Polyethylene Powder for Rotomoulding: LDPE Pellets Cut to -30 Mesh in an Air-Cooled Mill (Feder, Wedco, US 3,428,260)

Rotational moulding needs polyethylene as a fine, free-flowing powder, but grinding heats the plastic until it softens and clogs the mill. Feder's mill throws the pellets off a fast impeller into toothed cutters, while the impeller itself pumps air through to keep the particles cool. Result: low density polyethylene powder, -30 mesh, well suited to rotational moulding. Source: Feder, US 3,428,260 (Wedco, 1969), Operating Example. Picture drawn by Youblob.