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Methods of preventing cracks in PM compacts
selection criteria to be established. Ability of PM to attain properties not available by other means and use of sinter hardening were noted. When all available data and factors are considered good sintered materials can be designed and parts manufactured. APPLICATIONS OF HIGH PERFORMANCE MATERIALS AND PROCESSES
R.J.Causton et al. (Hoeganaes Corp, Riverton, USA.) A review of recent developments in materials for highly stressed applications was presented with particular note of alloys with high as-sintered hardness. Effects of alloy composition and cooling rates on properties were discussed. DYNAMIC PROPERTIES
OF GEARS
R.Steranko et al. (Engineered Sintered Components, USA.) Standard parts, notably gears, made from PM steels, were discussed. A study of gears, made from commercially available powders, with additions of Ni, MO and Cu, with the objective of optimizing dynamic performance, was described. Effects of density, C content, sintering and heat treatment temperatures were evaluated. Structures were investigated by optical and electron microscopy.
Crack detection prevention
and
FACTORS AFFECTING CRACKLNG OF MULTI-LEVEL PARTS DURING EJECTION
R.F.Unkel. (Cincinnati Inc, USA.) Cracking of parts during ejection was noted and factors contributing to this were identified as expansion of parts, ejection sequence in multi-level parts and tool deflection. How each factor produces cracks was reviewed. Recommendations were made for avoidance of cracking during ejection. METHODS OF PREVENTING IN PM COMPACTS
CRACKS
G.Wallis. (Dorst America Inc, USA.) Methods of preventing cracking of PM parts, calculation of tool deflections, prediction, control and measurement of tool movements and programming of tool movements, to compenste for springback cracking, were discussed. APPLICATION OF DIE WALL LUBRICATION AND RESONANCE TESTS TECHNOLOGIES
P.Bowen, R.Nash. (Quasar International Inc, USA.)
Detection of discontinuities in parts was shown to depend on response of undamped natural frequencies to attain sensitivity and discrimination in certain resonant modes. Presence of lubricant was also shown to cause damping. The potential for detection of defective parts was assessed with consideration of reduced admixed lubricant levels and use of die wall lubrication with resonant testing to detect defects in the green state. The hypothesis that reduced lubricant levels give a more ‘metallic’ response in testing was examined.
Computer modelling powder consolidation
PLASMA SPRAYING OF IRON ALUMINIDE FOIL
VSikka et al. (Oak Ridge National Laboratory, USA.) Use of plasma spraying to make Fe aluminide foils was reported. Effects of spray parameters, substrate dimensions and surface roughness on film thickness were investigated. Foils were rolled and properties determined. Rolled foils were shown to have good strength and ductility at ambient temperature and were compared with foils made by other means. Effects of spray conditions on structures were discussed.
of
A COMPLETE DIE COMPACTION SOFTWARE PACKAGE -PCS ELITE
K.E.Carr, E.S.Bono. (Concurrent Technologies Corp, USA.) PCS Elite software package for Windows was described. The program is a finite element analysis of die compaction and has 3 components: computer aided design for part and tooling, assignment of material and process conditions, and calculation and graphical presentation of results. Use for a multilevel part was demonstrated giving results for density distribution, tooling loads and part dimensions. Predicted and measured results were reported to agree within 2%. COMPUTER AIDED TOOL DESIGN WITH DEFLECTION ANALYSIS
M.Kim, D.Apelian. (Worcester Polytechnic Inst., USA.) It was reported that a computer aided tool design system had been developed. Design optimization was possible prior to tool fabrication. The software generates tool elements from a drawing of a part and can readily be updated. Finite element analysis is used to calculate tool deflections since these must lie within defined limits. The system was described and its usefulness demonstrated.
A MICRO-ENCAPSULATED POWDER APPROACH FOR ADVANCED MATERIALS
A.Bose et al. (Powdermet Inc, USA.) Use ofPM methods to make two-phase composite materials was discussed. It was shown that micro-encapsulated powders provide flexibility in that almost any powder can be coated with another material, giving beneficial and often unique properties. Benefits of using micro-encapsulated powders, coated by chemical vapour deposition, were illustrated.
Direct
fabrication
LASER ENGINEERED NET SHAPING OF INTERFACES IN FUNCTIONAL MULTI-ELEMENT MATERIALS
J.A.Romero et al. (Sandia National Laboratories, USA.) Recent developments in laser engineered net shaping were described. In particular the use of the technique to incorporate interfaces between separate elements of a part, to provide electrical isolation, was discussed. For this deposition of liquified particles may be needed. Mixing of materials and process conditions were examined. A model to describe melting of particles in the laser beam was suggested. Critical process variables, to ensure good properties, were identified. Structures and properties were determined and evaluated.
Deposition DEVELOPMENT OF NEAR NET SHAPE REFRACTORY METAL PARTS BY VACUUM PLASMA SPRAYING
C.A.Power et al. (Plasma Processes Inc, USA.) Increased use of refractory metal parts in aerospace applications was noted, including parts for furnaces to be used in microgravity. It was reported that vacuum plasma spray techniques had been used to make near net shape components in refractory metals including W, Re and MO. Processing and results were discussed.
