Die upsetting

Die-upsetting of fully dense hot compacted melt spun NdFeB powders produces axially anisotropic sheet-shaped magnets of about 300 microns thickness. The following properties were obtained //0M = 1.25 T, jUqHc = 1.33 T and (BH)mm = 290 kJ/m3 together with good mechanical integrity [138],... 

The fir.st punch and die upset the. stuck and neck-in the middle of the bar. This preiiminary upsetting and nicking of the stock is done in order to assure the proper centering and forming of an even collar which is neces.sary... 

Fig. 3.33. Hysteresis loops of mechanically alloyed resin-bonded (MM1) and compacted and hot die-upset anisotropic (MM3) NdI6Fe76B8-type magnets. The MM3 magnet was measured parallel and perpendicular to the press direction [3.80]...

Fig. 44. Schematic representation of high-temperature dies used for the hot-pressing (a) of melt-spun (over-quenched) Nd-Fe-B ribbons (A), and die upsetting (b) of the hot-pressed ribbons (B). In the final product (C) the width of the ribbons is considerably reduced.

Fig. 45. Temperature dependence of the residual magnetization (Br). intrinsic coercivity (jHc), and coercivity (fl//c) for hot-pressed (MQ2) and die-upset (MQ3) Nd0.i4(Fe091B0 09 ) 0 86. (After Lee et al.

Design Parameter Open Die Conventional Utilizing Preblocked Qosed Die Upset Precision Die... 

The coercivity of the magnets is expected to be enlarged by the fine grain sizes, and when an anisotropic HDDR powder can be prepared, the powder should have industrial cost-performance values comparable with those of anisotropic powders produced via die-upset forging and crushing (Gutfleisch and Harris 1998). 

The temperature coefficient of remanent induction for hot pressed and die-upset ribbons is -0.25%/°C (Lee et al. 1985). The temperature coeffident oi for hot pressed is —0.25%/°C and for die-upset ribbons —0.45%/°C. By aging in air at high temperatures the losses are smaller than for sintered magnets. 

Press-forging die, rolling die, upsetting die, rotary swaging die, closed-forging die, and so on... 

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