Introduction

POWDER METALLURGY parts can be broadly separated into three categories: those in which the P/M approach allows a lower-cost component to be produced, an intermediate category of cost-effective/high-performance parts, and those in which the P/M approach leads to a part with enhanced mechanical property characteristics (Ref 1, 2, 3). The first approach generally results in a product with lower mechanical properties than wrought product, the third is normally a higher-cost approach. The low-cost P/M product is the more traditional commercial approach, the second has been more recently established commercially, and high-performance parts represent a developing facet of P/M technology.

Many P/M parts are now used in a variety of industries, including automobiles, household appliances, yard and garden equipment, computers, fabric industry equipment, and orthodontic devices (Ref 4). The growth in North American metal powder shipments up to 1996 is shown in Table 1 (Ref 5).

Table 1 North American metal powder shipments

Shipments, tons

1992

1993

1994

1995

1996

Iron and steel

24ó,3GG

287,55G

337,85G

347,172

35G,óG3

Copper and copper base

2G,GGG

22,4GG

23,1GG

23,216

22,891

Aluminum

29,7GG

29,5GG

43,7GG

37,G44

34,179

Molybdenum

2,5GG(E)

2,5GG(E)

2,5GG(E)

2,5GG(E)

2,5GG(E)

Tungsten

1,45G

1,9GG

1,45G

1,445

1,GGG(E)

Tungsten carbide

4,5GG

5,2GG

ó,2GG

1G,84ó

11,2GG(E)

Nickel

9,900

9,600

10,000

10,476

11,600(E)

Tin

950

1,100

1,250

1,010

1,010

Total

315,300

359,750

426,050

433,709

Source: Ref 5

In 1995, North American powder metal shipments totaled 437,774 tons, a 2% increase from the previous year. Iron and steel powder shipments amounted to 347,172 tons, up 2.7% from 1994. Parts applications for iron/steel powders accounted for a record-high 312,974 tons, an increase of 3.1%. However, it was the first time in four years that the parts market improved by a percentage of less than double digits. In the 1992 to 1994 period, the parts market for North American iron and steel powder producers, the biggest market of its kind in the world, grew at an average annual rate of 18.6%.

Automotive parts continue to be the leading application of P/M parts. The typical U.S. automobile contains about 14 kg (30 lb) of P/M parts with an increase expected in the next several years (Fig. 1). A slightly lower amount is used in Japanese automobiles (Table 2) (Ref 6), but automotive application of P/M parts is still the dominant use in Japan as well (Fig. 2). The growth of P/M parts in automobiles is due to increased use of P/M components in engines, transmissions, brakes, airbags, and other complex parts. Emerging automotive applications are also described at the end of this article.

Table 2 Average weight of P/M components used in each Japanese car

Year

Cars, x103

P/M part, t

Weight

kg/car

lb/car

1980

11,175

33,923

3.03

6.68

1987

12,350

52,921

4.29

9.46

1988

12,819

60,046

4.68

10.3

1989

12,953

70,138

5.41

11.9

1990

13,592

75,459

5.55

12.2

1991

13,145

75,099

5.71

12.6

Year

Fig. 1 Growth of powder metallurgy in Ford automobiles

Fig. 2 Annual production amounts for P/M parts in Japan. Source: Ref 6
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