this pore configuration aided in nitridation, and manifested itself in a more uniform final microstructure. In addition, improved mechanical properties were achieved in the gelcast samples. This improvement can be attributed to green microstructure homogeneity. An additional finding of this study was that microwave hearing combined with gelcast forming resulted in SRBSN materials with improved mechanical properties.
Date: December 1995
Creator: Kiggans, J. O., Jr.; Nunn, S. D.; Tiegs, T. N.; Davisson, C. C.; Coffey, D. W. & Maria, J.P.
Partner: UNT Libraries Government Documents Department

Rapid tooling by electron-beam vapor deposition

Description: Electron-beam physical vapor deposition (EBPVD) of tooling metal, onto a shaped substrate to produce a replica of the substrate surface, offers the potential for significant cost savings over present methods of injection mold manufacturing. These savings are realized by the high deposition rate and the corresponding short manufacturing times provided by the EBPVD process. However, on route to realizing these gains, there are process technical issues which need to be resolved. Mold surfaces typically contain relatively high aspect ratio details that must be replicated to dimensional tolerances within +/- 2 mils. The deposited mold material must also provide high surface hardness and high fracture toughness. Good quality grain structure can be obtained in deposited Al 10-wt% Cu mold material when the substrate and corresponding deposit are at high process temperature. However, the resulting mold is subject to distortion during cooldown due to differential temperatures and shrinkage rates. Thermally controlled cooldown and the use of crushable substrate materials reduce these distortions, but not to the required levels of tolerance. Deposition of the Al-Cu at lower temperature produces columnar, poorly joined grains which result in a brittle and weakened mold material. When Al 10-wt% Cu metal vapor is deposited across high aspect ratio step features on the substrate surface, a grain growth defect can form in the step-shadowed regions of the deposited material, alongside the step feature. The step coverage defect consists of entrained voids which persist at intermediate deposition temperatures and produce a weakened mold. This final 1997 LDRD report investigates causes of this step coverage defect and offers methods for their control and elimination.
Date: February 25, 1998
Creator: Meier, T. C., LLNL
Partner: UNT Libraries Government Documents Department

Fastcast: Integration and application of rapid prototyping and computational simulation to investment casting

Description: The emergence of several rapid prototyping and manufacturing (RP and M) technologies is having a dramatic impact on investment casting. While the most successful of the rapid prototyping technologies are almost a decade old, relatively recent process advances in their application have produced some remarkable success in utilizing their products as patterns for investment castings. Sandia National Laboratories has been developed highly coupled experimental and computational capabilities to examine the investment casting process with the intention of reducing the amount of time required to manufacture castings, and to increase the quality of the finished product. This presentation will begin with process aspects of RP and M pattern production and handling, shell fabrication, burnout, and casting. The emphasis will be on how the use of Stereolithography (SL) or Selective Laser Sintered (SLS) patterns differs from more traditional wax pattern processes. Aspects of computational simulation to couple design, thermal analysis, and mold filling will be discussed. Integration of these topics is probably the greatest challenge to the use of concurrent engineering principles with investment casting. Sandia has conducted several experiments aimed at calibrating computer codes and providing data for input into these simulations. Studies involving materials as diverse as stainless steel and gold have been conducted to determine liquid metal behavior in molds via real time radiography. The application of these experiments to predictive simulations will be described.
Date: September 1, 1996
Creator: Maguire, M.C.; Baldwin, M.D. & Atwood, C.L.
Partner: UNT Libraries Government Documents Department

Clean ferrous casting technology research. Final technical report, September 29, 1993--December 31, 1995

