ANCORBOND™ Technical Publications
190. Segregation-free Premixes for Increased Productivity and Improved Performance: Powder mixes used in the PM industry contain ingredients of substantially different particle sizes and specific gravities that have a strong tendency to segregate during handling. Reducing or eliminating this segregation is essential for the part producer to achieve consistent precision and optimum performance. Treating the premixes with polymer binders helped to resolve this problem. Binder/lubricant systems have been developed that provide improved flow rates combined with increased green densities and green strengths. A review of these developments will be presented and their impact on overall productivity and performance will be outlined.
131. Methods to Improve the Fatigue Life of Sinter-Hardened Components: Previous experimental work showed that fatigue performance is affected by the alloy system, heat treatment method, and microstructural features of test specimens. The present study will present information concerning the effects of varying the sinter-hardening cooling rate (and subsequent microstructure features) on the mechanical properties sinter-harden steels and the Ancorloy® MDCL material system. Emphasis will be given to the rotating bending fatigue performance of these systems and how this experimental data correlates with the fatigue performance of the actual component in accelerated life testing.
100. Higher Green Strength Enhancements to Increase Process Robustness: The use of binder-treated premixes has grown dramatically since the introduction of the technology in the late 1980's. Decreased levels of respirable dust coupled with reduced segregation and significantly improved powder flow have helped to stimulate this growth. More recently, binder-treated premixes that significantly enhance the green strength of PM parts have been developed. The higher green strength results in more robust handling of green parts prior to the sintering operation and reduced levels of green scrap. In addition, the significantly higher green strength provides an opportunity for "green" machining of the PM parts prior to sintering. This paper will discuss recent advances in binder-treatment technology and will review production experience with binder-treated premixes.
87. Advances in Binder-Treatment Technology: The use of binder-treated premixes has grown dramatically since the introduction of the technology in the late 1980's. Decreased levels of respirable dust coupled with reduced amounts of alloy addition segregation and significantly improved powder flow have helped to stimulate this growth. More recently, binder-treated premixes have been developed that significantly enhance the green strength of PM parts. The higher green strength results in more robust green parts for handling prior to the sintering operation and reduced levels of green scrap. In addition, the significantly higher green strength provides the opportunity for "green" machining of the PM parts prior to sintering. This paper will discuss recent advances in binder-treatment technology and will review production experience with binder-treated premixes.
72. Advances in Binder - Treatment Technology Statistical Data on ANCORBOND™ Plus: Binder treatment technology has been well accepted in the marketplace to provide reduced segregation and better powder flowability. However, there is a need to increase the green strength of some parts for better handling of intricate shapes and also a need to improve the bonding of nickel and copper. ANCORBOND Plus is an engineered bonding technology that can produce very high green strength and green density based on conventional compaction processing. The system, which uses a zincless lubricant, is based on the optimization of the bonding mechanism and binder chemistry. This paper will present statistical data collected on parts processed in a production press.
65. Ancorloy® Premixes: Binder Treated Analogs of the Diffusion Alloyed Steels: The properties at two carbon levels of binder treated analogs of the diffusion alloyed steels are presented. These Ancorloy premixes are made according to a proprietary practice that does not include diffusion alloying. It is shown by direct comparison with compositionally similar premixes of the diffusion alloyed steels that the Ancorloys generally exhibit similar powder, green and dimensional change properties and significantly enhanced mechanical properties. Tensile, impact and fatigue property data in the sintered, sintered and tempered and quenched and tempered conditions are presented.
58. Higher Green Strength and Improved Density by Conventional Compaction: A new material system that can produce very high green strength and green density has been developed for conventional compaction processing. The system, which uses a zincless lubricant, is based on the optimization of the bonding mechanism and binder chemistry. This approach permits the bonding of copper particles in a FC-0208 mix. Examples of the binder-treatment of FN-0208, Ancorsteel® 145P, and Ancorsteel® 150 HP are also included.
