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Novel liquid phase sintering process using mixed prealloyed powders
Suggestions were m a d e for changes in t h e s i n t e r i n g p r o c e s s w h i c h c o u l d lead to i m p r o v e m e n t s in quality. M A N A G E M E N T O F A PM FACILITY THROUGH APPLICATION OF A QUALITY OPERATING SYSTEM R.H. Slattery (PresMet Corp, Worcester, USA). A m e t h o d for m o n i t o r i n g a PM facility for its operating efficiency was examined. E m p h a s i s was p l a c e d on i n f o r m i n g all employees. The key indicators relating to quality a n d t h e m e a n s of publicizing d a t a were discussed w i t h reference to actions s t i m u l a t e d a n d benefits realized. GAIN SHARING AS PART O F A TOTAL QUALITY M A N A G E M E N T PLAN G.E. Meek et al (University of Akron, Ohio, USA). The i n t r o d u c t i o n of statistical process control in t h e PM i n d u s t r y was discussed. It was shown t h a t t h i s was often at t h e i n s i s t a n c e of c u s t o m e r s a n d s o m e t i m e s m e t with employee resistance which h a s o n l y b e e n p a r t i a l l y o v e r c o m e . It w a s suggested t h a t some c o m p a n i e s h a d not realized t h e i m p o r t a n c e of SPC a n d t h a t t h e r e was difficulty in i m p l e m e n t i n g t o t a l quality management systems. R e c o m m e n d a t i o n s w e r e m a d e for t h e i n t r o d u c t i o n of g a i n s h a r i n g as p a r t of a total quality m a n a g e m e n t package in order to p r o v i d e a n employee incentive. The e l e m e n t s needed to be p u t in place were outlined.
COST O F QUALITY PROGRAMME G.T. S h t u r t z ( M e t a l P o w d e r P r o d u c t s , Indianapolis, USA). The cost of quality was discussed with p a r t i c u l a r regard to t h e p r o b l e m of h o w to assess t h e cost effectiveness a n d t h e effort p u t into quality a s s u r a n c e a n d control. It was s h o w n t h a t t h e i d e n t i f i c a t i o n a n d c o n t r o l of ' q u a l i t y c o s t s ' t h r o u g h a formalized quality programme can be effective in a t t a i n i n g this objective.
TRANSFORMATION OF CUSTOMER REQUIREMENTS INTO MEASURABLE R&D OBJECTIVES D.L. Kinosz (Aluminium Co of America, Pittsburg, USA). A p r o g r a m m e for r e l a t i n g c u s t o m e r r e q u i r e m e n t s to research a n d d e v e l o p m e n t objectives, b a s e d on a quality f u n c t i o n d e p l o y m e n t model, w a s described. The model was said to allow the gathering of requirements, assigning levels of priority to these, t h e d e v e l o p m e n t of m e a s u r e s a n d rewards needed to meet t h e r e q u i r e m e n t s a n d t h e setting of targets. Objectives were e s t a b l i s h e d a n d in i m p l e m e n t a t i o n t h e p e r f o r m a n c e was analysed.
49 MPR November 1993
PM tooling materials MANUFACTURE AND USE O F M I C R O G R A I N AND SPECIAL GRADES OF CARBIDES M.D. H u n t a n d V.P. Krutz (Carbide Corp, Irwin, Pennsylvania, USA). The manufacture, p r o p e r t i e s a n d applications of WC m a t e r i a l s were discussed. M e t h o d s of t e s t i n g w e r e c o n s i d e r e d . E l e c t r o d i s p e r s i v e m a c h i n i n g of c a r b i d e s a n d corrosion properties of carbides with a r a n g e of b i n d e r s were also discussed. NEW HIGH PERFORMANCE COLD WORK STEEL FOR METAL FORMING If. Bengtsson a n d J. Worbye ( U d d e h o l m Corp, Fairfield, New Jersey, USA). A novel high p e r f o r m a n c e tool steel, Vanadis 10, was r e p o r t e d to have p o t e n t i a l for use in severe service conditions, such as s t a m p i n g a n d m e t a l forming, w h e r e t h e r e is abrasive wear. The alloy was said to have a u s e f u l c o m b i n a t i o n of t o u g h n e s s a n d h a r d n e s s / c o m p r e s s i v e s t r e n g t h a n d n o t to need high t e m p e r a t u r e h e a t t r e a t m e n t . IMPROVED PM TOOLING PERFORMANCE DUE TO USE OF PVD THIN FILMS F,J. Teeter (Balzers Tool Coating Inc, USA). The use of TiN coatings to e n h a n c e t h e p e r f o r m a n c e of cutting tool m a t e r i a l s was discussed. It was r e p o r t e d t h a t TiN coated m a t e r i a l s h a d been used in PM tooling to e x t e n d tool life a n d to aid p a r t release. The trv'D process was e x p l a i n e d a n d TiN a n d Ti(C,N) c o a t i n g s w e r e e v a l u a t e d w i t h reference to specific examples.