Description: This is the final report covering work performed on research into methods of attaining clean ferrous castings. In this program methods were developed to minimize the formation of inclusions in steel castings by using a variety of techniques which decreased the tendency for inclusions to form during melting, casting and solidification. In a second project, a reaction chamber was built to remove inclusions from molten steel using electromagnetic force. Finally, a thorough investigation of the causes of sand penetration defects in iron castings was completed, and a program developed which predicts the probability of penetration formation and indicates methods for avoiding it.
Date: January 31, 1996
Creator: Bates, C.E.; Griffin, J.; Giese, S.R. & Lane, A.M.
Partner: UNT Libraries Government Documents Department

Gelcasting of CRYSTAR{reg_sign} silicon carbide ceramics. CRADA final report

Description: This Cooperative Research and Development Agreement (CRADA) was undertaken to assess the applicability the gelcasting process for forming ceramic green bodies using Saint-Gobain/Norton Industrial Ceramics Corporation`s proprietary CRYSTAR{reg_sign} silicon carbide powder. A gelcasting process, specifically tailored to Saint-Gobain/Norton`s powder composition, was developed and used successfully to form green bodies for property evaluation. This preliminary evaluation showed that the gelcast material had characteristics and properties comparable to Norton`s baseline material. Wafer carrier molds were received from Norton for gelcasting a complex-shaped configuration with CRYSTAR{reg_sign} silicon carbide. Gelcasting experiments showed that Norton`s standard plaster of paris molds were incompatible with the gelcasting process. Mold surface treatments and the use of alternative castable mold materials were investigated, however, a successful process was not identified. The highest quality parts were cast in either glass or aluminum molds.
Date: December 31, 1998
Creator: Nunn, S.D. & Willkens, C.A.
Partner: UNT Libraries Government Documents Department

Heat transfer at the mold-metal interface in permanent mold casting of aluminum alloys project. Quarterly project status report, January 1, 1998--March 31, 1998

Description: There have been numerous developments in the current project over the last three months. The most appropriate geometries for performing the interfacial heat transfer studies have been discussed with both of our Industrial Partners. Both companies have molds which may be available for adaptation to record the thermal history during casting required for determining interfacial heat transfer coefficients. The details of what instrumentation would be the most appropriate remain to be worked out, but the instrumentation would likely include thermocoupling in the mold cavity as well as in the mold wall, as well as pressure sensors in the squeeze casting geometry molds and ultrasonic gap monitoring in the low pressure and gravity fed permanent mold geometry molds. The first advisory committee meeting was held on February 6th, and the steering committee was apprised of the objectives of the program. The capabilities of the Industrial Partners were reviewed, as well as the need for the project to make use of resources from other CMC projects. The second full Advisory Committee Meeting will be held in early May.
Date: March 31, 1998
Creator: Pehlke, R.D.; Hao, Shouwei & Cookson, J.M.
Partner: UNT Libraries Government Documents Department

Injection Molding of Plastics from Agricultural Materials

Description: The objective of this research was to conduct a systematic study to relate injection molding parameters to properties of blends of starch and synthetic polymer. From this study, we wished to develop a thorough understanding of the injection molding process and gain significant insight into designing molds and aiding in developing products cheaply and efficiently.
Date: February 22, 2001
Creator: Bhattacharya, M. & Ruan, R.
Partner: UNT Libraries Government Documents Department

Dimensional errors in LIGA-produced metal structures due to thermal expansion and swelling of PMMA.

Description: Numerical methods are used to examine dimensional errors in metal structures microfabricated by the LIGA process. These errors result from elastic displacements of the PMMA mold during electrodeposition and arise from thermal expansion of the PMMA when electroforming is performed at elevated temperatures and from PMMA swelling due to absorption of water from aqueous electrolytes. Both numerical solutions and simple analytical approximations describing PMMA displacements for idealized linear and axisymmetric geometries are presented and discussed. We find that such displacements result in tapered metal structures having sidewall slopes up to 14 {micro}m per millimeter of height for linear structures bounded by large areas of PMMA. Tapers for curved structures are of similar magnitude, but these structures are additionally skewed from the vertical. Potential remedies for reducing dimensional errors are also discussed. Here we find that auxiliary moat-like features patterned into the PMMA surrounding mold cavities can reduce taper by an order of magnitude or more. Such moats dramatically reduce tapers for all structures, but increase skew for curved structures when the radius of curvature is comparable to the structure height.
Date: April 1, 2004
Creator: Kistler, Bruce L.; Dryden, Andrew S.; Crowell, Jeffrey A.W. & Griffiths, Stewart K.
Partner: UNT Libraries Government Documents Department