57. Application of High Performance Binder-Treated Materials: Binder treated materials such as ANCORBOND™ and ANCORDENSE™ increase the performance characteristics of ferrous powder premixes and PM parts. This paper will discuss the various characteristics of binder treated premixes and their potential applications. A review of the mechanical properties of ANCORDENSE materials will be presented.
46. Recent Applications of Binder Treatment Technology: The development of a practical binder treatment process in the late 1980's has since led to the commercialization of several new premix technologies that have had a major impact on PM competitiveness. To date, a great deal has been written about these technologies. However, until now, there has been little to suggest that they are inherently interrelated by a common approach, or that this approach has untapped potential for still newer and better technologies. In addition, it also happens that in spite of all that has been written on the existing technologies, there is nothing that serves as a comprehensive single source of information on all of them. Consequently, the purpose of the present paper is to document the indicated approach as well as to present a summary description of each of the technologies complete with one or more production case histories of recent origin. The aim of the latter is to present discriminating up-to-date examples of general interest as well as to highlight one or more of the various advantages of the associated technology.
39. Continuing Improvements in Binder Treatment Technology: The binder-lubricant concept in which the binder acts to lubricate as well as to bond is introduced. The binder treatment effects on premix properties of an ordinary binder versus one with lubricating properties are compared. It is shown that the lubricating binder is superior in terms of its effects on compressibility and die ejection forces. Otherwise, it is shown to be similar to the ordinary binder in suppressing dusting and segregation, and improving powder flow.
38. Powder Metallurgy Gears - Expanding Opportunities: Powder metallurgy (PM) is a precision metal forming technology for the manufacturing of parts to net, or near net shape. The powder metallurgy process is illustrated schematically in Figure 11. There are three basic steps to producing parts; mixing, compacting, and sintering. Variations to these basic steps such as infiltration, double pressing/double sintering, and powder forging may be used to achieve higher density parts. A sizing operation may be used to qualify critical part dimensions. Alternatively, a machining step may be added for the same purpose or to achieve a geometric feature not possible during rigid die compaction. PM parts may be through hardened or surface hardened as required by the intended application.
33. An Investigation Into the Effects of Processing Methods on the Mechanical Characteristics of High Performance Ferrous PM Materials: The mechanical properties of high performance ferrous PM materials are influenced by the material composition and processing method. This paper investigates the effects of the ANCORDENSE™ process, a new, high density, single compaction method, on the mechanical properties of Distaloy® 4800A based materials. The results of this study are discussed with a comparison to the mechanical properties for the same materials developed through single-pressed and double-pressed, doublesintered processing methods. In addition, a case study is performed on a component produced via the ANCORDENSE method.
28. Dust and Segregation-Free Powders For Flexible PM Processing: During the past few years, there has been increasing demand placed on PM parts producers to improve density uniformity, weight variation, alloy homogeneity and dimensional control. Enhanced flow and die fill characteristics are also required to improve productivity and reduce the percentage of green scrap. The ANCORBOND™ process developed by Hoeganaes has satisfied many of these requirements by bonding the alloy additives and fines to the base iron particles. Increased concerns regarding the inability to retrofit higher apparent density premixes to existing tool sets, a slight loss of compressibility and the desire to reduce the total organic content for improved burnout response led to further improvements in the bonding process. Several factors that contribute to the performance and greater flexibility of binder-treated mixes compared with regular mixes will be discussed in this paper.
27. Recent Developments in Ferrous Powder Metallurgy Alloys: A systems approach to engineered ferrous powder metallurgy (PM) materials is described. The approach encompasses the use of high compressible, high performance powders in premixes produced using proprietary mixing technology that employs patented binders. To ensure that an appropriate microstructure is achieved to suit the functional requirements of a particular application, alloys are formulated based on knowledge of the compaction and sintering cycle that will be used to make the PM parts. These premixes have improved flow and die filling characteristics that result in greater consistency throughout the entire PM part manufacturing process. In addition, the use of binder treated premixes leads to reduced dusting and segregation of alloy additions. Binder treated premixes produced using high compressible, prealloyed molybdenum steel powders are shown to be particularly well suited for quench-hardening, sinter-hardening, and high temperature sintering. They also form the basis for a series of chromium, manganese, and chrome-manganese PM Steels. The systems approach will be augmented during 1994 by the introduction of new material and process technology that enables part densities of 7.3 to 7.5 g/cm3 to be achieved through single compaction processing.