Liquid phase sintering NOVEL LIQUID PHASE SINTERING PROCESS USING MIXED PREALLOYED POWDERS R. T a n d o n a n d R.M. G e r m a n (Pennsylvania State University, Pennsylvania, USA). An investigation of densification a n d microstructural evolution during the s i n t e r i n g of m i x e d N i - b a s e s u p e r a l l o y powders was described. A single t h e r m a l cycle w a s s h o w n t o b r i n g a b o u t a c o m b i n a t i o n of t r a n s i e n t a n d supersolidus sintering. Effects of powder characteristics a n d process variables were studied. The results were discussed with regard to t h e sintering m e c h a n i s m s involved a n d were r e p o r t e d to lead to process optimization. The p o t e n t i a l of t h e t e c h n i q u e for p a r t p r o d u c t i o n was outlined. GRAVITY EFFECTS ON CRITICAL VOLUME FRACTION IN LIQUID PHASE SINTERING R.M. G e r m a n et al (Pennsylvania S t a t e University, Pennsylvania, USA).
It was r e p o r t e d t h a t a c o m b i n a t i o n of temperature, composition and gravity induced p h a s e s e p a r a t i o n can be used to p r e v e n t d i s t o r t i o n d u r i n g liquid p h a s e sintering. Gravity effects were studied in binary a n d t e r n a r y alloys w i t h differences in density between liquid a n d solid p h a s e s of 0-9 g m / m l a t a c o n s t a n t solid v o l u m e f r a c t i o n of 0.30. D e p e n d i n g o n d e n s i t y difference t h e solid particles settle a n d form a solid skeleton. Hot pressing, coalescence and grain packing were considered. A model, based on gravity induced contacts, sinter bond growth rate a n d r a n d o m grain packing was developed. EXPERIMENTAL DESIGN FOR LIQUID PHASE SINTERING IN MICROGRAVITY R.G. Iacocca a n d R.M. G e r m a n (Pennsylvania State University, Pennsylvania, USA). It was r e p o r t e d t h a t t h e s p a c e s h u t t l e will be used to carry out liquid p h a s e s i n t e r i n g e x p e r i m e n t s on W-Ni-Fe alloys in m i c r o g r a v i t y c o n d i t i o n s . T h e ground based experiments, based on five alloy compositions and three sintering cycles were described a n d t h e microgravity experiments outlined. I n f o r m a t i o n c o n c e r n i n g t h e p l a n n i n g of the space shuttle experiments was presented.