Final Report: PSP No.14402-10-02 Improved Manufacturing of MC4531 Mold Bodies Using High-Speed Machining

Description: Document is the final report for PSP project No. 14402-10-02 entitled ''Improved Manufacturing of MC4531 Mold Bodies Using High-Speed Machining (HSM)''. The basic physics of high speed machining is discussed in detail including multiple vibrational mode machining systems (milling and turning) and the effect of spindle speed regulation on maximizing the depth of cut and metal removal rate of a machining operation. The topics of cutting tests and tap tests are also discussed as well as the use of the HSM assistance software ''Harmonizer''. Results of the application of HSM to the machining of encapsulation molds are explained in detail including cutting test results, new tool speeds and feeds, dimensional and surface finish measurements and a comparison to the original machining operations and cycle times. A 38% improvement in cycle time is demonstrated while achieving a 50% better surface finish than required.
Date: October 2002
Creator: Jokiel, Bernhard, Jr.
Partner: UNT Libraries Government Documents Department

Application of statistical methods for analyzing the relationship between casting distortion, mold filling, and interfacial heat transfer in sand molds

Description: This report presents a statistical method of evaluating geometric tolerances of casting products using point cloud data generated by coordinate measuring machine (CMM) process. The focus of this report is to present a statistical-based approach to evaluate the differences in dimensional and form variations or tolerances of casting products as affected by casting gating system, molding material, casting thickness, and casting orientation at the mold-metal interface. Form parameters such as flatness, parallelism, and other geometric profiles such as angularity, casting length, and height of casting products were obtained and analyzed from CMM point cloud data. In order to relate the dimensional and form errors to the factors under consideration such as flatness and parallelism, a factorial analysis of variance and statistical test means methods were performed to identify the factors that contributed to the casting distortion at the mold-metal interface.
Date: March 31, 1999
Creator: Owusu, Y. A.
Partner: UNT Libraries Government Documents Department

Optimization of the gelcasting of a silicon nitride formulation

Description: An optimum gelcasting condition for a silicon nitride formulation was determined using the Taguchi statistical method. An L{sub 8}(4{sup 1} {times} 2{sup 4}) design, in which the effects of one factor at four levels and four factors at two levels were evaluated in only eight experiments, was used. The factors at two levels were: the total monomer concentration, the monomer/crosslinker ratio, the initiator concentration, and the initiator/catalyst ratio; the factor at four levels was the initiator concentration per mass of the slip. The primary criterion used to determine optimum design was the green strength of the dried part, although three other parameters were measured: initial slip viscosity, time for the slip viscosity to reach 300 mPa.s. at 25 C, and time for the slip to gel at 50 C. The optimum gelcasting conditions from the designed experiments predicted 80% increase in green strength (4.3 MPa versus 2.4 MPa, the initial value). The confirmation runs showed only a 60% increase (3.8 MPa).
Date: June 1, 1995
Creator: Omatete, O.O.; Pollinger, J.P. & O`Young, K.
Partner: UNT Libraries Government Documents Department

Sol-gel replicated optics made from single point diamond turned masters exhibit fractal surface roughness