26. High Performance Ferrous PM Materials For Automotive Applications: The majority of automotive components (transmission, chassis, suspension, and engine) for which parts with densities up to about 7.0 g/cm3 are suitable have already been converted to PM and there are few opportunities for growth in this density range. In order to meet the requirements of more demanding applications there has been a trend toward higher densities through the use of infiltration, double pressing/double sintering, or powder forging (l - 4) to produce parts such as synchronizer hubs, crankshaft sprockets, chain sprockets, gerotors, steering column tilt levers, planetary gear carriers, parking gears shift levers, and connecting rods. While powder forging has been shown capable of producing parts, which are superior to wrought, or cast products process economics have limited market penetration by this technology (5). The double press and sinter route also adds process costs and is probably too expensive for other than premium applications. There is a real need for a systems approach that will permit double pressed and sintered or infiltrated performance characteristics to be achieved by means of single compaction processing. The mechanical properties of PM materials are directly related to their microstructure and the size, distribution, and morphology of the porosity they contain. Alloying additions are made to develop specific material performance characteristics. However, the manner in which the alloys are constituted has a significant effect on the porosity and microstructure of the final product (6).
17. Sinter-Hardening Low-Alloy Steels: The availability of prealloyed steel powders employing molybdenum as the major alloying element offers new levels of compressibility and mechanical properties. When the prealloyed powders are combined with conventional PM additives such as copper, nickel and graphite, it is possible to develop high strength martensitic microstructures directly from the sintering cycle. The impact and tensile properties of copper, nickel, graphite premixes based upon the prealloyed molybdenum steels are compared under controlled cooled conditions. The ability to balance tensile strength, toughness and hardness by control of alloy chemistry is illustrated.
16. High Performance Ferrous PM Materials Utilizing High Temperature Sintering: Several new and more challenging PM applications require materials that exhibit higher strength along with improved dynamic property characteristics. To meet these requirements, development efforts focused on material grades capable of achieving high performance properties when sintered at elevated temperature. Several elements, specifically nickel and copper, were admixed to the water atomized, prealloyed low-alloy steel powders Ancorsteel® 85 HP and 150 HP using the patented ANCORBOND™ process. Tensile and impact performance of the resulting materials have been reviewed along with quantitative metallography of selected as-sintered samples. The results indicate the type and amount of each admixed element plays an important role in achieving specific characteristics. In addition, the overall performance values are greater for the single press and sinter technique used in this investigation than could previously be achieved using a double press - double sinter process.
12. Improved Dimensional Control and Elimination of Heat Treatment for Automotive Parts: The automotive industry has expressed concern about the general quality of heat treatment (austenization and quenching) and the desire to reduce or eliminate dependence upon this process whenever possible. Therefore, in a continuing effort for improvement during the past year, a process has been developed that eliminates the conventional heat treating operation for some applications. Some of these finished parts require both a high impact strength and a hardened wear resistant surface. The Charpy impact, tensile and TRS properties of a binder treated premix based on a partially alloyed powder have been evaluated utilizing a variety of processing conditions. These include various carbon contents, sintering temperatures and sintering times. Quantitative metallography was used to evaluate the pore size, pore shape and microstructural constituents present as a result of the various materials and processes. These factors were then correlated with the measured properties.