SOLID FREEFORM FABRICATION OF METAL COMPONENTS USING INJECTION MOULDING TECHNIQUES MKunstner et al. (Fraunhofer Inst. for Applied Materials Research, Germany.) Use of Multiphase Jet Solidification in fabrication of parts was described. The system used feedstocks used in injection moulding, such as stainless steel, tool steel and Ti, which are extruded through a translatable nozzle. Parts are built up layer by layer, under computer control. The need for expensive tooling is eliminated. The part is then treated as an injection moulded part, debound and
MPR February 1999 39
R.J.Causton et al. (Hoeganaes Corp, Riverton, USA.) A review of recent developments in materials for highly stressed applications was presented with particular note of alloys with high as-sintered hardness. Effects of alloy composition and cooling rates on properties were discussed. DYNAMIC PROPERTIES
OF GEARS
R.Steranko et al. (Engineered Sintered Components, USA.) Standard parts, notably gears, made from PM steels, were discussed. A study of gears, made from commercially available powders, with additions of Ni, MO and Cu, with the objective of optimizing dynamic performance, was described. Effects of density, C content, sintering and heat treatment temperatures were evaluated. Structures were investigated by optical and electron microscopy.
Crack detection prevention
and
FACTORS AFFECTING CRACKLNG OF MULTI-LEVEL PARTS DURING EJECTION
R.F.Unkel. (Cincinnati Inc, USA.) Cracking of parts during ejection was noted and factors contributing to this were identified as expansion of parts, ejection sequence in multi-level parts and tool deflection. How each factor produces cracks was reviewed. Recommendations were made for avoidance of cracking during ejection. METHODS OF PREVENTING IN PM COMPACTS
CRACKS
G.Wallis. (Dorst America Inc, USA.) Methods of preventing cracking of PM parts, calculation of tool deflections, prediction, control and measurement of tool movements and programming of tool movements, to compenste for springback cracking, were discussed. APPLICATION OF DIE WALL LUBRICATION AND RESONANCE TESTS TECHNOLOGIES
P.Bowen, R.Nash. (Quasar International Inc, USA.)
Detection of discontinuities in parts was shown to depend on response of undamped natural frequencies to attain sensitivity and discrimination in certain resonant modes. Presence of lubricant was also shown to cause damping. The potential for detection of defective parts was assessed with consideration of reduced admixed lubricant levels and use of die wall lubrication with resonant testing to detect defects in the green state. The hypothesis that reduced lubricant levels give a more ‘metallic’ response in testing was examined.
Computer modelling powder consolidation
PLASMA SPRAYING OF IRON ALUMINIDE FOIL
VSikka et al. (Oak Ridge National Laboratory, USA.) Use of plasma spraying to make Fe aluminide foils was reported. Effects of spray parameters, substrate dimensions and surface roughness on film thickness were investigated. Foils were rolled and properties determined. Rolled foils were shown to have good strength and ductility at ambient temperature and were compared with foils made by other means. Effects of spray conditions on structures were discussed.
of
A COMPLETE DIE COMPACTION SOFTWARE PACKAGE -PCS ELITE
K.E.Carr, E.S.Bono. (Concurrent Technologies Corp, USA.) PCS Elite software package for Windows was described. The program is a finite element analysis of die compaction and has 3 components: computer aided design for part and tooling, assignment of material and process conditions, and calculation and graphical presentation of results. Use for a multilevel part was demonstrated giving results for density distribution, tooling loads and part dimensions. Predicted and measured results were reported to agree within 2%. COMPUTER AIDED TOOL DESIGN WITH DEFLECTION ANALYSIS
M.Kim, D.Apelian. (Worcester Polytechnic Inst., USA.) It was reported that a computer aided tool design system had been developed. Design optimization was possible prior to tool fabrication. The software generates tool elements from a drawing of a part and can readily be updated. Finite element analysis is used to calculate tool deflections since these must lie within defined limits. The system was described and its usefulness demonstrated.
A MICRO-ENCAPSULATED POWDER APPROACH FOR ADVANCED MATERIALS
A.Bose et al. (Powdermet Inc, USA.) Use ofPM methods to make two-phase composite materials was discussed. It was shown that micro-encapsulated powders provide flexibility in that almost any powder can be coated with another material, giving beneficial and often unique properties. Benefits of using micro-encapsulated powders, coated by chemical vapour deposition, were illustrated.
Direct
fabrication
LASER ENGINEERED NET SHAPING OF INTERFACES IN FUNCTIONAL MULTI-ELEMENT MATERIALS
J.A.Romero et al. (Sandia National Laboratories, USA.) Recent developments in laser engineered net shaping were described. In particular the use of the technique to incorporate interfaces between separate elements of a part, to provide electrical isolation, was discussed. For this deposition of liquified particles may be needed. Mixing of materials and process conditions were examined. A model to describe melting of particles in the laser beam was suggested. Critical process variables, to ensure good properties, were identified. Structures and properties were determined and evaluated.
Deposition DEVELOPMENT OF NEAR NET SHAPE REFRACTORY METAL PARTS BY VACUUM PLASMA SPRAYING
C.A.Power et al. (Plasma Processes Inc, USA.) Increased use of refractory metal parts in aerospace applications was noted, including parts for furnaces to be used in microgravity. It was reported that vacuum plasma spray techniques had been used to make near net shape components in refractory metals including W, Re and MO. Processing and results were discussed.
SOLID FREEFORM FABRICATION OF METAL COMPONENTS USING INJECTION MOULDING TECHNIQUES MKunstner et al. (Fraunhofer Inst. for Applied Materials Research, Germany.) Use of Multiphase Jet Solidification in fabrication of parts was described. The system used feedstocks used in injection moulding, such as stainless steel, tool steel and Ti, which are extruded through a translatable nozzle. Parts are built up layer by layer, under computer control. The need for expensive tooling is eliminated. The part is then treated as an injection moulded part, debound and
MPR February 1999 39