Part Classification

The Metal Powder Industries Federation has classified P/M parts according to complexity. Class I parts are the least complex, and class IV parts are the most complex. To better understand the types of commercially available P/M compacting presses, and their advantages and limitations, an understanding of P/M part classification and tooling systems used to produce parts is necessary. Part thickness and number of distinct levels perpendicular to the direction of powder pressing determine classification—not the contour of the part.

Class I parts are single-level parts that are pressed from one direction, top or bottom, and that have a slight density variation within the part in the direction of pressing (Fig. 4a). The highest part density is at the surface in contact with the moving punch, and the lowest density is at the opposite surface. Parts with a finished thickness of —7.5 mm (0.3 in.) can be produced by this method without significant density variation.

Thin bushings

Thin gears

Thin cams

Thin bushings

Thin gears

Thin cams

(a) Class I parts

(a) Class I parts

(b) Class IV parts

Links

(b) Class IV parts

Links

Fig. 4 Basic geometries of (a) MPIF class I (simple) and (b) MPIF class IV (complex) parts

Class II parts are single-level parts of any thickness pressed from both top and bottom. The lowest density region of these parts is near the center, with higher density at the top and bottom surfaces.

Class III parts have two levels, are of any thickness, and are pressed from both top and bottom. Individual punches are required for each of the levels to control powder fill and density.

Class IV parts are multilevel parts of any thickness, pressed from both top and bottom (Fig. 4b). Individual punches are required for each level to control powder fill and density.

0 0

Post a comment