9. Properties of Parts Made from ANCORBOND™ Processed Carbon-Nickel-Steel Powder Mix(FN-0208): Studies were conducted to determine the effects on property variability of parts made from a bonded Ancorsteel 1000 mix containing 0.95% graphite, 2.0% nickel, 0.6% Acrawax and 0.3% zinc stearate. The part geometry studied was that of a cylindrical bushing. The treatment effects on powder properties and on several parts properties were determined. The powder properties included the traditional green and sintered properties and the graphite and nickel dusting resistance's. The parts properties surveyed included both green and sintered properties and sintered carbon and nickel contents. Similar studies of a companion regular mix of nominally the same composition were conducted for purposes of comparison. Compared with the regular mix, the bonded mix exhibited marked improvements in graphite and nickel dusting resistance and in powder flow properties. In the parts-making study, the bonded mix showed significant differences in mean dimensional change characteristics but was otherwise reasonably similar to the regular mix in terms of mean property values. In the case of variability, the bonded mix was statistically equivalent in green and sintered dimensional change characteristics and sintered nickel content but otherwise significantly improved relative to the regular mix in all of the other properties of interest. The latter included green weight and density and sintered density, hardness, crush strength and carbon content. The variability improvements in the parts from the bonded mix were attributed both to the effects of the binder treatment in improving powder flow properties and reducing carbon segregation. The difference in mean dimensional change characteristics between the parts from the bonded mix and those from the regular mix were also attributed to the effect of the binder treatment in improving alloy admix uniformity. The fact that the parts variability improvements of the bonded mix did not extend to the dimensional change characteristics was suspected to be due largely to a purely statistical effect arising from the dissimilarity in the mean dimensional change values relative to those of the regular mix. A limited laboratory-scale study was subsequently conducted to examine this possibility. In general, the findings supported the idea. In addition, they also presented a strong indication that it may be possible by virtue of the ANCORBOND process to effect significant reductions in the nickel contents of graphite-nickel mixes without sacrificing either mechanical 2 properties or dimensional change characteristics.
5. Statistical Process Control in Iron Powder Production and New Product Development: SPC is discussed with a view to indicating its implications not only to manufacturing and quality but to research and product development as well. In the manufacturing/quality area, the efforts and methods attending full-scale implementation of SPC are briefly reviewed with special reference to the differences inherent in powder making versus manufacturing of parts. SPC charting techniques suitable for powder making are described and discussed. In the product development area, it is shown how SPC influenced a major research program. The objective of the program was to improve premixed products with a view to reducing variability in parts manufacturing. ANOVA studies of production mixes generally showed that the main sources of premix variability were mix to mix differences and within mix differences arising from demixing subsequent to premix manufacture. It was recognized that SPC is especially applicable to dealing with the first of these and subsequent efforts to implement it to premixes are described. In the case of demixing, the developments of a new premixing process is reported in which the alloy admix ingredients are bonded to the iron. The general findings of extensive studies, which show the benefits of the new process in terms of reduced variability in parts manufacturing, are reviewed and the results of a study of a FC-0208 premix are presented as an example. SPC theory and concepts are used to indicate the significance of the results and their potential applicability to the production of parts.
2. Properties of Parts Made from a Binder Treated 0.45% Phosphorus Containing Iron Powder Blend: Studies were conducted to determine the effects on property variability of parts made from a binder treated blend. The blend was a lubricated admixture of Fe3P and Ancorsteel® 1000B iron powders. The parts were cylindrical bushings having a nominal wall thickness of 0.25 inches and otherwise measuring 1.5 inches in outside diameter and 2.0 inches in height. In conducting the study, an analysis of variance design was employed to enable assessment of the relative contributions of six variance sources as follows: 1) testing; 2) microsegretation; 3) part to part for pairs pressed back to back and sintered side by side; 4) sintering within trays; 5) sintering tray to tray, and 6) macrosegregation. Relative to parts made from a companion control blend, the results of the study showed that the binder treatment was effective in reducing variability in each of the following properties: dimensional change, crush strength, hardness and average phosphorus content. The Analysis of Variance results suggested that the observed reductions were due primarily to reductions in sintering was also indicated to be a significant variance source, although in this case, it also appeared to be affected by the presence of microsegregatlon. The findings are assessed and discussed both in traditional statistical terms and in terms of Statistical Process Control. The latter terms are employed to show how the variability reductions may be translated into quality and/or economic benefits in actual parts making situations.