Description: Deterministic optics manufacturing, notably single point diamond turning (SPDT) has matured such that the current generation of machines is capable of producing refractive and reflective optics for the visible wavelength region that are quite acceptable for many applications. However, spiral tool marks are still produced that result in unwanted diffractive scattering from grating-like features having a spatial frequency determined by the machine feed, tool radius, and other influences such as vibration and material removal effects. Such regular artifacts are the characteristic of deterministic manufacturing methods such as SPDT. The authors present some initial findings suggesting that fractal, or non-deterministic surfaces can be produced by SPDT through sol-gel replication. The key is the large isotropic shrinkage that occurs through monolithic sol-gel replication (a factor of 2.5) that results in all features, including tooling marks, being reduced by that amount. The large shrinkage itself would be a laudable-enough feature of the replication process. However, by an as-yet-not understood manner, the replication process itself seems to alter the roughness character of the replicated surface such that it appears to be fractal when analyzed using contact profilometry and the power spectrum approach.
Date: May 1, 1996
Creator: Bernacki, B.E.; Miller, A.C. Jr.; Evans, B.M. III; Moreshead, W.V. & Nogues, J.L.R.
Partner: UNT Libraries Government Documents Department

Rapid tooling for functional prototyping of metal mold processes: Literature review on cast tooling

Description: This report is a literature review on cast tooling with the general focus on AISI H13 tool steel. The review includes processing of both wrought and cast H13 steel along with the accompanying microstructures. Also included is the incorporation of new rapid prototyping technologies, such as Stereolithography and Selective Laser Sintering, into the investment casting of tool steel. The limiting property of using wrought or cast tool steel for die casting is heat checking. Heat checking is addressed in terms of testing procedures, theories regarding the mechanism, and microstructural aspects related to the cracking.
Date: November 1, 1995
Creator: Baldwin, M.D. & Hochanadel, P.W.
Partner: UNT Libraries Government Documents Department

Hybrid optics for the visible produced by bulk casting of sol-gel glass using diamond-turned molds

Description: Recent combinations of diffractive and refractive functions in the same optical component allow designers additional opportunities to make systems more compact and enhance performance. This paper describes a research program for fabricating hybrid refractive/diffractive components from diamond-turned molds using the bulk casting of sol-gel silica glass. The authors use the complementary dispersive nature of refractive and diffractive optics to render two-color correction in a single hybrid optical element. Since diamond turning has matured as a deterministic manufacturing technology, techniques previously suitable only in the infrared are now being applied to components used at visible wavelengths. Thus, the marriage of diamond turning and sol-gel processes offers a cost-effective method for producing highly customized and specialized optical components in high quality silica glass. With the sol-gel casting method of replication, diamond-turned mold costs can be shared over many pieces. Diamond turning takes advantage of all of the available degrees of freedom in a single hybrid optical element: aspheric surface to eliminate spherical aberration, kinoform surface for control of primary chromatic aberration, and the flexibility to place the kinoform on non-planar surfaces for maximum design flexibility. The authors discuss the critical issues involved in designing the hybrid element, single point diamond-turning the mold, and fabrication in glass using the sol-gel process.
Date: July 1, 1995
Creator: Bernacki, B. E.; Miller, A. C.; Maxey, L. C.; Cunningham, J. P.; Moreshead, W. V. & Nogues, J. L. R.
Partner: UNT Libraries Government Documents Department

Castability Assessment and Data Integration

Description: The report is divided into two sections. The first section deals with Equilibrium Analysis and Fill Pattern Reasoning for Die Casting Process. The second section covers Graphical User Interface for Cooling Line Functions and Surface Rendering.
Date: March 31, 2005
Creator: Miller, R. Allen
Partner: UNT Libraries Government Documents Department

''Heat Transfer at the Mold-Metal Interface in Permanent Mold Casting of Aluminum Alloys'' Final Project Report

Description: This project on heat transfer coefficients in metal permanent mold casting has been conducted in three areas. They are the theoretical study at the University of Michigan, the experimental investigation of squeeze casting at CMI-Tech Center (Now Hayes-Lemmerz Technical Center) and the experimental investigation of low pressure permanent mold casting at Amcast Automotive.
Date: December 14, 2001
Creator: Professor R. D. Pehlke, Principal Investigator, Dr. John M. Cookson, Dr. Shouwei Hao, Dr. Prasad Krishna, Kevin T. Bilkey
Partner: UNT Libraries Government Documents Department