Tribology WEAR MAP PRODUCTION FOR PM MATERIALS AND WEAR TRANSITIONS N. Trilk a n d P. I~eldsteen (Brunel University, Uxbridge, UIQ. The t r a n s i t i o n between mild a n d severe w e a r regimes was discussed w i t h regard to w e a r r a t e s . It w a s s u g g e s t e d t h a t a t r a n s i t i o n in t h e mild wear region m a y be significant a n d w e a r in a s i n t e r e d Fe was i n v e s t i g a t e d . F a i l u r e w a s f o u n d to b e caused by plastic d e f o r m a t i o n even t h o u g h t h e mild/severe w e a r t r a n s i t i o n was not exceeded. The p h e n o m e n o n was discussed w i t h reference to wear m a p s a n d use of t h e d a t a by design engineers. PRODUCTION AND WEAR PROPERTIES OF PM MATERIALS WITH OR WITHOUT ADDITION OF AN AIR HARDENING HARD PHASE P.D. N u r t h e n et al (Powdrex Ltd, Tonbridge, UK). Investigations of a r a n g e of PM m a t e r i a l s c o n t a i n i n g a d d i t i o n s of a i r h a r d e n i n g h a r d powders were described. Effects of sintering conditions a n d h e a t t r e a t m e n t on h a r d n e s s a n d abrasive wear p r o p e r t i e s were studied. It was r e p o r t e d t h a t a range of h a r d n e s s e s were o b t a i n e d d e p e n d i n g on cooling rate, composition and heat t r e a t m e n t . T h e p r e s e n c e of t h e h a r d particles was shown to increase abrasive wear resistance.
COST O F QUALITY PROGRAMME G.T. S h t u r t z ( M e t a l P o w d e r P r o d u c t s , Indianapolis, USA). The cost of quality was discussed with p a r t i c u l a r regard to t h e p r o b l e m of h o w to assess t h e cost effectiveness a n d t h e effort p u t into quality a s s u r a n c e a n d control. It was s h o w n t h a t t h e i d e n t i f i c a t i o n a n d c o n t r o l of ' q u a l i t y c o s t s ' t h r o u g h a formalized quality programme can be effective in a t t a i n i n g this objective.
TRANSFORMATION OF CUSTOMER REQUIREMENTS INTO MEASURABLE R&D OBJECTIVES D.L. Kinosz (Aluminium Co of America, Pittsburg, USA). A p r o g r a m m e for r e l a t i n g c u s t o m e r r e q u i r e m e n t s to research a n d d e v e l o p m e n t objectives, b a s e d on a quality f u n c t i o n d e p l o y m e n t model, w a s described. The model was said to allow the gathering of requirements, assigning levels of priority to these, t h e d e v e l o p m e n t of m e a s u r e s a n d rewards needed to meet t h e r e q u i r e m e n t s a n d t h e setting of targets. Objectives were e s t a b l i s h e d a n d in i m p l e m e n t a t i o n t h e p e r f o r m a n c e was analysed.
49 MPR November 1993
PM tooling materials MANUFACTURE AND USE O F M I C R O G R A I N AND SPECIAL GRADES OF CARBIDES M.D. H u n t a n d V.P. Krutz (Carbide Corp, Irwin, Pennsylvania, USA). The manufacture, p r o p e r t i e s a n d applications of WC m a t e r i a l s were discussed. M e t h o d s of t e s t i n g w e r e c o n s i d e r e d . E l e c t r o d i s p e r s i v e m a c h i n i n g of c a r b i d e s a n d corrosion properties of carbides with a r a n g e of b i n d e r s were also discussed. NEW HIGH PERFORMANCE COLD WORK STEEL FOR METAL FORMING If. Bengtsson a n d J. Worbye ( U d d e h o l m Corp, Fairfield, New Jersey, USA). A novel high p e r f o r m a n c e tool steel, Vanadis 10, was r e p o r t e d to have p o t e n t i a l for use in severe service conditions, such as s t a m p i n g a n d m e t a l forming, w h e r e t h e r e is abrasive wear. The alloy was said to have a u s e f u l c o m b i n a t i o n of t o u g h n e s s a n d h a r d n e s s / c o m p r e s s i v e s t r e n g t h a n d n o t to need high t e m p e r a t u r e h e a t t r e a t m e n t . IMPROVED PM TOOLING PERFORMANCE DUE TO USE OF PVD THIN FILMS F,J. Teeter (Balzers Tool Coating Inc, USA). The use of TiN coatings to e n h a n c e t h e p e r f o r m a n c e of cutting tool m a t e r i a l s was discussed. It was r e p o r t e d t h a t TiN coated m a t e r i a l s h a d been used in PM tooling to e x t e n d tool life a n d to aid p a r t release. The trv'D process was e x p l a i n e d a n d TiN a n d Ti(C,N) c o a t i n g s w e r e e v a l u a t e d w i t h reference to specific examples.