Die casting die deflections: Prediction and attenuation. Final report, July 1, 1995--September 30, 1997

Description: The objective of this work was to develop and test die casting design evaluation techniques based on the visualization of geometric data that is related to potential defects or problems. Specifically, thickness information is used to provide insight into potential thermal problems in the part and die. Distance from the gate and a special type of animation of the fill pattern is used to provide an assessment of gate, vent and overflow locations. Techniques have been developed to convert part design information in the form of STL files to a volume-based representation called a voxel model. The use of STL files makes the process CAD system independent. Once in voxel form, methods that were developed in this work are used to identify thick regions in the part, thin regions in the part and/or die, distance from user specified entry locations (gates), and the qualitative depiction of the fill pattern. The methods were tested with a prototype implementation on the UNIX platform. The results of comparisons with numerical simulation and field reported defects were surprisingly good. The fill-related methods were also compared against short-shots and a water analog study using high speed video. The report contains the results of the testing plus detailed background material on the construction of voxel models, the methods used for displaying results, and the computational geometric reasoning methods used to create die casting-related information from the voxel model for display to the user.
Date: May 1, 1998
Creator: Miller, R.Allen; Ahuett-Garza, Horacio; Choudhury, Aswin K. & Dedhia, Sanjay
Partner: UNT Libraries Government Documents Department

Computer simulation of the mold heating and cooling control loop, using conventional control strategies

Description: Mathematical models of the mold and fluid temperature responses were developed experimentally. Those models were then used with a digital computer simulation program in an effort to duplicate mathematically the physical plant dynamic response. The simulation program underwent a series of evolutionary steps until satisfactory duplication of the processes existed. Various control strategies were then simulated. The evolution of the simulation program and the simulation results are presented.
Date: February 1, 1978
Creator: Floersch, R.H.
Partner: UNT Libraries Government Documents Department

Reusable molds for casting U-Zr alloys

Description: Refractory oxides, carbides, nitrides and sulfides were examined as mold coating materials for use in casting nuclear fuel. The molds require excellent high temperature chemical and mechanical stability combined with reasonable room temperature ductility to allow for fuel removal. Coatings were applied onto quartz and refractory metal coupons using various techniques. Sessile drop tests employing molten U-10%Zr (by weight) at 1550{degrees}C were used to characterize coating performance. Results indicate that NbC, TiN, and Y{sub 2}O{sub 3} were non-wetting with U-10%Zr. However, only the Y{sub 2}O{sub 3} coating completely prevented adhesion of the fuel. The paper describes coating methods and details of the sessile drop experiments.
Date: September 1, 1992
Creator: Chen, P. S.; Stevens, W. C. & Trybus, C. L.
Partner: UNT Libraries Government Documents Department

Mold-filling experiments for validation of modeling encapsulation. Part 1, "wine glass" mold.

Description: The C6 project 'Encapsulation Processes' has been designed to obtain experimental measurements for discovery of phenomena critical to improving these processes, as well as data required in the verification and validation plan (Rao et al. 2001) for model validation of flow in progressively complex geometries. We have observed and recorded the flow of clear, Newtonian liquids and opaque, rheologically complex suspensions in two mold geometries. The first geometry is a simple wineglass geometry in a cylinder and is reported here in Part 1. The results in a more realistic encapsulation geometry are reported in Part 2.
Date: June 1, 2005
Creator: Castaneda, Jaime N.; Grillet, Anne Mary; Altobelli, Stephen A. (New Mexico Resonance, Albuquerque, NM); Cote, Raymond O. & Mondy, Lisa Ann
Partner: UNT Libraries Government Documents Department