Liquid phase sintering NOVEL LIQUID PHASE SINTERING PROCESS USING MIXED PREALLOYED POWDERS R. T a n d o n a n d R.M. G e r m a n (Pennsylvania State University, Pennsylvania, USA). An investigation of densification a n d microstructural evolution during the s i n t e r i n g of m i x e d N i - b a s e s u p e r a l l o y powders was described. A single t h e r m a l cycle w a s s h o w n t o b r i n g a b o u t a c o m b i n a t i o n of t r a n s i e n t a n d supersolidus sintering. Effects of powder characteristics a n d process variables were studied. The results were discussed with regard to t h e sintering m e c h a n i s m s involved a n d were r e p o r t e d to lead to process optimization. The p o t e n t i a l of t h e t e c h n i q u e for p a r t p r o d u c t i o n was outlined. GRAVITY EFFECTS ON CRITICAL VOLUME FRACTION IN LIQUID PHASE SINTERING R.M. G e r m a n et al (Pennsylvania S t a t e University, Pennsylvania, USA).
It was r e p o r t e d t h a t a c o m b i n a t i o n of temperature, composition and gravity induced p h a s e s e p a r a t i o n can be used to p r e v e n t d i s t o r t i o n d u r i n g liquid p h a s e sintering. Gravity effects were studied in binary a n d t e r n a r y alloys w i t h differences in density between liquid a n d solid p h a s e s of 0-9 g m / m l a t a c o n s t a n t solid v o l u m e f r a c t i o n of 0.30. D e p e n d i n g o n d e n s i t y difference t h e solid particles settle a n d form a solid skeleton. Hot pressing, coalescence and grain packing were considered. A model, based on gravity induced contacts, sinter bond growth rate a n d r a n d o m grain packing was developed. EXPERIMENTAL DESIGN FOR LIQUID PHASE SINTERING IN MICROGRAVITY R.G. Iacocca a n d R.M. G e r m a n (Pennsylvania State University, Pennsylvania, USA). It was r e p o r t e d t h a t t h e s p a c e s h u t t l e will be used to carry out liquid p h a s e s i n t e r i n g e x p e r i m e n t s on W-Ni-Fe alloys in m i c r o g r a v i t y c o n d i t i o n s . T h e ground based experiments, based on five alloy compositions and three sintering cycles were described a n d t h e microgravity experiments outlined. I n f o r m a t i o n c o n c e r n i n g t h e p l a n n i n g of the space shuttle experiments was presented.
Tribology WEAR MAP PRODUCTION FOR PM MATERIALS AND WEAR TRANSITIONS N. Trilk a n d P. I~eldsteen (Brunel University, Uxbridge, UIQ. The t r a n s i t i o n between mild a n d severe w e a r regimes was discussed w i t h regard to w e a r r a t e s . It w a s s u g g e s t e d t h a t a t r a n s i t i o n in t h e mild wear region m a y be significant a n d w e a r in a s i n t e r e d Fe was i n v e s t i g a t e d . F a i l u r e w a s f o u n d to b e caused by plastic d e f o r m a t i o n even t h o u g h t h e mild/severe w e a r t r a n s i t i o n was not exceeded. The p h e n o m e n o n was discussed w i t h reference to wear m a p s a n d use of t h e d a t a by design engineers. PRODUCTION AND WEAR PROPERTIES OF PM MATERIALS WITH OR WITHOUT ADDITION OF AN AIR HARDENING HARD PHASE P.D. N u r t h e n et al (Powdrex Ltd, Tonbridge, UK). Investigations of a r a n g e of PM m a t e r i a l s c o n t a i n i n g a d d i t i o n s of a i r h a r d e n i n g h a r d powders were described. Effects of sintering conditions a n d h e a t t r e a t m e n t on h a r d n e s s a n d abrasive wear p r o p e r t i e s were studied. It was r e p o r t e d t h a t a range of h a r d n e s s e s were o b t a i n e d d e p e n d i n g on cooling rate, composition and heat t r e a t m e n t . T h e p r e s e n c e of t h e h a r d particles was shown to increase abrasive wear resistance.